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荔枝与荔枝酒褐变控制 总被引:1,自引:0,他引:1
以荔枝及荔枝酒为试料,研究荔枝多酚氧化酶(PPO)的酶学特性及荔枝酒发酵过程中的褐变机理及控制措施。结果表明:荔枝PPO存在同功酶,荔枝PPO最适底物为没食子酸;以没食子酸为底物,荔枝PPO最适反应pH值为8.0,最适反应温度50℃,荔枝PPO的动力学参数为:米氏参数(Km)为26.033mmol/L,最大反应速度(Vmax)为34.816g/(L·min);荔枝PPO对酸碱、对热稳定性较差;荔枝酒发酵过程中褐变的主要原因是其PPO引起的酶促褐变。因此,低温贮藏和高温热处理可有效抑制荔枝及荔枝酒在贮藏和加工中酶促褐变反应。 相似文献
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S. Janjai N. Lamlert K. Tohsing B. Mahayothee B. K. Bala J. Müller 《International Journal of Food Properties》2013,16(2):251-260
The equilibrium moisture contents of litchi (Litchi Chinensis Sonn.) were experimentally determined using the dynamic method at temperatures of 30, 40, and 50°C over a range of relative humidity values of 12 to 95%. Five models were tested to fit the experimental isotherm data of litchi. The GAB model fitted the best to experimental isotherm data. The agreement between experimental and predicted values of this model is excellent (RMSE 1.8 to 3.4%). The isosteric heats of sorption water were also determined from the equilibrium data using the Clausius-Clapeyron equation and it was found to be a function of equilibrium moisture content. 相似文献
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以荔枝蜜为原料,利用葡萄酒活性干酵母BV818和沪酿1.01醋酸菌发酵制备荔枝蜜醋,以总酸和总酯含量为考察指标,通过单因素和响应面试验设计,优化荔枝蜜醋的一步法发酵工艺。结果表明:最佳工艺条件为醋酸菌接种量8.0%、初始糖度310.0 g/L、初始酒精体积分数3.0%、荷花粉破壁上清液添加体积分数2.4%、初始pH 4.0、葡萄酒高活性干酵母BV818的接种量0.3 g/L、培养温度29.5 ℃。经过14 d发酵,其总酸含量可以达到11.9 g/L,总酯含量可达2.9 g/L,酒精体积分数为2.0%,残糖含量172.1 g/L。在此最佳工艺条件生产的荔枝蜜醋醋味纯正,芳香清甜,风味柔和。 相似文献
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Mareike Reichel Rini Triani Julia Wellhöfer Pittaya Sruamsiri Reinhold Carle Sybille Neidhart 《Food and Bioprocess Technology》2013,6(5):1191-1206
To assess the fruit-specific determinants of pericarp browning, litchi pericarp was characterized in terms of appearance, the polyphenol pattern as specified by HPLC-DAD-MS n without and after thiolysis, and the activities of polyphenol oxidase (PPO) and peroxidase (POD) by exploring “Kwang Jao,” “O-Hia,” “Kim Cheng,” and “Chacapat” fruit on the respective harvest day, “Hong Huey” fruit also throughout 52 days of cold storage (5 °C, 95% relative humidity). At harvest, PPO activity was maximum for “Kim Cheng” pericarp (126 μkat/hg), whereas POD activity was striking for that of “O-Hia” (512 μkat/hg, including membrane-bound isoforms). Flavan-3-ol and proanthocyanidin patterns were consistent for all cultivars. However, cultivars with sharp-pointed and round–obtuse protuberances differed in pericarp anthocyanin and flavonol glycosylation patterns. The molar ratio of cyanidin 3-O-rutinoside to its glucoside was ≤6:1 for “Hong Huey” and “Kwang Jao,” but ≥43:1 for “Kim Cheng” and “Chacapat” pericarp. Long-term storage gave evidence of two key processes involved in pericarp browning: (1) PPO-mediated oxidation of abundant (?)-epicatechin (1.4–2.0 g/hg), resulting in dark brown pigments, and (2) microcrack-induced formation of light brown surface scurf, supposably with involvement of POD. Accordingly, an improved scheme for litchi pericarp browning was proposed. As regards recommendable postharvest concepts for each cultivar, “Chacapat” suited most for long-distance transports due to its overall low susceptibility to pericarp browning. Properties of “O-Hia” litchi, being prone to surface scurf formation, suggested preferred distribution via domestic markets. High contents of flavonols (e.g., quercetin glycosides, 166 mg/hg) and A-type-linked procyanidins (e.g., procyanidin A2, 1,092 mg/hg) qualified pericarp of “Hong Huey” litchi as raw material for polyphenol extracts exerting antioxidant properties. 相似文献
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为明确荔枝果肉的生物抗氧化和抗肿瘤保健功能,采用HepG2人肝癌细胞模型对我国南方地区主要种植的10种代表性荔枝品种果肉的细胞抗氧化活性(CAA值)和抗肿瘤细胞增殖活性进行了评价。结果表明,10种荔枝品种中,妃子笑荔枝果肉具有最大的CAA值,淮枝则最小;妃子笑抗HepG2肿瘤细胞增殖活性最强,糯米糍则最弱。荔枝果肉的CAA值与总多酚含量、总黄酮含量、多酚化学抗氧化能力指数(ORAC值)之间都有极显著的正相关性(p0.01),且与黄酮含量之间正相关性最大,说明荔枝果肉中起生物抗氧化作用的主要成分是黄酮类化合物;但荔枝果肉对HepG2肿瘤细胞的抗增殖活性与总多酚含量、总黄酮含量、ORAC和CAA值之间均呈现较弱的负相关性(p0.05),提示某些特殊酚类单体或其协同作用在抗肿瘤细胞增殖过程中发挥主要作用。 相似文献
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荔枝粗多糖提取工艺的研究 总被引:7,自引:1,他引:6
利用热水浸提三氯醋酸脱蛋白醇沉等工艺从荔枝干果中提取多糖,用蒽酮-硫酸法测定多糖含量,通过正交试验确定了提取多糖的条件.结果表明:荔枝多糖最佳提取工艺参数为:料液比1:50、浸提温度80℃、浸提时间4h. 相似文献
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荔枝果酒酿造工艺研究 总被引:3,自引:1,他引:2
以荔枝为主要原料,研究采用控温发酵技术酿制荔枝果酒的工艺流程,通过对比试验确定最佳工艺参数为:果胶酶用量为80mg/L,SO2添加量为50mg/L~100mg/L,发酵温度为22℃,含糖量调整为22%,酵母接种量为6%。 相似文献
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荔枝原汁保藏工艺探讨 总被引:4,自引:0,他引:4
本文通过检测经加热杀菌和钝化酶处理的荔枝原汁在冷藏、冻藏、室温贮藏及添加柠檬酸、异VC、山梨酸钾、NaHSO3等条件下,VC、总糖、总酸和褐变度变化情况,并进行感官评价,探讨荔枝原汁保藏工艺。结果表明,荔枝原汁在冻藏(-20℃)半年后,其营养成分和色香味基本保持稳定,品质最好;冷藏(0~4℃)过程中,其VC和总糖有一定损失,总酸和褐变度略有上升,贮藏半年后色香味有所下降,品质较冻藏差;室温(30℃左右)贮藏的荔枝原汁虽然添加不同保藏剂处理,但贮藏1个月后相继产气败坏。试验结果对荔枝原汁生产和贸易有一定参考价值。 相似文献
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采用DPPH自由基清除法和铁还原比色法研究荔枝多酚的抗氧化性。水相/有机相荔枝多酚的DPPH自由基清除能力及铁离子还原能力的动力学反应模式均表现为剂量及反应时间的双重依赖关系。荔枝多酚对温度敏感。随着温度的升高(25~70℃),其多酚含量及其抗氧化活性均呈下降趋势;荔枝多酚含量及抗氧化性在弱碱性范围内(pH8~9)较稳定;荔枝多酚对光照敏感,随着光照时间的延长(12~96h),其多酚含量及其抗氧化活性逐渐下降;荔枝多酚含量与其抗氧化活性相关性较强,当处理造成荔枝多酚含量发生改变时,其抗氧化活性也发生较大变化。低温、弱碱性及避光均有利于荔枝多酚含量与其抗氧化活性的稳定。 相似文献
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荔枝果酒酿造工艺研究 总被引:2,自引:1,他引:1
以荔枝为主要原料,研究采用控温发酵技术酿制荔枝果酒的工艺流程,通过对比试验确定最佳工艺参数为:果胶酶用量为80 mg/L,SO2添加量为50mg/L~100mg/L,发酵温度为22℃,含糖量调整为22%,酵母接种量为6%. 相似文献