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                                                                Radiation Physics and Chemistry 79 (2010) 490–494



                                                            Contents lists available at ScienceDirect


                                                  Radiation Physics and Chemistry
                                              journal homepage: www.elsevier.com/locate/radphyschem




Radiation processing and functional properties of soybean (Glycine max)
Mrinal Pednekar a,n, Amit K. Das b, Rajalakshmi Va, Arun Sharma a
a
    Food Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, Maharashtra, India
b
    Department of Food Engineering, CFTRI, Mysore 570020, Karnataka, India




a r t i c l e in f o                                   a b s t r a c t

Article history:                                       Effect of radiation processing (10, 20 and 30 kGy) on soybean for better utilization was studied.
Received 25 June 2009                                  Radiation processing reduced the cooking time of soybean and increased the oil absorption capacity of
Accepted 28 October 2009                               soy flour without affecting its proximate composition. Irradiation improved the functional properties
                                                       like solubility, emulsification activity and foam stability of soybean protein isolate. The value addition
Keywords:                                              effect of radiation processing has been discussed for the products (soy milk, tofu and tofu fortified
Radiation processing                                   patties) prepared from soybean.
Soybean                                                                                                                      & 2009 Published by Elsevier Ltd.
Tofu
Soya protein
Functional properties




1. Introduction                                                                              Radiation processing is an ecofriendly technology utilized for
                                                                                         nutritional safety and security. It can be used for value addition
    In most developing countries, per capita consumption of                              such as elimination of flatulence factors (Machaiah et al., 1999;
protein is below the recommended level resulting in widespread                           Machaiah and Pednekar, 2002), increase in starch and protein
protein calorie malnutrition. Soybeans with 40% protein and 20%                          depolymerization (Sharif and Farkas, 1993; Nene et al., 1975) and
oil have a great potential of solving the problem of protein calorie                     extractability.
malnutrition. Soy protein efficiently supplements cereal grain                                We have conducted studies to evaluate the effects of radiation
protein, because it corrects the lysine deficiency of cereals. In                         processing on functional properties like cooking time and the
some cases, for example in corn, it also corrects tryptophan                             yield of soy milk and tofu. Potato patties prepared from tofu
deficiency. Because of its quality, soybean protein can replace                           incorporation indicated good acceptability. Functional properties
animal protein without a significant decrease in nutritive value                          like solubility, foaming, emulsification capacity and gelling of
(Tripathi and Misra, 2005). In fact, soy protein has an advantage                        protein extracted from soybean were also evaluated.
over animal protein as it does not raise the serum cholesterol
values (Fukushima, 2001) and hence, is useful for people suffering
from cardiovascular disorder (De Kleijn et al., 2002). Soybean also                      2. Materials and Methods
has a number of phytochemicals found to be effective in fighting
osteoporosis (Anderson and Garner, 1997), obesity, cancer                                2.1. Irradiation
(Messina, 1999) and postmenopausal problems (Albertazzi et al.,
1998). Soy milk is used in cases of lactose intolerance. However,                            Soybean was purchased from a local market, cleaned and
soybean has a long cooking time, beany flavor, antinutritional                            irradiated at 10, 20 and 30 kGy. Irradiation was carried out in a
factors like raffinose family oligosaccharides and protease                               Gamma Cell-5000 loaded with Co60(Board of Radiation and Isotope,
inhibitors (Liener, 1994). Hence, processing of soybean is essential                     Mumbai, India) at an effective dose rate of 152.3 Gy/min. Dose rate
for better utilization. Most native proteins do not show desirable                       was determined using standard Fricke dosimetry (Sehsted, 1970).
functional properties and modifications for improving the nutri-                          Calibration was done by keeping the dosimeter vials in the
tional value and/or functional properties like protein solubility,                       irradiation chamber at different positions. Dosimeters were
foaming and gelling need to be induced (Chove et al., 2001). Such                        analyzed using a UV spectrophotometer. 9% variation in the dose
modifications imply changes in both protein structure and                                 distribution was recorded.
conformation at different levels by changing molecular composi-
tion or size.                                                                            2.2. Soybean flour

    n
        Corresponding author. Tel.: + 91 22 25595375.                                       Whole soybean seeds were pulverized into fine flour (710 mm)
        E-mail address: mrinal1854@yahoo.co.in (M. Pednekar).                            with a mixer grinder and stored in self sealable polyethylene bags.

0969-806X/$ - see front matter & 2009 Published by Elsevier Ltd.
doi:10.1016/j.radphyschem.2009.10.009
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                                          M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494                               491


2.3. Proximate analysis                                                        different sections of the Food Technology Division, BARC. The
                                                                               panelists belonged to age group of 25–55. The hedonic scale used
   Proximate analysis was carried out by standard AOAC methods                 was as follows:
(AOAC, 2007) for all samples including control after storing at                    7=like very much (LVM), 6= like moderately (LM), 5 =like
room temperature for 15 days. Lipid content of soy milk was                    slightly (LS),
determined by the Folch method (Folch et al., 1957).                               4=neither like nor dislike (NLND), 3= dislike slightly (DS),
                                                                               2= dislike moderately (DM),
2.4. Determination of water and oil absorption capacity                            1=dislike very much (DVM).


   For water and oil absorption capacities of soy flour the method              2.10. Preparation of soy protein isolate (SPI)
of Sathe et al., (1982) was followed. Soy flour (1 g) was mixed
with 10 mL of distilled water or 10 mL of edible oil and vortexed.                Soybean protein isolate was prepared by the isoelectric point
The samples were then allowed to stand at room temperature                     precipitation method. A modified method of Sathe et al. (1982) was
(21 1C) for 30 min, and centrifuged at 5000 rpm for 30 min.                    used to extract protein from the defatted soybean. Finely ground soy
The volume of the supernatant was measured in a 10 mL                          flour was defatted with petroleum ether (1:20, W/V). Defatted
graduated cylinder.                                                            soy flour was treated with 0.2% NaOH for 24 h (1:5, W/V). After
   Calculation:                                                                centrifuging (10,000 rpm, 30 min), the residue was re-extracted
   Water Absorption Capacity (g/g)=(Initial volume of the waterÀ               with 0.2% NaOH and again centrifuged. Protein from both the pooled
Final volume of water)                                                         supernatants was precipitated by adjusting the pH to 4 with 1 N HCl.
   Oil Absorption Capacity (g/g)=(Initial volume of the oil–Final              The precipitate was dissolved in a minimum amount of 0.2% NaOH.
volume of oil) Â 0.91n                                                         This protein solution was dialyzed against distilled water for 72 h
   (n = specific gravity of the oil used)                                       and freeze-dried.


2.5. Cooking time                                                              2.11. Protein solubility


   Overnight soaked seeds (control and irradiated) were pressure                  Protein solubility of SPI was studied from pH 1–12. The sample
cooked for 2, 4, 6, 8 and 10 min (after first pressure release).These           (100 mg) was dissolved in distilled water and pH was adjusted to
seeds were then allowed to cool at room temperature. The degree                the required value using 0.1 N HCl or NaOH. The volume was
of softness of the seeds was then measured using Texture                       made up to 20 mL. The protein solution was centrifuged at
Analyzer (TA.XT Plus, Stable Micro System, Surrey, U.K.).                      8000 rpm for 15 min. The protein in the supernatant was
                                                                               estimated using the Kjeldahl method.

2.6. Preparation of soy milk
                                                                               2.12. Determination of gelling capacity

   Soybean seeds (100 g) were soaked for 16 h in 300 mL water.
                                                                                  Gelling was studied using a modified method of Sathe et al.
Excess water was decanted off and 80 mL fresh water was added
                                                                               (1982). SPI was dissolved in different concentrations of 10%, 12%,
and seeds were pressure cooked for 10 min after first pressure
                                                                               14% and 16% in phosphate buffer (pH 7.6) and 20% sugar solution.
release. The cooked seeds were blended in the grinder by adding
                                                                               3 mL of the solution was dispensed in tubes and heated at 80 1C
300 mL of water. Further this homogenate was filtered through
                                                                               in a water bath for 30 min. The tubes were cooled rapidly by
muslin cloth, while filtering 600 mL of water was added. The
                                                                               keeping in cold water and kept refrigerated overnight. Gel
filtrate was heated in a boiling water bath for 15 min.
                                                                               formation was observed by tilting the tubes and observing the
                                                                               flow of the solution.
2.7. Preparation of tofu
                                                                               2.13. Foaming properties
   Tofu was prepared by a modified method of Nong Sun and
Breene (1991). Calcium sulfate (0.2 M) was added to warm soy
                                                                                   Whip ability and foam stability were studied according to the
milk in 1:10 ratio and was heated at 70 1C for 10 min for
                                                                               method of Coffman and Garcia (1977) with slight modification. SPI
coagulation to occur. The coagulated curd was separated using
                                                                               (500 mg) was solubilized in 25 mL distilled water and pH was
cheese cloth and the collected mass (tofu) was weighed.
                                                                               adjusted to 7.0. The solution was whipped in a homogenizer
                                                                               (Polytron PT 2100, Kinematica, Switzerland) for 3 min at 10,000 rpm
2.8. Preparation of tofu–potato patties                                        and poured into a 50 mL measuring cylinder. The total and drainage
                                                                               volume were noted at 0, 1, 30 min, 1, 2, and 24 h intervals.
   Potatoes (500 g) were cooked in a pressure cooker and mashed                    Whip ability and foam stability were calculated by the
with pre-moistened bread slices (4 slices each weighing 22 g).                 following formula:
This preparation (100 g) was mixed with tofu (15 g). This was                      Whip ability= (Total volume–Drainage volume)/Initial volume
molded desirably and a layer of semolina was applied to the                        Foam stability= (Initial volume–Drainage volume)/Initial
surface. This was then shallow fried with vegetable oil to a golden            volume  100
brown colour.
                                                                               2.14. Emulsification
2.9. Sensory evaluation of tofu–potato patties
                                                                                  Emulsification was carried out according to the method of
    Sensory evaluation of the tofu–potato patties was carried out              Bandyopadhyay and Ghosh (2002). 3 mL of 0.2% SPI solution at pH
using a 7-point hedonic scale ranging from ‘like very much’ to                 7 was homogenized with 1, 2 and 3 mL of peanut oil at
‘dislike very much’, with ‘neither like nor dislike’ as the midpoint           12,000 rpm. 100 ml of emulsion was added to 4900 ml of 0.1%
(ASTM, 1996). The taste panel consisted of 50 members from                     SDS and absorbance was read at 500 nm.
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Table 1
Proximate qualities of soybean.

 Sample                   Protein %                   Lipid %                         Moisture%                        Ash %                          Carbohydrates%

 Control                  36.5357 1.704               22.7007 0.582                   7.355 7 0.077                    0.787 70.033                   32.6237 0.293
 10 kGy                   37.590 7 1.730              22.22570.523                    7.345 7 0.190                    0.827 70.009                   32.013 70.489
 20 kGy                   36.103 7 1.595              21.6007 1.015                   6.475 7 2.27                     0.826 70.139                   34.9967 0.528
 30 kGy                   36.65 7 0.826               23.0507 0.825                   7.22 70.155                      0.733 70.094                   32.3477 0.386


The values presented are mean 7S.D. computed from 6 replicates.



2.15. Statistical analysis                                                         Table 2
                                                                                   Texturo-metric analysis of cooked soybean.

   All values are expressed as means and standard deviation of 6                                  Force (Kg)a
replicates with the exception of sensory evaluation. The results
are the mean and standard deviations of the observed values.                                      Control          10 kGy             20 kGy            30 kGy
Differences were considered significant at po0.05 after perform-
                                                                                     2 min        6.047 7 1.252    3.834 7 0.581      2.4487 1.282      2.505 7 0.781
ing students’t’ test.
                                                                                     4 min        6.646 7 1.923    3.3327 0.960       3.1977 0.964      2.038 7 0.364
                                                                                     6 min        7.140 7 0.764    3.323 7 1.538      3.6527 0.977      1.3117 0.551
                                                                                     8 min        4.581 7 0.942    1.7197 0.726       2.7617 0.133      1.5247 0.658
                                                                                     10 min       4.064 7 0.526    2.028 7 0.987      2.613 7 1.174     1.1577 0.748
3. Results and discussion
                                                                                       a
                                                                                           S.D. computed from 6 replicates.
3.1. Proximate analysis of soy flour

   Proximate analysis of control and irradiated (10, 20 and
                                                                                   3.4. Qualitative analysis of soy milk
30 kGy) soy flour was carried out and the results obtained are
presented in Table 1. It is evident from the table that there was no
                                                                                      It was evident from the data that the protein concentration in
significant effect of radiation processing on the macronutrient
                                                                                   soy milk from irradiated seeds nearly doubled (0.58270.08 in
content of the soybean.
                                                                                   control soy milk to 1.04470.1 in 30 kGy treated soy milk).
                                                                                   This can be correlated to better extractability of proteins
3.2. Oil and water absorption capacity                                             from irradiated seeds. Similar results were reported by Byun
                                                                                   and Kang (1994).
   Oil and water absorption capacity of flours prepared from
control and radiation processed seeds was found to be within the                   3.5. Preparation of tofu
range observed with various legume flours (Adebowale and
Lawal, 2004). Variation in the presence of polar and non-polar                         The results indicated that irradiation increased the yield of
side chains among flour which bind to water or hydrocarbon side                     tofu from 5.27% in control to 11.36% in 30 kGy treated samples.
chains of oil possibly make the difference in water or oil-binding                 The yield increased as the dose increased. This can be correlated
capacity of flours. The data showed a non significant increase                       to the higher concentration of protein in the milk from irradiated
in water absorption capacity due to radiation processing                           samples. Byun et al., (1993) have observed a similar pattern.
(2.5770.082 in control to 3.0870.075 in 30 kGy treated
samples). Water absorption capacity is important functional
                                                                                   3.6. Sensory evaluation
property for flours as they swell and impart characteristics like
body thickness and viscosity. Radiation processing also led to
                                                                                       The data of the sensory analysis was analyzed and responses
increase in oil absorption capacity of soy flours (1.587 0.16 in
                                                                                   (%) were plotted against hedonic ratings. As seen in Fig. 1, tofu–
control to 1.97 70.18 in 30 kGy samples). Rahma and Mustafa
                                                                                   potato patties, a tertiary product from soybean irradiated at
(1988) have reported similar observations with irradiation
                                                                                   20 kGy dose has scored maximum (40%) as ‘Like very much’,
of peanut flours. Dissociation and denaturation results in the fat
                                                                                   whereas 55% of the panel members rated the same as ‘Like
and water absorption of treated proteins compared to native
                                                                                   moderately’. It is also noteworthy that products from soybean
proteins (Siddharaju et al., 2002). Radiation processing may
                                                                                   irradiated with other doses (10 and 30 kGy) scored more than the
have resulted in protein unfolding leading to exposure of certain
                                                                                   product prepared from control tofu which showed the lowest
buried functional groups resulting in increased oil absorption
                                                                                   scores among all. This can be attributed to the fact that soybean
capacity.
                                                                                   has a typical beany flavor and taste which are also expected to be
                                                                                   present in its secondary (control tofu) as well as tertiary (tofu–
3.3. Determination of cooking time of soybean                                      potato patties) products. Irradiation may have caused reduction of
                                                                                   the beany flavor, as the scores for the products prepared from
    Cooking time is a significant characteristic of legumes. It is the              irradiated soybean were always higher than those for the control
time of boiling during which the legumes attain desirable softness                 soybean.
wherein at least 90% of the seeds are soft enough to masticate.
Our results indicated a dose-dependent decrease in cooking time                    3.7. Functional properties of soy protein isolate
of irradiated beans (Table 2). There was 30% decrease in cooking
time at 10 kGy which decreased to 60% at 30 kGy. The observed                      3.7.1. Protein solubility
reduction in cooking time of irradiated soybean is consistent with                    The solubility profiles of SPI in water at different pH values are
reports of other workers (Rao and Vakil, 1985; Byun et al., 1993).                 presented in Fig. 2. At pH 4 and 5, which encompasses the
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                                                                     M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494                                                  493



                                 Product A         Product D                                                           700                         Control
                                 Product B         Product E
                                                                                                                       600                         10kGy
                                 Product C
                  100                                                                                                  500                         20kGy




                                                                                                           EAI value
                                                                                                                                                   30kGy
                   80                                                                                                  400
% Acceptability




                                                                                                                       300
                   60
                                                                                                                       200
                   40
                                                                                                                       100

                   20                                                                                                    0
                                                                                                                             0min      5min        0min         5min        0min         5min
                    0
                                                                                                                                1 ml oil                2 ml oil                  3 ml oil
                             e




                                                            ste


                                                                         te



                                                                                     e


                                                                                                y
                                       r


                                                  ur
                                   ou
                            nc




                                                                                   ur


                                                                                               lit
                                                                       as
                                               do


                                                          Ta




                                                                                  xt


                                                                                           bi
                                    l
                          ra




                                                                    rT
                                 Co


                                              O




                                                                                Te


                                                                                          ta
                        ea




                                                                 fte




                                                                                          ep
                   pp




                                                                                                                               Fig. 3. Emulsifying activity index (EAI) of SPI.
                                                                                        cc
                                                                A
                  A




                                                                                       A
                                                                                     ll
                                                                                   ra
                                                                                 ve
                                                                                O




                                                          Attributes                                      hydrophilic groups which increase the interactions of
                                                                                                          hydrophilic amino acids with water molecules. Protein from the
Fig. 1. Sensory evaluation of Tofu fortified potato patties. A–Control Product                             20 kGy treated sample showed a slightly different pattern. It
(without Tofu); B–Control Tofu (mixed with Tofu obtained from un irradiated
Soya); C–Mixed with Tofu obtained from Soybean irradiated with 10 kGy dose;
                                                                                                          showed the least solubility up to pH 3, but then increased after
D–Mixed with Tofu obtained from Soybean irradiated with 20 kGy dose; E–Mixed                              isoelectric point showing higher solubility than the control in the
with Tofu obtained from Soybean irradiated with 30 kGy dose.                                              alkaline range. Physical treatments such as high pressure have
                                                                                                          been found to unfold the protein resulting in exposure of
                                                                                                          hydrophobic sites altering the functional properties of proteins
                                                                                                          (Molina et al., 2002). Irradiation at high doses has been found to
                  100                                                                                     alter protein structure. Such alterations must have changed the
                                                                                                          protein solubility pattern at different doses due to alterations in
                                                                                                          amino acids at the surface as well as length of polypeptides
                                                                                                          (Bautista et al., 2006).
                   80

                                                                                                          3.7.2. Gelation
% Solubility




                                                                                                             In order to form gels, partial denaturation is desirable, since
                   60
                                                                                                          unfolding of the tertiary structure gives long chains without
                                                                                                          breakage of covalent bonds. At the lowest concentration tried
                                                                                                          (12%), proper gels could not be obtained with control protein
                   40                                                                                     while SPI from irradiated soybean showed gelling at 12%
                                                                                           Control
                                                                                           10 kGy         concentration. It is a known fact that factors like pH, ionic
                                                                                           20 kGy         strength, reducing agents and the presence of non-protein
                   20                                                                      30 kGy         compounds (carbohydrates) affect gelling. Sucrose is a main
                                                                                                          ingredient in commercial gel mixes and when gelling was done in
                                                                                                          20% sugar solution, even the control sample showed gelling at 12%
                         0         2              4          6           8           10          12       concentration. The gels were of coagulant type indicating the
                                                              pH                                          presence of more non-polar residues (Moure et al., 2006).
                                                                                                          Moreover the gels from treated samples were observed to be
                                           Fig. 2. Protein solubility of SPI.                             homogenous and smooth, when compared with control gels.


isoelectric point of soy proteins, nitrogen solubility was                                                3.7.3. Foaming properties
significantly low for all the samples. This is in concurrence with                                            There was no significant difference observed between control
the data obtained by McWatters and Holmes (1979) for soy flour.                                            and irradiated sample at the concentration tried (2%). It is a
As the pH increased above 5, nitrogen solubility increased steeply                                        known fact that flexible protein molecules can have good
reaching almost a plateau around neutral pH. The solubility                                               foamability by reducing the surface tension.
remained consistently higher in the case of protein extracted from
irradiated soybean. SPI extracted from 10 kGy treated samples                                             3.7.4. Emulsification
showed higher solubility (100%) at most of the pH values.                                                    It can be seen from Fig. 3 that the emulsification activity as
However, in the range encompassing the isoelectric point dose                                             well as the stability of protein extracted from treated seeds was
dependency was evident. The amino-acid composition,                                                       significantly higher compared to the control. Qi et al., (1997)
particularly at the protein surface influences protein solubility.                                         observed an increased emulsification activity index (EAI) after
Higher solubility is related to the presence of low numbers of                                            pancreatic hydrolysis of soy protein isolate, reaching maximum at
hydrophobic residues (Moure et al., 2006). Irradiation at this dose                                       15% degree of hydrolysis (DH). It indicates that at 15% DH, the
must have led to formation of smaller peptides exposing                                                   hydrophilic and hydrophobic groups are well balanced. We
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494                                                    M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494


observed that with 1 mL of oil, 10 kGy treated samples showed                                 Bautista, F.R., Thomson, R.H., Cain, R.F., 2006. Changes in amino nitrogen, total
the highest activity. With 2 mL oil, a significant dose-dependent                                  soluble nitrogen and TCA-soluble nitrogen content of beef as influenced by pre
                                                                                                  -irradiation, irradiation level and storage at 341 F. Journal of Food Science 26,
increase was observed (pr0.05). With 3 mL oil, the increase was                                   15–20.
not significant, however in all the irradiated samples the                                     Byun, M.W., Kwon, J.H., Mori, T., 1993. Improvement of physical properties
emulsification stability index (ESI) was significantly higher                                       of soybeans by gamma irradiation. Radiation Physics and Chemistry 42,
                                                                                                  313–317.
(pr0.05) than the control. Venkatesh and Prakash (1993) have                                  Byun, M.W., Kang, I.J., 1994. Effect of g-irradiation on soybean proteins. Journal of
reported increased emulsification activity after autoclaving                                       the Science of Food and Agriculture 66, 55–60.
of sunflower protein. A good correlation between surface                                       Chove, B.E., Grandison, A.S., Lewis, M.J., 2001. Emulsifying properties of soy protein
                                                                                                  isolate fractions obtained by isoelectric precipitation. Journal of Science of
hydrophobicity and emulsifying property is reported (Wagner                                       Food and Agriculture 81, 759–763.
and Gueguen, 1999). Emulsifying property depends on initial                                   Coffmann, C.W., Garcia, V.V., 1977. Functional properties and amino acid
solubility of the protein. As more protein dissolves in the system,                               content of protein isolate from mung bean flour. Journal of Food Technology
                                                                                                  12, 473–484.
more protein will be at the interface between the oil phase
                                                                                              De Kleijn, M.J., van der Schouw, Y.T., Wilson, P.W., Grobbee, D.E., Jacques, P.F.,
and the continuous phase during emulsification. Our results                                        2002. Dietary intake of phytoestogens is associated with a favourable
indicated increased solubility of protein after irradiation. A close                              metabolic cardiovascular risk profile in postmenopausal U.S. women: the
relationship between emulsifying properties and solubility of soy                                 Framingham study. Journal of Nutrition 132, 276–282.
                                                                                              Folch, J., Lees, M., Stanley, G.H.S., 1957. A simple method for the isolation and
proteins has been reported by McWatters and Holmes (1979).                                        purification of total lipids from animal tissues. Journal of Biological Chemistry
Formation of longer polypeptides are essential for this purpose.                                  226, 497–509.
Our studies indicated that among the samples the 10 kGy samples                               Fukushima, Danji, 2001. Recent progress in research and technology on soybeans.
                                                                                                  Food Science and Technology Research 7 (1), 8–16.
were found to form more stable emulsions, suggesting dose-                                    Liener, J.E., 1994. Implications of antinutritional components in soybean foods.
dependent breakdown of polypeptide chain to smaller units.                                        Critical Reviews in Food Science and Nutrition 34, 31–37.
                                                                                              Machaiah, J.P., Pednekar, M.D., Thomas, P., 1999. Reduction in flatulence factors
                                                                                                  in mung beans (Vigna radiata) using low–dose g-irradiation. Journal of the
                                                                                                  Science of Food and Agriculture 79, 648–665.
4. Conclusion                                                                                 Machaiah, J.P., Pednekar, M.D., 2002. Carbohydrate composition of low
                                                                                                  dose radiation processed legumes and reduction in flatulence factors. Food
                                                                                                  Chemistry 79, 293–301.
   The results indicate that radiation processing up to 30 kGy
                                                                                              McWatters, K.H., Holmes, M.R., 1979. Influence of pH and salt concentration on
reduced the cooking time without affecting the proximate                                          nitrogen solubility and emulsification properties of soy flour. Journal of food
compositional properties. It was also helpful in increasing the                                   Science 44, 770–781.
protein concentration in soy milk as well as tofu yield. The                                  Messina, M.J., 1999. Legumes and soybeans: overview of their nutritional profiles
                                                                                                  and health effects. American Journal of Clinical Nutrition 70, 439S–450S.
acceptability of potato patties containing tofu from radiation                                Molina, E., Papadopoulou, A., Defaye, A., Ledward, D.A., 2002. Functional properties
processed seeds was better than the control. The functional                                       of soy proteins as influenced by high pressure: Emulsifying. In Progress
properties like protein solubility, gelling and emulsification                                     in Biotechnology 19, 557–562 (Trends in High Pressure Bioscience and
                                                                                                  Biotechnology).
were found to be better in protein extracted from irradiated                                  Moure, A., Sineiro, J., Dominguez, H., Parajo, J.C., 2006. Functionality of oilseed
beans. These results clearly indicate the value addition effect of                                protein products: A review. Food Research International 39, 945–963.
radiation processing.                                                                         Nene, S.P., Vakil, U.K., Sreenivasan, A., 1975. Effect of gamma radiation on the
                                                                                                  physio–chemical characteristics of red gram (Cajanus cajan) proteins. Journal
                                                                                                  of Food Science 40, 815–819.
                                                                                              Nong Sun, Breene, W., 1991. Calcium sulphate concentration influence on yield
Acknowledgement                                                                                   and quality of tofu from five soybean varieties. Journal of Food Science 56,
                                                                                                  1604–1607.
                                                                                              Qi, M., Hettiarachchy, N.S., Kalapathy, U., 1997. Solubility and emulsifying
   The authors are grateful to Dr. Sahayog N Jamdar (BARC) for                                    properties of soy protein isolates modified by pancreatin. Journal of Food
his invaluable help and expertise rendered in the preparation of                                  Science 62, 1110–1115.
manuscript and also for his technical suggestions.                                            Rahma, E.H., Mustafa, M.M., 1988. Functional properties of peanut flour as affected
                                                                                                  by different heat treatments. Journal of Food Science and Technology 25, 11–25.
                                                                                              Rao, V.S., Vakil, U.K., 1985. Effect of gamma radiation on cooking quality and
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    effect of dietary soy supplementation on hot flushes. Obstetrics & Gynecology                  reference to human and animal food. Food Chemistry 78, 187–205.
    91, 6–11.                                                                                 Sharif, M.M., Farkas, J., 1993. Analytical studies into radiation induced starch
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    Nutrition Research 17, 1617–1632.                                                         Tripathi, A.K., Misra, A.K., 2005. Soybean–a consummate food: A review. Journal of
AOAC, 2007. Official Methods of Analysis, 18 th Ed. Association of Official                         Food Science and Technology 42, 111–119.
    Analytical Chemists, Washington DC, USA.                                                  Venkatesh, Aruna, Prakash, V., 1993. Functional properties of the total
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    manual 26 2nd Ed. ASTM, West Conshohocken, PA, USA, pp. 54–72.                                chemical treatments. Journal of Agricultural and Food Chemistry 41, 18–23.
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Radiation Processing And Functional Properties Of Soybean (Glycine Max)

  • 1. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
  • 2. Author's personal copy ARTICLE IN PRESS Radiation Physics and Chemistry 79 (2010) 490–494 Contents lists available at ScienceDirect Radiation Physics and Chemistry journal homepage: www.elsevier.com/locate/radphyschem Radiation processing and functional properties of soybean (Glycine max) Mrinal Pednekar a,n, Amit K. Das b, Rajalakshmi Va, Arun Sharma a a Food Technology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, Maharashtra, India b Department of Food Engineering, CFTRI, Mysore 570020, Karnataka, India a r t i c l e in f o a b s t r a c t Article history: Effect of radiation processing (10, 20 and 30 kGy) on soybean for better utilization was studied. Received 25 June 2009 Radiation processing reduced the cooking time of soybean and increased the oil absorption capacity of Accepted 28 October 2009 soy flour without affecting its proximate composition. Irradiation improved the functional properties like solubility, emulsification activity and foam stability of soybean protein isolate. The value addition Keywords: effect of radiation processing has been discussed for the products (soy milk, tofu and tofu fortified Radiation processing patties) prepared from soybean. Soybean & 2009 Published by Elsevier Ltd. Tofu Soya protein Functional properties 1. Introduction Radiation processing is an ecofriendly technology utilized for nutritional safety and security. It can be used for value addition In most developing countries, per capita consumption of such as elimination of flatulence factors (Machaiah et al., 1999; protein is below the recommended level resulting in widespread Machaiah and Pednekar, 2002), increase in starch and protein protein calorie malnutrition. Soybeans with 40% protein and 20% depolymerization (Sharif and Farkas, 1993; Nene et al., 1975) and oil have a great potential of solving the problem of protein calorie extractability. malnutrition. Soy protein efficiently supplements cereal grain We have conducted studies to evaluate the effects of radiation protein, because it corrects the lysine deficiency of cereals. In processing on functional properties like cooking time and the some cases, for example in corn, it also corrects tryptophan yield of soy milk and tofu. Potato patties prepared from tofu deficiency. Because of its quality, soybean protein can replace incorporation indicated good acceptability. Functional properties animal protein without a significant decrease in nutritive value like solubility, foaming, emulsification capacity and gelling of (Tripathi and Misra, 2005). In fact, soy protein has an advantage protein extracted from soybean were also evaluated. over animal protein as it does not raise the serum cholesterol values (Fukushima, 2001) and hence, is useful for people suffering from cardiovascular disorder (De Kleijn et al., 2002). Soybean also 2. Materials and Methods has a number of phytochemicals found to be effective in fighting osteoporosis (Anderson and Garner, 1997), obesity, cancer 2.1. Irradiation (Messina, 1999) and postmenopausal problems (Albertazzi et al., 1998). Soy milk is used in cases of lactose intolerance. However, Soybean was purchased from a local market, cleaned and soybean has a long cooking time, beany flavor, antinutritional irradiated at 10, 20 and 30 kGy. Irradiation was carried out in a factors like raffinose family oligosaccharides and protease Gamma Cell-5000 loaded with Co60(Board of Radiation and Isotope, inhibitors (Liener, 1994). Hence, processing of soybean is essential Mumbai, India) at an effective dose rate of 152.3 Gy/min. Dose rate for better utilization. Most native proteins do not show desirable was determined using standard Fricke dosimetry (Sehsted, 1970). functional properties and modifications for improving the nutri- Calibration was done by keeping the dosimeter vials in the tional value and/or functional properties like protein solubility, irradiation chamber at different positions. Dosimeters were foaming and gelling need to be induced (Chove et al., 2001). Such analyzed using a UV spectrophotometer. 9% variation in the dose modifications imply changes in both protein structure and distribution was recorded. conformation at different levels by changing molecular composi- tion or size. 2.2. Soybean flour n Corresponding author. Tel.: + 91 22 25595375. Whole soybean seeds were pulverized into fine flour (710 mm) E-mail address: mrinal1854@yahoo.co.in (M. Pednekar). with a mixer grinder and stored in self sealable polyethylene bags. 0969-806X/$ - see front matter & 2009 Published by Elsevier Ltd. doi:10.1016/j.radphyschem.2009.10.009
  • 3. Author's personal copy ARTICLE IN PRESS M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494 491 2.3. Proximate analysis different sections of the Food Technology Division, BARC. The panelists belonged to age group of 25–55. The hedonic scale used Proximate analysis was carried out by standard AOAC methods was as follows: (AOAC, 2007) for all samples including control after storing at 7=like very much (LVM), 6= like moderately (LM), 5 =like room temperature for 15 days. Lipid content of soy milk was slightly (LS), determined by the Folch method (Folch et al., 1957). 4=neither like nor dislike (NLND), 3= dislike slightly (DS), 2= dislike moderately (DM), 2.4. Determination of water and oil absorption capacity 1=dislike very much (DVM). For water and oil absorption capacities of soy flour the method 2.10. Preparation of soy protein isolate (SPI) of Sathe et al., (1982) was followed. Soy flour (1 g) was mixed with 10 mL of distilled water or 10 mL of edible oil and vortexed. Soybean protein isolate was prepared by the isoelectric point The samples were then allowed to stand at room temperature precipitation method. A modified method of Sathe et al. (1982) was (21 1C) for 30 min, and centrifuged at 5000 rpm for 30 min. used to extract protein from the defatted soybean. Finely ground soy The volume of the supernatant was measured in a 10 mL flour was defatted with petroleum ether (1:20, W/V). Defatted graduated cylinder. soy flour was treated with 0.2% NaOH for 24 h (1:5, W/V). After Calculation: centrifuging (10,000 rpm, 30 min), the residue was re-extracted Water Absorption Capacity (g/g)=(Initial volume of the waterÀ with 0.2% NaOH and again centrifuged. Protein from both the pooled Final volume of water) supernatants was precipitated by adjusting the pH to 4 with 1 N HCl. Oil Absorption Capacity (g/g)=(Initial volume of the oil–Final The precipitate was dissolved in a minimum amount of 0.2% NaOH. volume of oil)  0.91n This protein solution was dialyzed against distilled water for 72 h (n = specific gravity of the oil used) and freeze-dried. 2.5. Cooking time 2.11. Protein solubility Overnight soaked seeds (control and irradiated) were pressure Protein solubility of SPI was studied from pH 1–12. The sample cooked for 2, 4, 6, 8 and 10 min (after first pressure release).These (100 mg) was dissolved in distilled water and pH was adjusted to seeds were then allowed to cool at room temperature. The degree the required value using 0.1 N HCl or NaOH. The volume was of softness of the seeds was then measured using Texture made up to 20 mL. The protein solution was centrifuged at Analyzer (TA.XT Plus, Stable Micro System, Surrey, U.K.). 8000 rpm for 15 min. The protein in the supernatant was estimated using the Kjeldahl method. 2.6. Preparation of soy milk 2.12. Determination of gelling capacity Soybean seeds (100 g) were soaked for 16 h in 300 mL water. Gelling was studied using a modified method of Sathe et al. Excess water was decanted off and 80 mL fresh water was added (1982). SPI was dissolved in different concentrations of 10%, 12%, and seeds were pressure cooked for 10 min after first pressure 14% and 16% in phosphate buffer (pH 7.6) and 20% sugar solution. release. The cooked seeds were blended in the grinder by adding 3 mL of the solution was dispensed in tubes and heated at 80 1C 300 mL of water. Further this homogenate was filtered through in a water bath for 30 min. The tubes were cooled rapidly by muslin cloth, while filtering 600 mL of water was added. The keeping in cold water and kept refrigerated overnight. Gel filtrate was heated in a boiling water bath for 15 min. formation was observed by tilting the tubes and observing the flow of the solution. 2.7. Preparation of tofu 2.13. Foaming properties Tofu was prepared by a modified method of Nong Sun and Breene (1991). Calcium sulfate (0.2 M) was added to warm soy Whip ability and foam stability were studied according to the milk in 1:10 ratio and was heated at 70 1C for 10 min for method of Coffman and Garcia (1977) with slight modification. SPI coagulation to occur. The coagulated curd was separated using (500 mg) was solubilized in 25 mL distilled water and pH was cheese cloth and the collected mass (tofu) was weighed. adjusted to 7.0. The solution was whipped in a homogenizer (Polytron PT 2100, Kinematica, Switzerland) for 3 min at 10,000 rpm 2.8. Preparation of tofu–potato patties and poured into a 50 mL measuring cylinder. The total and drainage volume were noted at 0, 1, 30 min, 1, 2, and 24 h intervals. Potatoes (500 g) were cooked in a pressure cooker and mashed Whip ability and foam stability were calculated by the with pre-moistened bread slices (4 slices each weighing 22 g). following formula: This preparation (100 g) was mixed with tofu (15 g). This was Whip ability= (Total volume–Drainage volume)/Initial volume molded desirably and a layer of semolina was applied to the Foam stability= (Initial volume–Drainage volume)/Initial surface. This was then shallow fried with vegetable oil to a golden volume  100 brown colour. 2.14. Emulsification 2.9. Sensory evaluation of tofu–potato patties Emulsification was carried out according to the method of Sensory evaluation of the tofu–potato patties was carried out Bandyopadhyay and Ghosh (2002). 3 mL of 0.2% SPI solution at pH using a 7-point hedonic scale ranging from ‘like very much’ to 7 was homogenized with 1, 2 and 3 mL of peanut oil at ‘dislike very much’, with ‘neither like nor dislike’ as the midpoint 12,000 rpm. 100 ml of emulsion was added to 4900 ml of 0.1% (ASTM, 1996). The taste panel consisted of 50 members from SDS and absorbance was read at 500 nm.
  • 4. Author's personal copy ARTICLE IN PRESS 492 M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494 Table 1 Proximate qualities of soybean. Sample Protein % Lipid % Moisture% Ash % Carbohydrates% Control 36.5357 1.704 22.7007 0.582 7.355 7 0.077 0.787 70.033 32.6237 0.293 10 kGy 37.590 7 1.730 22.22570.523 7.345 7 0.190 0.827 70.009 32.013 70.489 20 kGy 36.103 7 1.595 21.6007 1.015 6.475 7 2.27 0.826 70.139 34.9967 0.528 30 kGy 36.65 7 0.826 23.0507 0.825 7.22 70.155 0.733 70.094 32.3477 0.386 The values presented are mean 7S.D. computed from 6 replicates. 2.15. Statistical analysis Table 2 Texturo-metric analysis of cooked soybean. All values are expressed as means and standard deviation of 6 Force (Kg)a replicates with the exception of sensory evaluation. The results are the mean and standard deviations of the observed values. Control 10 kGy 20 kGy 30 kGy Differences were considered significant at po0.05 after perform- 2 min 6.047 7 1.252 3.834 7 0.581 2.4487 1.282 2.505 7 0.781 ing students’t’ test. 4 min 6.646 7 1.923 3.3327 0.960 3.1977 0.964 2.038 7 0.364 6 min 7.140 7 0.764 3.323 7 1.538 3.6527 0.977 1.3117 0.551 8 min 4.581 7 0.942 1.7197 0.726 2.7617 0.133 1.5247 0.658 10 min 4.064 7 0.526 2.028 7 0.987 2.613 7 1.174 1.1577 0.748 3. Results and discussion a S.D. computed from 6 replicates. 3.1. Proximate analysis of soy flour Proximate analysis of control and irradiated (10, 20 and 3.4. Qualitative analysis of soy milk 30 kGy) soy flour was carried out and the results obtained are presented in Table 1. It is evident from the table that there was no It was evident from the data that the protein concentration in significant effect of radiation processing on the macronutrient soy milk from irradiated seeds nearly doubled (0.58270.08 in content of the soybean. control soy milk to 1.04470.1 in 30 kGy treated soy milk). This can be correlated to better extractability of proteins 3.2. Oil and water absorption capacity from irradiated seeds. Similar results were reported by Byun and Kang (1994). Oil and water absorption capacity of flours prepared from control and radiation processed seeds was found to be within the 3.5. Preparation of tofu range observed with various legume flours (Adebowale and Lawal, 2004). Variation in the presence of polar and non-polar The results indicated that irradiation increased the yield of side chains among flour which bind to water or hydrocarbon side tofu from 5.27% in control to 11.36% in 30 kGy treated samples. chains of oil possibly make the difference in water or oil-binding The yield increased as the dose increased. This can be correlated capacity of flours. The data showed a non significant increase to the higher concentration of protein in the milk from irradiated in water absorption capacity due to radiation processing samples. Byun et al., (1993) have observed a similar pattern. (2.5770.082 in control to 3.0870.075 in 30 kGy treated samples). Water absorption capacity is important functional 3.6. Sensory evaluation property for flours as they swell and impart characteristics like body thickness and viscosity. Radiation processing also led to The data of the sensory analysis was analyzed and responses increase in oil absorption capacity of soy flours (1.587 0.16 in (%) were plotted against hedonic ratings. As seen in Fig. 1, tofu– control to 1.97 70.18 in 30 kGy samples). Rahma and Mustafa potato patties, a tertiary product from soybean irradiated at (1988) have reported similar observations with irradiation 20 kGy dose has scored maximum (40%) as ‘Like very much’, of peanut flours. Dissociation and denaturation results in the fat whereas 55% of the panel members rated the same as ‘Like and water absorption of treated proteins compared to native moderately’. It is also noteworthy that products from soybean proteins (Siddharaju et al., 2002). Radiation processing may irradiated with other doses (10 and 30 kGy) scored more than the have resulted in protein unfolding leading to exposure of certain product prepared from control tofu which showed the lowest buried functional groups resulting in increased oil absorption scores among all. This can be attributed to the fact that soybean capacity. has a typical beany flavor and taste which are also expected to be present in its secondary (control tofu) as well as tertiary (tofu– 3.3. Determination of cooking time of soybean potato patties) products. Irradiation may have caused reduction of the beany flavor, as the scores for the products prepared from Cooking time is a significant characteristic of legumes. It is the irradiated soybean were always higher than those for the control time of boiling during which the legumes attain desirable softness soybean. wherein at least 90% of the seeds are soft enough to masticate. Our results indicated a dose-dependent decrease in cooking time 3.7. Functional properties of soy protein isolate of irradiated beans (Table 2). There was 30% decrease in cooking time at 10 kGy which decreased to 60% at 30 kGy. The observed 3.7.1. Protein solubility reduction in cooking time of irradiated soybean is consistent with The solubility profiles of SPI in water at different pH values are reports of other workers (Rao and Vakil, 1985; Byun et al., 1993). presented in Fig. 2. At pH 4 and 5, which encompasses the
  • 5. Author's personal copy ARTICLE IN PRESS M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494 493 Product A Product D 700 Control Product B Product E 600 10kGy Product C 100 500 20kGy EAI value 30kGy 80 400 % Acceptability 300 60 200 40 100 20 0 0min 5min 0min 5min 0min 5min 0 1 ml oil 2 ml oil 3 ml oil e ste te e y r ur ou nc ur lit as do Ta xt bi l ra rT Co O Te ta ea fte ep pp Fig. 3. Emulsifying activity index (EAI) of SPI. cc A A A ll ra ve O Attributes hydrophilic groups which increase the interactions of hydrophilic amino acids with water molecules. Protein from the Fig. 1. Sensory evaluation of Tofu fortified potato patties. A–Control Product 20 kGy treated sample showed a slightly different pattern. It (without Tofu); B–Control Tofu (mixed with Tofu obtained from un irradiated Soya); C–Mixed with Tofu obtained from Soybean irradiated with 10 kGy dose; showed the least solubility up to pH 3, but then increased after D–Mixed with Tofu obtained from Soybean irradiated with 20 kGy dose; E–Mixed isoelectric point showing higher solubility than the control in the with Tofu obtained from Soybean irradiated with 30 kGy dose. alkaline range. Physical treatments such as high pressure have been found to unfold the protein resulting in exposure of hydrophobic sites altering the functional properties of proteins (Molina et al., 2002). Irradiation at high doses has been found to 100 alter protein structure. Such alterations must have changed the protein solubility pattern at different doses due to alterations in amino acids at the surface as well as length of polypeptides (Bautista et al., 2006). 80 3.7.2. Gelation % Solubility In order to form gels, partial denaturation is desirable, since 60 unfolding of the tertiary structure gives long chains without breakage of covalent bonds. At the lowest concentration tried (12%), proper gels could not be obtained with control protein 40 while SPI from irradiated soybean showed gelling at 12% Control 10 kGy concentration. It is a known fact that factors like pH, ionic 20 kGy strength, reducing agents and the presence of non-protein 20 30 kGy compounds (carbohydrates) affect gelling. Sucrose is a main ingredient in commercial gel mixes and when gelling was done in 20% sugar solution, even the control sample showed gelling at 12% 0 2 4 6 8 10 12 concentration. The gels were of coagulant type indicating the pH presence of more non-polar residues (Moure et al., 2006). Moreover the gels from treated samples were observed to be Fig. 2. Protein solubility of SPI. homogenous and smooth, when compared with control gels. isoelectric point of soy proteins, nitrogen solubility was 3.7.3. Foaming properties significantly low for all the samples. This is in concurrence with There was no significant difference observed between control the data obtained by McWatters and Holmes (1979) for soy flour. and irradiated sample at the concentration tried (2%). It is a As the pH increased above 5, nitrogen solubility increased steeply known fact that flexible protein molecules can have good reaching almost a plateau around neutral pH. The solubility foamability by reducing the surface tension. remained consistently higher in the case of protein extracted from irradiated soybean. SPI extracted from 10 kGy treated samples 3.7.4. Emulsification showed higher solubility (100%) at most of the pH values. It can be seen from Fig. 3 that the emulsification activity as However, in the range encompassing the isoelectric point dose well as the stability of protein extracted from treated seeds was dependency was evident. The amino-acid composition, significantly higher compared to the control. Qi et al., (1997) particularly at the protein surface influences protein solubility. observed an increased emulsification activity index (EAI) after Higher solubility is related to the presence of low numbers of pancreatic hydrolysis of soy protein isolate, reaching maximum at hydrophobic residues (Moure et al., 2006). Irradiation at this dose 15% degree of hydrolysis (DH). It indicates that at 15% DH, the must have led to formation of smaller peptides exposing hydrophilic and hydrophobic groups are well balanced. We
  • 6. Author's personal copy ARTICLE IN PRESS 494 M. Pednekar et al. / Radiation Physics and Chemistry 79 (2010) 490–494 observed that with 1 mL of oil, 10 kGy treated samples showed Bautista, F.R., Thomson, R.H., Cain, R.F., 2006. Changes in amino nitrogen, total the highest activity. With 2 mL oil, a significant dose-dependent soluble nitrogen and TCA-soluble nitrogen content of beef as influenced by pre -irradiation, irradiation level and storage at 341 F. Journal of Food Science 26, increase was observed (pr0.05). With 3 mL oil, the increase was 15–20. not significant, however in all the irradiated samples the Byun, M.W., Kwon, J.H., Mori, T., 1993. Improvement of physical properties emulsification stability index (ESI) was significantly higher of soybeans by gamma irradiation. Radiation Physics and Chemistry 42, 313–317. (pr0.05) than the control. Venkatesh and Prakash (1993) have Byun, M.W., Kang, I.J., 1994. Effect of g-irradiation on soybean proteins. Journal of reported increased emulsification activity after autoclaving the Science of Food and Agriculture 66, 55–60. of sunflower protein. A good correlation between surface Chove, B.E., Grandison, A.S., Lewis, M.J., 2001. Emulsifying properties of soy protein isolate fractions obtained by isoelectric precipitation. Journal of Science of hydrophobicity and emulsifying property is reported (Wagner Food and Agriculture 81, 759–763. and Gueguen, 1999). Emulsifying property depends on initial Coffmann, C.W., Garcia, V.V., 1977. Functional properties and amino acid solubility of the protein. As more protein dissolves in the system, content of protein isolate from mung bean flour. Journal of Food Technology 12, 473–484. more protein will be at the interface between the oil phase De Kleijn, M.J., van der Schouw, Y.T., Wilson, P.W., Grobbee, D.E., Jacques, P.F., and the continuous phase during emulsification. Our results 2002. Dietary intake of phytoestogens is associated with a favourable indicated increased solubility of protein after irradiation. A close metabolic cardiovascular risk profile in postmenopausal U.S. women: the relationship between emulsifying properties and solubility of soy Framingham study. Journal of Nutrition 132, 276–282. Folch, J., Lees, M., Stanley, G.H.S., 1957. A simple method for the isolation and proteins has been reported by McWatters and Holmes (1979). purification of total lipids from animal tissues. Journal of Biological Chemistry Formation of longer polypeptides are essential for this purpose. 226, 497–509. Our studies indicated that among the samples the 10 kGy samples Fukushima, Danji, 2001. Recent progress in research and technology on soybeans. Food Science and Technology Research 7 (1), 8–16. were found to form more stable emulsions, suggesting dose- Liener, J.E., 1994. Implications of antinutritional components in soybean foods. dependent breakdown of polypeptide chain to smaller units. Critical Reviews in Food Science and Nutrition 34, 31–37. Machaiah, J.P., Pednekar, M.D., Thomas, P., 1999. Reduction in flatulence factors in mung beans (Vigna radiata) using low–dose g-irradiation. Journal of the Science of Food and Agriculture 79, 648–665. 4. Conclusion Machaiah, J.P., Pednekar, M.D., 2002. Carbohydrate composition of low dose radiation processed legumes and reduction in flatulence factors. Food Chemistry 79, 293–301. The results indicate that radiation processing up to 30 kGy McWatters, K.H., Holmes, M.R., 1979. Influence of pH and salt concentration on reduced the cooking time without affecting the proximate nitrogen solubility and emulsification properties of soy flour. Journal of food compositional properties. It was also helpful in increasing the Science 44, 770–781. protein concentration in soy milk as well as tofu yield. The Messina, M.J., 1999. Legumes and soybeans: overview of their nutritional profiles and health effects. American Journal of Clinical Nutrition 70, 439S–450S. acceptability of potato patties containing tofu from radiation Molina, E., Papadopoulou, A., Defaye, A., Ledward, D.A., 2002. Functional properties processed seeds was better than the control. The functional of soy proteins as influenced by high pressure: Emulsifying. In Progress properties like protein solubility, gelling and emulsification in Biotechnology 19, 557–562 (Trends in High Pressure Bioscience and Biotechnology). were found to be better in protein extracted from irradiated Moure, A., Sineiro, J., Dominguez, H., Parajo, J.C., 2006. Functionality of oilseed beans. These results clearly indicate the value addition effect of protein products: A review. Food Research International 39, 945–963. radiation processing. Nene, S.P., Vakil, U.K., Sreenivasan, A., 1975. 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