• Journal of Biosystems Engineering
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• 제41권2호
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• pp.85-92
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• 2016

Background: The same plant, Camellia sinensis, is used to produce all types of tea, and the differences among the various types arise from the different processing steps that are used. Based on the degree of fermentation, tea can be classified as black, green, white, or oolong tea. Of these, black tea is the most or fully fermented tea. The oxidized polyphenolic compounds such as theaflavins (TF) and thearubigins (TR) formed during fermentation are responsible for the color, taste, flavor, and aroma of black tea. Results: Research indicates that an optimum ratio of TF and TR (1:10) is required to ensure a quality cup of tea. The concentrations of TF and TR as well as desirable quality characteristics increase as fermentation time increases, reaching optimum levels and then degrading if the fermentation time is prolonged. It is also necessary to control the environment for oxidation. There are no established environment conditions that must be maintained during the fermentation of the ruptured tea leaves. However, in most cases, the process is performed at a temperature of $24-29^{\circ}C$ for 2-4 h or 55-110 min for orthodox tea or crush, tear, and curl (CTC) black tea, respectively, under a high relative humidity of 95-98% with an adequate amount of oxygen. Conclusion: The polyphenolic compounds in black tea such as TF and TR as well as un-oxidized catechins are responsible for the health benefits of tea consumption. Tea is rich in natural antioxidant activities and is reported to have great potential for the management of various types of cancers, oral health problems, heart disease and stroke, and diabetes and to have other health benefits such as the ability to detoxify, improve urine and blood flow, stimulate, and improve the immune system.

• 한국식생활문화학회지
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• 제24권3호
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• pp.308-314
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• 2009

In this study, we examined the composition of catechins, theaflavins and alkaloids in leaves during processing to fermented black tea, which is produced by withering, roll breaking, and fermentation of Korean Yabukida tea plant. In addition, we determined the optimal conditions for the production of fermented black tea. The average moisture content in fresh leaves was 70.85%, which dropped to 3.07% in fermented black tea at the last stage of production. When the leaves were analyzed by HPLC, seven types of catechins, four types of theaflavins and three types of alkaloids were identified. The levels of catechins, theaflavins, and alkaloids were then evaluated after being processed into fermented tea. From these experiments, we found that the level of theaflavins, which determines the property of the tea, increased during fermentation. This effect resulted from the change in EGCG, ECG, EGC, EC during the process of fermentation. We also found that the maximal amount of theaflavins was created after 1-2 hours of fermentation. Thus, our results imply that the best condition for producing fermented black tea would be to ferment for 1-2 hours.

• Preventive Nutrition and Food Science
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• 제7권1호
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• pp.37-42
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• 2002

Factors affecting the production of bacterial cellulose and organic acids in Kombucha fermentation were investigated. Kombucha was obtained by the fermentation (for 12 days at 3$0^{\circ}C$) of the green/black tea extract, supplemented with 10% white sugar, using an Oriental tea fungus as starter. Hitgher initial pH increased acid production with decreased cellulose production. With a cellulose pellicle or tea fungus broth as a starter, a 1~3 mm thick cellulose layer developed as a top layer every four days, and was removed subsequently while continuing fermentation. Addition of 30 mL tea fungus broth (13%, v/v) in Kombucha fermentation resulted in maximum production of a cellulose pellicle, indicating weak acid production. Yield of cellulose production at an early stage of fermentation was also higher when Kombucha was inoculated with a cellulose pellicle. In fact, addition of 1% (v/v) alcoholic beverage in the Kombucha fermentation activated the cellulose production, coupled with four times higher acid production.

• Asian-Australasian Journal of Animal Sciences
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• 제27권11호
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• pp.1571-1576
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• 2014

Nutritive values of green and black tea by-products and anti-nutritive activity of their tannins were evaluated in an in vitro rumen fermentation using various molecular weights of polyethylene glycols (PEG), polyvinyl pyrrolidone (PVP) and polyvinyl polypyrrolidone as tannin-binding agents. Significant improvement in gas production by addition of PEG4000, 6000 and 20000 and PVP was observed only from black tea by-product, but not from green tea by-product. All tannin binding agents increased $NH_3$-N concentration from both green and black tea by-products in the fermentation medium, and the PEG6000 and 20000 showed relatively higher improvement in the $NH_3$-N concentration. The PEG6000 and 20000 also improved in vitro organic matter digestibility and metabolizable energy contents of both tea by-products. It was concluded that high molecular PEG would be suitable to assess the suppressive activity of tannins in tea by-products by in vitro fermentation. Higher responses to gas production and $NH_3$-N concentration from black tea by-product than green tea by-product due to PEG indicate that tannins in black tea by-product could suppress rumen fermentation more strongly than that in green tea by-product.

• 생명과학회지
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• 제6권1호
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• pp.56-65
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• 1996

10%의 sucrose를 첨가한 홍차추출물에 tea fungus를 접종하여 (30^{\circ.)$에서 정치배양하여 발효하였다. 14일 동안의 발효에 의해 배양액의 전표면에 7~8mm의 두꺼운 피막이 생겼으며, 배양액의 pH가 2.5 부근으로 저하되었다. 발효 과정 중 아래쪽의 배양액에서는 효모(Saccharomyces cerevisiae and Eeniella sp.)와 여러종류의 세균(Bacillus subtilis, Kurthia zopfli, Gluconobacter oxydans와 Deinococcus sp.)이 분리되었다. 반면에 피막 부위에서는 Acetobacter aceti의 단일균주가 분리되었으며 이 세균은 통상의 Acetobacter와는 달리 점질상의 덩어리로 성장하였다. 발효음료는 달고 새콤한 맛과 약간의 달콤한 과일향을 나타내었다. 이상의 결과로부터 tea fungus에 의한 홍차발효는 다양한 미생물이 공동으로 작용하여 진행되는 symbiotic acetate발효로서, 발효음료는 생물학적으로 안전할 뿐만아니라 적당한 발효조건에 의해 좋은 향미를 갖춘 유망한 음료로 판단되었다.

• 한국식품영양과학회지
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• 제39권12호
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• pp.1807-1813
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• 2010

안전성이 확보된 후발효차를 제조하기 위해 Bacillus subtilis, Saccharomyces cerevisiae 및 Lactobacillus bulgaricus를 이용하여 후발효차를 제조한 후 발효 시간에 따른 화학성분의 변화와 관능적 기호도의 변화를 측정하였다. 발효 진행 정도에 따른 색상변화에서는 lightness는 감소하고 redness와 yellowness는 모두 증가하였으며 특히 B. subtilis에 의한 후발효차 제조 시 가장 많은 수색의 변화를 보였다. Chlorophyll의 함량변화에서는 발효가 진행됨에 따라 균종에 관계없이 모두 비슷한 수준으로 감소하였다. 총 카테킨의 함량변화에서는 B. subtilis균의 발효에 의하여 카테킨의 함량이 가장 많이 감소하는 것으로 나타났으며 발효기간이 증가할수록 유의적으로 낮은 함량을 나타내었다. 그러나 L. bulgaricus균에 의한 발효에서는 카테킨의 함량은 감소하지 않았다. Caffeine 함량변화에서는 모든 발효차에서 발효전의 함량보다는 다소 감소하였지만 많은 함량의 변화는 없는 것으로 나타났다. 발효기간별 관능검사 결과에서는 색, 향, 맛 및 종합적 기호도 모두 B. subtilis를 이용한 후발효차가 가장 우수한 것으로 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권12호
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• pp.1728-1736
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• 2006

The effects of green tea (Camellia sinensis) waste silage and supplemental polyethylene glycol (PEG) on rumen fermentation and blood components were studied in cattle. Six Holstein steers were fed three diets in a 3${\times}$3 Latin square design, replicated twice. One diet was a control with no added silage, and the other two diets were supplemented (20% of the dry matter) with green tea waste silage either with (PEG) or without PEG (tea). Most of the fermentation parameters including major volatile fatty acids (VFA) were not affected by the diet treatments. The concentrations of high density lipoprotein cholesterol in the PEG group and urea nitrogen in the tea and PEG groups were greater than those in the control before morning feeding. The plasma 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid equivalent concentration was not different before morning feeding, but 3 h after morning feeding, its concentrations in both the tea and PEG groups were higher than in the control. Although the concentration of plasma vitamin A in the animals was not affected by feeding green tea waste silage, the concentrations of plasma vitamin E were significantly higher in the tea and PEG groups than in the control, both before and 3 h after morning feeding. The results from the present study suggest that feeding diets containing 20% of the dietary dry matter as green tea waste silage to Holstein steers has no negative impact on their ruminal fermentation, and increases their plasma antioxidative activity and concentration of vitamin E.

• Asian-Australasian Journal of Animal Sciences
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• 제27권7호
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• pp.937-945
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• 2014

Green and black tea by-products, obtained from ready-made tea industry, were ensiled at $10^{\circ}C$, $20^{\circ}C$, and $30^{\circ}C$. Green tea by-product silage (GTS) and black tea by-product silage (BTS) were opened at 5, 10, 45 days after ensiling. Fermentation characteristics and nutrient composition, including tannins, were monitored and the silages on day 45 were subjected to in vitro ruminal fermentation to assess anti-nutritive effects of tannins using polyethylene glycol (PEG) as a tannin-binding agent. Results showed that the GTS and BTS silages were stable and fermented slightly when ensiled at $10^{\circ}C$. The GTS stored at $20^{\circ}C$ and $30^{\circ}C$ showed rapid pH decline and high acetic acid concentration. The BTS was fermented gradually with moderate change of pH and acid concentration. Acetic acid was the main acid product of fermentation in both GTS and BTS. The contents of total extractable phenolics and total extractable tannins in both silages were unaffected by storage temperatures, but condensed tannins in GTS were less when stored at high temperature. The GTS showed no PEG response on in vitro gas production, and revealed only a small increase by PEG on $NH_3$-N concentration. Storage temperature of GTS did not affect the extent of PEG response to both gas production and $NH_3$-N concentration. On the other hand, addition of PEG on BTS markedly increased both the gas production and $NH_3$-N concentration at any ensiled temperature. It can be concluded that tannins in both GTS and BTS suppressed rumen fermentation, and tannins in GTS did more weakly than that in BTS. Ensiling temperature for both tea by-products did not affect the tannin's activity in the rumen.

• 한국식품저장유통학회지
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• 제13권5호
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• pp.596-602
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• 2006

본 연구는 한지역에서 생산된 동종의 차 엽을 같은 시기에 채취하여 불발효차와 반발효차로 발효정도가 다르게 제다하여 주요 성분과 생리활성을 비교하였다. 불발효차인 녹차는 일반 가공 방식대로 만든 녹차, 채엽하여 실내 위조의 과정을 거쳐서 만든 위조 녹차로 만들었고, 반발효차인 황차는 햇볕에서 제다한 중(中)발효차인 일쇄차와 강하게 발효를 한 황차를 시료로 하였다. 주요 성분은 일반성분 및 폴리페놀과 카페인의 함량을 분석하였고, 차의 수색,전자공여능에 의한 항산화 활성 및 ACE 저해능을 조사하였다. 결과는 다음과 같다. 차의 일반성분은 발효정도와 제다방법에 따라 큰 차이는 없는 것으로 나타났다. 차의 기능성분을 조사해 본 결과 total phenolic compound 함량은 $3.59%{\sim}3.87%$의 범위로 나타나 발효정도와 제다방법에 따라 큰 차이는 없는 것으로 나타났다. 반면 caffeine 함량은 녹차가 5.81%로 가장 높았으며, 위조차가 5.75%, 일쇄차가 3.46%, 황차가 2.66% 순으로 발효정도에 따라 caffeine 함량이 감소하는 경향을 보였다. 차의 수색은 발효정도가 강할수록 명도(L)는 감소하였고, 녹색도(-a)가 낮아지면서 적색(a)에 가까워졌으며, 황색도(b)는 발효정도에 따라 높아지는 경향을 보였다. 차의 전자공여능에 의한 항산화 활성은 녹차가 85.6%로 가장 높았으며, 위조차가 81.24%, 일쇄차가 72.84%, 황차가 28.85% 의 순으로 불발효차 일수록 항산화활성이 뛰어났으며 ACE 효소 활성 역시 불발효차 일수록 증가하는 경향을 보였지만 그 차이는 미비하였다.

• 한국식품영양과학회지
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• 제40권8호
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• pp.1073-1078
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• 2011

위생적으로 안전성이 확보된 후발효차를 제조하기 위해 Bacillus subtilis, Saccharomyces cerevisiae 및 Lactobacillus bulgaricus를 이용하여 후발효차를 제조한 후 발효시간에 따른 항산화 성분 및 활성의 변화를 측정하였다. 후발효차의 ascorbic acid의 함량은 발효기간 내내 균종에 관계없이 녹차(66.74 mg%)에 비하여 비교적 낮은 함량(43.62~62.84 mg%)을 보였고 산소와의 접촉을 최소화한 L. bulgaricus 균에 의한 발효가 비교적 적은 변화를 보였다. Polyphenol 화합물의 함량은 녹차의 경우 14.88%였으며 후발효차는 11.54~14.12%로 세 균주 모두 발효가 진행됨에 따라 함량이 다소 감소하였다. 실험에 사용한 녹차의 flavonoid 함량은 7.78 mg%였으며 미생물을 이용한 후발효차의 경우에는 4.33~7.88 mg%로 대부분 녹차에서의 함량보다 적은 것으로 나타났다. 항산화 활성의 경우, 녹차의 DPPH 전자공여능 및 ABTS 항산화 활성은 각각 87.47% 및 203.22 AEAC mg%였으나 발효기간에 따른 후발효차에서는 녹차에 비하여는 낮은 활성을 보여 후발효차 제조 시 어느 정도 항산화 성분의 함량 및 활성이 다소 감소하게 되지만 미생물을 이용하여 후발효차를 제조 시 위생적이고 기호도가 우수한 제품을 생산할 수 있는 것으로 판단되었다.