Effect of Preservation Methods on Retention of Main Quality Compnents in Fresh Tea Leaves
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摘要: 为准确反映茶鲜叶生化成分的组成特征,对11个茶树品种鲜叶分别进行冷冻固样、热风固样和微波固样,并通过二维"点集"分布视图和主成分分析,对不同固样方法所获得供试样品的茶多酚总量、游离氨基酸总量、咖啡碱含量、主要儿茶素和游离氨基酸组分进行比较分析。结果表明:热风固样与冷冻固样样品存在较明显的类群区分,且热风固样样品中的茶多酚总量、表没食子儿茶素没食子酸酯、表儿茶素、表儿茶素没食子酸酯、天冬氨酸、精氨酸、丝氨酸、胱氨酸均显著低于冷冻固样;微波固样与冷冻固样无明显的样品类群区分。综合考虑简便性、保真性、节能性等方面,微波固样更适用于茶鲜叶取样制备,其样品生化检测结果可为茶鲜叶质量的化学评价提供参考依据。Abstract: Fresh leaves plucked from tea bushes of 11 varieties were preserved by freezing, hot-air drying or microwave heating to compare the retention of polyphenols, free amino acids and caffeine in the leaves. The two-dimensional point set distribution and principal component analyses were performed to determine the data variances among the samples. The results showed that the contents of polyphenols, EGCG, EC, ECG, aspartate, arginine, serine and cystine were significantly lower in the tea leaves treated by hot-air than by freezing. Either microwaved or frozen leaves could largely retain the original composition. However, being convenient and efficient in handling and for preservation, the microwave method was recommended for the application.
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Key words:
- fresh tea leaves /
- freezing /
- hot-air drying /
- microwave heating
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表 1 3种固样方法茶叶样品
Table 1. Codes for samples of 3 preservation methods
茶树品种 冷冻固样 热风固样 微波固样 茗科1号 F1 H1 M1 黄观音 F2 H2 M2 金凤凰 F3 H3 M3 矮脚乌龙 F4 H4 M4 北斗 F5 H5 M5 铁观音 F6 H6 M6 紫牡丹 F7 H7 M7 白鸡冠 F8 H8 M8 奇丹 F9 H9 M9 白芽奇兰 F10 H10 M10 紫鹃 F11 H11 M11 表 2 不同固样方法样品茶多酚总量、游离氨基酸总量、咖啡碱含量
Table 2. Effect of preservation methods on contents of polyphenols, free amino acids and caffeine in tea leaves
[单位/(mg·g-1)] 固样方式 茶多酚 游离氨基酸 咖啡碱 冷冻固样 216.69±18.11Aa 31.75±5.39 32.98±3.15 热风固样 144.99±19.74Bb 34.38±4.21 31.35±3.7 微波固样 204.13±15.77Aa 32.36±3.35 31.25±5.08 注:同列数据后不同大、小写字母表示差异达极显著(P < 0.01)或显著(P < 0.05)水平,无字母标记表示差异不显著,下表同。 表 3 供试样品的主要儿茶素和游离氨基酸组分含量
Table 3. Contents of main catechins and free amino acids in tea samples
[单位/(mg·g-1)] 处理 EGC EGCG EC ECG Thea Asp His Arg Ala Glu Ser Thr Cys Lys 冷冻固样 38.27±9.94Aa 114.84±20.75a 9.67±2.51Aa 33.09±7.99Aa 11.60±3.91 Aa 1.81±0.68a 2.21±0.82 Aa 4.76±2.42Aa 0.09±0.04Bb 1.12±0.75 Aa 0.55±0.12a 0.30±0.05b 1.17±0.25Aa 0.01±0.01b 热风固样 40.29±8.94 Aa 90.90±22.53b 6.44±2.6Bb 24.91±5.89Bb 11.65±2.77 Aa 1.14±0.66b 2.56±0.84 Aa 1.63±1.55Bb 0.31±0.20Aa 0.99±0.67 Aa 0.36±0.23b 0.32±0.04ab 0.03±0.08Bb 0.04±0.03a 微波固样 35.47±9.06 Aa 105.30±17.30ab 9.16±2.92ABa 29.88±6.63ABab 10.84±4.06 Aa 2.00±0.87a 2.10±0.57 Aa 3.49±2.05ABa 0.07±0.08Bb 0.86±0.45 Aa 0.51±0.10a 0.35±0.03a 0.14±0.13Bb 0.01±0.02ab -
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