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多酚氧化酶(PPO)促褐变影响苹果鲜果和果汁的品质。探讨高压脉冲电场(PEF)钝化苹果鲜果PPO的可行性。在电压、停留时间、频率、脉冲宽度等单因素试验的基础上,采用响应曲面分析法优化钝酶工艺。结果表明,PEF对红富士多酚氧化酶活性抑制的最佳条件为:电压25 k V,频率530 Hz,停留时间45 s和脉冲宽度8μs,此条件下多酚氧化酶的抑制率达51.86%。鲜榨果汁的色值和褐变指数与PPO的相对活力直接相关。PEF处理能够抑制果汁的酶促褐变,与对照组相比,由最优钝化条件下处理的果块制备的果汁(4 h时)的色值极显著大于对照组(P0.01),总可溶性固形物,pH值没有发生显著改变(P0.05),还原型维生素C呈下降趋势,但下降不显著(P0.05)。 相似文献
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超高压对马铃薯多酚氧化酶和过氧化物酶的钝化研究 总被引:1,自引:0,他引:1
研究了超高压对马铃薯多酚氧化酶和过氧化物酶的影响。结果表明:超高压处理后的多酚氧化酶,过氧化物酶活力低于对照试样的活力,超高压对酶活有影响;保压时间30 min,100~200 MPa压力范围内,多酚氧化酶和过氧化物酶被激活,压力超过200 MPa时酶的活性下降;压力为400 MPa,随着时间的延长,多酚氧化酶和过氧化物酶活性都呈下降趋势;400 MPa,10 min条件下,pH在5.5~6.0之间时酶的活性最大;超高压对马铃薯多酚氧化酶钝化的最佳方案:pH 6.0,保压时间40 min,压力400 MPa,过氧化物酶钝化的最佳方案:pH 8.0,保压时间40 min,压力为400 MPa。 相似文献
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以新鲜南国梨果实为原料,邻苯二酚为底物,采用分光光度法研究南国梨多酚氧化酶的酶学特性。结果表明:p H和温度对新鲜南国梨PPO活性有明显的影响,最适p H为6.8,新鲜南国梨PPO最适温度为40℃。进一步研究了抑制剂抗坏血酸、柠檬酸、亚硫酸氢钠、L-半胱氨酸、EDTA-2Na和各种金属盐[CuSO_4、CaCl_2、Na_2SO_4、Al(NO_3)_3、CdCl_2、HgCl_2、MnCl_2]对南国梨PPO的影响,其中0.1 mmol/L的抗坏血酸对新鲜南国梨PPO活性有明显抑制作用高达50%。南国梨PPO催化底物邻苯二酚的酶促反应动力学与米氏方程高度符合,R2=0.998,其动力学方程为1/[V]=0.002/[S]+0.019,最大反应速率Vmax为52.632 U/min,米氏常数Km为0.010 5 mol/L。 相似文献
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热处理法钝化蕨菜多酚氧化酶活性的工艺条件研究 总被引:1,自引:0,他引:1
研究了热处理法钝化蕨菜多酚氧化酶(PPO)活性,从而控制酶促褐变的工艺条件及效果。结果表明,用沸水蒸气处理2.5~5min后再于35~70℃条件下烘干至成品,能有效钝化蕨菜PPO活性,很好的控制了酶促褐变,得到的产品质量最好。也可用85~100℃热水烫漂1~5min后于35~70℃条件下烘干至成品,得到产品质量好,PPO活性得到抑制。热风钝化、自然日光晒干或晾干均不是蕨菜干制加工的最佳方法。 相似文献
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高压CO2处理钝化香蕉果肉多酚氧化酶的动力学 总被引:1,自引:0,他引:1
研究影响高压CO2处理钝化香蕉果肉多酚氧化酶的因素,并应用两段模型分析了高压CO2处理对香蕉果肉多酚氧化酶的钝化动力学。结果表明:CO2压力、处理温度、处理时间和样品pH值都能显著影响高压CO2处理钝化香蕉果肉多酚氧化酶的效率;高压CO2处理对香蕉果肉多酚氧化酶的钝化过程符合两段模型;高压CO2处理能有效的钝化香蕉果肉多酚氧化酶,提高CO2压力和处理温度、延长处理时间和适当降低样品的pH值都能显著增强高压CO2处理钝化酶的速率;20MPa、55℃的高压CO2处理40min后能钝化83.5%的香蕉果肉多酚氧化酶,当温度升到60℃,20 MPa的高压CO2处理时,20min处理后仅残留有4.2%的多酚氧化酶活力。 相似文献
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High-intensity pulsed electric fields (HIPEF) were applied to strawberry juice to study the feasibility of inactivating polyphenoloxidase (PPO). Response surface methodology was used to evaluate the effect of HIPEF processing, in which total treatment time (1000 to 2000 μs), pulse frequency (50 to 250 Hz), pulse width (1.0 to 7.0 μs), and polarity (monopolar or bipolar) were the controlled variables at a constant electric field of 35 kV/cm. The proposed 2nd-order response functions were accurate enough to fit experimental results. Strawberry juice PPO was strongly reduced within the range of assayed conditions. HIPEF treatments were more effective in bipolar than in monopolar mode in inactivating PPO. Treatments of longer duration resulted in reductions of the enzyme activity. Moreover, it was feasible to minimize residual PPO activity (down to 2.5%) by selecting bipolar treatments at frequencies higher than 229 Hz and pulse widths between 3.23 and 4.23 μs for a constant total treatment time of 2000 μs. 相似文献
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采用响应面法分析优化脉冲强光对枯草芽孢杆菌致死的工艺参数。在单因素实验基础上,选取脉冲电压、脉冲次数、照射距离为影响因素,致死率为指标,通过响应面法进行优化设计。结果表明:脉冲强光对枯草芽孢杆菌的致死效果极显著(p<0.01),根据最优条件并结合实际操作,优化工艺参数为脉冲电压2450 V、脉冲次数65次、照射距离5 cm时,致死率可达到99.95%,各因素对致死率影响大小顺序为A(脉冲电压)>C(照射距离)>B(脉冲次数),为日后食品保藏和加工中枯草芽孢杆菌的灭活提供依据。 相似文献
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为研究脉冲强光杀菌技术对巴氏奶杀菌的效果,以巴氏奶为研究对象,用霉菌灭菌率作为衡量脉冲强光灭菌技术的指标。在单因素实验基础上,选取闪照次数、闪照距离、闪照能量和样液厚度为自变量,霉菌灭菌率为响应值,利用Box-Benhnken中心组合设计原理和响应面分析法,确定最佳条件为闪照次数35次、闪照距离12.8cm、闪照能量300J、样液厚度2mm。在此条件下,霉菌灭菌率达到99.97%。借助电子鼻测定分析,通过线性判别分析法(LDA)进行气味信息的分析和判断,利用Alphasoft分析软件对奶样进行货架期预测,得到空白样和对照样的预测货架期天数分别是5d和7d,说明脉冲强光灭菌技术可以有效延长巴氏奶的货架期。 相似文献
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低度淡爽型苦瓜啤酒的研制 总被引:2,自引:0,他引:2
针对人们消费需求的变化,研制开发了具有保健作用的苦瓜啤酒。对苦瓜汁的制备、添加以及苦瓜啤酒生产工艺、质量要求进行了研究,并就影响产品质量的关键因素进行了探讨。 相似文献
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Total inactivation of lipoxygenase in whole soya bean by pulsed light and the effect of pulsed light on the chemical properties of soya milk produced from the treated soya beans 下载免费PDF全文
Abeer Alhendi Wade Yang Renee Goodrich‐Schneider Paul J. Sarnoski 《International Journal of Food Science & Technology》2018,53(2):457-466
The inactivation of lipoxygenase (LOX) in the whole soya bean prevents lipid oxidation that produces an off‐flavour of soya food. The inactivation of lipoxygenase in the whole soya bean by pulsed light (PL) was examined with three distances (5, 7 and 9 cm) from the PL strobe and for different durations. Soya bean was treated with PL with and without ice surrounding the soya bean sample tray for limiting the rise in sample temperature. Results show that without ice surrounding the sample tray, the lowest LOX residual activity was 4.7%, 0.4% and 0.0% for 80‐s duration at 5 cm distance from the PL strobe, 110 s at 7 cm from the strobe and 150 s at 9 cm from the strobe, respectively; the soya bean temperature after treatment was 109.6, 116.3 and 114.8 °C, respectively. The instantaneous temperatures of the soya bean core measured during PL operating were above 100 °C. The lipoxygenase band was disappeared after longest PL treatments of each distance compared with the LOX band control as assessed by electrophoresis. The pulsed light had no negative effect on peroxide value of produced soya milk. However, PL reduced significantly the total solid amount and changed the colour of the produced soya milk. The residual activity with sample cooling by ice during treatment was 79.0%, 98.8% and 95.7%, with sample temperatures of 81.7, 91.2 and 66.9 °C, respectively. This study indicates that PL illumination could fully inactivate LOX in whole soya beans, with the photo‐thermal effect of PL as the main factor responsible for the inactivation of LOX. 相似文献