3. โข Food processing is the transformation of agricultural raw products into food, or of
one form of food into other forms
โข Food processing includes many forms of processing foods, from grinding grain to
make raw flour to home cooking to complex industrial methods used to make
convenient /instant foods
โข Some food processing methods play important roles in reducing food waste and
improving food preservation, thus reducing the total environmental impact of
agriculture and improving food security
Food processing is defined as any procedure that alters food from its natural state, such
as heating, canning, freezing, drying, milling, and fermenting
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5. Processing levels
1. Primary food processing turns agricultural products, such as raw wheat kernels or
livestock, into something that can eventually be eaten
โข This category includes ingredients that are produced by ancient processes such as drying,
separating, sorting and milling grain, and butchering animals for meat
โข It also includes deboning and cutting meat, freezing and smoking fish and meat, extracting
and filtering oils, canning food, preserving food through food irradiation, and candling eggs,
as well as homogenizing and pasteurizing milk
โข Contamination and spoilage problems in primary food processing
โข The term processing is very broad and encompassing many techniques
โข These include threshing/ beating, dehusking, polishing and grinding in case of food
grains
โข To operations such as cleaning, washing, sorting, grading, peeling, blanching and
cutting, drying to fermentation, pickling, pasteurization, emulsification
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6. 2. Secondary food processing
โข Secondary food processing is the everyday process of creating food from ingredients that
are ready to use
โข Baking bread is an example of secondary food processing
โข Fermenting fish and making wine, beer, and other alcoholic products are traditional forms
of secondary food processing
โข Sausages are a common form of secondary processed meat, formed by comminution
(grinding) of meat that has already undergone primary processing
โข Most of the secondary food processing methods known to human are commonly
described as cooking methods
3. Tertiary food processing
โข Tertiary food processing is the commercial production (processed food)
โข These are ready-to-eat or heat-and-serve foods, such as frozen meals and instant noodles
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7. The main objectives of food processing are:
1. Removal of unwanted matter from the food
2. Making food safe for consumption e.g. trypsin inhibitors in soybeans, food toxins such
as aflatoxin
3. Preserve the food by preventing them from spoilage due to microbes
4. Increasing digestibility, most foods are difficult to digest unless they are cooked
5. Enhance flavor, color and taste, e.g. caramelization of sugar
6. Improve texture & consistency e.g. emulsification, aeration, gel formation & increase in
viscosity
7. Enhance the nutritive quality by minimizing nutrient loss or adding nutrient
8. Extending shelf life by dehydration, cold storage, canning & pasteurization
9. Increasing acceptability and availability of ready to eat foods throughout the year
10. Ease of storage, transportation and distribution systems
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9. What is rheology of food?
Rheology describes the flow of materials
๏ผ rheo โ to flow
๏ผ logy โ the study of
โข Is the study of the flow of materials that behave in normal or an
interesting or unusual manner
โข Unusual materials such as sauce, ketchup, mayonnaise, peanut butter,
chocolate, bread dough, dairy products, etc
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10. โข Food is a very complex structured material
โข Food comprises varied biological components
โข It consists of proteins, carbohydrates, fats, fibers, and water
โข All these components have diverse rheological characters
โข The flow and structural behavior of food depend on its components, and the stability of
structured fluids depends on its behavior and other factors
โข An essential aspect of the food industry is to understand food texture and its behavior
โข The behavior of a food product can be determined via its dispersion properties
โข These are the key attributes of foods, which is used to define product quality and
acceptability
โข Determination of food behavior answers some key questions, such as whether a particular
food product will deform easily, flow through a pipe, or work well as a topping
โข Rheological characterization is essential for the development, optimization, and processing
of foods
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12. Newtonian fluids are fluids which exhibit a linear
increase in the shear stress with the rate of shear
E.g. water, clear juices, vegetable oils
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13. Rheological Classification of fluid food
โข With only a few exceptions, most of the food products are non-Newtonian and
possess a variety of internal structures
โข Cellular, viscous and fibrous structures are found in fruits and vegetables, meats
โข All foods contain protein, carbohydrate, or fat-crystal networks
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14. +
K = consistency coefficient
n = flow behavior index
n<1
n=1
n>1
Herschel-Bulkley Model
Non-Newtonian behaviors
+
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15. Liq chocolate
Starch in water
Butter, mayonnaise
Peanut butter, condensed milk
Ketchup
tomato paste
n>1
n<1
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18. โข The transition of thixotropic to rheopectic behavior depending on shear rate of tomato
paste even in tomato juices fortified with soy proteins
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19. Application of Rheology in the Food Industry
Rheology has multiple applications in consideration of food acceptability, food processing,
and food handling
โข Helps in creating a new product
โข Aids in the determination of physical characteristics of fluid and semi-solid foods
โข Assessing the quality of the raw materials to be used for the development of a specific
product, while the quality of the food product is also evaluated at different stages of its
developing process
โข Determining the shelf-life of food products
โข Evaluating the sensory properties of food products
โข Helps in understand food microstructure and texture of food
โข Rheological data helps to develop industrial plant designs that include the selection of
pumps and pipes
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21. Same raw material but different product rheological property
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22. Examples of Application of Rheological Study in the Food Industry
1. Meat products: To evaluate type of breed, meat tenderness or toughness
โข To evaluate effect of pickling, chilling, aging, preservation,
โข For measurement of toughness and compactness of meat and meat products
โข Establishment of quality grade for marketing and export
2. Fruits and vegetables: To evaluate variety of crop
โข For predicting the time and further effects of storage and ripening period on process
โข In prediction of stage of harvesting and stage of maturation
3. Snack foods: To evaluate formula for dough making and paste,
โข For measurement and adjustment of solids content;
โข For measurement of textural properties like crispiness, hardness, softness and other
properties to decide packaging and packing material
โข Helps in predicting shelf-life of product under given storage conditions, pre-treatments
and processing unit operations
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23. 4. Confectioneries: To evaluate the quality of raw material
โข To optimize the processing parameters
โข To decide the ingredient varieties to be used
โข For measuring properties like thickness of coating, chewiness, elasticity,
brittleness and shelf life of product
5. Bakery: To evaluate dough consistency, adsorption of water
โข To estimate floor time and rise time
โข Effect of additives; prediction of shelf life
6. Dairy products: To evaluate the effect of ingredients i.e. creaming in fat-free dairy
products
โข For inclusion of fat mimic products by using whey protein concentrate
โข Desired quality of mozzarella, cottage, hard, cheddar or others
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24. Types Of Rheometers:
โข Capillary Rheometer
โข Extensional Rheometer
โข Torque Rheometer
โข Interface Rheometer
Rheometers and viscometers have wide and varied applications in the material science and chemical industries
Types Of Viscometers
โข Rotational viscometer
โข Vibrational viscometer
โข Falling piston viscometer
โข Falling sphere viscometer
โข Capillary tube viscometer
Instrument used to measure the way in which a liquid,
suspension or slurry flows in response to applied forces
Rheometer can measure rheological properties, fluidโs internal
flow resistance and flow properties of liquids
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