단백질 가수분해물의 제조 및 특성

Production and characteristics of protein hydrolysates

Hydrolysis of food proteins is carried out for many reasons, including improving nutritional characteristics, retarding deterioration, imparting texture, increasing or decreasing solubility, adding forming or coagulation properties, adding emulsifying capacity, preventing undesired interactions, removing off-flavor or odors, and removing toxic or inhibitory ingredients. In the preparation of hydrolysates, choice of materials, enzymes, processing methods, and quality control are key aspect. The proteins used most commonly in nutritional products containing protein hydrloysates are casein, whey protein, soy protein, gelatin, potato, egg albumen, and fish. Protein hydrolysis can be accomplished with enzymes, acids, or alkali. Acid and alkaline hydrolysis can destroy L-form amino acids, produce D-form amino acids, and can form toxic substances like lysino-alanine. Enzymatic hydrolysis is strongly preferred over strictly chemical methods for producing hydrolysates in nutritional applications. Enzymatic hydrolysis can produce hydrolysates with well-defined peptide profiles. However, when food proteins are enzymatically hydrolyzed, changes in flavor and taste often occur. These flavor changes include the development of bitterness or other off flavors. Bitter arises by the proteolytic cleavage of food proteins, resulting in the formation of bitter-tasting peptides after extensive hydrolysis. The development of bitter-tasking peptides limits the use of protein hydrolysates as it may cause taste defects in the products in which they are used. Consequently, the reduction, prevention, or removing of bitterness from protein hydrolysates has been studied intensively and is still an area that receives much attention. The hydrolysis process can be controlled through hydrolysis parameters. The most critical parameters to monitor in commercial production are temperature, time of hydrolysis, pH, and degree of hydrolysis. Hydrolysis conditions are controlled to meet specific and product characteristics, such as amino acid distribution, molecular weight distribution, and amount of residual intact protein. Also, processing methods, such as charcoal treatment, filtration/ultrafiltration, and drying affect hydrolysate characteristics including flavor, color, amino acid profile, and molecular weight distribution. Great care and attention to quality assurance of processed hydrolysates is essential. General areas of concern for quality control include microbiological, chemical and physical, biochemical, and immunological parameters. Protein hydrolysates continue to play an important role as primary ingredients in the formulation of specialized medical diets that are tailored for specific disease states. As these diets increase in complexity, it becomes essential to develop a better understanding of the structure-property relationship of peptides. Progress has been made in understanding the relationship between degree of hydrolysis, on a macro level, and hydrolysates’ functionality. However, studies on the role of protease specificity and its effect on functionality of the resulting hydrolysates are very limited and further research is needed. Also, information on the interaction between hydrolysate molecules and other additives in the formula is lacking. Studies are needed to elucidate the nature of such interactions and their influence on product long-term stability.