Light milk product

Enantiomers have very similar chemical properties, but they rotate polarized light in opposite directions (optical activity, see pp. 36,58). The same applies to the enantiomers of lactic acid. The dextrorotatory L-lactic acid occurs in animal muscle and blood, while the D form produced by microorganisms is found in milk products, for example (see p.l48). The Fischer projection is often used to represent the formulas for chiral centers (cf.p. 58). 

Figure 3.4 — (A) FIA manifold for the determination of L-lactic acid in milk products P peristaltic pump C carrier S sample V injection valve AD air damper FTC flow-through cell W waste BFB bifurcated fibre LS light source PMT photomultiplier tube R recorder. (B) Cross-section of lactic acid optrode. (Reproduced from [39] with permission of VCH Publishers).

Bosset, J.O., Sieber, R., Gallmann, P.U. 1995. Light transmittance Influence on the shelf life of milk and milk products. In Technical Guide for the Packaging of Milk and Milk Products, 3rd edn, Bulletin 300, pp. 19-39, International Dairy Federation, Brussels. 

For making light-coloured meringues, therefore, it is essential to use the non-reducing sucrose. This Maillard reaction is important in the storage of milk products, since cows milk contains 0.3 M lactose and the dietary value of various proteins is often limited by their lysine content. 

Humans receive cobalamins from food— mainly from meat and meat products, and to a lesser extent from milk and milk products. Cobalamins are found in food in five forms hydroxycobalamin, AdoCbl, MeCbl, suphitoco-balamin and cyanocobalamin. AdoCbl and hydroxycobalamin are the most frequent types, followed by MeCbl (Farquharson and Adams 1976). Nevertheless both AdoCbl and MeCbl are light-sensitive, with light evoking a photodissociation of the Co C bond. The naturally found hydroxycobalamin is the product of photolysis of the light-sensitive cobalamins (Farquharson and Adams 1976 Seetharam and Alpers 1982). 

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