Milk products, various effects

Figure 38.19 shows the contour plots of the foaming behaviour, uniformity of air cells and the sweetness of a whipped topping based on peanut milk with varying com syrup and fat concentrations [16]. Clearly, fat is the most important variable determining foam (Fig. 38.19A), whereas com syrap concentration determines sweetness (Fig. 38.19C). It is rather the mle than the exception that more than one sensory attribute are needed to describe the sensory characteristics of a product. An effective way to make a final choice is to overlay the contour plots associated with the response surfaces for the various plots. If one indicates in each contour plot which regions are preferred, then in the overlay a window region of products with acceptable properties is left (see Fig. 38.19D and Sections 24.5 and 26.4). In the...

Nutritional Effects Due to the Presence of the Maillard Products. Many physiological or antinutritional effects have been attributed to the Maillard products. Specific effects have been attributed to the Amadori products deoxyfructosylphenylalanine (a model substance not likely to be present in large quantities in foods) appears to depress the rate of protein synthesis in chicks (32) and to partially inhibit in vitro and in vivo the absorption of tryptophan in rats (33). The compound e-deoxyfructosyllysine inhibits the intestinal absorption of threonine, proline, and glycine and induces cytomegaly of the tubular cells of the rat kidneys (34) as does lysinoalanine. In parenteral nutrition the infusion of the various Amadori compounds formed during sterilization of the amino acid mixture with glucose is associated with milk dehydration in infants and excessive excretion of zinc and other trace metals in both infants and adults (35,36,37). 

Some of these compounds could be considered as dietary additives, but various other terms, including pesticides, can also be used. They can have beneficial effects on the environment and this aspect will be discussed later. The ionophore monensin, which is an alicyclic polyether (Figure 1), is a secondary metabolite of Streptomyces and aids the prevention of coccidiosis in poultry. Monensin is used as a growth promoter in cattle and also to decrease methane production, but it is toxic to equine animals. " Its ability to act as an ionophore is dependent on its cyclic chelating effect on metal ions. ° The hormones bovine somatotropin (BST) and porcine somatotropin (PST), both of which are polypeptides, occur naturally in lactating cattle and pigs, respectively, but can also be produced synthetically using recombinant DNA methods and administered to such animals in order to increase milk yields and lean meat production. "... 

Sensory quality can be defined as texture, flavour (taste), aroma and visual aspect. The sensory properties of milk are highly influenced by its fat content (Phillips et al., 1995a). As a result, research has examined the effects of various food additives on sensory quality when used as a substitute for fat in milk (Philips et al., 1995b). Frpst et al. (2001) showed that a combination of thickener, whitener and cream aroma in 0.1% fat milk was successful in mimicking the sensory quality of 1.3% fat milk. With the interest in the production of milk enriched with cis-9, trans-l 1 CLAs, owing to their relevance to human health (Tricon et al., 2004), recent research has examined the effects of CLA on the sensory quality of dairy products and found that it is possible to produce CLA-enriched dairy products with acceptable sensory characteristics (Jones et al., 2005). 

The book does not cover the technology of the various dairy products, although brief manufacturing protocols for some products are included to facilitate discussion however, a number of textbooks on various aspects of dairy technology are referenced. Neither are the chemical analyses, microbiology and nutritional aspects of dairy products covered, except in a very incidental manner. The effects of dairy husbandry on the composition and properties of milk are discussed briefly, as is the biosynthesis of milk constituents in both cases, some major textbooks are referenced. 

For any individual animal, fat content decreases slightly during successive lactations, by c. 0.2% over a typical productive lifetime (about five lactations). In practice, this factor usually has no overall effect on the fat content of a bulk milk supply because herds normally include cows of various ages. The concentration of fat (and of all other milk-specific constituents) decreases markedly on mastitic infection due to impaired... 

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