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2nd Sem Food Science Notes

Effect of factors like heat, acid, alkali on food constituents: Food Processing

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Last updated: 8 July 2023

Heat

High temperatures destroy harmful micro-organisms due to the coagulation of cellular proteins and inactivation of enzymes required
For the metabolism of these organisms. Heat also causes dehydration which makes water unavailable for microorganisms to survive in.

Acids (Acetic Acid, Citric Acid)

Acids reduce the ph. level of foods below the growth range and also Inhibit metabolic activity.

Alkali

It causes high osmotic pressure causing plasmolysis (breakdown of cell walls) of cells. It dehydrates food by drawing out water and dehydrates microbial Cells. It ionizes to yield chlorine which is harmful to microorganisms. It reduces the solubility of oxygen in the moisture . It also interferes with the activity of proteolysis enzymes

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Syllabus BHM117

01 Definition and scope of food science

  1. It’s inter-relationship with food chemistry, food microbiology and food processing.

02 Carbohydrates

  1. Introduction
  2. Effect of cooking (gelatinisation and retrogradation)
  3. Factors affecting texture of carbohydrates (Stiffness of CHO gel & dextrinization)
  4. Uses of carbohydrates in food preparations

03 Fat & Oils

  1. Classification (based on the origin and degree of saturation)
  2. Autoxidation (factors and prevention measures)
  3. Flavour reversion
  4. Refining, Hydrogenation & winterisation
  5. Effect of heating on fats & oils with respect to smoke point
  6. Commercial uses of fats (with emphasis on shortening value of different fats)

04 Proteins

  1. Basic structure and properties
  2. Type of proteins based on their origin (plant/animal)
  3. Effect of heat on proteins (Denaturation, coagulation)
  4. Functional properties of proteins (Gelation, Emulsification, Foamability, Viscosity)
  5. Commercial uses of proteins in different food preparations(like Egg gels, Gelatin gels, Cakes, Confectionary items, Meringues, Souffles, Custards, Soups, Curries etc.)

05 Food Processing

  1. Definition
  2. Objectives
  3. Types of treatment
  4. Effect of factors like heat, acid, alkali on food constituents

06 Evaluation of Food

  1. Objectives
  2. Sensory assessment of food quality
  3. Methods
  4. Introduction to proximate analysis of Food constituents
  5. Rheological aspects of food

07 Emulsions

  1. Theory of emulsification
  2. Types of emulsions
  3. Emulsifying agents
  4. Role of emulsifying agents in food emulsions

08 Colloids

  1. Definition
  2. Application of colloid systems in food preparation

09 Flavour

  1. Definition
  2. Description of food flavours (tea, coffee, wine, meat, fish spices)

10 Browning

  1. Types (enzymatic and non-enzymatic)
  2. Role in food preparation
  3. Prevention of undesirable browning