This PowerPoint summarizes one of the processing of food by heat removal, that is, chilling. Content - 1) Theory 2) Equipments 3) Chill Storage 4) Effects of chilling

2.  Temperature of food is reduced to between -1°C and +8°C.
 Expensive distribution system consisting of chill stores, refrigerated transport, retail chill display cabinets,
etc.
Biochemical & Microbial
changes ↓ ↓
~~ sensory
characteristics &
nutritional properties
Image source: https://doi.org/10.1016/j.tsep.2020.100550
Chilling:

3. 3 categories:
-1°C to +1°C
0°C to +5°C
0°C to +8°C
Chilled Food:

4. 1. Rate of enzymic and microbiological changes, respiration by fresh food are
retarded.
2. Factors affecting shelf life of chilled foods:
I. Part of the crop selected.
II. Condition of the food at harvest.
III. Temperature at different stages.
3. Climacteric fruits - Fruits such as apple, apricot, banana show quick ripening along
with increased ethylene production, ultimately increasing respiration rate.
Fresh foods

5. 4.Chilling injury, at temperatures below specific optimum temperature,
imbalanced metabolite production that then becomes toxic to tissues.
5.Cold shortening, happens when the meat is rapidly refrigerated before
rigor mortis making meat more tough.
6.Sensible heat and heat produced by respiration both need to be
removed.
Fresh foods

6. • Thermophilic and Mesophilic microorganisms prevented.
• Food poisoning.
• Aeromonas hydrophilia, Listeria spp, Yersinia enterocolitica, some strains of Bacillus
cereus, Vibrio parahaemolyticus and enteropathogenic Escherichia coli.
• Factors affecting chilled processed foods:
 Degree of processing.
 The barrier properties of the package.
Processed Foods

7. I. Alternative of “Cook n serve”.
II. Flexibility, time management, no nutritional loss.
III. Divided into 4 classes.
Raw or
uncooked
Mix of cooked
and raw
Cooked and
packaged
REPFEDs
(processed)
I II
III
IV
Cool-Chill systems

8. Mechanical refrigerators
Cool low
pressure Vapor
High pressure
hot vapor
Cool high
pressure
liquid
Cool low
pressure
liquid/gas
Refrigerants:
1. Ammonia
2. Carbon dioxide
3. CFCs (Freon 22)
Other methods of cooling:
1. Hydrocooling
2. Vacuum cooling
3. Scraped surface heat
exchangers
Equipment

9. Cryogenic Systems
 Deposited onto or mixed with food in trays or on conveyors
 Cryogen absorbs the heat from the food and in turn, changes
phase.
 Solid and liquid Carbon dioxide, liquid Nitrogen.
 Batch or continuous chilling.
Equipment

10.  Foods are stored on pallets, racks or hung from hooks.
 Food should be stacked properly such that air is circulated from every
side.
 Stores are cooled by circulating cool air. Temperature, relative humidity
or atmospheric composition can also be controlled.
Chill Storage

11.  Temperature monitoring is very crucial for product safety and
quality management.
 Temperature sensors connected to data logger.
 Air temperature or food temperature can be measured.
 Modifications are possible.
Chill Storage

12.  Chilling Injury
 Lipolysis, Lipid oxidation
 Retrogradation of starch
 Hardening due to solidification of
fats and oils
Effect on Foods

13. migration of oils, syneresis, loss of moisture
Vitamin losses
Apple
Carrot
Lettuce
Potato
Vit-C
0.5
0.6
9.7
10.7
Thiamin
-
-
4.7
1.3
Riboflavin
-
-
5.4
-
Effect on Foods

14.  Clark, S., Jung, S., & Lamsal, B. (Eds.). (2014). Chilling and Freezing of
foods. In Food processing: Principles and applications (2nd ed., pp. 79–
105). John Wiley & Sons.
 Fellows, P. (Ed.). (2000). Chilling. In Food processing technology:
Principles and practice (2nd ed., pp. 379–405). Ellis Horwood.
 Dohmeyer Catalogue(https://twcryo.com/wp-
content/uploads/2018/09/Dohmeyer-Catalogue_opt.pdf)
References: