Effects Of Zein Hydrolysate On The Stability Of Emulsion And Protection Role Of Its Digesta Against Caco-2 Cell Oxidation Damage

Lipid oxidation is one of the main reasons for the deterioration of the quality of food emulsions.Adding natural source antioxidants such as antioxidant peptides to food emulsions to improve their stabilty is able to enhance food quality.However,whether antioxidant peptides will affect lipid digestion of emulsion is unknown.At the same time,although antioxidant peptides have a certain antioxidant activity,whether they have better antioxidative effects after digestion will require further study.Understanding these issues helps in the design and development of high-quality nutritional foods.In this paper,zein hydrolysates with antioxidant activity were used as co-emulsifiers to prepare emulsions.The effect of zein hydrolysates on the physical and oxidative stability and lipid digestion of emulsions were investigated.The antioxidative effect of zein hydrolysate after gastrointestinal digestion was investigated using static digestion model and Caco-2 cell model,.The main results were as follows:（1）Turbidity and TBARS were used as indicators to investigate the effect of zein hydrolysates on the physical and oxidative stability of the emulsions during storage.The effect of zein hydrolysate on lipid digestion in the emulsions was investigated using the microstructure and particle size of the emulsions and the release of free total free fatty acid and individual free fatty acid.The results show that the zein hydrolysate can improve the physical and oxidative stability of the emulsion.The zein hydrolysate promoted lipid digestion by inhibiting the aggregation of emulsified particles during the digestion process and increases the release of free fatty acid.When compared with the static model,the dynamic gastric model dispalyed a higher lipid digestion rate with the total free fatty acid release rate of 95%.（2）The antioxidant activity of gastrointestinal digestas of zein hydrolysates was investigated using hydroxyl radical scavenging ability,DPPH free radical scavenging ability,ferrous ion chelating ability,and reducing power as indicators.And the cell antioxidative activity of the gastrointestinal digestas of zein hydrolysate was investigated by Caco-2 cell model using CAA as an indicator.The results showed that the antioxidant activity of zein hydrolysates after gastric digestion decreased.However,further intestinal digestion could increase their antioxidant activity.Intestinal digestion products of zein hydrolysate can effectively remove free radicals produced in Caco-2 cells.（3）The protective effects of gastrointestinal digestas of zein hydrolysates on H₂O₂-induced oxidative stress in Caco-2 cells were investigated using IL-8,MDA,protein carbonyl,glutathione,and antioxidant enzyme activities as indicators.The results showed that pretreatment with the gastrointestinal digest reduced intracellular IL-8 content,reduced lipid and protein oxidation,increased glutathione,and enhanced antioxidant enzymes（CAT,SOD,GPx,GR）,GST,γ-GCS)activity of zein hydrolysate.（4）The transcriptome sequencing method was used to analyze the cell antioxidative mechanism of ZH.The results of differentially expressed genes,GO enrichment,COG classification,and KEGG pathway suggested that the gastrointestinal digesta of ZH might protect cell from oxidation by increasing NADP dehydrogenase and protecting mitochondria from oxidative damage.In summary,the zein hydrolysate can increase the stability of the emulsion and promote the lipid digestion of emulsions.After gastrointestinal digestion,intracellular antioxidant enzymes and NADP dehydrogenase activity can be increased to reduce the degree of oxidative damage to cells.