Transcript Food Processing and Preservation

Ch.1 Food Processing and
Preservation
Prepared by:
Mohammed Sabah
Course Contents
(description)
In this course we examine the scientific methods of food
processing, including the methods of fermentation, dehydration,
cooling and freezing, the use of high temperature and radiation
and the use of food additives. The practical part of this course
comprises applications of some processing methods on local
foods.
Course Objectives
 Showing the methods to extend the shelf life to allow time for
distribution, sales and home storage.
 How to increase variety in the diet by providing a range of
attractive flavours, colours, aromas and textures in food (collectively
known as eating quality, sensory characteristics or organoleptic
quality); .
How to provide the nutrients required for health (termed
nutritional quality of a food).
How to generate income for the manufacturing company.
 Defining the technology and theories for all units operations that
used in food industries
After completing this course, the student should be able to:
1- Explain how the different food constituents affect the properties of
foods.
the
2- Explain the concept of "unit operations" in the food industry, and list the unit
operations involved in the production of foods.
3- Appreciate the significance of food quality as a concept, and be aware of the
food standards, and quality factors as to how they are evaluated, and their
significance in formulating his decision of acceptance or rejection of a food.
4- Choose the right method and equipment for the preservation and processing
of the various foods with the highest sensory, nutritional, and sanitary quality
for the longest possible time.
5- Acquire the skill for producing and preserving some common foods, and
identify the most important aspects of their processing and preservation.
Textbook and References
(Online Resources)
Main Book
 Karel. M., D.B. Lund. 2003. Physical Principles of Food
Preservation Principles and Practice, 2th Ed., Marcel Dekker,
INC. New York (text book).
Other referense
Hui. Y. H. 2006. Handdbook of Food Science Tecknology and
Engineering , 1th Ed. Published by Taylor & Francis. (CRC), New
York.
lecture topics
week
Chapter 1: Introduction, food science as a discipline unit 1
operations concept, material handling , cleaning , separating,
disintegration , mixing, heat exchanging , evaporation , drying,
forming , packaging, controlling
Chapter 2: Water Activity and Food Preservation
2-3
Water activity concept, dehydration & solar drying , effect on
food properties, drying methods, effect on nutritional value of
foods.
Chapter 3: Fermentation
3-4
As a process, fermentation consists of the transformation of
simple raw materials into a range of value-added products
by utilizing the phenomena of the growth of
microorganisms and their activities on various substrates.
Chapter 4: Dehydration
5-6
Dehydration (or drying) is defined as ‘the application of heat under
controlled conditions to remove the majority of the water normally
present in a food by evaporation.
Chapter 5: Pasteurization
7-8
Pasteurization is a relatively mild heat treatment, in which food is heated
to below 100 ºC. it is used to minimize possible health hazards from
pathogenic micro-organisms and to extend the shelf life of foods for
several days.
Chapter 6. Blanching food
Blanching serves a variety of functions, one of the main ones being to
destroy enzymatic activity in vegetables and some fruits, prior to further
processing by heat.
9-10
Chapter 7. Heat processing using hot oils (Frying)
Frying is a unit operation which is mainly used to alter the eating quality
of a food. A secondary consideration is the preservative effect that
results from thermal destruction of micro-organisms and enzymes, and a
reduction in water activity at the surface of the food (or throughout the
food, if it is fried in thin slices)
Chapter 8. Irradiation
10-11
Ionizing radiation takes the form of -rays from isotopes or, commercially to a
lesser extent, from X-rays and electrons. It is used to preserve foods by
destruction of micro-organisms or inhibition of biochemical changes.
11-12
Chapter 9. Freezing
Freezing is the unit operation in which the temperature of a food is reduced below
its freezing point and a proportion of the water undergoes a change in state to form
ice crystals. The immobilisation of water to ice and the resulting concentration of
dissolved solutes in unfrozen water lower the water activity (aw) of the food
12-13
Chapter 10: Chilling
Chilling is the unit operation which is used to reduce the rate of biochemical and
microbiological changes, and hence to extend the shelf life of fresh and processed
foods. It causes minimal changes to sensory characteristics and nutritional
properties of foods and, as a result, chilled foods are perceived by consumers as
being convenient, easy to prepare, high quality and ‘healthy’, ‘natural’ and ‘fresh
14-15
Chapter 11: Food Packaging
It is the outer layer of a object to keep the inside protected. such as food are
wrapped in plastic to keep germs out
1.Introduction
• Food processing is the set of methods and techniques used to
transform raw ingredients into food or to transform food into other
forms for consumption by humans or animals either in the home or
by the food prosessing industry.
• Food preservation is the process of treating and handling food to
stop or slow down spoilage (loss of quality, edibility or nutritional
value) and thus allow for longer storage.
Food processing methods
• Removal of unwanted outer layers, such as potato
peeling or the skinning of peaches.
• Chopping or slicing e.g. diced carrots.
• Liquefaction, such as to produce fruit juice
• Fermentation e.g. in yogurt
• Emulsification
• Cooking, such as boiling, broiling, frying, steaming or
grilling
•
•
•
•
Deep frying
Baking
Mixing
Addition of gas such as air entrainment for bread or
gasification of soft drinks
• Spray drying
• Pasteurization
• Packaging
Preservation
• Add heat
• Remove heat
• Remove water
• Reduce pH
• Add preservatives
• Fermentation
• Packaging
The major aims of the food processing and preservation
activities are to:
• Extend the shelf-life of food
• Increase the organoleptic (flavor, color, texture) quality of
food
• Provide food with the nutrients required for enhancing good
health
• Help build communities and generate income for the farmers
and manufacturers
Food processing divided into:
• Unit operations combination of procedures to
achieve the intended changes to the raw materials.
• Unit operations are grouped together to form a
process. The combination and sequence of
operations determines the nature of the final
product.
• Unit operations that take place at ambient
temperature and involve minimum heating of foods
• operations that heat foods to extend the shelf life or
to alter the eating quality
• operations that remove heat from foods to extend
the shelf life with minimal changes in nutritional
qualities and sensory characteristics
Consumer demand for foods
• fewer synthetic additives,
• fewer changes during processing.
• ‘healthy’ or ‘natural’ image
• This demands effect on food processing industry to
launch food products:
 Free from synthetic additives
 low-fat,
 sugar-free
 low-salt
 Supplemented with vitamins, minerals and probiotic
cultures
 Organic products
Motivation and changes of food industry
• improved quality assurance and quality
control
• reduces production costs
• Reduce wastage
• increases production efficiency,
• automation
• Heat has important influences on food processing in a
number of respects:it is the most convenient way of extending the shelf life of
foods by destroying enzymic and microbiological activity,
or by removing water to inhibit deterioration; it changes
the nutritional and sensory qualities of foods; and
generation of heat is a major processing cost.