utilization of renewable source of energy for food processing energy efficiently and cost effectively

1. 1

2. UNIVERSITY OF HORTICULTURAL SCIENCES,
BAGALKOT
College of Horticulture , Bengaluru.
I Seminar
Name of the Student : SUJAYASREE.O.J
ID No. : UHS14PGM533.
Degree Programme and Subject : M.Sc., (Hort.) in Postharvest Technology
College : College of Horticulture, Bengaluru.
2

3. Fruits & Vegetables
• Perishable- Many of these fruits and
vegetables contain a large quantity of initial
moisture content.
• They are highly susceptible to rapid quality
degradation leading to the extent of
spoilage.
• Need to convert these perishable products
into more stabilized products by processing
such as drying.
3

4. Drying Fruits & Vegetables
Drying is the oldest method of preserving food
by removing water from food (reducing water
activity).
Advantages include:
-Make product safe
-Convenience
-Increase shelf life
-Reduce weight
4

5. Methods of drying
▪ Drying by mechanical
driers
▪ Sun drying
▪ Solar drying
▪ Osmotic Drying
▪ Freeze drying
▪ Spray drying
▪ Foam mat drying
▪ Drum Drying
5

6. Open air sun drying has been used since time
immemorial to dry plants, seeds, fruit, meat,
fish,wood and other agricultural or forest products as
a means of preservation.
6

7. OPEN AIR
SUN
DRYING
SPOILT PRODUCT
LOSS OF PRODUCE
LABOUR INTENSIVE DETERIORATION
OF PRODUCE
TIME CONSUMING
LARGE AREA
REQUIREMENT
7

8. ARTIFICIAL
MECHANICAL
DRYING
Expensive
Energy
intensive
Non
renewable
source
High
product
cost
8

9. BACKGROUND
Energy has become the highest cost contributor and
paradoxically the same energy becomes a scarce product just in
times of need in all kind of industries.
Huge postharvest losses due to their perishable nature, poor
postharvest handling and lack of cheap and appropriate
postharvest technology.
During the harvest the high quantity of food can not be sold out
due to seasonal market gluts and the surplus can be utilized for
value addition
Cost of dehydration,energy consumption and quality of dried
product has important role in choosing an apropriate drying
process.
9

10. 10

11. 11

12. POTENTIALITIES AND PROSPECTUS OF
SOLAR DRYING IN VALUE ADDITION OF
FRUITS AND VEGETABLES
12

13. INTRODUCTION
TYPES OF SOLAR DRYERS AND ITS
COMPONENTS
WORKING PRINCIPLE OF SOLAR DRYERS
SOLAR DRIER FOR VALUE ADDITION OF
FRUITS AND VEGETABLES
CASE STUDIES
CONCLUSION
13

14. What is solar drying?
• It is often differentiated from sun drying by the
use of equipment to collect the sun‘s radiation in
order to harners the radiative energy for drying
applications.
• The employment of solar drier traps on the freely
available sun energy while ensuring good product
quality via judicious control of radiative heat.
14

15. Solar food processing brings in two emerging
technologies together to solve two major problems of
the world:
How to generate energy enough for an expanding1.
global population?
As the issue of global food losses and waste has2.
recently received much attention and has given high
visibility, to answer how to feed the constantly
expanding world population?
15

16. Total horizontal solar insolation and sunshine hours
for some developing countries
COUNTRY Average insolation
(kWh/m² day)
Sunshine hours
(h/day)
Cameroon 3.8 -5.5 4.5-8.0
Egypt 6 9.6
Guatemala 5-5.3 -
India 5.8 8-10
Papua New Guinea 4.6-9.6 4.5-8
Malaysia 4.41 -
Togo 4.4 5.5-7.2
Nigeria 3.8-7.15 5-7
Mali 4.34 8.4
HANDBOOK OF INDUSTRIAL DRYING
Developing countries are situated in
climatic zones of the world where
the insolation is considerably higher
than the world average of 3.82
kWh/m² day
16

17. Solar radiation map of India
TROPICS AND SUBTROPICS HAVE ABUNDANT SOLAR
RADIATIONS
OBVIOUS OPTION FOR DRYING WOULD BE THE
NATURAL CONVECTION SOLAR RADIATIONS
India is ideally suitable for harnessing solar
radiation to meet its energy needs.
Daily average solar incidence across the country
varies from 4-7kwh/m²
17

18. STEPS FOR FOOD DRYING
Selection (fresh, healthy F & V)
Cleaning (washing & disinfection)
Preparation (peeling, slicing etc)
Pre-treatment
Drying
Cooling down
Packaging
Storage: dry, dark, cold 18

19. SOLAR
DRYING
Faster
Cheap
Hygienic
&
healthier
Efficient
19

20. Classification of solar dryers and drying
mode
Leon et al., 2002
20

21. 21

22. DIRECT(A),INDIRECT(B),MIXED(C),HYBRID DRIER(D),SOLAR TUNNEL DRIER(E)
E
22

23. Main parts of solar dryers
Drying space
Collector to convert solar radiation into heat
Auxillary energy source(optional)
Means of keeping the drying air in flow
Heat storage unit(optional)
Measuring and control equipment(optional)
Ducts,pipes and other appliances
23
SOLAR POWER METER ANEMOMETER

24. Solar Drying Essentials
• A drying chamber in
which food is dried.
• A solar collector that
heats the air.
• Air flow system.
24

25. Working principle of solar driers
DIRECT SOLAR DRIER
INDIRECT SOLAR DRIER
Sharma et al., 2009
25

26. DRYING RATE CURVE FOR A FOOD PRODUCT
POTENTIAL HEAT TRANSFER MECHANISM IN DRYING 26

27. Bala and Janjai, 2009
CASE STUDY 1
27

28. Location:➢ Bangladesh Agricultural University,Mymensingh
and Silpakom University at Nakhon Pathom,Thailand .
Large scale field level studies were conducted:➢
(Natural convection solar drier and Forced convection solar drier)
Demonstration of:➢
Solar tunnel dryer
Greenhouse solar dryer
Roof integrated solar dryer
Studied the➢ simulated performance of driers
Neural network prediction➢ of performance of dries.
MATERIAL AND METHODS
28Bala and Janjai, 2009

29. Roof integrated solar dryer Greenhouse solar
dryer
Solar tunnel dryer
29
Bala and Janjai, 2009

30. Fig:1.1.Variation of moisture content with time for a typical
experimental run during solar drying of mango
The solar tunnel drying required 3 days to dry mango samples from
78.87% to 13.47% as compared to 78.87% to 22.48% in 3 days in
control. 30
Bala and Janjai, 2009

31. Fig:1.2.Comparison of the moisture contents of chilli inside
the greenhouse dryer with the traditional sun drying method
for a typical experimental run.
The moisture contents of chilli at three different locations in
27 hours of drying in three days.
31Bala and Janjai, 2009

32. Simulated results
Fig:1.3.Observed and simulated air
temperature along the length of the
dryer in drying of chilli.
Fig:1.4.Experimental and simulated
moisture content at the outlet end of
drier during drying of green chilli.
32Bala and Janjai, 2009

33. Neural network prediction
Fig:1.6.Variation of predicted
moisture content and observed
moisture content of jackfruit leather
with drying time.
Fig:1.5.Predicted and observed
values of the moisture content of
chilli
33
Bala and Janjai, 2009

34. CONCLUSION
Pv ventilated solar driers are appropriate for production
of quality dried fruits, vegetables, herbs and spices.
Reduction in drying time and quality products are
obtained compared to natural convection solar drying.
The product obtained from solar drier was superior in
quality than sun dried products.
The neural network prediction of model has been found
very good and can be used to predict the potential of
drier for different locations.
34
Bala and Janjai, 2009

35. SOLAR DRYING OF FRUITS AND
VEGETABLES
• FRUITS: Apples, apricots, grapes, pineapples, banana
(taste great when dried), melon, plums, mangoes, dates
& figs.
• VEGETABLES :Cabbage, broccoli, peppers, herbs,
onions, squash, tomatoes, asparagus, celery, potatoes,
peas, carrots & yams.
35

36. Solar dried products
Fruits• : Mango bars/rolls, Guava bars/rolls, Chikku bars/rolls, Mixed
Fruit bars/rolls, Khatta-Meetha bars/ rolls, Papaya bars/rolls, Apple
bars/rolls, Plum bars/ rolls, Pineapple bars/rolls, Strawberry
bars/rolls, Apricot, Grapes, Banana, and fruit slices.
Vegetables• : Potatoes, Carrot, Tomato, Mushrooms, Bitter gourd,
Onion etc., in the form of powders.
• ƒGreen leafy vegetables: Curry leaves, Spinach leaves,
Fenugreek leaves, Tamarind leaves, Mint leaves, Drumstick leaves,
Coriander leaves, Amaranth leaves, etc., in the form of powders.
36

37. FRUIT BARS AND FRUIT ROLLS PRODUCED USING SOLAR
CABINET DRYERS
Prepared during the peak of the season when fruits are in plenty and➢ cheap
➢ With the cabinet type solar dryer has been able to produce a variety of fruit
bars under hygienic conditions which are clean and nutritious and have a long
shelf life.
Procedure➢ : preparation of fruit pulp which is mixed with appropriate amount
of sugar and glucose (to avoid sugar crystallization), pectin, citric acid and a
preservative such as sodium or potassium metabisulphite.
The formulated fruit pulp is spread in dryer trays at➢ 7 kg/m2 and dried at 55–
60 °C cabinet temperature.
The average drying time to attain a➢ 12 % final moisture content for a two
layer fruit bar is 16 sunny hours.
(Ramakrishna Rao et al. 2005).
Several fruit slices such as
mango,pineapple and papaya
can also be dehydrated
through solar drying
37

38. Abrol et al., 2014
CASE STUDY 2
38

39. MATERIAL AND METHODS
Mangoes and papaya were cut into slices while➢
bananas were made into rings (thickness of 1 ± 0.1 cm)
➢ All these were kept under solar tunnel drier at a
temperature of 60 ± 2 ̊ C for 6 h.
The dried samples of fruits were immediately vacuum➢
packed in high density polyethylene bags and stored at
ambient conditions.
Physico➢ -chemical analysis
Stastistical➢ analysis
39Abrol et al., 2014

40. Fruits TSS (B) Rehydration
ratio
Moisture
content( %)
acidity(%) Reducing
sugars(%)
Total
sugars(%)
Fresh basis
Mango 17.73 ± 0.16 - 79.63±0.45 0.207±0.014 5.08±0.14 11.52±0.37
Banana 23.30 ± 0.16 - 75.57±0.22 0.125±0.002 7.23±0.16 19.22±0.03
Papaya 15.57 ± 0.19 - 94.17±0.31 0.215±0.01 6.15±0.03 8.17±0.04
After drying
Mango 60.00 ± 0.06 3.93 : 1 - 0.953±0.025 26.47±0.03 42.64±0.01
Banana 64.60 ± 0.16 3.14 : 1 - 0.99 ±0.01 38.33±0.02 45.96±0.02
Papaya 60.13 ± 0.09 4.90 : 1 - 0.829±0.013 40.80±0.65 54.27±0.25
Table :2.1.Phisico-chemical analysis of fresh and dried mango,banana and
papaya fruits
All data are the mean ± SD of five replicates 40
Abrol et al., 2014

41. Fruits Ascorbic acid
(mg/100g)
Total caroteniod(mg/100gm)
Fresh basis
Mango 34.67 ± 0.19 6.32 ± 0.34
Banana 20.06 ± 0.16
papaya 68 ± 2.16 5.03 ± 0.33
After drying
Mango 7.59 ± 0.10 30.12 ± 0.14
Banana 5.32 ± 0.18
Papaya 15.13 ± 0.50 26.04 ± 0.10
Table:2.1.Effect of solar drying on antioxidant compounds of mango,
banana and papaya fruits
All data are the mean ± SD of five replicates.
41
Abrol et al., 2014

42. Fig:2.1.Effect of solar drying on total phenols (mg/100 g) of
mango, banana and papaya fruits
42Abrol et al., 2014

43. Fig:2.2.Effect of solar drying on antioxidant activity (%) of
mango, papaya and banana fruits
• Solar tunnel drier results in increase in
TSS,acidity,reducing sugars and total sugars.
• Drying of these fruits reduces the bulk and
maintains quality without altering much in its
functional properties.
• Solar tunnel drier resulted in increase in total
phenols and carotenoids and a decrease in
ascorbic acid,but at overall antioxidant activity
is increased.
• Solar tunnel drying is the least cost effective
and safe method of preserving the quality of
fruits.
43Abrol et al., 2014

44. Mongi et al., 2015
44

45. MATERIAL AND METHODS
• Location: Sokoine University of Agriculture (SUA),
Morogoro, Tanzania and Norwegian University of Life
Sciences (NMBU), Aas Norway
• Plant materials: Mango , banana and pineapple and
tomato .
• Drying equipment: Cabinet direct dryer-CDD, Cabinet
mixed mode dryer-CMD and Hoeinheim Tunnel dryer-
TD.
• Design: CRD
• The samples were analyzed for dry matter, total phenolic
content and antioxidant.
45
Mongi et al., 2015

46. (A) Cabinet direct dryer-CDD, (B) Cabinet mixed mode dryer-CMD
and (C) Tunnel dryer-TD
46
30-55 ̊ C
25-49 ̊ C 60-73 ̊ C
Mongi et al., 2015

47. Table:3.1.Dry matter content (%) of fresh and dried fruits and vegetable
varieties of three solar drying methods.
Data presented as arithmetic means ± SD (n = 3). Means in row with different small letter
are significantly different (p<0.05) between drying methods for the same variety.
47
Mongi et al., 2015

48. Table:3.2.Total phenolic contents (mgGAE/100g DM) of fresh and dried fruits and
vegetable varieties of three solar drying methods
Data presented as arithmetic means ± SD (n = 3). Data in parentheses represent percent recovery
relative to untreated. Means within fruit/ vegetable in row with different superscript letters are
significantly different (p<0.05). 48
Mongi et al., 2015

49. Table:3.4.Ferric Reducing Antioxidant Power (FRAP) (μmol/100 g DM) of fresh and dried
fruits and vegetable varieties of three solar drying
Data presented as arithmetic means ± SD (n = 3). Data in parentheses represent percent recovery relative
to untreated. Means within fruit/vegetable in row with different superscript letter are significantly different
(p<0.05). 49
Mongi et al., 2015

50. CONCLUSIONS
Tunnel dried samples have lower decline in TPC and•
antioxidant activities than cabinet dried samples due to
higher drying temperature and shorter drying rate.
The percentage recoveries of total phenols and•
antioxidant capacities of dried fruits and vegetables
differ according to varieties.
The antioxidant capacities of plants materials including•
fruits and vegetables are strongly depend on the total
phenolic compounds present .
Use of solar tunnel drier in drying and extending shelf•
life of agricultural produces is highly recommended.
50
Mongi et al., 2015

51. PROCESSING OF VEGETABLE PRODUCTS
• The vegetables were washed
thoroughly, blanched at 93 °C
in plain water or in 2 % NaCl
water for 3–4 min and sliced.
• The sliced products were
loaded at 5 kg/m2 and dried in
Solar Cabinet Dryers.
• The time taken for achieving
4 % final moisture was 10–
12 h.
• Dried tomatoes and dried
carrots by this process
retained their bright color.
White onion,
cabbage etc are
widely use for
solar drying
51

52. PROCESSING OF GREEN LEAFY VEGETABLES
Mature leaves such as curry•
leaves, drumstick and mint
were removed from the stem
and washed thoroughly in
water and drained.
The washed leaves were•
blanched for 60 s in a solution
containing 0.1–0.2 %
magnesium oxide at 90 °C to
retain the green color.
• The blanched leaves were
spread in dryer trays at 5–
6 kg/m2.
Drumstick leaves when dried•
under blue filter (simulated
shade drying) retain higher β-
carotene level.
(Bamji, 2008).
52

53. Processing of vegetables in a solar dryer
in arid areas
Nahar, 2008
CASE STUDY 4
53

54. MATERIAL AND METHODS
Vegetables were cut into pieces and loaded in optimally•
tilted dryer in direct and indirect mode.
OBSERVATIONS TAKEN
Air temperature inside the drier1.
Ambient air temperature2.
Solar radiation3.
Initial and final moisture content of the product4.
Efficiency of solar drier is calculated.5.
54
Nahar, 2008

55. Table:4.1.Mean daily solar radiation (MJ m-2) on horizontal and optimally
inclined surfaces.
55
Nahar, 2008

56. Direct mode Indirect mode
56
Nahar, 2008

57. Fresh vegetables 57

58. VEGETABLES INITIAL MOISTURE
CONTENT OF
VEGETABLES(%)
FINAL MOISTURE CONTENT
OF VEGETABLES(%)
TOMATO 95.8 2.2
SPINACH 95.7 2.4
CARROT 93.4 2.6
ONION 89.9 5.9
TURMERIC 87.6 1.3
CORIANDER 89.7 4.7
OKRA 94.0 5.0
FENUGREEK 89.9 0.8
MINT 89.7 2.0
• It takes 20 % more time in drying of vegetables in in-
direct mode.
Table:4.2.Reduction in moisture content of selected vegetables
58
Nahar, 2008

59. CONCLUSION
A optimally tilted type solar dryer can be used both in direct and•
indirect mode for dehydration of fruits and vegetables.
The farmers can dehydrate vegetables when these are available in•
plenty and at low cost.
Dehydrated vegetables can be sold in the off season when prices of•
vegetables are high and farmers can generate more income.
The use of solar dryer will be a great boon for farmers in the•
developing countries.
The efficiency of solar drier was found to be• 17.95%.
59
Nahar, 2008

60. Solar Dehydration of Sliced Onion
Elzubeir, 2014
CASE STUDY 5
60

61. MATERIAL AND METHODS
LOCATION: South China•
Agricultural University ,
Guangzhou, China.
Bulb onions washed and sliced•
manually into 3-mm-thick
rings, which were not blanched
to retain flavor.
Batches of sliced onion, initial•
weight 6 kg and initial
moisture content 83% were
loaded.
Drying• curve,drying
parameters,comparision of
dryers,collector and dryer
data,meteriological data were
recorded. 61

62. Fig:5.1.Variation in relative humidity of the solar system over
time.
62
Elzubeir, 2014

63. Fig:5.2.Drying curve of onion slices over three consecutive 7-h drying
periods in a solar dryer.
• Considerable quantity of moisture was evaporated between the first
and second day of drying.
• The rate of evaporation of water/unit area/time remained constant.
• The rate of diffusion slowed as drying progressed and rate of
evaporation fell.
63Elzubeir, 2014

64. Parameter Value
Inlet air Flow rate(m3/s) 0.05
Temperature(oc) 30.1
Relative
humidity(%)
59.3
Product Initial moisture
content(%)
83
Useful quality(kg) 1.074
Table:5.1.DRYING TEST RESULTS
64
Elzubeir, 2014

65. CONCLUSION
• Drying time of sliced onion could be reduced from 7 to 3 days using
solar heated air compared to open-air sun drying to reach the safe
storage moisture content.
• The solar dryer accelerated drying rate 2.3-fold over open-air sun
drying.
• The area needed for solar drying was only about 25% of the area
required for equal air-drying intensity.
• Dehydration of onion reduces packing costs, eliminates refrigeration
requirements, lowers transportation and storage costs, and provides
food of greater economic value.
65

66. Number of products from various categories
processed through Solar Dryers
66

67. DEVELOPMENT OF SOLAR FOOD
PRODUCT
In the last few• years,solar
dryers are used for the
processing of fruits and
vegetables using solar dryers
for value addition and long
shelf life on a commercial scale
The dehydration process•
requires pre-
treatments,addition of Class II
preservatives to enhance shelf-
life, and fast drying to reduce
the moisture levels.
This process can be•
accomplished with low or zero
energy cost, unlike the
electrical dryers,in solar
powered solar air dryers.
67

68. Employment oppurtunities
• Solar drying is a basis for establishment of an enterprise
within the food processing industry for solar drying of fruits
and vegetables.
• It lay the foundation for youths and women to engage in
small-scale processing enterprises for employment creation.
• Considering the importance of agriculture in national
economy against high post-harvest losses of agriculture
produces and unemployment rate, solar drying seems to
offer hopes for solution.
• It is high time for unemployed youth and women be
empowered on individual or group basis to establish small
and medium enterprises in this sub sector.
68

69. Future thrusts
• There is a need for solar drying technology advocacy in the country
for reducing the alarming postharvest losses.
• More research and fabrication of affordable local tunnel dryer
comparable to the industrial ones are needed.
• Further studies to ascertain shelf life above 6 months including more
parameters are highly recommended.
• Tracking and monitoring performance and establishing feasible
targets of solar drying.
• Manufacturing for improved performance and reduced cost.
69

70. CONCLUSION
Solar drying which is a low❖ -cost food drying technologies can be
readily introduced in food processing sector for value addition of
fruits and vegetables.
The eventual objective of employing these appropriate drying❖
technologies is to reduce spoilage, improve product quality and
overall processing hygiene to significantly improve the agricultural
returns for farmers in appreciation of the hard effort they have
devoted in crop cultivation.
Solar tunnel drying is the cost effective and safe method of❖
preserving the quality of fruits in terms of bioactive components and
nutritional retention.
❖ At the same time, this can be used to promote the application of
renewable energy sources as an income-generating option in the
context of increased cost and shortage of non-renewable energy
sources.
70

71. Thank you for your kind attention...71