| The by-products of mixed edible fungi fruiting bodies produced during the preparation process of edible fungi soup base for hot pot still have a large amount of functional components,it will be a huge waste of resources to discard them directly.In order to realize the high-value utilization of edible fungi by-products and reduce the production cost of enterprises,the soluble substances were extracted in edible fungi by-products by ultrasonic-assisted enzymatic hydrolysis in this study,and the enzymatic hydrolysate was further dehydrated and concentrated to prepare a rich flavor of edible fungi extract.The main research contents were divided into the following four parts:(1)The influence of different enzymes on enzymatic hydrolysis effect of edible fungi byproducts were investigated.The enzymatic hydrolysate(EH)was prepared by cellulase(Cel),papain(Pap)and neutral protease(Nep)with alone and combined treatment.The changes of reducing sugar content in EH with enzymatic hydrolysis time and enzyme addition amount under different treatment conditions were compared and analyzed.The enzymes suitable for enzymatic hydrolysis of edible fungi by-products was screened by the quality of the EH.The results showed that Cel could effectively destroy the cell wall and membrane of edible fungi by-products,hydrolyze cellulose to produce the reducing sugar,promote the infiltration of enzymes and solvents into the tissues of the edible fungi by-products,and facilitate the hydrolysis of proteins by Pap and Nep.Among them,Cel+Pap had the best enzymatic hydrolysis effect and the highest hydrolysis degree(25.80±1.28%),which was the best combination for enzymatic hydrolysis of edible fungi by-products.(2)The extraction conditions of ultrasound-assisted enzymatic hydrolysis were optimized.The soluble components in edible fungi by-products were extracted step by step by ultrasoundassisted enzymatic hydrolysis.In stage 1,Cel and pectinase(Pec)complex enzymatic hydrolysis was used for extraction after ultrasound(US)treatment,and then Pap enzymatic hydrolysis was used for stage 2 extraction.The results showed that the soluble substances in the fruiting body by-products of edible fungi could be hydrolyzed and extracted by stepwise enzymatic hydrolysis.In stage 1,US treatment could destroy the dense structure of the cell wall and membrane of edible fungi by-products and accelerate the migration of solvents and enzymes into the cell interior.Cel and Pec further accelerated the decomposition of the cell wall and membranes on the basic of US treatment,and promoted the hydrolysis of cellulose to produce reducing sugar.Meanwhile,Pap specifically hydrolyzed protein in stage 2 and significantly increased the content of free amino acids(FAAs)in EH,which increased the umami by 12.19 times.The results of the two-stage optimization were as follows: Stage 1,the US time was 15 min,the US power was 900 W,the enzyme addition amount was 0.50%,the enzymatic hydrolysis time was 3.76 h,the enzymatic hydrolysis temperature was 50.91℃,and the enzymatic hydrolysis p H was 4.5.Stage 2,the enzyme addition amount was 0.33%,the enzymatic hydrolysis time was 3 h,the enzymatic hydrolysis temperature was 61.40℃,and the enzymatic hydrolysis p H was 7.68.After optimization,the antioxidant activity of the EH was enhanced,and the contents of total polyphenols(TPC)and total flavonoids(TFC)were increased by 2.21 times and 1.91 times,respectively.(3)The influence of different concentration methods on edible fungi extracts was studied.The EH was dehydrated by hot air concentration(HAC),infrared hot air concentration(IHAC),rotary evaporation concentration(REC)and freezing concentration(FC)to prepare edible fungi extract(the water content was 20%).The results showed that FC edible fungi extract had the best quality,followed by REC extract.After concentration,the umami perception of edible fungi extracts was significantly enhanced,as FC > REC > IHAC > HAC.The edible fungi extracts were rich in bioactive volatile compounds such as linalool,linalyl acetate,d-limonene,anisole and(-)-4-terpenol.In addition,the edible fungi extracts were rich in mineral elements,and there was no risk of excessive heavy metals(Cd,Pb,Hg and As).(4)The quality changes and the shelf-life models of edible fungi extracts under different storage conditions were studied.Four types of edible fungi extracts were stored at 4℃(90 d),10℃(90 d)and 25℃(45 d),respectively.The changes of quality indexes such as microorganisms,color,turbidity,umami response value,p H value,TPC and TFC were monitored during storage.The results showed that there was a negative correlation between the L* value and turbidity of the edible fungi extracts,with a decrease in brightness and an increase in turbidity overall,and it had a most significant change occurring when stored at 25℃.4℃was most conducive to the preservation of edible fungi extracts,and no coliform bacteria and staphylococcus aureus were detected during storage.However,25℃ was more conducive to the growth of microorganisms,resulting in the umami of edible fungi extracts decreased by18.74 times.The shelf life of edible fungi extracts at 4℃,10℃ and 25℃ was 61 d,47 d and24 d,respectively. |
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