Proteins, changes during heating

Ikeda S, Nishinari K (2001) Structural changes during heat-induced gelation of globular protein dispersions. Biopolymers 59 87-102... 

Starch changes during cooking of pasta are reported to vary from a hydration-driven gelatinization process in the outer layer to a heat-induced crystallite melting in the center.525 It is speculated that both the state of the starch and the surface structure contribute to the development of the elastic texture and stickiness of pasta. Interactions between starch and the surrounding protein matrix are evident in the outer and intermediate layer. In the center of cooked pasta, wheat starch granules retain their shape due to limited water diffusion, and the protein network remains dense. 

Yamauchi, K., Shimizu, M., Ardo, T. 1982. Milk fat globule membrane proteins in aseptically packed ultra-heat-treated milk Changes during storage. Agric. Biol. Chem. (Tokyo), 46, 823-825. 

Hamm, R., and EE. Deatherage. 1960a. Changes in hydration and charges of muscle proteins during heating of meat. Food Res. 25 573-586. 

Such chemical changes may lead to compounds that are not hydrolyzable by intestinal enzymes or to modifications of the peptide side chains that render certain amino acids unavailable. Mild heat treatments in the presence of water can significantly improve the protein s nutritional value in some cases. Sulfur-containing amino acids may become more available and certain antinutritional factors such as the trypsin inhibitors of soybeans may be deactivated. Excessive heat in the absence of water can be detrimental to protein quality for example, in fish proteins, tryptophan, arginine, methionine, and lysine may be damaged. A number of chemical reactions may take place during heat treatment including decomposition, dehydration of serine and threonine, loss of sulfur from cysteine, oxidation of cysteine and methio-... 

Effect of Deteriorative Changes of Soybean Protein During Heating on Enzyme Digestibility... 

BSs protected cereal leaf cells from heat shock or saline stress. Leaf pre treatment with BSs decreased cell ultrastructure degradation from heat shock and high salt conditions. BSs increased HSG formation which is supposed to protect preformed mRNA in plant cells during heating. BSs enhanced heat shook resistance of the leaf protein-synthesizing system. The effect of BSs on RNA and protein synthesis was shown earlier (14). We observed protein synthesis activation in wheat leaves by BSs in normal and under stress conditions. Two-dimensional SDS-FAAGE of dS-methionine labeled proteins demonstrated BS-induced changes in the set of polypeptides synthesized in leaves and in the rate of their synthesis. 

The reaction U->I may not be first order, but second order. A case in point is aggregation of unfolded protein, which is rather common during heating of not very dilute protein solutions. The extent of denaturation then is generally estimated from the increase in turbidity or from the proportion of protein having become insoluble. Often, the overall reaction order so observed is between one and two, and it may change in the course of the reaction. 

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