Study On Processing Key Techniques Of Edible Mushrooms-Whey Protein Beverages And Edible Mushrooms-Lactic Acid Bacteria Beverages

Edible mushrooms(Auricularia auricular-judae and Tremella fuciformis)have high edible value and medicinal value.However,most of the current processing is mainly processed products,accompanied by a single product structure,low precision and deep processing ratio,and low added value of products.This paper chose A.auricular-judae and T.fuciformis as raw materials,to investigate the stability,microstructure,and digestibility of edible mushroom polysaccharide-whey protein isolate complexes.Moreover,the quality characteristics and stability of whey protein isolate-edible mushroom polysaccharide complexes during processing and storage were studied.In addition,the quality characteristics of edible mushroom beverages after fermentation by lactic acid bacteria were initially explored.The main research contents and research results were as follows.(1)The stability of whey protein beverages is poor in the low p H range.Studies in this paper have shown that under the condition of p H 4.5,T.fuciformis polysaccharide(TP)and whey protein isolate(WPI)could form soluble complexes(5% WPI,0.4% TP).The complexes were stably dispersed in an aqueous solution,thus TP could effectively improve the stability of the high-concentration whey protein isolate solution at low p H.Rheological studies showed that the T.fuciformis polysaccharides enhanced WPI solution exhibited characteristics of pseudoplastic fluid.Microstructure studies showed that the TP–WPI complexes formed more orderly structures than that of the two monomers.In this paper,a new limited proteolysis-coupled mass spectrometry technique was utilized to characterize the in vitro digestibility of TP–WPI complexes.Based on the analysis of the present technology,the rate of digestion of TP–WPI complexes was shown to be significantly lower than that of WPI,which would reduce gastric emptying time and increase satiety.Simultaneously,the digestibility of each protein in whey protein and the binding region of protein to polysaccharides were also accurately revealed by this new technique.(2)In order to clarify the effects of sterilization process and storage time on the stability and quality characteristics of edible mushrooms polysaccharide-whey protein isolate complex solution,the paper studied the viscosity,?-potential and structural properties of Auricularia auricular-judae polysaccharide(AP)-whey protein isolate(WPI)solution in pasteurization and low temperature storage.AP–WPI complexes(2% WPI w/w,0.2% AP w/w)formed at p H 4.7 could disperse well in aqueous solution and solutions did not phase separate during storage.After 15 minutes of pasteurization at 85?,the stability of the AP-WPI solution was further improved,which was reflected in the decrease of the ?-potential of the complex solution,the particle size of the complex becomed small,and the viscosity of the complexsolution becomed larger.At the same time,the secondary structure of the complex changed,and the absorption peak of the ?-helix at 200 nm changed to the absorption peak of?-free curl at 208 nm.During the four-week storage at 4?,the ?-potential of pasteurization-treated AP–WPI complexes solutions(2% WPI w/w,0.2% AP w/w)was always less than-30 m V,and the viscosity remained at around 0.5 Pa.s.No microbial growth was detected in the complex solutions.(3)In order to develop a new type of probiotic beverage,the gallbladder-resistant Lactobacillus plantarum was inoculated into the prepared A.auricular-judae broth to explore its quality characteristics.Within 72 hours of fermentation,the growth kinetics of L.plantarum,p H values,the content of lactic acid,and taste of the A.auricular-judae probiotic beverage were determined.In addition,volatile compounds of the A.auricular-judae probiotic beverage were extracted by headspace solid-phase microextraction(HS-SPME)and their compositions were analyzed by gas chromatography–mass spectrometry technology(GC-MS).The results showed that the p H of the A.auricular-judae probiotic beverage inoculated with L.plantarum reached 3.86 and the lactic acid content exceeded 0.6 mg/m L.During the fermentation process,L.plantarum in the A.auricular-judae probiotic beverage grew rapidly,and the number was higher than 7.8 Log CFU/m L.The taste studies showed that the sourness of A.auricular-judae probiotic beverage was enhanced,and the bitterness and astringency were weakened,which helped to reduce the woody taste contained in the A.auricular-judae.Volatile compounds studies showed that the total peak area of volatile compounds in the A.auricular-judae probiotic beverages was much larger than that of the control samples.And the content of 1-hexanol and phenylethyl alcohol,which exhibitsed floral and sweet odor,was increased.The flavor of the A.auricular-judae probiotic beverage was enhanced.Our results could provide valuable information for the production of A.auricular-judae probiotic beverage.