Dairy Chemistry

1. Physical Chemistry of Milk                                                                              3 (2 + 1)

Constituents and gross composition of milk of different species and breads of milch animals, Colloidal State : Distinction between true and colloidal solution, lypophilie and lypophobic solution, properties of colloidal system. Properties of colloidal systems, Gels – Their formation and properties. Milk as a colloidal system and its stability. Elementary idea about emulsion. Density : Density and specific gravity, pyknometer method, hydrometer lactometer. Density and specific gravity of milk, effect of various processing variables on the density  and specific gravity of milk. Liquid State : Surface tension, surface energy interfacial tension. Surface tension of mixtures. Surface tension of milk and the factors affecting it. Viscosity – Definition of viscosity, Newtonian and non- Newtonian liquids, stokes law, influence of temperature and concentration of solute on viscosity. Viscosity of milk, evaporated milk and condensed milk. Refractive index. Colligative Properties of Dilute  solution : Vapour pressure, Raoults Law, Depression of freezing point, Elevation of boiling point. Freezing  Freezing point and boiling point of milk. Osmosis and Osmotic pressure. Inter-relation of colligative  properties. Aqueous solution of Electrolytes : Electrolytes : non-electrolytes, ionic mobility, electrical conductance, Ostwald Dilution Law, Kohlrawsch  Law, Electrical conductance of milk. Ionic Equilibria : Dissociation of water, ionic product of water concept of pH and POH and their scale. Acids and bases : Bronsted Lewis concepts of acids and bases, dissociation constants of acids and bases. Salt-their hydrolysis. Buffer solutions. Derivation  of Henderson – Hasselbach equation and it application, buffer capacity and buffer index, milk as a buffer system. Equilibrium of electrolytes. pH indicators. Oxidation-Reduction : Redox potential, Nernst equation, electrochemical cells. Hydrogen, glass and calomel electrodes. Redox system of milk. Nuclear Chemistry : the nature of isotopes, radio isotopes. Half life period of radio isotopes. Some of the important radio isotopes. Occurrence of radio nuclide in milk and milk products. Molecular Spectroscopy : The spectrum of electro magnetic radiation, the laws of Lambert and Beer, visible, and ultra-violet Spectroscope. Mention of mass, NMR spectroscopy.

 

Practical : Determination of density and specific gravity of milk using pyknometer, hydrometer and lactometer. Determination of viscosity of milk using Ostwald viscometer. Determination of surface tension of milk using Stalagmometer. Interfacial tension between water-oil phase. Determination of freezing point of milk. Preparation of a buffer solution. Determination pH of buffer solution and milk electrometrically. Determination of acidity of milk electrometrically. Determination of electrical conductance of milk. Determination of redox potential of milk. Coagulation of milk using electrolytes. Determination of refractive index of skim milk and whey. Titration of amino acid in the presence and absence of formaldehyde. Determination of PKa1  PKa2 and PL. Verification of Lambert Beer law.

 

2.  Chemistry of Milk                                                                                            3 (2 + 1)

Definition and structure of milk, factors affecting composition of milk, Nomenclature and classification of milk proteins, Casein : Isolation, fractionation and chemical composition, physico-chemical properties of casein, Whey proteins : Preparation of total whey proteins : α-Lactalbumin and β- Lactoglobuline. Properties of α-Lactalbumin and β- Lactoglobuline, Immmunoglobulin and other minor milk proteins and non proteins nitrogen constituents of milk, Hydrolysis and denaturation of milk proteins under different physical and chemical environments, Estimation of milk proteins using different physical and chemical methods, Importance of genetic polymorphism of milk proteins, Milk enzymes with  special reference to lipases, Xanthine Oxidase, phosphates, proteases and lactoperoxidase, Milk carbohydrates their status and importance. Physical and chemical properties of lactose, Sugar amine condensation, amadori re arrangement, production of hydroxyl methyl furfural (HMF), Processing related degradation of lactose, Definition, general composition and classification of milk lipids. Nomenclature and general structure of glycerides, factors affecting  the fatty acid composition. Milk phospholipids and their role in milk products, Unsaponifiable mater and fat soluble vitamins, Milk Salts : Mineral in milk (a) major mineral (b) Trace elements, physical equilibria among the milk salts and Milk contact surface and metallic contamination.

 

Practical : Sampling techniques of chemical examination of milk. Determination of pH and titratable acidity of milk. Determination of fat in milk by different methods. Determination of total solids and solids not fat  in milk. Determination of total milk proteins by Kjeldahal method. Determination of casein, whey proteins and NPN in milk. Estimation of alkaline phosphatase and lipase in milk. Determination of lactose in milk. Determination of chloride in milk. Determination of temporary and permanent hardness of water. Estimation of available chlorine from bleaching powder.

 

3.  Chemical Quality Assurance                                                                           3 (2 + 1)

Importance of chemical quality control in dairy industry ; setting up quality control laboratories and testing facilities : mobile testing laboratories. Sampling procedures ; labelling of samples for analysis: choice of analytical tests for milk and milk products for chemical analysis; instrumental methods of analysis. Calibration of dairy glassware including butyrometer, pipettes, burettes, hydrometers, lactometers and freezing point thermometer. Preparation and standardization of reagents required in the analysis of milk and milk products. Application of PFA, AGMARK, BIS and codex related to dairy products for the quality control of milk and milk products. Preservatives, neutralizers and adulterants in milk and milk products and their detection.  Accreditation of analytical laboratories ; hazard analysis and critical control points (HACCP). Prediction of shelf life behaviour of milk and milk products. Milk contact surfaces, metallic contamination, environmental contaminates such as pesticides, antibiotics, heavy metals in dairy products: methods of estimation. Soft and hard water, temporary and permanent hardness, softening of hard water.

 

Practical : Calibration of dairy glassware such as pipette, burette, volumetric flaska, hydrometer, butyrometers. Preparation and standardization of dairy reagents such as acids, alkalies, sodium thiosulfate, silver nitrate, Fehlings. EDTA solutions etc. Detection of adulterants, preservatives, and neutralizers in milk and milk products Chemical analysis of permissible additives used in milk and milk products. Chemical analysis of detergents and sanitizers. Preparation and testing of Gerber sulphuric acid used in fat determination. Testing the amyl alcohol used for fat determination. Analysis of market samples of milk and milk products.

 

4. Food Chemistry                                                                                                            3 (2 + 1)

Water : Water binding and chemical reactions mediated by water. Food Proteins: Classification, physic-chemical properties, reaction involved in processing, Reactions with alkali, Enzyme catelysed reactions involving hydrolysis and proteolysis, Theories of formation of texturised proteins. Lipid : reactions involved during deep frying of food viz., autoxidation of saturated acyl lipids and polymerization. Lipoprotein and membrane ; definition, classification and involvement in the formation of biological membranes. Unsaponifiable matter contents in various fats and oils. Edible fats and oils , classification and chemical composition. Carbohydrates: Legumes, jellies polysaccharide viz. Linear, branched and modified. Properties and utilization of common polysaccharides viz. Cellulose, glycogen, hemicelluloses and pectin. Enzymatic degradation of polysaccharides, viz. Agar, alginate. Carrangeenan, gums and starch. Production of dextrans and malto dextran. Food enzymes: Hydrolases and lipases, utilization in food industry, effect of inhibitors, pH and temperature. Minerals in foods : Main Elements, trace elements in eggs, cereal and cereal products, vegetables and fruits. Aroma compounds in foods : threshold value, off flavours. Food additives : Vitamins, amino acids, minerals. Aroma substance flavour enhancers-monosodium glutamate, nucleotides. Sugar substitutes,  sorbitol. Sweeteners-saccharin, cyclamate. Food colours. Anti-nutritional factors and food contanimant : Toxic-trace elements, radio nuclides. Cereals and cereal products : Individual constituents, like proteins, lipids, carbohydrates and vitamins in cercals flour and their relationship in dought making. Type of flours, bread making and non-bread making : chemical composition, influence of additives/minor ingredients on baking properties. Physic-chemical changes during baking. Legumes : Classification composition and physic-chemical  properties. Vegetables and fruits: Classification, general composition, chemical changes during ripening and storage. Jams, jellies and pickles : Classification, composition and preservation. Beverages: Classification, Coffee, /Tea and Cocoa-gradation, composition, chemical changes during processing, volatile compounds. Preservation of Foods: General principles of food preservation, chemical preservation, preservation through irradiation.

 

Practical : Determination of moisture, acidity and gluten content  in flour . Determination of total ash and acid insoluble ash in flour. Determination of starch in flour. Determination of total nitrogen in cereal products. Determination of acidity and vitamin C in citrus fruits. Analysis of tomato ketchup for total solids, acidity, ash and salt. Determination of total sugar in tomato ketchup. Determination of total ash and alkalinity of soluble ash in tea. Determination of water extractive in tea leaves. Determination of presence of Chicory in coffee powder. Determination of reducing sugars in Jam. Determination of iron in infant foods.

 

5. Biochemistry and Human Nutrition                                                               3 (2 + 1)

Biochemistry : Enzymes Ribozymes, isozymes, allosteric enzymes, zymogens, regulatory, Classification and mechanism of enzyme action, Factors affecting rate of enzyme catalyzed reaction, enzyme inhibition, enzymes coenzymes and co-factors immobliation of enzymes, Nucleic acids and Bioenergetics : Structure and function, definition and composition. Structure of RNA & DNA- Anabolism and Catabolism of carbohydrates, lipids and proteins. Vitamins and Hormones : Structure and functions, general description. Relationship between vitamins and hormones in terms of their biological role. Elementary knowledge of milk synthesis in mammary gland.

Human Nutrition : Theory and definition, scope of nutrition : Functions of the various nutrients in body. Digestion, absorption and assimilation of nutrients. Comparative requirements and nutritional requirement of different age groups (WHO and ICMR standard) methods of evaluation of nutritive value of foods Nutritional value of cow, buffalo and human milk. Milk intolerance : lactose deficiency and protein hyper sensitivity , Safety aspects of food additives, toxic elements, radionuclides, pesticides and antibiotic residues in milk and  milk products. Institutional feeding of workers. Planning and implementation of national food and nutrition policies and programme. Regulatory aspects of nutrition, IDA code on nutrition, nutrition facts under NLEA, Nutrient descriptors, serving size and nutritional claims.

 

Practical : Biochemistry Estimation of alkaline phosphatase and the effect of temperature and pH on its activity. Estimation of catalases and the effect of temperature and pH on its activity. Determination of the Michealis constant of an enzyme. Estimation of RNA by colorimetric method Estimation of DNA by colorimetric method. Measurement of proteolysis. Lipolysis, Amylase activity. Estimation of vitamin ‘A’ in ghee. Estimation of ascorbic acid in milk. Estimation of vitamin D in milk. Estimation of proteins by Lowry’s method. Buret method. Estimation of Lipids and Lipids analysis by TLC. Estimation of cholesterol in milk. Estimation of denaturation of proteins in heated milk by dye binding method. Estimation of HMF content in food.

 

6. Organic Chemistry                                                                                           3 (2 + 1)

 Hydrogen bonding : Concepts of hydrogen bounding inter and intra molecular hydrogen bonding in alcohol, carboxylic acids and other molecule. Hydrophobic interactions : Elementary idea of hydrophobicity  and its importance in the structure of proteins. Alcohols: important properties of mono, di and trihydric alcohols (Glycol and Glycerol).
Aldehydrs and Ketone : Reactions of aldehydes and ketones. Importance of carbonyl compuntds in food flavours. Carboxylic acids: Ionization constant and strength of carboxylic acids. Important reactions of carboxylic acid, Derivatives : Esters, Amides, Lactones their preparation and reactions. Amines : Basic character of amines, important reactions. Phenols: Acidic character of phenols and effect of nuclear subsituents  on it. Reactions in phenols. Substituted carboxylic acid : important reactions of halogen substituted, Keto and Hydroxy acids. Zwilter-ion forms, its properties viz. Melting point and volatility. Amino acids and peptides : Synthetic and natural amino acids General properties of amino acids. Definition and classification of proteins. Primary, secondary, tertiary and quaternary structure of Proteins. Carbohydrates : Definition, Classification and isomerism. Derivation of structure of Glucose, open chain and ring structure, evidences for ring structure stereochemistry and stability of anomers. Reactions of monosaccharides. Fatty acids and Lipids : Definition and classification. Important reaction of fatty acids (saturated and unsaturated) Structure and properties of Neutral lipids, phospholipids and cholesterol.

 

Practicals :  Systematic identification of Organic Compounds : aliphatic and Arimatic character, Instauration, Detection of elements (Nitrogen, sulphur and Halogens), Detection of functional groups (Alcoholic, Phenolic, Carboxylic, Carbonyl, Aldehyde, Ketonic esters, amino, Amide, Nitro etc. ). Preparation of derivatives : Dinitrophenylhydrazone, Oxime and Osazone. Qualitative test for amino acids and Proteins : Biuret test, Million’s test, Nitroprusside  Test, Ninhydrin test, Xantho proteic test, Hopkin’s cole reaction. Detection of carbohydrates (reducing & non reducing sugars) by : Molisch/Orchnol/Resoreinol/ Silvermirror test. Detection of lipids and phospholipids.