| Ginkgo biloba(Ginkgo biloba Linn.)is also called maidenhair tree or Gongsun tree,belonging to Ginkgoaceae ginkgo gymnosperms.Ginkgo biloba originates from China.The fruit of Ginkgo biloba is rich in proteins,reducing sugar,amino acids,minerals and vitamins.Thus,Ginkgo biloba fruit can be used either as food or medicine.However,Ginkgo biloba fruit contains several toxic compounds.For this reason,Ginkgo biloba fruit can not be consumed for a large amount.The toxic compounds mainly locate in the germ of Ginkgo biloba fruit.Recently,more and more Ginkgo biloba fruits are produced in China.However,Ginkgo biloba fruits are not sold well.In order to reduce the toxicity of Ginkgo biloba fruits,as well as increase their values,the effects of germination and various processing methods on the bioactive compounds of Ginkgo biloba fruits were studied.Moreover,germinated Ginkgo biloba seeds were used to produce milk beverage containing calcium.The main results are shown below:1.Water immersing was used to germinate Ginkgo biloba seeds.The germination temperature,humidity and duration were 25 ?,80%and 30 d,respectively.The physiochemical and physicochemical properties of endosperm and germ of Ginkgo biloba seeds at different stages of germination were measured.Generally,the germination can be divided into 4 stages according to the shoot length,namely Budding,Shoot whiting,Sprouting ?,Sprouting ?.Starch content in endosperm decreased gradually during germination.At the end of germination,the starch content in endosperm of Ginkgo biloba seeds was 34.25 g/100g DW.Protein contents first increased and then decreased,whereas reducing sugar content first decreased and then increased.Total flavoids contents showed a decreasing trend.Ginkgolides and amygdalin contents decreased to 0.51 and 5.15 g/100g DW at the end of germination.Gingkolic acid content reached minimum at Stage 2 and total phenolic content increased gradually.Antioxidant abilities measured by ABTS and FRAP assays decreased,reaching minium at the end of germination.On the other hand,starch content in germ increased gradually,being 6.35 g/100 g after germination.Protein content in germ first increased and then decreased.Reducing sugar content exhibited an opposite trend.Total flavoids and gingkolic acid contents increased,whereas amygdalin content decgraded,being 0.014 g/100gDW after germination.Furthermore,total phenolic content decresed,reaching 0.25 mg/gDW at Stage 4.Antioxidant ability measured by ABTS assay increased gradually,reaching the highest at Stage 4.In contrast,the antioxidant ability measured by FRAP assay decreased,reaching minium at Stage 4.2.Effects of different processing methods on the bioactive compounds of germinated ginkgo biloba seeds were also studied.It was found that boiling at 100? resulted in the increae of starch content,reaching 13.31 g/100gDW.Protein content decreased gradually,and reducing content first increased and then decreased.Boiling resulted in the decrease of ginkgolic acid and the increase of flavoids.After 15-min boiling treatment,total flavoid content increased by 55%.Amygdalin content degraded and total phenolic content increased,being 0.3 mg/gDW and 47.23 mg/gDW after 15-min boiling treatment.With the increase of boiling duration,the antioxidant ability of ginkgo biloba seeds increased simultaneously.750-W microwave treatment resulted in the decrease of starch content in germinated ginkgo biloba seeds.After microwave irradiation for 15 s,starch content decreased by 58.47%.Protein content first increased and then decreased during microwave treatment,whereas reducing sugrar showed an opposite trend.Total flavoids content increased significantly after microwave treatment,which increased by 25.0%after 15-s microwave treatment.Microwave treatment resulted in the degradation of phenolics,ginkgolic acid and amygdalin.With the increase of microwave irradiation duration,antioxidant activity also enhanced gradually.Hot-air drying reduced the contents of starch,protein and reducing sugar.After drying at 80? for 24 h,their contents were decreased by 12.49%,28.27%and 46.48%,respectively.Similar to microwave treatment,hot-air drying resulted in the the degradation of phenolics,ginkgolic acid and amygdalin.Hot-air drying resulted in the increase of antioxidant activity of ginkgo biloba seeds.Lastly,the contents of starch,protein and reducing sugar decreased by 3.00%,0.90%and 1.04%,respectively after freeze drying.Ginkgolic acid content in germinated ginkgo biloba seeds was 5.71%lower than that in un-germinated ginkgo biloba seeds after freeze drying.The flavonoid content was increased 2.5 times and the total phenols increased by 16.91%.The antioxidant activity of germination ginkgo was stronger than that of ginkgo without germination.In summary,boiling for 15 min was the suitable way to reduce toxic compounds in germinated Ginkgo biloba seeds.3.Germinated ginkgo biloba seeds were mashed,enzymetic treated and then added to fresh milk including calcium.Specifically,single factor experiment and orthogonal test were used to optimize the formulation of ginkgo biloba juice,milk and sugar.The effect of different types of calcium on the milk quality was also studied.Moreover,the type and amount of emulsifier and stabilizer added to milk were also studied.It was found that the optimal mixture of ginkgo biloba juice,milk and sugar was 4:5:85.The best type of calcium added was milk calcium.The optimized combination of stabilizer was avicel and agar and carrageenan(1:1:1,w:w:w).The optimized combination of emulsifier was sucrose esters,mono ester and PGA=1:1:1(w:w:w).The addition of both emulsifier and stabilizer was 0.3g/100 g.In addition,ultra high temperature instantaneous sterilization,high temperature and high pressure sterilization and pasteurization were used to process the resulting milk beverage.It was found that the product quality could meet the national standard after both ultra high temperature instantaneous sterilization and high temperature and high pressure sterilization.Additionally,the milk beverage containing germinated ginkgo biloba seeds had low content of toxic compounds and considerably high content of flavoids. |
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