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.
WANG Jinjin
,
YUAN Haibo
,
TAO Ruitao
,
HUA Jinjie
,
DENG Yuliang
,
DONG Chunwang
,
JIANG Yongwen
,
WANG Jiyun
. Effects of Frost-free Refrigerator and Direct-cooled Ice Bar on Storage Quality of Longjing Green Tea[J]. Journal of Tea Science, 2019
, 39(5)
: 555
-566
.
DOI: 10.13305/j.cnki.jts.2019.05.007
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