Milk Quality

Milk has played a major contribution to the human diet in many different countries across the world since the dawn of time. The dairy cow was domesticated over 6000 years ago, she was the object of worship in the Middle East 2000 years before Christ, and milk and milk products are mentioned more than 50 times in the Bible. Milk and dairy products have become a major part of the human diet in many countries. It is not surprising therefore, that over many years considerable attention has been paid to improving the quality of milk. We have worked to improve the yield, the compositional quality and the hygienic quality, and have striven to minimise the level of contaminants which can find access to this, perhaps our most natural, unrefined and highly nutritious foodstuff. The chain of people involved in the milk industry extends from milk production-farmers, veterinarians and farm advisors-through transport to processing-quality controllers, manufacturers-and on to retailers, legislators, nutritionists, dairy educators and consumers. All will be interested in the quality parameters of milk which are reg- ularly measured for commercial reasons, for trade, for legal requirements and for reasons of nutrition.

Table of Contents:
1 World milk production.- 2 Milk production: Factors affecting milk composition.- 2.1 Introductio.- 2.2 Synthetic and secretory tissues of the mamary gland.- 2.3 The initiation and establishment of lactation.- 2.4 The milk ejection reflex.- 2.5 Effect of breed on milk composition and yield.- 2.6 Role of genetics in milk production.- 2.7 Effect of environment on milk composition and yield.- 2.8 Dairy cattle nutrition and its influence on milk yield and composition.- 2.9 The effects of milking management practices on milk quality.- 2.10 Influence of age and stage of lactation on milk component yield 22 References and further reading.- 3 Mastitis and milk quality.- 3.1 Introduction.- 3.2 Causative organisms.- 3.3 Contagious and environmental pathogens.- 3.4 Inflammation.- 3.5 Compositional changes.- 3.6 Milk losses.- 3.7 Impact on dairy products.- 3.8 Control of mastitis.- 3.9 Measurement.- 3.10 Summary 37 Further reading.- 4 Hygienic quality.- 4.1 Milk production, plant cleaning, on-farmstorage and collection of milk.- 4.2 Types of bacteria.- 4.3 Cooling and storage of milk on the farm.- 4.4 Collection, delivery and reception of milk.- 4.5 Delivery and storage prior to processing 47 4.5.1 Storage of milk prior to processing.- 4.6 Importance of hygienic quality of milk.- 4.7 Measurement of the hygienic quality of milk.- 4.8 The future.- 4.9 Sampling, storage, preservation and transportation of samples 55 4.9.1 Sample transport and preservation.- References and further reading.- 5 Adulteration of milk.- 5.1 Introduction.- 5.2 Extraneous water.- 5.3 Freezing point test for detecting adulteration.- 5.4 Sources of contamination by extraneous water.- 5.5 How to avoid getting water into milk at the farm.- 5.6 Control of extraneous water through payment schemes.- 5.7 Other sources of adulteration.- References and further reading.- 6 Compositional quality.- 6.1 Composition of milk.- 6.2 Measurement of total solids in milk.- 6.3 Measurement of the solids-not-fat (SNF) of milk.- 6.4 Major constituents.- 6.5 The use of instruments in assessing compositional quality.- 6.6 Dairy herd improvement (DHI) and quality payment laboratories.- 6.7 Quality payment systems for milk.- References and further reading.- 7 Milk from sheep and goats.- 7.1 Introduction.- 7.2 Milking practices.- 7.3 Compositional quality.- 7.4 Measuring cow’s milk in sheep’s or goat’s milk products.- 7.5 Instrumental methods of analysis.- References and further reading.- 8 The impact of raw milk quality on product quality.- 8.1 Introduction.- 8.2 Compositional quality.- 8.3 Opportunities for manipulation of compositional quality.- 8.4 The effect of raw milk hygienic quality on product quality.- 8.5 Animal health.- 8.6 Physical handling of milk.- 8.7 Taints and contaminants.- 8.8 Pasteurised milk and cream.- 8.9 UHT products.- 8.10 Cheese.- Further reading.- 9 Processed milk.- 9.1 Introduction.- 9.2 Heat treatments.- 9.3 Quality control of heat-treated milks.- 9.4 Milks of modified compositionalquality.- 9.5 Compositional quality of fluid milk products.- References and further reading.- 10 Contaminants.- 10.1 Introduction.- 10.2 Veterinary drugs.- 10.3 Keeping antibiotics out of milk.- 10.4 Hormones (BST).- 10.5 Disinfectants.- 10.6 Nitrates, nitrites and nitrosamines.- 10.7 Pesticides.- 10.8 PCBs.- 10.9 Motoxins.- 10.10 Toxic metals.- 10.11 Dioxins.- 10.12 Radionuclides in milk.- 10.13 Irradiation.- Further reading.- 11 Nutritional aspects.- 11.1 Introduction.- 11.2 Milk fat.- 11.3 Dietary cholesterol.- 11.4 Proteins.- 11.5 Milk allergy and intolerance.- 11.6 Cultured or fermented milks.- 11.7 Immune milk.- 11.8 Minerals.- 11.9 Vitamins.- Further reading.