Detoxification Of Ginkgo Biloba Seeds By High Pressure Steam Burst And Lactobacillus Plantarum Fermentation And Its Application

Ginkgo biloba seed has high nutritional value.Its functions presented in the traditional Chinese medicine include warming lung,replenishing heart and prolonging life.However,the toxicity of Ginkgo products has restricted the development of Ginkgo industry.At present,commercial products of Ginkgo biloba seeds are very rare.Currently,it is lack of efficient and environmental friendly detoxification technology.In this study,Ginkgo biloba seeds were used as raw material to study their toxic components,contents and distributions of hydrocyanic acid,MPN and ginkgolic acid were quantitatively detected.The detoxification technology was studied through physical burst and microbial fermented method,respectively,in order to reduce the toxicity of Ginkgo biloba seeds safely and efficiently.Lastly,based on the two detoxification technologies,the detoxified Ginkgo biloba seeds were developed into new a safe and delicious product,which would be helpful on industrialization of Ginkgo biloba food.Analysis of hydrocyanic acid,MPN and ginkgolic acid in Ginkgo biloba seeds showed that the hydrocyanic acid was unable to be detected.The content of MPN was 2.21±0.84 mg/g,and ginkgolic acid was the one that presented in five isomeric forms.Oleanolic acid?C15:1?was the highest proportion of ginkgolic acids,followed by dioctylmethane allyl ginkgolic acid?C17:1?and dioctylmethane diallyl ginkgolic acid?C17:2?.The three of ginkgolic acids were accounted for more than 95%of the total ginkgolic acids content.Results show that the content of ginkgolic acid in Ginkgo biloba seeds was 255.30?g/g;however,the oleanolic acid?C15:1?content was 163.56?g/g.According to the distribution of toxicity in Ginkgo biloba seed,the contents in endopleura,endosperm and gametophyte were detected.It was found that MPN concentration in endosperm was much higher than that in gametophyte;however,84.58%of ginkgolic acid was concentrated in gametophyte.Secondly,a high temperature steaming method was applied to physically burst the Ginkgo biloba seeds in order to achieve detoxify.The following parameters were investigated,i.e.soaking time,water addition,burst pressure,burst time,burst rate and removal rate were investigated;meanwhile,the toxicity content after removing gametophytes was detected.Results showed that the water addition had no significant impact on the burst rate and burst size of Ginkgo biloba seeds;however,the burst rate of soaked seeds was higher than that of unsoaked group,and the burst rate and burst size were increased with the increase of pressure and time.When Ginkgo biloba seeds were soaked for 4 h,and burst for 30 min at 0.142 MPa with 200 mL water,the highest burst rate was achieved?81.98%?.The removal rate was independent of all factors,with an average value of 30.83%.In addition,the toxic content of Ginkgo biloba seeds after removing gametophytes showed that the MPN was unable to be detected because of thermal decomposition,which the total ginkgolic acid content was decreased by 93.69%,and the removal rate of oleanolic acid?C15:1?was reached to 100%,which was better than those after water boiling and microwave heating.There was no significant difference in the content of active ingredient ginkgolide B in Ginkgo biloba seeds before and after bursting.The seeds without gametophytes were developed into butter coconut flavored snack.Sensory evaluation of the snack showed that the seeds without gametophytes were more favored in flavor,texture and taste without its original bitterness.The microbial fermented method was used to detoxify the main toxic ginkgolic acid in Ginkgo biloba seeds in this study as well.In order to better hydrolyze the macromolecule substances in Ginkgo biloba seeds into small molecules for microbial fermentation,Ginkgo biloba seeds were enzymatically hydrolyzed by a high temperature-endured?-amylase;and the optimal process was explored.Results showed that the ratio of material to liquid was 1:5;the content of high temperature-endured?-amylase was 1.0%;the enzymatic hydrolysis time was 20 min;and the effect of adding 2.0%glucoamylase and 0.2%neutral protease at 55.0?for 2 h was better when the reducing sugar content was reached to 62.56 mg/mL.In addition,different fermentation strains were selected to study the detoxification of Ginkgo biloba seeds.It was found that Lactobacillus plantarum was more effective than other strains.Single factors,e.g.sugar content,fermentation temperature and inoculum on the detoxification were investigated;and the fermentation conditions were optimized simultaneously.The detoxification rate of fermented Ginkgo biloba seeds was reached to 70.12%after one week when the sugar content was 13.5?Brix at the fermentation temperature of 38.0?and 2.6%of inoculation.Based on the change of ginkgolic acid content during fermentation,the highest detoxification rate was 90.19%after two weeks,and the concentration of ginkgolide B was decreased slightly.The quality of Ginkgo fermented beverage was tested and evaluated.It was proved that the acute oral LD₅₀ in mice was higher than 120 mL/kg,which is able to be defined as a non-toxic substance.Hydrocyanic acid and MPN in beverage were not detected;and the content of ginkgolic acid was only 1.03 mg/L with the number of viable bacteria of2.0×10⁶ CFU/mL.