| Sesame(Sesamum indicum L.),also known as flax,is an important oil crop.It is mainly divided into white sesame and black sesame.In recent years,with the unique nutritional value of black food,black sesame and its products have attracted more and more attention.Articles by microwave and roasted heat treatment preparation two kinds of black sesame paste up to similar chromaticity values(L*),as heating endpoint,research physical and chemical indexes and feature of protein,and combined sensory evaluation were analyzed of two regions of black sesame paste,and make a comprehensive assess and final choice 800W/4 min and 200℃ 8min heat treatment in vitro digestion experiment.To study the changes of nutrients,bioactive components,microstructure and antioxidant activity of black sesame paste after oral,gastric and intestinal digestion.The main research contents and conclusions were as follows:(1)The black sesame seeds from Myanmar and Jiangxi were heat treated by microwave(600W/7 min and 800W/4 min)and roasting(170℃/16 min and 200℃/8 min).Through the water content,color,fatty acid,lipid oxidation index(acid value,peroxide value,anisidine),protein index(amino acid composition,soluble nitrogen content,SDS-PAGE)and volatile compound composition of black sesame paste were determined,found after different heat treatment of black sesame paste,the water content of roasting was lower than microwave heated paste,even at a similar heating endpoint(p <0.05).The peroxide value and p-anisidine value of the black sesame paste were lower at microwave 800W/4 min and roasting 200℃/8min,results showed that at 800W/4 min and 200℃/8 min heating,the lipid oxidation degree was lower,the results of nitrogen solubility index(NSI)and SDS-PAGE showed that protein degradation,aggregation and denaturation were greater at 170℃/16 min and 600W/7 min dealing.In addition,both microwave and roast heating produce more volatile flavor substances.Such as pyrazine,alkanes,aldehydes and other volatile substances.Heating greatly enriched the types and quantities of flavor substances of black sesame paste.(2)By measuring the total sugar,reducing sugar,oxalic acid,free amino acid and taste activity value of black sesame paste,and taste intensity value combined with sensory evaluation to analyze the black sesame paste from Myanmar and Jiangxi,China found compared with the unheated black sesame paste,the oxalic acid content of black sesame paste samples of the two regions at 170℃/16 min heating reached the highest value.After heat treatment,the content of total sugar increased and the content of reducing sugar decreased,and the contents of total sugar and reducing sugar were the highest at 800W/4 min and 200℃/8min.The contents of essential amino acids and the ratio of essential amino acids to total amino acids were higher under 800W/4 min and 200℃/8 min treatments.In addition,the sensory evaluation results of 800W/4 min and 200℃/8 min were better than 600W/7 min and 170℃/16 min dealing,had better taste,texture,and acceptability(3)Microwave and roasting were used to simulate oral,gastric and intestinal digestion of black sesame paste.The fatty acid composition,protein indicators(amino acids,degree of hydrolysis and digestion rate)and nutrition index(total sugar,reducing sugar,dietary fiber and minerals)measurement analysis of release in the digestive tract environment,and by particle size,scanning electron microscope(SEM)and laser confocal microscope(CLSM)to study the microscopic structure of black sesame paste,found that compared with the unheated black sesame paste,after heat treatment,the contents of total hydrophobic amino acids(HAA)and antioxidant amino acids(AXA)in black sesame paste increased during digestion.During intestinal digestion,protein digestibility and total sugar content of microwave treatment were higher than roasting treatment.Compared with unheated black sesame paste,microwave treated black sesame paste had a higher reducing sugar content at the same digestion stage;The content of dietary fiber and calcium,magnesium and iron in mineral elements after microwave treatment was higher than that of roasting;As digestion progressed,the particle size of the black sesame paste increased after microwave and roasting.Confocal laser images showed that during digestion,proteins were digested into small molecular fragments and the oil clumps together form a larger droplet.(4)The contents of melanin,sesame lignan,flavonoids,polyphenols,and DPPH,·OH,ABTS radical scavenging ability and iron reducing power(FRAP)of black sesame paste were determined by simulated vitro digestion experiment.Found the content and bioaccessibility of melanin in black sesame paste after microwaving were higher than those treated by roasting.At different digestion stages,the content of sesamol in microwave treatment was higher than that by roasting,and had the highest content in the intestinal phase with the progress of digestion.Heat treatment increased the contents of flavonoids and polyphenols,especially in hydrophilic digestive solutions.After microwave treatment,the contents of flavonoids and polyphenols in black sesame paste at all digestive stages were higher than that of roasting treatment.The DPPH,·OH,ABTS free radical scavenging rate and FRAP of hydrophilic components of black sesame paste after simulated digestion increased with the increase of digestion time.Both lipophilic and hydrophilic digestive liquid showed that microwave treatment had a higher free radical scavenging rate and FRAP than roasting treatment. |
