| With the development of society and the continuous improvement of human living standards,a healthy diet has become an increasingly pursued goal of human beings.Polyphenols are getting more and more attention and favor from consumers because of their more physiologically active functions,such as antioxidant activity.Polyphenols will inevitably come into contact with other substances,such as protein and starch-based food ingredients.Existing studies have shown that polyphenols will interact with proteins and starches to a certain extent,and have a certain impact on their respective functional characteristics.In the daily diet,when tea,wine and other beverages containing polyphenols encounter collagen staple fish meat,tyrosine protein milk and casein starch buns and other staple foods,the impact is unknown.Therefore,this thesis will study the interaction between phenolic compounds and proteins(collagen(C),casein(CS))and starches(wheat starch(WS))and the characteristics of simulated digestion in vitro,and discuss the occurrence of interactions on their functional characteristics,it can provide the rational guidance for a healthy diet.In this thesis,the interaction between polyphenols(tannic acid(T)and gallic acid(G))was studied using aquatic hypertension—fish skin collagen and milk 's main component—casein as raw materials;Explored the effects of interactions on the digestive properties of proteins and starch and the antioxidant properties of polyphenols and their complexes during in vitro simulated digestion.And the practical application effects of interaction were discussed.The main contents and results of the study are as follows:(1)Firstly,the interaction between polyphenols and proteins was studied.The mechanism of the interaction was studied by using fluorescence spectroscopy.Secondly,Circular dichroism,Fourier infrared spectroscopy,Scanning electron microscopy and atomic force microscopy were used to study the influence of the structural characteristics of polyphenols and protein complexes.The results show that tannic acid and gallic acid have a fluorescence quenching effect on fish skin collagen and casein.Among them,the affinity of tannic acid and protein is significantly stronger than that between gallic acid and protein.The quenching type of polyphenols on fish skin collagen is mainly based on static quenching and supplemented by dynamic quenching.The quenching on casein is a static quenching type.The interaction between protein and polyphenol is mainly hydrophobic,van der Waals force and hydrogen bonding.In the study of protein structural characteristics,it was found that casein binds to polyphenols through C = O,C-N and N-H,collagen mainly binds to polyphenols through C-N and N-H,and hydrogen bonding is also a key factor that promotes the binding of proteins and polyphenols.Studies on the microstructure of protein and polyphenol complexes have shown that the addition of polyphenols makes the structure of the protein more loose and porous,proving that hydrogen bonding and hydrophobic interaction forces are the key factors that promote the combination of selected proteins and polyphenols.(2)Secondly,in the research process of the interaction between polyphenols and wheat starch,the effects of polyphenols on the properties of wheat starch pH,iodine binding force,particle size,rheology,solubility and swelling,and microstructure were investigated.Studies have shown that polyphenols have reduced the pH and iodine binding power of the wheat starch solution.Among them,the tannic acid and gallic acid pH were reduced from 5.62 to 3.22 and 4.36,and the iodine binding power was reduced by 16.2%.It is proved that polyphenols can interact with amylose in wheat starch.Infrared analysis studies have shown that polyphenols and starch combine through non-covalent interactions such as hydrogen bonding.It is found in the microstructure that food-borne polyphenols can effectively reduce the water loss of starch-based foods and prevent the role of starch retrogradation.Experimental studies on solubility and swelling show that tannic acid and gallic acid have a certain inhibitory effect on the overflow of starch granules during the expansion process.Based on the above speculation,the combination of tannic acid and gallic acid with wheat starch through hydrogen bonding and hydrophobic interaction,which further affects the digestion characteristics of starch(3)Finally,the digestion characteristics of the complex formed between polyphenols and proteins,starch were studied through an in vitro simulation.And explored the effects of interactions on the antioxidant activity of polyphenols and complexes.The results showed that the digestion of casein and fish skin collagen mainly occurred in the small intestine stage.Secondly,after the addition of polyphenols,the degree of hydrolysis of the protein decreases,deducing that the polyphenols and complexes inhibit the activity of digestive enzymes,thereby reducing the degree of hydrolysis of the protein.The in vitro simulated digestion test of polyphenols and wheat starch showed that when the polyphenol content was 10% of the starch content,the polyphenols reduced the content of fast-digestible starch(RDS)by 20.7% and 9.7%,respectively.And the content of slow-digesting starch(RS)was moderately increased,which was 9.92% and 11.1%,respectively.And the content of resistant starch(SDS)showed different increases and decreases due to different concentrations.Secondly,polyphenols effectively inhibited the enzyme activity of ?-amylase and glucosidase,and reduced the digestibility of wheat starch.During the study of antioxidant activity,the formation of complexes significantly reduced the antioxidant activity of polyphenols.In the practical application of milk-black tea,fish-wine,steamed bun-black tea and steamed bun-wine,it was found that black tea and wine reduced the degree of hydrolysis of milk and fish,and the antioxidant activity of the mixture during the digestion stage was significantly reduced. |
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