Milk also has unique nutritional Properties that make it an especially important food, particularly for the young, it is commonly pasteurized & homogenized. Milk can be separated into its principal components, Cream & Skim Milk, which may be further separated into butter fat, casein & other milk proteins & lactose.
The whole milk may be modified by condensing, drying, flavoring, fortifying, demineralizing & its other treatments, whole milk or its components may be combined in various proportions for incorporation into numerous manufactured food products such as milk chocolate, bread, cakes, sausage, confectionary items, soups & many other food Products.
Milk processing industry has always been on toe to control the quality of milk due it is highly perishable nature. Milk processing has always been a challenge as milk is primary raw material for preparing dairy-based product like cheese, butter, ice cream, yoghurt, curd, and butter. In our previous article we had stated the occurrence of possible hazard in milk from farm to industry. In continuation to the occurrence in hazard in milk processing, we shall be looking in details the occurrence of hazard during processing of various dairy based product. Dairy based products have various processing steps with requirement of different type of processing equipment. Hazards are broadly categorized as physical, chemical, and microbial hazard.
Dairy Based Product and Hazards: –
Physical and chemical hazard that can occur during dairy product processing are quite common for all.
Physical hazards in dairy product includes the presence of unwanted substances such as sand, soil, hair, metal parts from equipment, etc. Physical hazards are usually of less concern in dairy industry as milk undergoes sufficient filtration in all processing stages which prevents the final product contaminated by these physical hazards.
Chemical hazards in milk and dairy products are unintentional presence or intentional addition of chemicals causing health risk to humans. Chemical hazards usually enter the milk from one of the three ways: contaminated feed, grazing on contaminated soil or veterinary medicines. Chemical hazards in milk and dairy products includes mycotoxins, plant toxins, pesticides residues, heavy metals, cleaning detergents, etc.
At ambient conditions, milk has the shelf life of only few hours while at refrigeration conditions (below 4°C) it is 3-5 days. This fact led to the development of shelf stable products derived from milk which lasts longer than milk retaining its nutritive properties. Microbial hazards are rather specific in products. Some of the dairy product and associated microbial hazard are mentioned-
Cream is obtained by separating non- fat portion from un-homogenized milk. monocytogenes, S. aureus and verocytotoxin-producing Escherichia coli (VTEC) are the usually reported source of microbial hazards in cream.
Butter is defined as the water in oil emission containing at least 80% fat. Commonly reported hazard in butter are Salmonella spp., Shiga toxin-producing E. coli (STEC), L. monocytogenes, and S. aureus. Organic pollutants such as dioxins and PCBs can accumulate in butter.
Cheese made from coagulation of milk with an enzyme called rennin, and lactic acid with or without further treatment of heat, pressure, salt & ripening (fermentation) with selected microorganisms. Aflatoxin M1 is a higher matter of concern in cheese than milk as it is more concentrated, and levels may be 5 times higher in hard cheese than in milk. Toxins produced by S. Aureus remains active even after pasteurization.
4. Ice cream:
Ice cream is a frozen dairy product. Disinfectants such as quaternary ammonium compound (QAC) are found in ice cream samples. Ice cream composed of milk fat & Milk Solids non-fat derived from these ingredients, plus sugar, stabilizers, emulsifier, flavorings agents, water & Air. Microbial hazards associated with ice cream are Listeria monocytogenes, Salmonella species, Escherichia coli (pathogenic strains), Staphylococcus aureus (coagulase positive) and Bacillus cereus. Nuts used as an ingredient in ice cream could be the source of mycotoxins. Ice cream is having stick to hold it need to be taken care to avoid ingress of wood splinters.
5. Powdered milk/ Dried milk:
Powdered milk is obtained by removing 95% of water from milk. Hazards reported in milk powder are due to Cronobacter sakazakii and Salmonella spp. Spores of Clostridium botulinum have been found in powdered dairy products.
Though processing of milk reduces it nutritional value, but it makes milk more shelf stable and reduces the risks of hazards. Processed milk and dairy products are more trusted than raw milk from local vendors, still there are certain critical points which need to be monitored to ensure the safety of the product. HACCP implementation, Good Manufacturing Practices, hygienic practices during farm procurement, and others such practices when combined, provide much needed nutritious product.
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