成熟度对‘红地球’葡萄氨基酸营养价值的影响

【目的】探明不同成熟度对‘红地球’葡萄氨基酸营养价值的影响。【方法】以不同成熟度(盛花期后88~123 d)的‘红地球’葡萄为试材,测定果实氨基酸含量。同时,以鸡蛋蛋白质为标准蛋白,WHO/FAO氨基酸参考模式为评价标准,进行氨基酸营养价值评估。【结果】‘红地球’葡萄至少包含18种氨基酸,包括8种必需氨基酸、2种儿童必需氨基酸。氨基酸含量随着采摘期变化而变化,其中必需氨基酸、非必需氨基酸、儿童必需氨基酸、药用氨基酸、支链氨基酸、增香与着色氨基酸、伯胺基氨基酸、特殊功效氨基酸含量(w,后同)分别为557.3~659.7、1 176.3~1 690.8、326.8~703.8、1 130.0~1 644.1、231.7~285.3、926.1~1 404.8、1 126.0~1 609.0、1 032.9~1 510.7 mg·kg^-1,组间差异显著(p <0.05),在完全成熟期Ⅰ达到峰值;精氨酸、天门冬氨酸和谷氨酸等风味氨基酸含量与其味觉阈值的比值分别介于2.62~6.31、4.50~5.47和4.64~6.09,随着采摘期的延长呈先升后降变化趋势。氨基酸评分、化学评分和氨基酸比值系数分依次为11.33~14.07、18.32~4.43、49.70~57.04。苯丙氨酸等8种氨基酸含量相对不足,赖氨酸和苏氨酸含量相对过剩。【结论】不同成熟度对‘红地球’葡萄氨基酸含量及其营养价值影响显著。

Effects of maturity on amino acid nutrition in 'Red Globe' grape(Vitis vinifera L.)

【Objective】The study investigated the amino acid nutrition in‘Red Globe’grape(Vitis vinifera L.)at different maturities and analyzed the contents of 18 amino acids in grape fruit.【Methods】Grape samples were harvested at 88 d,95 d,102 d,109 d,116 d,and 123 d after full bloom(marked as initial maturity,maturity,complete maturityⅠ,complete maturityⅡ,over maturity,and senescence),respectively.Ten clusters of grape berries were randomly collected for each period.Ten grape berries were chosen from each cluster for amino acid determination.To detect the content of Trp,sample(2-3 g)was hydrolyzed with 4 mol·L^-1 LiOH and analyzed with an auto amino acid analyzer(LC8800,Shimadzu).For the other 17 amino acids,sample was hydrolyzed in 6 mol·L^-1 HCl and detected according to the national standard(GB 5009.124-2016).Amino acids were classified into different groups,such as essential amino acids,non-essential amino acids,essential amino acids for child,medical amino acids,branched chain amino acids,flavoring and coloring amino acids,primary amine amino acids,and special function amino acids.Based on the obtained data,the amino acid nutrition value was evaluated according to egg protein model and the ideal model recommended by FAO/WHO.A series of indexes,such as the amino acid score(AAS),chemical score(CS),and score of ratio coefficient of amino acid(SRC),were calculated.【Results】As Gln and Asn were degraded into Glu and Asp under acid hydrolysis,at least 16 amino acids,including 8 essential amino acids,2 essential amino acids for child,were found in‘Red Globe’grape during the whole harvesting period.All were components for protein.The contents of essential amino acids,non-essential amino acids,essential amino acids for child,medical amino acids,branched chain amino acids,flavoring and coloring amino acids,primary amine amino acids,and amino acids with special function were in the ranges of 55.73-65.97,117.63-169.08,32.68-70.38,113.00-164.41,23.17-28.53,92.61-140.48,112.60-160.90 and 103.29-151.07 mg·100 g^-1,respectively.The differences among grape berries at different maturities were significant(p<0.05).The highest values for all indexes were found in the completely matureⅠgroup.From the maturity to completely maturityⅡ,the contents of total amino acids and essential amino acids were higher than that in apple,grapefruit,and tangerine.The content of essential amino acids for child in grape was lower than that in banana,pomegranate,Rosa roxburghii,and Hippophae rhamnoides,but higher than that in apple,peach,orange,kumquat,grapefruit,and tangerine.The percentages of essential amino acids for child,medical amino acids,branched chain amino acids,flavoring and coloring amino acids,primary amine amino acids,and special function amino acids against total amino acids were 18.44%-29.94%,63.34%-69.95%,41.58%-44.57%,63.34%-69.95%,41.58%-44.57%,52.25%-59.77%,63.53%-68.57%,and 58.28%-64.46%,respectively.The highest values were also found in the completely matureⅠgroup.The values of E/T and E/N ranged from 31.26%to 36.57%and from 45.48%to 57.65%,respectively.These indexes of grape in all groups except the senescing berries were lower than the standard value recommenced by FAO/WHO.The ratio of content and taste threshold(RCT)was used for evaluating the effects of flavor amino acids on the grape flavor.The RCT of Arg,Asp,and Glu in grape ranged from 2.62 to 6.31,4.50 to 5.47,and 4.64 to 6.09,respectively,which was higher than that of strawberry and orange.The results indicated that these amino acids were the key amino acids for the flavor of grape.Their RCT showed an increase trend firstly,and then declined.The highest RCTs were found in completely maturityⅠ.The RCT of the other 12 amino acids were lower than 1.The percentage of flavoring and coloring amino acids to total amino acids in grape was higher than that of strawberry,orange and tangerine.The percentage of primary amine amino acids in grape was higher than that in Chinese kiwifruit and Phyllanthus emblica.The percentage of medical amino acids against total amino acids in grape was higher than that in ginseng,cordyceps sinensis,and Chinese wolfberry.The contents of(Phe+Tyr),Val,Ile,Leu,Trp,and(Met+Cys)were insufficient,while the contents of Lys and Thr were relatively surplus.The most restricting amino acid in‘Red Globe’grape was Met+Cys.The values of AAS,CS,and SRC of grape with different maturities ranged from 11.33 to 14.07,18.32 to 24.43,and 49.70 to 57.04,respectively.【Conclusion】The character of amino acid composition in‘Red Globe’grape varied constantly during berry maturation and senescence.The edible value of grape could be improved by complementing with other foods,such as mushroom(rich in Met and Cys)or grain(poor in Lys and Thr).