1. Essential oils of peppermint, parsley, and sweet flag were encapsulated into different matrixes including whey protein concentrate, skimmed milk powder, dextrin, and pectin using a spray drying process. 2. Losses of parsley essential oil during spray drying were up to 80%, while peppermint essential oil was retained more effectively at a loss of 10-20%. Losses of calamus oil were between 30-50%. 3. The compositions of individual volatile constituents in the essential oils were analyzed before and after drying, with some changes observed.

1. Process Optimisation and
Minimal Processing of Foods
Proceedings of the first main meeting
European Commission
COPERNICUS PROGRAMME
Concerted action CIPA-CT94-0195
Escola Superior de Biotecnologia, Porto, Portugal, December 1995
Editor : Jorge C. Oliveira
Project Coordinator : Fernanda A. R. Oliveira
Area leader : Andrejz Lenart
Volume 3: Drying

2. The proceedings of the first workshop organised by the COPERNICUS concerted action Process
Optimisation and Minimal Processing of Foods in December 1995 at Escola Superior de Biotecnologia,
Porto, Portugal consist of five booklets, one for each project area:
• Thermal Processing
• Freezing
• Drying
• High Pressure
• Minimal and Combined Processes
Each booklet includes all communications that were presented at the meeting and later forwarded by
the authors as written text, plus the questions and answers that were recorded.
The editors found that the style of writing and correctness of language use was very varied, as would be
expected, and have tried to contribute to a greater harmonisation by taking liberties with everybody’s
English. Not being native English speakers ourselves, it is evident that fully correct English has not
resulted from this exercise, but we hope that in this way all texts are fully comprehensible and more
similar in style. However, the revision was not thorough and some typing mistakes plus grammatical
errors can certainly be found here and there. No review has been made concerning the scientific content
of the communications. The sole purpose of the edition of the texts was concerned with the language
and style and if any change in meaning has resulted, we sincerely apologise for the fact.
It is reminded that at the end of the project the communications that were orally presented in the three
project meetings as area overviews, plenary lectures and short communications will be collected for the
publication of a book, through a professional scientific publisher. The contents will then be scientifically
reviewed by the area leaders and the publisher will make a professional review of the English.
We would like to thank all project participants and particularly those that have contributed with written
versions of the presentations, thus allowing for the production of this set of booklets that we consider
to be most valuable for promoting the interchange of results among partners and for providing a
valuable project dissemination.
We look forward to receiving any suggestions regarding these booklets.
Finally, we would like to leave a warm word of appreciation to Mrs. Isabel Lino, who had to deal with
everything that had to do with typing, file converting, scanning, and all those very boring computing
tasks that were required for the final editing and publishing and also for her commitment and work
towards this project.
Porto, November 12th, 1996
Fernanda A. R. Oliveira
Jorge C. Oliveira
i
Proceedings of the first project workshop
Foreword

3. Proceedings of the first project workshop Drying
Pedro Fito, Amparo Chiralt, José Manuel Barat & Andres Alvarruiz
An Approach to the Modelling of Osmotic Dehydration Operations 1
Darius Piotrowski & Andrezj Lenart
The Influence of Step Changes in Air Temperature and Velocity on the Drying Kinetics of Apples 18
Peter de Pauw, Koen Dewettink, Filip Arnaut & Andre Huyghebaert
Fluid-Bed Microencapsulation of Fumaric Acid by Water-Soluble Biopolymers: 26
New Means of Controlling the Quality of Sourdough Breads
João Paulo Sousa e Silva & João Paulo Ferreira
Microcapsules for Sustained Release of Thiamine Hydrochloride 41
Elisabeth Dumoulin, Zeki Berk & Nicolas Krimitsas
Application of Agglomeration and Coating to Produce Powders Containing Iron and Ascorbic Acid 45
Harris N. Lazarides, Vassilis Gekas & Nikolaos Mavroudis
Mass Diffusivities in Fruit and Vegetable Tissues Undergoing Osmotic Processing 50
Victor Nederitã, Rodica Amarfi, Cheorge Turtoi & Corneliu Popa
New Drying Technology: Preliminary Study on the Drying of Vegetables Using Intense Light Pulses 57
Leonard A. Ilincanu, Fernanda A. R. Oliveira, M. Cláudia Drumond, Maria de Fátima Machado & Vassilis Gekas
Modelling Moisture Uptake and Soluble Solids Losses During Rehydration of Dried Apple Pieces 64
Rui M. Costa, Fernanda A. R. Oliveira & Vassilis Gekas
Water Loss During Frying of Thin Potato Slices 70
Chelo Gonzalez, Vassilis Gekas, Pedro Fito, Harris Lazarides & Ingegerd Sjoholm
Characterization of Osmotic Solutions 76
P. Rimantas Venskutonis & E, Dauk∂as
Effectiveness of Encapsulation of Some Essential Oils into Different Matrixes 83
P. Rimantas Venskutonis
The Influence of Drying on the Composition of Volatile Constituents in some Aromatic Plants 88
Tadeusz Matuszek & Marek Gralak
An Approach to Freeze Drying Sublimation Process Design 95
Javier Martinez-Monzó, Nuria Martinez-Navarrete, Pedro Fito & Amparo Chiralt
Changes on Viscoelastic Properties of Apple (Granny Smith) due to Vacuum Impregnation 101
D. Salvatori, J. da Silva, Amparo Chiralt & Pedro Fito
Vacuum Impregnation of Fruits: Coupling of Deformation-Impregnation Phenomena 110
ii
Table of Contents

4. Essential oils of peppermint (Mentha piperita L.), parsley (Petroselinum crispum Mill.) and sweet
flag (Acorus calamus L.) were immobilised into different matrixes consisting of whey protein
concentrate (WPC), skimmed milk powder (SMP), dextrin and pectin. Immobilisation was
performed by preparing an emulsion of the ingredients which was spray dried afterwards. The
results obtained show that the losses of parsley essential oil during spray drying were most
considerable, up to 80%. Peppermint essential oil was retained by all matrixes used quite
effectively, the losses constituting approximately 10-20% of the oil added to the emulsion. The
losses of calamus oil were in between, i.e., 30-50%. The compositions of individual volatile
constituents before and after drying of the emulsion were also analysed by using capillary GC and
some changes were found.
Flavours, as a rule, are complex mixtures of more or less volatile substances and labile
components that can change as a result of oxidation, chemical interactions or vaporisation. To
minimise the danger of this happening, microencapsulation processes are widely used in the
flavour industry to entrap liquid flavouring substances in a carrier matrix and convert them into
dry, free-flowing materials which are easier to handle. By selection of the correct carrier matrix,
they play a crucial role in making some applications at all possible.
The following points should be taken into account in the course of product development
(Eckert, 1995).
• type of raw materials employed (natural, nature-identical, artificial);
• auxiliary substances eventually incorporated (solvents, carriers);
• solubility of the liquid flavour (water soluble, oil soluble);
• world-wide legislation, food regulation requirements and laws;
• application-specific processing parameters which the microencapsulated flavour must
withstand;
• aromatization (when and how it takes place);
83
Venskutonis & Dauk∂as Drying
Summary
1. Introduction
Effectiveness of Encapsulation of Some Essential Oils into Different Matrixes
P. R. Venskutonis and E. Dauk∂as
Dept. of Food Technology, Kaunas University of Technology, Kaunas, Lithuania

5. • flavour release mechanism;
• requirements regarding particle size, bulk density and storability;
• dosage guidelines for the selection of the optimal flavour loading;
• price guidelines/aromatizing costs.
Spray-drying is certainly one of the most widely-used encapsulation processes in the food
industry and has been used since the nineteen thirties for the encapsulation of flavours. When
carried out correctly, the process is extremely economical and demonstrates outstanding
flexibility due to the large number of factors which can be varied. The first step in the
manufacture of a spray-dried flavour is the selection of a suitable carrier material. Ideally, it
should have good emulsifying properties, be a good film former, not lead to high viscosities at a
high solid content (<500 cps at >45% dry substance), be economical, neutral in flavour, stable
and not very hygroscopic. In addition, it is essential that the encapsulated flavour is released
again in the application. As a rule hydro-colloids are used, such as gelatine, modified whey
proteins, modified starches, dextrin, vegetable gums and suitable mixtures. When a biopolymer,
B, has a group that attracts and binds the aroma molecule, A, then the following equation is valid
(Belitz & Grosch, 1987).
where K is a single binding constant; and Cf is the concentration of the free aroma compound.
The following matrixes were used for encapsulation of essential oils:
• skimmed milk powder (SMP);
• whey protein concentrate (WPC);
• conventional dextrin;
• citrus pectin.
Matrixes were dispersed in water at 40˚C and, after cooling, homogenised with 13% of
essential oil dissolved in alcohol with ratio 1:1. Emulsions were spray-dried in a Buchi 190 Mini
Spray Dryer using the following parameters: temperatures - spray nozzle - 145˚C-150˚C, outlet
air - 75˚C-80˚C; pressure - 750-800 mm/H2O.
Essential oils were distilled from the matrixes in a Clevenger-type apparatus. Individual
constituents in the essential oils were examined by capillary gas chromatography (GC) on a dual
column Hewlett-Packard 5890A chromatograph with FID under the following conditions: split
inlet 1:100; hydrogen as carrier gas at inlet pressure 20psi and linear velocity 35cm/s; fused silica
dimethylpolysiloxane DB-1 and polyethylene glycol DB-WAX columns, both 60m length, 0.25mm
K
BA
C Bf
=
[ ]
[ ]
84
Process Optimisation and Minimal Processing of Foods Process Assessment
2. Materials and Methods

6. id and 0.25mm film thickness; temperature programming from 50˚C to 238˚C (8min hold)
increasing at 4˚C/min; injector’s temperature 220˚C, detector’s 260˚C.
Retentions of parsley, peppermint and calamus essential oils in different matrixes are
tabulated in table I. It is obvious that the
losses of parsley essential oil during
spray-drying were very high and in all
cases exceeded 70% of the oil initially
added. Milk origin matrixes were more
effective than dextrin and pectin.
The losses of peppermint oil during
spray-drying were considerably lower
and in all cases did not exceed 25% of
the oil initially added. Contrary to
parsley oil, dairy matrixes were less effective in retaining peppermint oil than dextrin and pectin.
It is difficult to explain all reasons for significant differences between the retention of parsley and
peppermint oil, however, one of the main reasons could be the composition of the oils. Highly
hydrophobic non-polar monoterpene compounds prevail in parsley oil, whereas oxygenated
compounds, menthol and menthone, are the major constituents of peppermint oil.
The losses of calamus essential oil ranged from approximately 30% (SMP) to 47% (dextrin). The
composition of calamus essential oil is very complex with shyobunones, acorenones and asarones
as dominating constituents (Venskutonis & Dauk∂as, 1995). Therefore, it is rather difficult to
relate its composition to the results obtained.
Curves in figure 1 clearly demonstrate that retention of oil during drying increases almost linearly
with the increase of dry matter in the emulsion. Thus, when dry matter concentration was only 10%
retention of parsley oil was less than 5%. However, the spray-drying of emulsions with 50% of dry
matter was rather difficult
to perform.
The changes of the
percentual composition of
the main constituents of
peppermint and parsley
essential oils after
encapsulation into
different matrixes are
presented in tables II and
85
Venskutonis & Dauk∂as Drying
3. Results and Discussion
TableI
Retention of essential oils in different
matrixes, %
Matrix Parsley Peppermint Calamus
SMP 28.0 81.3 70.3
WPC 27.9 86.7 63.8
Pectin 17.4 90.9 53.3
Dextrin 19.2 90.2 52.9
Figure 1 - Effect of dry matter concentration in the emulsion on the retention
of parsley essential oil

7. III, respectively. The concentrations of the main compounds of peppermint in the matrixes were
very close to those in pure oil. There is some tendency for a better retention of alcohol - menthol,
the content of which was found to be slightly higher in matrixes than in the pure oil. Relative
concentrations of non-oxygenated terpenes, on the contrary, were reduced in the matrixes. It could
be explained by the ability of alcohols to form hydrogen bonds with biopolymer binding sites.
The changes of some individual compounds in parsley oil during drying were more
significant, most likely due to the considerable losses. Exceptionally low concentration of
86
Process Optimisation and Minimal Processing of Foods Process Assessment
Table II
Percentage composition of the main constituents of peppermint essential oil (EO) before
and after encapsulation into different matrixes
Compound Pure essential
oil (EO)
EO from SMP EO from WPC EOfrom
SMP+WPC (1:1)
α-Pinene 0.49 0.38 0.39 0.35
β-Pinene 0.56 0.47 0.47 0.42
Limonene 3.71 3.25 3.27 2.95
Menthone 20.75 21.67 20.56 19.77
Isomenthone 2.27 2.24 2.17 2.11
Borneol 2.16 2.3 2.24 2.26
Menthol 63.81 66.02 66.87 67.92
β-Caryophyllene 2.27 1.65 1.88 1.68
Germacrene D 1.21 0.85 0.96 0.86
TableIII
Percentage composition of the main constituents of parsley essential oil before and after
encapsulation into different matrixes
Compound
Pure
essential
oil (EO)
EO
from
SMP
EO
from
WPC
EOfrom
SMP+WPC
EOfrom
SMP +
dextrin
EOfrom
pectin
α-Pinene 6.02 6.13 5.62 6.17 6.89 5.02
β-Pinene 3.85 4.32 4.08 4.19 4.69 1.75
Myrcene 25.38 25.74 22.36 10.97 29.86 26.75
α-Phellandrene 1.49 2.09 2.18 2.78 2.01 2.54
β-Phellandrene 10.65 14.50 14.41 16.60 11.49 5.69
Limonene 7.44 9.77 9.54 10.49 9.52 9.95
α, p-Dimethylstyrene 12.22 15.89 15.85 14.07 16.11 16.93
Myristicin 11.8 16.02 19.22 21.18 17.27 23.03

8. myrcene was determined in the oil distilled from SMP+WPC. It should be said that similar results
were obtained on both columns - DB-1 and DB-WAX. ß-Phellandrene also varied in a wide range
- from 5.69% in pectin to 16.60% in SMP+WPC. The content of myristicin was significantly higher
in the matrixes than in the pure oil. It is hard to explain these fluctuations within the scope of
this study.
Results obtained demonstrate that encapsulation of essential oils by spray-drying is a
complicated process, the effectiveness of which depends on the origin of the oil and on the
matrix used.
Retention of peppermint oil consisting mainly of oxygenated monoterpenes was very high in
all matrixes used.
Losses of parsley oil during spray-drying exceeded 70%, which could be attributed to the oil
composition, consisting mainly of highly hydrophobic monoterpenes.
Retention of calamus oil was approximately 50% to 70%, depending on the matrix used.
Composition of immobilised peppermint oil was quite similar to the initial material, while the
changes of some individual parsley oil compounds were significant, most likely due to the
considerable overall losses.
The authors wish to thank Dr. Teris van Beek of the Department of Organic Chemistry at
Wageningen Agricultural University for his assistance in performing GC analyses of essential oils.
Belitz, H.-D. & Grosch, W.(1987). In: Food Chemistry. Springer Verlag, Berlin.
Eckert, M. (1995). Microencapsulated Flavours: Manufacture and Possible Applications. Dragoco
Report. Flavouring Information Service. 1, 5-19.
Venskutonis, P.R. & Dauk∂as E. (1995). Composition of Essential Oil of Calamus (Acorus calamus L.).
Food Chem. and Technol., Vilnius “Academia”, 28, 73-77.
87
Venskutonis & Dauk∂as Drying
4. Conclusions
Acknowledgements
References