Effect of freezing treatment in tea preparation using Camellia sinensis leaves
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ORIGINAL ARTICLE
Effect of freezing treatment in tea preparation using Camellia sinensis leaves Hun-Sik Chung1 • Kwang-Sup Youn2
Revised: 6 April 2020 / Accepted: 15 April 2020 Ó Association of Food Scientists & Technologists (India) 2020
Abstract This study was conducted to examine the effect of freezing in the tea preparation using Camellia sinensis leaves in order to develop new technology for improving tea quality. Effects of single and combined treatments of freezing (F: - 20 °C, 15 days), steaming (S: 100 °C, 3 min), and hot-air drying (HD: 50 °C, 12 h) on the physicochemical characteristics of tea (powder and hotwater leachate) prepared from treated Camellia sinensis leaves were investigated. The L*, b*, and C* values of the powder were the highest in SHD-treated leaves, followed by HD-, SFHD-, and FHD-treated leaves. Redness (?a* value) was only seen in FHD-treated leaves and greenness (- a* value) was the highest in SHD-treated leaves. Browning index of the leachate was significantly lower in SHD- and SFHD-treated leaves than in FHD-treated leaves (p \ 0.05). Soluble solids, acidity, and phenolic compounds of FHD-treated leaves were significantly lower than in SHD- and SFHD-treated leaves (p \ 0.05). Sucrose was highest in SHD-treated leaves and glucose was highest in FHD-treated leaves. Sensory preference was better evaluated in FHD-treated leaves than in SHD- and SFHD-treated leaves. These results suggest that freezing treatment in tea processing promotes browning and component
& Hun-Sik Chung [email protected] & Kwang-Sup Youn [email protected] 1
Department of Food Science and Technology, Pusan National University, 1268-50 Samnangjin-ro, Miryang 50463, Republic of Korea
2
Department of Food Science and Technology, Daegu Catholic University, 13-13 Hayang-ro, Gyeongsan 38430, Republic of Korea
decomposition and enhances sensual preference. Therefore, freezing has a potential application in the tea manufacturing. Keywords Camellia sinensis Tea Freezing Steaming Leachate
Introduction Camellia sinensis is an evergreen shrub that can be grown in tropical and subtropical climates. Young leaves of C. sinensis are picked and processed into various tea forms, which contain catechin, caffeine, protein, amino acids, organic acid, sugar, vitamin A and C, and inorganic salts that produce a unique flavor in harmony with astringent, bitter, umami, and sweet tastes (Kang 2011; Kim et al. 2014b). Recently, public interest has been increasing in the health functionalities of this tea, such as its antioxidant, anticancer, antibacterial, and antitoxin properties (Yang and Liu 2013; Friedman 2007). Therefore, it is necessary to diversify tea processing methods and improve tea quality, aiming at increasing tea consumption. Tea is generally prepared by treating C. sinensis leaves through heating (roasting, steaming), wilting, rolling, fermentation, and drying (Kim et al. 2009). The raw material remains the same but it acquires different flavors and health functionalities according to the kind of treatment and
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