梁王茶叶及其速溶茶粉的化学成分分析和抗氧化研究

以掌叶梁王茶叶为原料制备速溶茶粉,并研究其化学成分和抗氧化性,为梁王茶的深度开发提供科学依据。采用热水浸提法制备速溶茶粉,通过比色法研究梁王茶叶及其速溶茶粉的化学组分及其抗氧化能力,并对梁王茶叶17种游离氨基酸进行测定。结果表明,梁王茶叶的主要化学组分为:水溶性总糖47.32 g/kg、总多酚13.76 g/kg、水溶性蛋白质9.58 g/kg、水溶性氨基酸5.91 g/kg、水溶性多糖1.89 g/kg、总黄酮0.88 g/kg。梁王茶叶含量最多的游离氨基酸是组氨酸45.74 mg/kg。梁王茶叶速溶茶粉的最佳浸提条件为料液比1∶30(g/mL),温度85℃,浸提60 min,浸提次数3次,此条件下速溶茶粉的提取率达到39.88%。所得梁王茶叶速溶茶粉的主要化学组分为:水溶性总糖236.05 g/kg、水溶性蛋白质99.47 g/kg、水溶性氨基酸30.83 g/kg、总多酚27.08 g/kg、水溶性多糖17.99 g/kg、总黄酮2.03 g/kg。梁王茶叶及其速溶茶粉清除DPPH自由基的IC50分别为3.92、1.60 mg/mL;清除ABTS自由基的IC50分别为12.84、1.36 mg/mL。速溶茶粉浓度为3.5 mg/mL时,其还原力为3.343;茶叶浓度为15 mg/mL时,其还原力为2.966。研究表明梁王茶叶速溶茶粉营养丰富,并含有一定量的多酚、黄酮及多糖等生物活性成分,有较强的抗氧化能力,是一款较为健康的速溶茶饮品。

Study on Chemical Composition and Antioxidant Activity of Liangwang Tea Leaves and Its Instant Tea Powder

Leaves of Liangwang tea[Nothopanax delavayi(Franch.)Harms ex Diels,LWC]were used to prepare instant tea powder,chemical composition and antioxidant activities were investigated to provide scientific evidence for deepening utilization of LWC.LWC leaves were used to prepare instant powder by hot water extraction using orthogonal design,colorimetric method was used to investigate the chemical composition and antioxidant activity of LWC leaves and its instant tea powder.Seventeen free amino acids of LWC leaves were also studied.Results showed that the main chemical components of LWC leaves were total water soluble carbohydrate 47.32 g/kg,total polyphenols 13.76 g/kg,water soluble protein 9.58 g/kg,water soluble amino acids 5.91 g/kg,water soluble polysaccharides 1.89 g/kg,total flavonoids 0.88 g/kg.The most abundant free amino acid of LWC leaves was histidine,with amount of 45.74 mg/kg.Moreover,to make LWC instant tea powder,optimal extraction parameters were as follows:solid to liquid ratio of 1∶30(g/mL),temperature of 85oC,extraction duration of 60 min,and extraction times of 3.The extraction rate of instant tea powder under optimal condition was 38.86%.The main chemical composition of resulted LWC instant powder were total water soluble carbohydrate 236.05 g/kg,water soluble protein 99.47 g/kg,water soluble amino acids 30.83 g/kg,total polyphenols 27.08 g/kg,water soluble polysaccharides 17.99 g/kg,total flavonoids 2.03 g/kg.Additionally,IC50 of DPPH free radical scavenging capacity of LWC leaves and its instant tea powder were 3.92 mg/mL,and 1.60 mg/mL,respectively.IC50 of ABTS free radical scavenging capacity of LWC leaves and its instant tea powder were 12.84 mg/mL,1.36 mg/mL,respectively.The reducing power of LWC instant tea powder at concentration of 3.5 mg/mL was 3.343,while it was 2.966 of LWC leaves at concentration of 15 mg/mL.It can be concluded that LWC instant tea powder is rich in nutrient,containing certain amount of bioactive substances,namely polyphenols,flavonoids,and polysaccharides,as well as with substantial antioxidant activity,making it a relatively healthy instant tea product.