Study On Ginkgo Toxicity Reduction And Stability Of Cloudy Beverage

China has a wealth of ginkgo resources and the annual output of ginkgo seeds exceeds 18,000 tons.However,due to the presence of toxic substances such as cyanide and ginkgolic acid in ginkgo seeds,it has severely restricted the processing and utilization of ginkgo seeds,resulting in excess output of ginkgo seeds.Ginkgo beverages can help to solve the excess production problem.However,ginkgo cloudy beverages have abundant carbohydrates and proteins,which lead to delamination and sedimentation problems during shelf life.The stability of cloudy beverage is a key issue in the processing process.In this paper,ginkgo seeds(Ginkgo biolba L)was used as the raw material.The content of cyanide and ginkgolic acid in ginkgo seeds was firstly measured.Then different treatment methods were employed to reduce ginkgolic acid.Finally,the detoxified ginkgo seeds were chosen to investigate the effect of enzymolysis process,stabilizer formulation and homogenization process on the stability of ginkgo cloudy beverages.Firstly,distilling isonicotinic acid-pyrazolone method,acid-hydrolyzed isonicotinic acidbarbituric acid method and enzymatic ion chromatography were applied to measure cyanide content in ginkgo seeds;High performance liquid chromatography was used to determinate ginkgolic acid.The result showed that trace amounts of cyanide were detected in the ginkgo germ by acid hydrolysis and enzymatic hydrolysis method,which cyanide contant was 0.36 ± 0.08 mg/kg and 0.29 ± 0.05 mg/kg,respectively;the total ginkgo acid content in ginkgo seeds was 163.11 ± 2.31 mg/kg.Secondly,the effect of infrared,microwave and boiled heat treatment on the degradation of ginkgo acid and flavonoids were investigated.It can be seen that,compared with freezedrying treatment,infrared,microwave and boiled treatment can significantly reduce the ginkgolic acid content(P<0.05).Boiled treatment had the greatest impact on reducing ginkgolic acid,followed by infrared treatment;the microwave treatment had a little effect on the ginkgolic flavonoids.Moreover,the effect of alkali treatment on ginkgolic acid reduction were stuied.Under the same heat treatment conditions,ginkgolic acid was more easily degraded after alkali soaking and it was not dependent on the soaking time.Compared to alkaline solution soaking treatment,alkaline solution boiling treatment can reduce ginkgolic acid more effectively,which 75% of ginkgolic acid can be removed after 0.05% alkaline solution boiling treatment for 20 min.However,alkali treatment had more flavonoids danage than other treatment.Subsequently,combined treatments were utilized to study the effect of ginkgolic acid reduction.The result indicated combined treatment can decrease more ginkgolic acid content than single treatment methods(P<0.05).Considering ginkgolic acid reduction and ginkgo flavonoid loss,the combination of alkali boiled and infrared heat treatment was the most effective method to reduce ginkgolic acid content to 10 mg/kg.Finally,the detoxified ginkgo seeds were chosen to prepare ginkgo cloudy beverage.The effects of enzymolysis process,stabilizer formulation and homogenization process on the stability of the cloudy beverage were investigated.The physical properties such as viscosity,Zeta potential and particles of the cloudy juice were changed significantly after enzymolysis treatment(P<0.05).When the enzymolysis DE value reached 40%~55%,ginkgo cloudy beverage appeared good stability.The optimal stabilizer formulation for beverages: microcrystalline cellulose(MCC)0.26%,sodium caseinate 0.15%,sucrose fatty acid ester(SE-11)0.13%,monoglyceride 0.04% were optimized by uniform design method.The effects of different homogenization pressure treatments on the particle size,Zeta potential,suspension stability,and change in backscattered light intensity((35)BS)of beverages were investigated.It was found that the homogenization process can significantly improve the stability of beverages.Furthermore,Turbiscan analysis showed that when the homogenization pressure exceeds 70 MPa,the suspended particles in the beverage were more likely to accumulate together during storage,which is not conducive to the stability of the beverage.The beverage homogenized by 70 MPa and 2 cycles had the best stability.After 6-months storage,though the particle size,potential,pH and color had a little change,ginkgo cloudy beverages still appeared excellent stability without delamination and precipitation phenomenon.