Postbiotic extract and preparation process and use thereof

A process for of producing a postbiotic extract, comprising the steps of:

• a) providing a whey protein having an isoelectric point of 4.4 and a dextrin having an isoelectric point of 5.2;
• b) admixing the whey protein and a probiotic bacterium with water having a pH value of 7.5, so as to form a mixture,
• wherein the probiotic bacterium is selected from the group consisting of Lactobacillus plantarum CB102, Lactobacillus acidophilus JCM1132, Lactobacillus casei JCM1134, Bifidobacterium bifidum JCM1255, Bifidobacterium lactis JCM10602, Bifidobacterium longum CB108, and combinations thereof;
• c) adding the dextrin into the mixture, followed by adjusting the pH value of the dextrin-added mixture to between 4.4 and 5.2, so that a precipitate is formed;
• and
• d) subjecting the precipitate to an acid hydrolysis treatment with lactic acid to isolate the cell wall of the probiotic bacterium, so as to obtain the postbiotic extract.