Discrimination Of Digestion Products Of Proteins From Different Kinds Of Meat

Meat has been known as an important source for human nutrition,which contains high-value proteins,lipids,minerals and vitamins B.Increasing meat consumption results in more and more attention to the relationship between meat consumption and human health.However,meat protein digestion has been paid much less attention because of their complex components.It is crucial to characterize the complex proteins from raw or cooked meat and the complex digestion products of meat proteins when they go through the stomach and the intestine.The objectives of the present study were to characterize the in vitro digested products with pepsin and trypsin from cooked pork under different cooking temperatures by mimicking gastrointestinal digestion in the human body to investigate the effect of cooking on in vitro digestibility and peptide profiling of pork protein.We also characterized in vitro digestion products of pork,beef,chicken and fish cooked in the certain temperature treated with pepsin and trypsin,and to characterize gastric and jejunal contents obtained from the rats fed the four meat proteins for 7 days to find the meat species digestion diversity.The details and conclusions are as follows:1.Effect of cooking on in vitro digestion of pork proteinsGastrointestinal digestion of cooked pork was simulated in which meat was treated with pepsin alone or followed by trypsin treatment.Digested products were identified by using MALDI-ToF MS and nano LC-Q-Exactive-MS-MS analyses.Cooking led to a reduction in digestibility and in band intensities on SDS-PAGE gels.Peptide profiling and identification analyses also showed significant difference in the m/z ranges and number of peptides from the pepsin-digested products between raw(4?)and very well done samples(100 ?).Peptides sequenced from pepsin-digested samples under lower degrees of doneness disappeared as the temperature increased.Meanwhile,the trypsin cleavages appeared more consistent among different degrees of cooking.Further work may be needed to evaluate the bioavailability of the digested products under different cooking temperatures.2.Discrimination of in vitro and in vivo digestion products of meat proteins from pork,beef,chicken and fishCooked pork,beef,chicken and fish were homogenized and incubated with pepsin alone or followed by trypsin.The digestion products with molecular weights of less than 3,000 Da were identified with MALDI-ToF-MS and nano LC-Q-Exactive-MS-MS.Gastric and jejunal contents obtained from the rats fed the four meat proteins for 7 days were also analyzed to confirm the difference between dietary proteins.After pepsin digestion,pork and beef samples had a greater number of fragments in similarity than chicken and fish samples.The in vitro digestibility was the greatest for pork but the smallest for beef samples.After trypsin digestion,the species differences were less pronounced.Nano LC-Q-Exactive-MS-MS analysis showed a total of 822 different digestion products from 800 m/z to 3000 m/z differing with meat species and enzyme treatments,of which 116 peptides predicted to be bioactive.However,the bioactive peptides were different between pepsin-treated and pepsin + trypsin treated samples.The nano LC-Q-Exactive-MS-MS analysis of peptides from rat gastric and jejunal contents also showed significant different in the number and type.The bioactive peptides exhibited a great change during they passed through the gastrointestinal tracts.The results could interpret for the differences in protein bioavailability from different species of meat.