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Protein Denaturation

Protein, from the Greek meaning “first” or “foremost,” is the most important macronutrient in a bariatric diet. Proteins constitute over half the dry weight of most humans and are the instruments carrying genetic information to the cell [42]. They are large molecules that undergo changes in their structure as they are cleaved into amino acids by digestive enzymes and during the cooking or drying process.

Heat, exposure to extremes in pH, and treatment with certain reagents cause proteins to become insoluble and lose their biological activity without damage to the covalent backbone [43]. This process is known as denaturation or unfolding of their protein structure, which results in a loss of activity when heated to 65°C. A denatured globular protein frequently becomes insoluble in an aqueous solution of pH 7 and usually loses its biological activity. A familiar example of protein denaturation is cooking an egg. The white of the egg or albumen coagulates into a white solid upon heating. It does not revert to a clear solution upon cooling because the heat has changed it or denatured the albumen protein.

Denaturation also explains why most proteins are biologically active over a narrow temperature range 0°С-40°С. Temperatures higher than those, for a living organism can cause hydrogen bond disruption or denaturation [44]. Powdered protein formulas used for sports and bariatric nutrition supplements that are treated with organic solvents and strong acids/bases disrupt the hydrogen bonds leading to denaturation that can thus fail to meet bariatric patients’ protein needs.

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