| Acid tea, as a unique food, has been eaten and drunk in China, Thailand and Myanmar with a long history. Despite of having special healthy function and playing important roles in the people’s life, acid tea is still self-production and owned consumption in China and Thailand for lack of research. This experiment is based on the habit that China has eaten acid tea. Although the summer and autumn tea leaves are abundant in China, lots of them aren’t utilized. There are many kinds of fermented tea products in China and the potential market of these products is enormous. For these reasons, the fermentation technology of the summer and autumn tea leaves were studied, and acid tea was fermented successfully using Camellia sinensis leaves through solid-state anaerobic fermentation. Through analyzing the changes of main components of acid tea by single-factor and orthogonal experiments, the optimum fermentation technology of acid tea was obtained. The qualities of acid teas fermented by two different fermentation ways were compared, and the health qualities of acid tea were analysed and the quality standard of acid tea was proposed. Four different flavor products of acid tea were produced preliminary.The main results are showed as follows:1. Research on the fermentation technology of pickled acid teaOn the basis of single factor experiments, orthogonal design experiment on three factors, namely salt concentration (0%、4%、8%)、fermentation time (20d、30d、40d) and fermentation temperature (room temperature、28℃、37℃) was conducted. The results indicated that low concentration, short time or high temperature all led to poor quality and bad taste. High concentration or long time also resulted in stuffy flavor. The salt concentration affected extremely significantly (P<0.01) on the majority chief constituent, but fermentation time and temperature only affected significantly (P<0.05) on a tiny minority constituent. The optimum technology process parameters of acid tea are as follow:4% of salt concentration,30 days of fermentation time,28℃of fermentation temperature, blanching fixation, rolling 5min slightly,60% of water content in pickled leaves. Basic Technological Process:fresh leaves'cleanout'blanching fixation'slushing'salted'bottle'compaction and airproof'anaerobic fermentation'finished product.2. The dynamic of quality formation of acid TeaDuring two months of fermentation, the pH value and soluble sugar in acid tea showed an extremely significant decreased trend (P<0.01) while water extract increased extremely significantly (P<0.01), but the caffeine and tea polyphenol were relative stable and no significant change (P<0.05) at different stages. Soluble sugar was reduced significantly (P<0.05) about 19.76%, and the change of free amino acid was fluctuant extremely significantly (P<0.01). The score of sensory evaluation increased extremely significantly (P<0.01) at the first half of the fermentation and decreased extremely significantly (P<0.01) at the other half. The last values of pH (4.78), water extract (432.22±9.56 g/kg) and sensory evaluation (75±1.25) were different extremely significantly (P<0.01) to those of unfermented, and the last content of soluble sugar (63.99±3.51 g/kg) also was different significantly (P<0.05) to that of unfermented, but the last contents of tea polyphenol (156.41±5.87 g/kg), free amino acid (28.27±0.19 g/kg) and caffeine (10.40±1.00 g/kg) were not changed significantly (P<0.05) compared to those of unfermented.3. Effect of different fermentation methods on the quality of acid teaThrough two different methods of fermentation, in acid tea, the total contents of tea catechins increased 13.80% and 13.52% by sterile fermentation and natural fermentation, respectively. The contents of ester type catechins (ECG、EGCG、GCG) decreased but more than those of green tea and the contents of nonester type catechins (EC、EGC) increased. By sterile fermentation and natural fermentation, the growth rates were 51.30% and 57.52% of EC,64.39% and 97.56% of EGC, respectively. By sterile fermentation and natural fermentation, GA increased 14 and 16 times in comparison with control sample, respectively, and higher 8～10 times than that of green tea. Through the fermentation, theanine reduced from 5.679 g/kg to 4.522g/kg. There were 17 types of amino acid in acid tea, in which 7 types are essential to man. The content of lysine, leicuine and phenylalanine increased from 0.043 g/kg to 0.2 g/kg,0.063 g/kg to 0.105 g/kg and 0.087 g/kg to 0.144 g/kg, respectively. The contents of 2 types of amino acid with fresh tasty, aspartic acid and glutamic acid increased from 0.004 g/kg to 0.015 g/kg and 0.359 g/kg to 0.372 g/kg, respectively. According to the different categories and contents of aromatic components, the main aromatic components of acid tea were esters, alcohols, alkene and ketone compounds, In acid tea, there were not only with the aromatic matters of tea such as alpha-cadinol and copaene, but also with the aromatic matters of salted vegetables such as beta-cyclocitral with lemon fragrance and geraniol with clean fragrance, and with lots of esters aromatic matters. The change of tea pigments was similar in sterile fermentation and natural fermentation:theaflavin decreased from 1.40g/kg to 1.17g/kg, thearubigins decreased from 75.74g/kg to 70.88g/kg, and theabrownins decreased from 51.18g/kg to 35.80g/kg. The coarse fiber with a great change in sterile fermentation and natural fermentation, decreased from 222.59g/kg to 152.49g/kg and 172.69g/kg, respectively, and the reduction rates were 31.49% and 22.42%, respectively.4. Health quality of acid teaIn the health indexes of acid tea, arsenic is 0.054 mg/kg much high, plumbum, cadmium and nitrite are 0.52 mg/kg,0.01 mg/kg,1.4 mg/kg, respectively, lower than those ofpickles. The number of microbe in acid tea is much lower than that of pickles: the number of bacterial colony, mould and coliform are 130CFU/g,40CFU/g,<30 MPN/100g, respectively. The pathogenic bacterium (Salmonella, Shigella, Staphylococcus aureus, Hemolytic streptococcus) were not detected out.5. Quality standard of acid teaBased on the national standards of pickles and Food contaminants limits, the quality standard of acid tea was concluded:plumbum (Pb)/(mg/kg)≤1.00, arsenic (As)/(mg/kg)<1.00, cadmium (Cd)/(mg/kg)<0.05, nitrite salt (NaNO2)/(mg/kg)≤4.00, total number of bacterial colony (CFU/g)<10,000, mould (CFU/g)≤50, coliform (MPN/100g)≤90 (in bulk) and≤30 (in bottles or bags), no pathogenic bacterium (Salmonella, Shigella, Staphylococcus aureus, Hemolytic streptococcus).6. Four different flavors products of acid tea were produced preliminaryBy adding different materials, four different flavor products of acid tea were produced and their optimum formulas were as follows:Original acid tea:8% colza oil,4% ginger,4% garlic,2% sesame and 10% peanut.Five-spice acid tea:8% colza oil,4% ginger,4% garlic,5% chili sauce and 3% five-spice powder.Hot-sour acid tea:8% colza oil,4% ginger,3% paprika and 5% vinegar.Hot-spicy acid tea:8% colza oil,4% ginger,3% paprika powder and 6% pepper. |
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