| Duanwucha is a traditional herbal tea in Songyang, Zhejiang. Its main functional components are flavonoids, amino acids, trace elements, etc. In this paper, a herbal tea beverage was developed based on the traditional formula of Duanwucha, the preparation technology, storage stability, nutrition, and in vitro antioxidant activity of the herbal tea were investigated to provide a theoretical basis and practical guidance for the factory production of Duanwucha herbal tea.Single factor experiment was applied to study the influence of extraction time, extraction temperature, liquid to solid ratio, extraction times on the extraction rate of flavonoids of Duanwucha herbal tea. Then, Response Surface Methodology was used to further optimize the extraction process based on the results of single factor experiment. Single factor experiment showed that:extraction time, temperature, and liquid to solid ratio had a significant effect on the extraction rate of flavonoids, while extraction times had little effect on extraction rate of flavonoids, the optimum extraction conditions obtained from single factor experiment were:extraction time60min, extraction temperature85℃liquid to solid ratio30:1, the extraction rate of flavonoids was1.81%in primary extraction conditions. Response Surface Methodology study showed that:extraction time and temperature had significant interaction effect on extraction rate of flavonoids, while the interaction effect of extraction time and liquid to solid ratio, extraction temperature and liquid to solid ratio were not significant, the optimum extraction conditions obtained from Response Surface Methodology were:extraction time65min, extraction temperature81℃, liquid to solid ratio32:1, and the extraction rate of flavonoids was1.89%, which was4.4%higher than the results of the single factor experiment.The extracting herbal tea was treated with β-cyclodextrin, HB801resin, and activated carbon to remove the bitter and dry taste. Results showed that:β-cyclodextrin and HB801resin could be used to remove the bitter and dye taste,1.0%β-CD can effectively remove the bitter and dry taste, without affecting the flavonoids content, and0.8%HB801resin showed a remarkable removal effects of the bitter and dry taste with a2.98%loss of the flavonoids content. The comprehensive removal effects of β-cyclodextrin and resin were further evaluated by fuzzy evaluation method and exhibited that the herbal tea treated with β-cyclodextrin had a better sensory score than resin, the process requirements can be achieved by adding1.0%(3-cyclodextrin under80℃for lOmin.The optimum blending process obtained from orthogonal test was3%sucrose,20%glycyrrhiza, and1.0%(3-CD, the herbal tea obtained under the conditions had the following characteristic:a high sensory score(95.6), an unique remarkable herbal tea flavor, moderate sweetness, slightly bitter, and no astringency.The variation of flavonoids, browning degree, pH, clarity, and soluble solids over time was studied by accelerated test under25℃,37℃,50℃storage conditions. Then, the Arrhenius model was applied to investigate the rate formula of flavonoids content under the influence of temperature. Results showed that:the flavonoids showed a negatively correlated with the storage temperature and time, the variation of flavonoids followed the first-kinetic model, the activation energy(Ea) was24.5kJ/mol, the Arrhenius Equation was Ink=-2951x1/T+4.5086. After35days storage, the loss rate of flavonoids was less than30%under different temperatures, and less than15%under25℃storage temperature. The browning degree A420abs increased with the extension of storage time and temperature, the variation of browning degree followed zero-order kinetics and the activation energy(Ea) was16.5kJ/mol. Clarity, pH, and soluble solids with a slight change after90days storage, demonstrated that temperature has a little effect on the Clarity, pH, soluble solids. Microbial indicators were in the safety limits after60days storage.Amino acid composition was studied by automatic amino acid analyzer. Results showed that solid raw Duanwucha contained17kinds of amino acids, including7kinds of essential amino acids, total amino acids content was6.58g/100g, the essential amino acids content accounting for34.2%of the total amino acids content; The herbal tea contained14kinds of amino acids, including5kinds of essential amino acids, total amino acids content was204.2μg/mL, the essential amino acids content accounting for4.9%of total amino acids content.The trace elements was analyzed by ICP-AES, results showed that Duanwucha was rich in Fe, Cu, Mn, Zn, the toxic metals As, Cd, Pb were not detected in both raw and herbal tea.Duanwucha herbal tea and other11kinds of herbal tea purchased from the market were assessed for their DPPH radical scavenging activity and Fe3+reducing power. Results indicated that all the12kinds of herbal tea had a certain antioxidant activity in the studying antioxidant evaluation systems, and Duanwucha herbal tea showed a better antioxidant activity among the studying herbal teas. The contents of flavonoids of12kinds of herbal tea varied from0.078mg/mL to0.607mg/mL, the contents of polyphenol varied from54.5μg/mL to243.4μg/mL, the flavonoids of Duanwucha herbal tea was0.594mg/mL, only less than K herbal tea, while the polyphenol contents of Duanwucha herbal tea was highest among the12kinds herbal tea. The Pearson correlation analysis showed that the flavonoids and polyphenol contents was highly correlated, the correlation coefficient was0.954. The correlation analysis of antioxidants with the DPPH radical scavenging, FRAP value showed that there was a significant correlation between flavonoids content, polyphenol content and DPPH radical scavenging, FRAP value. The correlation coefficient between flavonoids content and DPPH radical scavenging, FRAP value was higher than polyphenol content. |
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