madhushree,drying mad
TRANSCRIPT
-
8/4/2019 Madhushree,Drying Mad
1/13
Drying and fermentation
methods of preservationMadhushree.A
MK 819
-
8/4/2019 Madhushree,Drying Mad
2/13
-
8/4/2019 Madhushree,Drying Mad
3/13
Introduction
Drying means the removal of water. It isused for drying under the influence ofnon-conventional energy like sun and
wind. Microorganisms need moisture to grow so
when the concentration of water in thefood is brought down below a certainlevel, they are unable to grow. Hencethrough drying we can preserve the food.
-
8/4/2019 Madhushree,Drying Mad
4/13
Factors affecting the rate of drying:-
Composition of raw material
Size, shape and arrangement of stackingof produce
Temperature as well as humidity and
velocity of air Pressure
Heat transfer to surface.
-
8/4/2019 Madhushree,Drying Mad
5/13
Advantages Drying has some advantages compared to
other methods of preservation: The weight of a produce is reduced to
1/4th to 1/9th its original or fresh weight
and thus the cost of its transport isreduced.
Due to reduction in bulk of the product, itrecords less storage space.
Cost of processing is very low, as lesslabour and no sugar is required.
-
8/4/2019 Madhushree,Drying Mad
6/13
Types of drying
There are three basic types of dryingprocess:
sun drying, solar drying Atmospheric drying including batch and
continuous
Sub-atmospheric dehydration.
-
8/4/2019 Madhushree,Drying Mad
7/13
Steps for drying of fruits andvegetables
1. Fruits/ vegetables(mature and free frominsects and diseases)
2. Washing3. Peeling
4. Preparation5. Blanching6. Spreading on flat wooden trays7. Sulphuring
8. Drying/dehydration9. Sweating10. Packing(air tight container)11. storage
-
8/4/2019 Madhushree,Drying Mad
8/13
Spoilage of dried productsdefects causes prevention
moulding high productmoisture
Reduce watercontent down tooptimum values.Pack in air tightpackages.
infestation Presence in driedproducts of larvaeor insects.
Fumigation ofpacked productsand of package.disinfection by heatof products before
packing.Browning Chemical reactions Reduce as much as
possible watercontent. store atlow temperature.
Reducedreh dration ratio
Too hightem erature in final
Operate inside finaltem erature as
-
8/4/2019 Madhushree,Drying Mad
9/13
Some common driers used for drying are:
Air convention driers
Drum or Roller driers
Vacuum driers
-
8/4/2019 Madhushree,Drying Mad
10/13
Fermentation
Decomposition of carbohydrates byMicroorganisms or enzymes is calledfermentation.
Fermentation of food results in theproduction of organic acids, alcohol, etc.which not only help in preserving the food
but may also produce distinctive new foodproducts.
-
8/4/2019 Madhushree,Drying Mad
11/13
Acetic , lactic and alcoholic are thethree important kinds of fermentation
involved in fruit and vegetable preservation.Some industrial fermentations in fruit andvegetable industries are
a. Acetic acid fermentation(acetic andbacteria)
b. lactic acid fermentation (lactic acidbacteria)
c. alcoholic fermentation(yeasts)
-
8/4/2019 Madhushree,Drying Mad
12/13
Reference:
Fruit and vegetable preservation
principles and practices
--R P Srivastava Sanjeevkumar
-
8/4/2019 Madhushree,Drying Mad
13/13