Denaturation Maillard reaction

Once the final expansion has occurred the proteins start to denature and the starch gelatinises. The proteins also undergo Maillard reactions, particularly at the outside of the product, which is the hottest part. 

Instantized milk powder normally exhibits low bulk density but higher water dispersibility than conventionally spray-dried powder. However, the extra heat exposure from the agglomeration and redrying treatments causes additional Maillard reaction, whey protein denaturation, and related chemical and physicochemical reactions that tend to lower product quality. 

As is the case with some chemical changes occurring in biological systems, such as the blood-clotting cascade system, deteriorative reactions considered to have a beneficial effect are found in foods. For example, the Maillard reaction (lJ7,lj3) is used to produce flavors and colors in such foods as beverages and baked goods. Heat treatment (involving denaturation) has been found to increase the nutritional value of raw soybean meal by... 

Hydrolysis now has been completed successfully by proteolytic enzymes from bacteria and moulds. In these reactions there are no problematic side products because they operate under mild conditions as mentioned above. The further processing after enzymatic hydrolysis is similar to the classically hydrolyzed products by heating and consecutive Maillard reaction. In the heating step the enzymes are denatured and destroyed [5]. 

Saccharomyces cerevisiae was cultivated with potato protein liquor (PPL) and glucose (starch hydrolysate) as substrate. Before the start of the cultivation PPL was sterilized at various temperatures between 80 and 120 °C for different periods between 5 s and 30 min [27]. The foaminess of PPL was very low before the sterilization. The foaminess increased with the temperature and time during sterilization and, at 120 °C and 30 min, 2 was enlarged by a factor of 2x10. This effect is due to the denaturation of proteins [4] and the formation of Maillard reactions between reducing sugars and amino adds [28]. 

Many biochemical reactions can be induced by temperature increase in foods Maillard reactions, vitamin degradation, fat oxidation, denaturation of thermally unstable proteins (resulting in variation of solubility or of the germinating power of grains, for example), enzyme reactions (which can either be promoted or inhibited), and so on. Some of these biochemical reactions generate components suitable, for example, for their sensory properties (flavor development) others may be more or less undesirable for nutritional or potential toxicity reasons (vitamin losses, changes in color, taste or aroma, formation of toxic compounds). All the reactions are linked to the simultaneous evolution of product composition, temperature and water content (or chemical potential, or water activity), these factors varying diflferently from one point to another, from the center to the surface of the products. 

Biochemical Degradation Biochemical degradation is another harmful transformation that occurs with most biological products. There are four key reactions to consider lipid oxidation, Maillard browning, protein denaturation, and various enzyme reactions. These reactions are both heat- and moisture-dependent such that control of temperature and moisture profiles can be very important during drying. 

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