Mito
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- Dec 10, 2016
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“The true ileal digestibility of cooked and raw egg protein amounted to 90.9 ± 0.8 and 51.3 ± 9.8%, respectively.”
“After ingestion of the cooked egg protein meal, a substantial quantity of nitrogen was recovered in the ileal effluent over 24 h. The calculated yield of endogenous nitrogen (i.e., 0.40 g N) was close to the yield of 0.55 g N obtained by other researchers after ingestion of 17 g of pea protein (Gausserès et al. 1994). The calculated true ileal digestibility of cooked egg protein amounted to 91%. This finding demonstrates that even cooked egg protein, which has generally been considered to be easily digestible, is malabsorbed to some extent after ingestion of a physiologic load. Incomplete assimilation of dietary protein may have important consequences not only from a nutritional point of view, but also from a gastrointestinal point of view. Indeed, some metabolites resulting from bacterial fermentation of malabsorbed proteins in the colon have been implicated in the ethiopathogenesis of diseases such as colonic cancer and ulcerative colitis (Macfarlane and Cummings 1991, Pitcher and Cummings 1994, Visek 1978). It has already been reported extensively that food processing can influence protein digestibility both beneficially and detrimentally (Öste 1991). Egg white protein is generally considered to be less digestible than heat-pretreated egg white protein. However, no data are available concerning the magnitude of this impairment in vivo. In this study, it was shown that after ingestion of 25 g of raw egg protein, almost 50% is malabsorbed over 24 h. The higher digestibility of cooked egg protein presumably results from structural changes in the protein molecule induced by heating, thereby enabling the digestive enzymes to gain broader access to the peptide bonds. It has been suggested that the reduced digestibility of raw egg white is at least partially related to the presence of trypsin inhibitors in raw egg white (Matthews 1990). Ovomucoid is quantitatively the most important trypsin inhibitor (Gilbert 1971, Kassell 1970). Ovomucoid, however, does not react with human trypsin and, moreover, is relatively heat stable (Kasell 1970). Whether other egg trypsin inhibitors (e.g., ovoinhibitor or papain inhibitor) interfere with the digestibility of unprocessed egg white protein is unknown.”
Digestibility of Cooked and Raw Egg Protein in Humans as Assessed by Stable Isotope Techniques
“After ingestion of the cooked egg protein meal, a substantial quantity of nitrogen was recovered in the ileal effluent over 24 h. The calculated yield of endogenous nitrogen (i.e., 0.40 g N) was close to the yield of 0.55 g N obtained by other researchers after ingestion of 17 g of pea protein (Gausserès et al. 1994). The calculated true ileal digestibility of cooked egg protein amounted to 91%. This finding demonstrates that even cooked egg protein, which has generally been considered to be easily digestible, is malabsorbed to some extent after ingestion of a physiologic load. Incomplete assimilation of dietary protein may have important consequences not only from a nutritional point of view, but also from a gastrointestinal point of view. Indeed, some metabolites resulting from bacterial fermentation of malabsorbed proteins in the colon have been implicated in the ethiopathogenesis of diseases such as colonic cancer and ulcerative colitis (Macfarlane and Cummings 1991, Pitcher and Cummings 1994, Visek 1978). It has already been reported extensively that food processing can influence protein digestibility both beneficially and detrimentally (Öste 1991). Egg white protein is generally considered to be less digestible than heat-pretreated egg white protein. However, no data are available concerning the magnitude of this impairment in vivo. In this study, it was shown that after ingestion of 25 g of raw egg protein, almost 50% is malabsorbed over 24 h. The higher digestibility of cooked egg protein presumably results from structural changes in the protein molecule induced by heating, thereby enabling the digestive enzymes to gain broader access to the peptide bonds. It has been suggested that the reduced digestibility of raw egg white is at least partially related to the presence of trypsin inhibitors in raw egg white (Matthews 1990). Ovomucoid is quantitatively the most important trypsin inhibitor (Gilbert 1971, Kassell 1970). Ovomucoid, however, does not react with human trypsin and, moreover, is relatively heat stable (Kasell 1970). Whether other egg trypsin inhibitors (e.g., ovoinhibitor or papain inhibitor) interfere with the digestibility of unprocessed egg white protein is unknown.”
Digestibility of Cooked and Raw Egg Protein in Humans as Assessed by Stable Isotope Techniques
