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GUEST COLUMN – Milk concerns not fully addressed


Robert D. Lucas

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RECENTLY, in the local Press, concerns have been raised about the labelling as “fresh” and the refrigerated storage of ultra-pasteurised milk (UP). Pine Hill Dairy (PHD), in an attempt to address these concerns, placed full-page advertisements in the Press. I will now explain the concepts of pasteurisation, sterilisation and fresh as applied to food products. A critical examination of the PHD advertisement is also given.Pasteurisation is the process whereby a food product is heat-treated, destroying all pathogenic or disease-causing organisms present in the food. Pasteurisation does not result in the destruction of all of the micro-flora (organisms) present. Some of the organisms which survive pasteurisation can cause spoilage. Therefore, all pasteurised foods must be kept refrigerated (pasteurised canned hams, pasteurised milk and so on). Sterilisation is the process in which all pathogenic and non-pathogenic spoilage organisms, including most spores, are destroyed. No attempt is made to destroy all of the micro-flora present since such an action results in the destruction of nutrients as well as the texture of the food. In food, this process is called commercial sterilisation. Ultra high temperature (UHT) treated milk is a commercially sterile product. According to the Code of the Federal Register (CFR) Paragraph 101.95 sub part F – Food Labelling: “The term fresh is used to describe pasteurised whole milk” because the term does not imply that the food is unprocessed (consumers commonly understand that milk is nearly always pasteurised). Title 21, Food and Drug Administration (FDA) 2010, Department of Health and Human Services, United States.When milk is heat-treated, sugars in the milk, in the presence of amino acids, undergo the Maillard reaction(non-enzymatic browning). This results in a burnt or cooked flavour and the development of off colours. The longer the exposure to heat and the higher the temperature, the greater the adverse effect. For this reason, all pasteurised foods are rapidly cooled down. UHT milk is no exception to this rule. According to (Anon) 2007 Dairy Foods Science Notes, Cornell University: “Ultra-pasteurised milks will often have more of a cooked flavour when compared to conventionally pasteurised milk.” It should be noted here that neither pasteurisation nor sterilisation destroys native alkaline proteinases as well as bacterial proteinases found in milk. Also, when heated, lipolysis (the breakdown of fats into free fatty acids) occurs. All of these processes affect the flavour of milk. An examination of the graph given by PHD as well as the use of the term “spiked” tend to indicate that the time taken to raise the temperature of UP milk from 80°C to 138°C was instantaneous. PHD failed to point out that there are direct and indirect methods of heat-treating UHT milk. When direct heating is done, the heat process for UHT milk takes 45 seconds – Goff (2010) UHT Processing, University of Guelph.  In food processing, the time taken to raise the temperature of a food from temperature X to temperature Y is called the “coming-up time”. It is noticeable that PHD does not indicate how long the coming-up time was. One is left to wonder why PHD would stop producing a product with a shelf-life of six to 12 months at ambient (room) temperature, to which the consumers’ taste buds were accustomed, in preference for one with a shelf-life of three months and which must also be refrigerated. Energy costs in Barbados are very high. UHT procedures require complex equipment and a high level of technical know-how. “Complexity of equipment and plant are needed to maintain sterile atmosphere between processing and packaging (packaging materials, pipe work, tanks, pumps); higher skilled operators; sterility must be maintained through aseptic packaging.” – Goff (2010). Aseptic packaging of UHT milk differentiates it from UP milk. As a result, the latter must be refrigerated. It should be noted here that UHT milk has been produced in Trinidad since the 1970s. Indeed, in 1973 I visited Nestlé as a food science student to observe the process. In food, the processor never has preconceived notions of the food preference of the consumer. This is what I find most amusing about the advertisement. When the Coca-Cola corporation introduced new coke and tried to force it down the throats of American consumers, they refused to purchase it. Coke had to revert to its original formula. It is only when a company has a monopoly that it can ride roughshod over the views of the consumer. The PHD advertisement alluded to tests being done locally. There was some mention elsewhere about overseas testing. Nowhere was it mentioned if the tests were done by trained panels of local testers. Was the testing done in-house or outsourced? Were statistical analyses of the data done? Was a consumer preference taste-test done, employing 1 000 or so persons? The latter test gives a true indication of the likes and dislikes of the consuming population. Testing overseas is a waste of time because taste varies from place to place. Finally, the advertisement extols the fact that the pack for UP milk consists of six layers. According to the Alaska Commission on Aging (2006) Senior Meal Planning Guide: “UHT milk is packed in a five-layer sterile laminated box.” In both instances, the packs for UHT and UP are non-environmentally friendly. Robert D. Lucas, PhD is a food biotechnologist.

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