| The thermal reactions(such as lipid oxidation,caramelization reaction,Maillard reaction,etc.),as a key step in the processing of sesame paste,will significantly affect the quality of the sesame paste.Among them,the sugar-based Maillard reaction and caramelization reaction significantly affect the color,flavor,texture,and nutrition of sesame paste.Carbohydrates,as an important component of sesame,are rich in structural sugars,accounting for 19% of whole sesame seeds.And it can also be used as an important precursor for the Maillard reaction and caramelization reaction,affecting the quality of food.This is of great importance for investigating the effect of the thermal reaction of structural polysaccharides in sesame seeds on the quality of sesame paste.However,structural polysaccharides are generally stable,and enzymatic treatment can be used to disrupt their structure,increasing the rate of thermal reactions and observing their relationship with the quality of sesame paste.Therefore,this study first investigated the relationship between the thermal reactions of sesame kernel structural polysaccharides and proteins and the quality and nutritional digestibility of sesame paste.Then the caramelization reaction and the Maillard reaction were promoted by using different enzymes to enzymatically hydrolyze sesame seed structural polysaccharides and proteins to provide theoretical support for improving the quality of sesame paste and reducing the production of hazardous substances.The main research contents and findings are as follows:1.The relationship between the thermal reactions of structural polysaccharides and proteins of sesame kernels and the quality of sesame paste was investigated,and the thermal reactions of the two were carried out at 140°C,160°C,180°C,and 200°C.Then,the sesame paste was prepared by simulating the sesame paste system.The results showed that the total amino acid and polysaccharide contents of sesame meal decreased from 48.31 and 16.99g/100 g to 40.61 and 14.19 g/100 g,respectively,with the enhancement of thermal reaction.Among them,serine(Ser),cysteine(Cys),lysine(Lys),and arginine(Arg)were important reaction precursors.Moreover,the ΔE of sesame paste increased from 19.43 to 49.63 as the thermal reaction temperature increased.In addition,the thermal reaction of structural polysaccharides and proteins of sesame kernels at 180°C resulted in the highest hardness(42.14 g)and viscosity(135.9 g·sec)of sesame paste,improving the storage stability of sesame paste.2.The relationship between the thermal reaction of sesame kernel structural polysaccharides and proteins and the nutritional digestibility of sesame paste was investigated by simulating the in vitro digestion of prepared sesame paste and analyzing the protein hydrolysis,digestibility,amino acid,and sugar content.The results showed that with the increase of thermal reaction between the sesame kernel structural polysaccharides and proteins,the enzymatic hydrolysis of pepsin and pancreatic enzyme was inhibited,and the digestibility and hydrolysis of protein decreased from 55.26% and 18.65% to 39.16% and14.85%,respectively.Furthermore,with the increasing of thermal reaction temperature,the content of polysaccharides,reducing sugars,and amino acids in sesame paste decreased,especially causing the loss of essential amino acids(from 29.11% to 22.69%),which affects the absorption of nutrients during digestion.However,analysis of the antioxidant activity showed that the thermal reaction of polysaccharides and proteins produced a large number of melanoidin,heterocyclic,and pyrenoid compounds,which contributed to the scavenging of free radicals and the improved antioxidant capacity of sesame seed paste.3.The relationship between the thermal reactions of sesame kernel polysaccharides and proteins under different enzyme treatments and the quality of sesame paste was investigated.Sesame meal was pretreated with a combination of enzymes(cellulose-papain,hemicellulose-papain,and pectin-papain)to increase the rate of structural polysaccharide and protein thermal reactions.The results showed that the cellulose-papain complex enzymes were the most effective,producing more small molecules of sugars and peptides,increasing the rate of thermal reactions,and producing the highest levels of heterocyclic flavor substances,which improved the flavor formation of sesame paste.The degree of thermal reactions of structural polysaccharides and proteins in sesame kernels was enhanced after enzymatic treatment,resulting in an increase in ΔE from 61.85 to 70.72 in sesame paste.In addition,compared to hemicellulose and pectin in sesame kernels,the thermal reaction between cellulose and protein degradation resulted in better stability of sesame paste(9.66%oil separation),and its flow behavior index decreased from 0.74 to 0.71 and hardness increased from 23.67 to 25.14 g,resulting in an increase in viscosity and heaviness of sesame paste.4.The relationship between the low-temperature thermal reaction of sesame kernel polysaccharides and proteins under enzyme treatment and the quality and safety of sesame paste was investigated.Sesame meal was treated with cellulose-papain enzyme and subsequently thermally reacted at different temperatures.The results showed that the sample enzyme treatment followed by thermal reaction at 180°C resulted in the highest heterocyclic amine content of 85.67 ng/m L.Meanwhile,it had the lowest D50 value(40.7)and better stability.The low-temperature enzyme treated(CEP150)and high-temperature non-enzymatic treated(UEP180)samples were close in aldehyde and heterocyclic compounds and showed a non-significant difference in ΔE(61.57-61.85).In addition,the low-temperature enzyme treated and high-temperature non-enzymatic treated samples had similar rheological properties according to the dynamic oscillation test analysis.In conclusion,sesame paste with similar quality to the high-temperature non-enzymatic treatment(e.g.UEP180 and CEP150)can be obtained by low-temperature enzyme treatment,which can effectively prevent the high-temperature thermal reaction from generating a large number of harmful substances and provide theoretical guidance for the production of sesame paste in factories.In summary,this study initially clarified the effects of the thermal reactions of sesame kernel polysaccharides and proteins on the quality of sesame paste.Serine,cysteine,lysine,and arginine were found to be the main amino acids during the thermal reaction,and cellulose was the main reacting polysaccharide.As the degree of thermal reaction between the sesame kernel polysaccharides and proteins increased,the sesame paste color deepened and more aldehydes and heterocyclic flavor compounds were produced,which played an important role in the formation of the color and flavor of the sesame paste.In addition,the thermal reaction between the sesame kernel polysaccharides and proteins causes a loss of amino acids and sugars in the sesame paste,which reduces the absorption and utilization of nutrients by the body.However,the thermal reaction improves the antioxidant activity of sesame paste during digestion.Finally,compared to the high-temperature non-enzyme treated samples,by using cellulose-papain complex enzymes,it was found that the low-temperature enzyme treatment not only enabled the sesame paste to maintain its original color,flavor,and other qualities but also reduced the production of harmful substances such as heterocyclic amines in the sesame paste,ensuring food safety.These findings can provide theoretical support for understanding the effects of the thermal reactions of sesame kernel structural polysaccharides and proteins on the quality of sesame paste,to guide the production of safe and good quality sesame paste in factories. |
PDF Full Text Request