| In recent years,the incidence rate of hyperuricemia is increasing worldwide.Uric acid(UA)reducing lactic acid bacteria(LAB)can be the new tool for the prevention and treatment of hyperuricemia.At present,LAB mainly reduce UA through two ways:reducing the production of UA and decomposing the already formed UA.However,the underlying mechanism remains largely unknown.Therefore,26 strains of LAB were isolated from traditional fermented milk in Hulunbeier of Inner Mongolia,LAB were screened by xanthine oxidase(XO)inhibition test and UA reduction test respectively,the application of related strains in fermented dairy products was studied.In order to reduce the production of UA,6 strains of LAB with strong inhibitory effect on XO were screened by ultraviolet and visible spectrophotometry.The results showed that the suspension,cell free intracellular extract(CFE)and cell-free excretory supernatant(CFS)of six strains of LAB(Lactiplantibacillus plantarum HN2-3.Lactobacillus helveticus M11、L.helveticus M1-2、Lacticaseibacillus rhamnosus N1-4、L.plantarum N2-4、Streptococcus thermophilus ST0)had strong inhibitory effect on XO.The CFS of HN2-3,M1-1,N1-4 and N2-4 significantly inhibited XO compared with the CFE(P<0.05);There was no significant difference in the intracellular and extracellular secretions of dead and live bacteria in STO(P>0.05);There was no significant difference in the inhibition of XO between the CFS and the CFE of M1-2(P>0.05);The above results showed that the inhibition of XO by different LAB was different.Furthermore,it was found that regardless of whether the LAB survived or not,the bacterial suspension,CFS,and CFE of the 6 strains had varying degrees of scavenging effects on hydroxyl radicals,superoxide anions,and DPPH radicals.There was a positive correlation between the XO inhibition and antioxidant activity of live lactobacillus,but no correlation between the XO inhibition and antioxidant activity of dead lactobacillus.With the aim of exploring the decomposition effect of LAB on UA,five strains of lactobacilli with UA lowering activity were screened using high-performance liquid chromatography(HPLC).Here,five UA-lowering lactobacilli strains(L.rhamnosus N1-2,L rhamnosus N1-5、L.helveticus LH3,L.helveticus T1(1)-1 and Lactobacillus paracasei LP4)exhibited strong hypouricemic activity(41.96%,42.5%,44.18%,46.22%and 37.33%,respectively).Importantly,live bacteria on lowering UA is significantly higher than that of dead bacteria(P<0.05),but the UA-lowering effect of live bacteria and dead bacteria cell lysates is similar and was higher than the whole live cell(P<0.05).Furthermore,the hypouricemic effect of the lactobacilli was not significantly related to the cell wall,extracellular secretions,and other components.At the same time,it has no obvious relationship with the activity of intracellular uricase,which is widely believed to play a key role,but had a close relationship with the cell membrane.The 11 strains of LAB screened above were further applied,and the fermentation characteristics of LAB with UA lowering and XO inhibition were determined.The results show that S.thermophilus STO and L.helveticus LH3,L.paracasei LP4,L.helveticus M11,L.helveticus M1-2 reached the final fermentation point within 10 h,and the acidity was 74,80,80,70° T,respectively.After ripening for 12 h,the pH was 4.34,4.33,4.36,4.39;the number of viable bacteria was 8.61,8.89,8.6,8.38 Lg CFU/ml,respectively;the waterholding capacity after ripening increased significantly by 68.84%,65.23%,67.39%,61.13%;the viscosity was 2638,2862,3302,1858 mPa·s;the hardness was 48.32,40.05,42.19,35.93 g,and the water-holding capacity increased by 68.84%,65.23%,67.39%,61.13%,respectively.The consistency was 339.3 g·s,310.04 g·s,343.44 g·s,277.7 g·s,and the cohesion was-14.02 g·s,-45.02 g·s,-43.27 g·s,-21.33 g·s,respectively.The sensory evaluation scores of the 4 groups were higher,and the fermented milk had better fermentation characteristics.So it could be used as a potential functional product. |
PDF Full Text Request