为探究采用风冷冰箱和直冷冰吧贮藏对龙井绿茶品质的影响,把茶叶分别存储于风冷冰箱的冷藏室和冷冻室、直冷冰吧的冷藏室和冷冻室等4种不同的贮藏环境中贮藏90、180、270、360βd时分别取样,通过生化成分含量测定及感官审评等分析比较不同贮藏条件对绿茶的存储效果。结果表明,整个贮藏期内,冷冻室对生化成分的存储效果优于冷藏室,其中风冷冰箱冷冻室能有效地保持茶叶低含水率,贮藏180βd时其含水率显著低于直冷冰吧(P<0.05),直冷冰吧冷冻室则对叶绿素、维生素C、咖啡碱等含量保持效果较好,贮藏180βd时其维生素C和咖啡碱含量显著高于风冷冰箱(P<0.05);在0~180βd的贮藏期内,氨基酸、茶多酚、儿茶素均在风冷冰箱的冷冻室保留率高(均约为95%),贮藏后期则在直冷冰吧的冷冻室保留率高,且贮藏结束时均与风冷冰箱差异显著(P<0.05)。风冷冰箱有利于绿茶滋味和香气的保持,直冷冰吧有利于绿茶外形的保持,即不同贮藏条件对茶叶的感官分属性的影响不同。正交偏最小二乘判别分析(OPLS-DA)结果表明,汤色、滋味、香气、咖啡碱和维生素C等品质指标在不同的贮藏方式间差异较大。结合两设备的特点可知,茶叶相对短期存储时可选择风冷冰箱,长期存储时则直冷冰吧更优。
The effects of frost-free refrigerator and direct-cooled ice bar on the storage quality of longjing green tea were explored. Teas were stored in the cold storage room and freezer room of the frost-free refrigerator and direct-cooled ice bar respectively, and the storage effects of the different storage conditions on green tea were compared by measuring the contents of biochemical components and sensory quality evaluation when the teas were stored for 90, 180, 270 and 360 days. The results show that the storage effect on biochemical components in freezer room was better than that in cold storage room during the whole storage process and the freezer room of frost-free refrigerator could keep the lower water content, with the tea water content for 180 days significantly lower than that of the direct-cooled ice bar (P<0.05). The freezer room of direct-cooled ice bar was conducive to the maintenances of chlorophyll, vitamin C, caffeine, and the contents of vitamin C and caffeine when the tea was stored for 180 days. During the storage period of 180 days, the retention rates of amino acids, tea polyphenols, catechins were higher in the freezer room of the frost-free refrigerator (they were all around 95%). But the retention rates were higher in the freezing chamber of straight colder bar during the later stage of storage, and were significantly higher than those of the frost-free refrigerator (P<0.05). Frost-free refrigerator was conducive to maintaining the taste and aroma of green tea. While direct-cooled ice bar was conducive to maintaining the appearance of green tea, suggesting the effects of storage conditions on the organoleptic properties of tea are different. Orthogonal partial least squares discriminant analysis (PLS-DA) showed that the quality indexes of liquor color, taste, aroma, caffeine and vitamin C were significantly different under different storage conditions. Combined with the characteristics of two devices, it can be seen that frost-free refrigerator is more suitable for short-term storage of tea, while direct-cooled ice bar is better for the long-term storage of tea.
[1] Hopley C.The empire of tea: the remarkable history of the plant that took over the world[J]. Gastronomica, 2005, 5(3): 136-137.
[2] Bravi F, La Vecchia C, Turati F.Green tea and liver cancer[J]. Hepatobiliary surgery and nutrition, 2017, 6(2): 127-129.
[3] Janghyun P, Seunghee N, Song J H, et al.Quality changes of green tea on anaerobic treatment by various storage temperature and period[J]. Korean Journal of Horticultural Science & Technology, 2012, 30(5): 519-526.
[4] 黄力华. 碧螺春绿茶贮藏期间品质劣变及保鲜技术研究[D]. 扬州: 扬州大学, 2005: 44-46.
[5] Lee J H, Chambers D H.Flavors of green tea change little during storage[J]. Journal of Sensory Studies, 2010, 25(4): 512-520. DOI: 10.1111/j.1745-459X.2010.00283.x.
[6] 王近近, 袁海波, 邓余良, 等. 绿茶、乌龙茶、红茶贮藏过程中品质劣变机理及保鲜技术研究进展[J]. 食品与发酵工业, 2019, 45(3): 281-287.
[7] 马汉祥. 一种毛尖茶叶的无害保鲜方法: 中国, 201710825342.0[P].2017-09-14 [2019-01-16].
[8] 李先明, 刘宝林, 李维杰, 等. 不同包装对风冷冰箱中冷冻猪肉品质的影响[J]. 制冷学报, 2016, 37(6): 104-112.
[9] Ledesma S, Belman-Flores J M. Mathematical application to analyze the thermal behavior of a domestic refrigerator: influence of the location of the shelves[J]. International Journal of Refrigeration, 2017, 74: 362-370. DOI: 10.1016/j.ijrefrig.2016.10.023.
[10] 李铁汉, 方仕茂, 王玉洁, 等. 绿茶贮藏保保鲜技术研究进展[J]. 中国茶叶加工, 2019(2): 27-32, 39.
[11] Roberts E A H, Smith R F. Spectrophotometric measurements of theaflavins and thearubigins in black tea liquors in assessments of quality in teas[J]. Analyst, 1961, 86(10): 94-98.
[12] Carraturo F, Castro O D, Troisi J, et al.Comparative assessment of the quality of commercial black and green tea using microbiology analyses[J]. Bmc Microbiology, 2018, 18(1): 1-12.
[13] 林津, 曹婵月, 杨文建, 等. 纳米包装及急冷处理对绿茶保鲜品质的影响[J]. 食品科学, 2012, 33(6): 247-251.
[14] 崔峰, 骆耀平, 陈一心, 等. 茶叶贮藏过程中品质变化及其影响因素研究进展[J]. 茶叶, 2008, 34(1): 2-5.
[15] 宋婷婷. 绿茶贮藏过程中品质因子的变化研究[D]. 杭州: 浙江大学, 2010, 11-12.
[16] Han Wenyan, Huang Jigang, Li Xin, et al.Altitudinal effects on the quality of green tea in east China: a climate change perspective[J]. European Food Research and Technology, 2017, 243(2): 323-330. DOI: 10.1007/s00217-016-2746-5.
[17] 赵熙, 黄浩, 银霞, 等. 绿茶贮藏过程中主要生化成分和抗氧化活性的变化及相关性研究[J]. 广东农业科学, 2016, 43(3): 120-124.
[18] Zhang X B.Differences of polyphenols content in anxi tieguanyin tea among different seasons and relationship between polyphenols and tea quality[J]. Agricultural Science & Technology, 2014, 15(7): 1191-1195.
[19] 黄艳, 陈荣冰, 李京, 等. 不同包装材料对武夷水仙茶品质的影响[J]. 中国农学通报, 2016, 32(35): 40-45.
[20] Zhao L Y, Li F, Chen G T, et al.Effect of nanocomposite-based packaging on preservation quality of green tea[J]. International Journal of Food Science & Technology, 2012, 47(3): 572-578. DOI: 10.1111/j.1365-2621.2011.02879.x.
[21] 赵熙, 黄怀生, 粟本文, 等. 不同茶树品种制绿茶贮藏过程中品质变化规律[J]. 茶叶通讯, 2014, 41(4): 18-22.
[22] 邓余良, 江用文, 滑金杰, 等. 温差消除措施对茶叶低温贮藏效果的影响[J]. 中国茶叶, 2018, 40(2): 36-38.
[23] 朱丹实, 刘贺, 张慜. 不同温度、湿度和包装条件对茶叶干品贮藏的影响[J]. 食品工业科技, 2009, 30(4): 300-303.
[24] 李晓静, 游芳宁, 李磊磊, 等. 不同工艺不同品种坦洋工夫红茶品质的比较[J]. 食品工业科技, 2018, 39(19): 33-39, 45.
[25] Zhang Y, Huang J F, Wang F M, et al.An extended prospect: advance in the leaf optical properties mo-del separating total chlorophylls into chlorophyll a and b[J]. Scientific Reports, 2017, 7(1): 1-10. DOI: 10.1038/s41598-017-06694-y.
[26] 郭丽, 赖凌凌, 屈艳勤, 等. 绿茶“三绿”特征成分的研究进展[J]. 食品与发酵工业, 2016, 42(9): 285-290.
[27] 滑金杰, 袁海波, 江用文, 等. 温度补偿处理和低温贮藏对绿茶保鲜效果的影响[J]. 现代食品科技, 2017, 33(8): 248-253.
[28] 杨家干. 都匀毛尖成分及其部分生理功能研究[D]. 广州: 华南农业大学, 2016: 21-22.
[29] Ananingsih V K, Sharma A, Zhou W.Green tea catechins during food processing and storage: a review on stability and detection[J]. Food Research International, 2013, 50(2): 469-479. DOI: 10.1016/j.foodres.2011.03.004.
[30] Mirasoli M, Gotti R, Di Fusco M, et al.Electronic nose and chiral-capillary electrophoresis in evaluation of the quality changes in commercial green tea leaves during a long-term storage[J]. Talanta, 2014, 129(21): 32-38. DOI: 10.1016/j.talanta.2014.04.044.
[31] 肖文军, 胡详文, 龚志华, 等. 优质绿茶贮藏过程品质劣变的研究[J]. 天然产物研究与开发, 2006, 18(6): 999-1002, 1047.
[32] Huang B M, Zha Q L, Chen T B, et al.Discovery of markers for discriminating the age of cultivated ginseng by using UHPLC-QTOF/MS coupled with OPLS-DA[J]. Phytomedicine, 2018, 45: 8-17. DOI: 10.1016/j.phymed.2018.03.011.