Food Engineering - AgriMoon

1 food Engineering Sunil M. Patel food Engineering Course Developers Sunil M. Patel Department of Dairy Engineering AAU, Anand This Book Download From e-course of ICAR Converted By: Course Outline SN Lesson Page No Module 1. Rheology of Foods 1 Rheological Properties of Foods 1-4 2 Rheology of Processed Foods 5-9 3 Rheological Methods 10-11 4 Measurement of Rheological Parameters 12-14 5 Rheological Properties of Fluid Foods 15-19 6 Rheological Properties of Granular Foods and Powders 20-23 7 Properties of Solid Foods 24-28 8 Viscoelastic Models 29-33 9 Measurement of food Texture 34-37 10 Instruments for Rheological Measurement 38-39 Module 2. food Freezing 11 Thermal Properties of Frozen Foods 40-44 12 Prediction of Freezing Rates 45-46 13 Planck s Equation and related Problems 47-49 14 Problems on Planck s Equation 50-53 15 Neumann s Problems and Tao solution 54 16 Design of food Freezing Equipment 55-61 17 Study of Batch Ice cream Freezer 62-64 18 Study of Continuous Ice cream Freezer 65-68 19 Care and Maintenance of Ice Cream Freezers and Hardening Cabinets: 69-71 20 Design Problems on Batch Freezers 72-74 21 Design Problems on Continuous Freezers 75-76 22 Air Blast Freezers 77-80 23 Plate Freezers and Immersion Freezers 81-83 24 Storage of Frozen Foods 84-92 Module 3.

2 food Dehydration 25 Water activity and mass transfer 93-96 26 The Stages of Drying 97-99 27 Estimation of Drying Time for food Products 100-102 28 Constant rate period and falling rate period dehydration 103-104 29 Diffusion Controlled Falling Rate Period 105-106 30 Heat and Mass Balance of Continuous Dryers 107-109 31 Fixed Tray Dehydration 110 32 Cabinet drying 111-112 33 Tunnel Drying 113-115 34 Problems on Drying 116-126 Module 4. Freeze Dehydration 35 Principle of Freeze Drying 127-129 36 Heat And Mass Transfer In Freeze Dehydration 130-133 37 Industrial Freeze Dryers 134-136 38 Calculation of Freeze Drying Time 137-140 Module 5. food Processing Equipments and Unit Operations 39 Equipment for pulping 141-145 40 Fruit Juice Extraction 146-152 41 Blanching 153-158 42 Dehulling 159-164 43 Size reduction 165-171 44 Distillation 172-175 Module 6.

3 Recent Trends in food Processing 45 Microwave Processing 176-180 46 Irradiation, Pulsed Electric Field, Ultrasound Processing, Nano technology 181-183 47 High pressure processing 184-187 48 Microfluidization 188-192 food Engineering 1 Module 1. Rheology of Foods Lesson 1. Rheological Properties of Foods INTRODUCTION Rheology is the science of flow and deformation of matter and describes the interrelation between force, deformation and time. It is the study of the manner in which materials respond to applied stress or strain. The term comes from Greek rheos meaning to flow. The science of rheology is only about 76 years of age. It was founded by two scientists meeting in the late 20s and finding out having the same need for describing fluid flow properties.

4 The scientists were Professor Marcus Reiner and Professor Eugene Bingham. Sensory evaluation as a scientific discipline represents a very unique technique that harnesses human behavioral instincts of perception, learning, cognition, psychophysics and psychometric for the evaluation of foods. The textural properties of a food are that group of physical characteristics that are sensed by the feeling of touch, are related to the deformation, disintegration and flow of food under application of force. Textural characteristics are an important factor in the overall quality of many food products. Unless these quality attributes meet the standards which the consumer expects, the product will be rejected regardless of its nutritional value.

5 PSYCHORHEOLOGY Psychorheology of foods is the scientific study of man s perception of texture of foods. It may be devided into two major areas (i) Qualitative psychorheology work concerns the attributes of texture to which man responds, the structure of his mental lexicon of texture descriptors and the cluster of similar meaning texture descriptors. (ii) Quantitative work may consider mathematical relations between pairs of texture descriptors, or functions relating one or several subjective textural properties. The major thrust of quantitative psychorheology has been to ascertain the class of functions relating mechanical to subjective properties and through experimentations to quantify the parameters of those functions.

6 Now it is well established that the psychorheological models are important in texture studies. IMPORTANCE OF RHEOLOGY Study of rheological properties is important in food science due to its utility in food processing operations and sensory characteristics. It gives information about the microstructure of a food . Rheology properties are manifestation of the rate and nature of the deformation that occurs when a material is stressed. These parameters can be used to predict how the fluid will behave in a process and in determining the energy requirement for transporting the fluid from one point to another in processing plant. Rheologyical parameters are also useful in defining the quality attribute of food products.

7 food Engineering 2 Rheology is very important in the following area in the food industry (i) Mixing-Two or more material are blended manually or mechanically. (ii) Flow Control-Flowablity of material varies from very thin to highly viscous. (iii) Dispensing- Material comes out easily or with difficulty. (iv) Settling/ Floating Material with different specific gravity either settle or float depending on viscosity of the material. (v) Pumping- Liquids or semi-solids are forced through the pipe (vi) Coating- Spreading of one material as thin layer over other. (vii) Cleaning Soil removal from the surface of the equipments and pipeline. (viii) Control of processing parameters- velocity, magnitude of pressure drop, piping design, pumping requirement for fluid transport system, power requirement of agitation, power requirement of mixing and blending, amount of heat generated during extrusion etc.

8 (ix) Influence on unit operations Heat transfer, Mass transfer, mixing, grinding, sedimentation, separation, filtration, evaporation and drying etc. (x) Study of rheology helps to select proper method of harvesting and sorting of raw materials (xi) Study of rheology helps to select proper ingredients to manufacture processed foods. (xii) Study of rheology helps to select proper technology/equipment to manufacture processed foods with desirable sensory and rheological properties. (xiii) Study of rheology helps in newer product development ( dietetic ice cream, paneer, low fat mozzarella cheese etc.) (xiv) Study of rheology helps in designing processing equipment, packaging machines, transportation system etc.

9 (xv) Study of rheology helps to improve sensory quality of the products (xvi) Study of rheology helps in marketing the products. Importance of Rheological Studies in Dairy Industry Rheological studies of dairy products are important at a juncture when the need for modernizing the manufacturing and marketing of Traditional Indian Dairy Products (TIDP) is being emphasized in India. It helps to evaluate ingredient for potential contribution to creaminess in fat-free dairy products. Rheological studies also helps to evaluate quality of cheese and applicability of cheese for various applications like suitability for pizza topping. Further, the Bureau of Indian Standards (BIS) is actively considering the views of describing the food products based on their structure and rheology.

10 Most fluid foods including dairy fluids like cream, ice cream mix, stirred yoghurt and liquid infant foods shows complex flow behaviour at different stages of processing and it requires study of its flow behaviour for better control over the processing parameters. Viscoelastic characteristics of foods are of great importance to the manufacturer, the trade and the consumers as these properties affect food Engineering 3 'eating quality', usage properties such as ease of cutting, spreading and melting characteristic as well as handling and packaging characteristics. Recent developments in rheological instruments hold out a definite scope for generating valuable informations on the basic rheological parameters of these products.