| In order to investigate the effect of different type and concent of assimilable nitrogen sources on the fermentation performance and quality of seedless lychee wine preliminary,the organic nitrogen source and inorganic nitrogen source of 60,120,240,360 mg · N · L-1 was added in seedless lychee wine making processes,respectively.Dry weight method,high performance liquid chromatography and solid phase microextraction and gas chromatography coupled with mass spectrometry?SPME-GC-MS?were adopted to analyze the effects of them on the fermentation quality of seedless lychee wine.The main results were as follows:1.The analysis results of seedless lychee juice ingredients:The seedless lychee juice was rich in organic acids,and the major organic acids were malic acid?2.8 mg/mL?and succinic acid?1.45 mg/mL?.The content of tartaric acid,citric acid,acetic acid was relatively low.17 kind of free amino acids were identified,the total content was 128.65 mg/100mL.Proline,arginine,alanine content higher than others,proline accounted for 50.96%of the total amino acids,while arginine for 13.48%,alanine for 10.17%.The content of isoleucine,leucine,phenylalanine,threonine,glutamic acid,methionine content was less,and the proportion was less than 1%.The soluble solid contens was higher,which was 15.2 °Brix.2.Effect of acidic amino acid on the fermenting performance and quality of seedless lychee wine.Compared with the blank sample,Asp and Glu240 treatments increased the yeast growth rate obvious.The alcohol content increased in the most of the acidic amino acid treatment.The glycerol content decreased in the range of 0.57?1.34 mg/mL in acidic amino acid treatment.pH value increased in the range of 0.05-0.09.Obvious change of organic acid was observed,while Aspartic acid at 120?360 mg N·L-1 decreased about 0.21 mg/mL.The content of isoamyl acetate,ethyl acetate,ethyl octanoate,ethyl decanoate increased obviously,while the content of higher alcohol and acetaldehyde decreased at different extent.3.Effect of basic amino acid on the fermenting power and quality of seedless lychee wine.Compared with the blank sample,basic amino acids treatment at 60 mg·N L-1 increased the yeast growth rate and the consumption rate of soluble solid contens.With the increase of the concentration,the alcohol content in the Arg treatment increased gradually,while the alcohol content in the His treatment increased first and then decreased.The glycerol content decreased in the range of 0.84-1.86 mg/mL.pH value increased in the range of 0-0.13.Organic acid content varied at different degrees,while the content of acetic acid decreased 0.09 mg/mL in the His60 treatment.The content of esters increased significantly,especially His60 treatments.The content of higher alcohol and acetaldehyde decreased significantly in arginine treatments,whereas the content of higher alcohol and acetaldehyde increased in His60 treatments.4.Effect of neutralc amino acid on the fermenting performance and quality of seedless lychee wine.Compared with the blank sample,tyrosine treatments increased the biggest number of yeast cells and the yeast growth rate,and neutral amino acids treatment at 240 mg-N L-1 increased the consumption rate of soluble solid contents.The alcohol content increased in the most of the neutralc amino acid treatment.The content of glycerol decreased in the range of 0.34?1.80 mg/mL.The pH value increased 0.05?0.14.The content of organic acids was obviously changed in Lychee wine,the content of acetic acid decreased in the range of 0.05?0.2 mg/mL.The content of esters increased significantly,especially Phe240 treatment.The content of isoamyl acetate,ethyl acetate,ethyl octanoate,decanoate,phenethyl alcohol increased at different degrees,whereas the content of higher alcohol,acetaldehyde nonanal and benzaldehyde decreased significantly.5.Effect of inorganic nitrogen sources on the fermenting performance and quality of seedless lychee wine.Compared with the blank sample,the yeast growth rate and the consumption rate of soluble solid contens increased,while ammonium chloride treatment increased the biggest number of yeast cells.Alcohol content increased 0.4?0.13%vol and the glycerol content increased sightly.The pH value increased in the most of the neutralc amino acid treatment.The content of organic acids was obviously changed in Lychee wine,in addition to diammonium phosphate treatment at 120 mg·N·L-1,acetic acid content increased in the range of 0.06-0.15 mg/mL.The content of esters and higher alcohol increased at different degrees,the content of isoamyl acetate,ethyl acetate,and ethyl caprylate increased at different degrees,whereas the content of acetaldehyde decreased obviously. |
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