基于漆酶的时间-温度指示剂研究

目的研制基于漆酶的时间-温度指示剂(time-temperatureintegrators,TTI),指示并预测相应食品的货架期。方法利用漆酶对愈创木氧化分解反应的催化作用,通过调节加酶量,使愈创木酚的氧化反应产生随时间和温度累积的颜色变化效应,从而获得4种不同效果的TTI。在4、10、25、35℃恒温条件下对4种不同TTI动力学参数进行了研究,计算其反应活化能值。结果 4种TTI的活化能指示范围分别为0～50、17～67、15～65、11～61kJ/mol。结论该方法操作简单,颜色变化所产生的指示效果明显。根据TTI反应的终点与食品货架寿命的终点相吻合的原则, 4种TTI可分别用于牛奶、肉类新鲜度的指示。     

淀粉酶纳米花型时间-温度指示剂的制备及性能分析

目的：研制基于蛋白质杂化纳米技术和酶促反应的淀粉酶纳米花型时间-温度指示剂（time-temperature indicator,TTI）,确定其活化能及适合指示的食品种类。方法：利用淀粉酶与铜离子之间相互作用,对淀粉酶进行固定化,形成淀粉酶@Cu纳米花,改变淀粉酶用量,筛选出花形最好的纳米花,并测试纳米花中淀粉酶的生物活性及保存稳定性;以15 mL 40 g/L可溶性淀粉溶液为底物,4.5 mL 1 g/L碘液为指示剂,分别加入10、20、30、40、50、60 mg的淀粉酶@Cu纳米花,制备出6 种配方的TTI;在5、15、25、35 ℃的恒温条件下,研究6 种TTI的性能,观察变色过程,测定动力学参数,计算反应活化能值。结果：淀粉酶质量浓度为0.5 mg/mL时,淀粉酶@Cu纳米花的花形最完整,淀粉酶活性提高到3.42 倍,保存稳定性显著提高;6 种TTI呈现出从深蓝色到无色的变化过程,活化能分别为14.84、21.00、28.85、33.03、32.55 kJ/mol和32.83 kJ/mol。结论：淀粉酶纳米花型TTI操作简单,指示效果明显,根据TTI与食品匹配原则,该系列TTI适用于监测由扩散控制、酶反应、脂肪氧化等原因引起腐败变质的食品质量变化。     

时间-温度指示器在食品保质期预测中的应用

食品保质期预测对航天食品、远洋食品至关重要,时间-温度指示器（Time-temperature indicator,TTI）是食品保质期预测的关键技术,它通过监测食品流通温度来预测食品热敏营养成分的变化情况,并指示产品剩余货架信息,从而降低食品的损耗,保证食品安全。本文论述了TTI的基本概念、基本原理、动力学模型及其应用情况,介绍了基于物理型、化学型、生物型和酶型及其它不同工作原理TTI的研究现状,总结了TTI在水产品、肉制品、果蔬和鲜牛乳储运监测中的应用以及TTI的商业价值和未来的发展趋势,以期为推广TTI技术应用,减少食品浪费做出贡献。     

重组毕赤酵母生产耐高温α-淀粉酶发酵条件的优化

利用重组毕赤酵母诱导表达可产生耐高温α-淀粉酶,在摇瓶发酵基础上,从诱导时间、甲醇添加量、pH值、接种量4个因素考察发酵条件对耐高温α-淀粉酶酶活力的影响,结合四元线性回归正交试验设计研究方法构建出甲醇诱导重组毕赤酵母生产耐高温α-淀粉酶的回归模型;优化最佳工艺参数为：诱导时间96h、甲醇添加量0.5%、接种量150mL/100mL、摇床转速200r/min。确定最优工艺条件下,耐高温α-淀粉酶酶活为217.2U/mL。     

几种耐高温淀粉酶的酶活影响因素研究

淀粉酶是食品、发酵行业应用最广泛的酶种之一。从最适温度、最适p H值、保存温度、缓冲溶液p H值等方面对5种不同的耐高温α-淀粉酶酶活的影响进行了研究。结果表明:耐高温α-淀粉酶B的耐酸性最好,在p H4.00~7.50之间,相对酶活为98%~100%;耐高温淀粉酶A的耐高温性最好,在反应温度70℃~100℃之间,相对酶活为100%~121%;耐高温α-淀粉酶A的缓冲溶液稳定性最好,在缓冲溶液p H4.50~7.00之间,酶活维持在91%~100%;耐高温α-淀粉酶E温度稳定性质最好,在储存温度30℃~60℃之间,相对酶活为98%~100%。为淀粉酶的选择奠定基础。     

α-淀粉酶水解玉米淀粉的研究

研究了中温和耐高温α-淀粉酶水解玉米淀粉制取糊精，确定了它们水解适宜的工艺条件。中温α-淀粉酶晟佳的工艺条件为温度84℃、时间20min、酶用量16U／g；而寸高温α-淀粉酶最佳的工艺条件为温度95℃、时间40min、酶用量15U／g。     

α-淀粉酶热稳定剂及失活动力学研究

α-淀粉酶在高温条件下半衰期短,易失活,提高其热稳定性的方法有:添加稳定剂、化学修饰、固定化等.研究了加入热稳定剂醋酸钙、乳酸钠后α-淀粉酶的热稳定性及失活动力学,测定了半衰期(t1/2)、失活速率常数(k)、活化能(Ea)等参数.结果表明,在α-淀粉酶中加入0.01 mol/L醋酸钙后,80℃酶的半衰期(t1/2)从<1.8 min提高到89.9 min,加入0.02 mol/L乳酸钠后提高到167.1 min,大大提高了α-淀粉酶的热稳定性;未加热稳定剂的淀粉酶失活动力学符合一级反应(R2>0.99);添加热稳定剂后酶的失活动力学发生变化,但失活中后期符合一级反应(R2>0.98).     

添加耐高温α-淀粉酶对马铃薯糊化的影响

马铃薯粉的糊化起始温度为65.5℃;马铃薯粉糊化醪最高粘度高达21Pa·s,糊化过程中须添加耐高温α-淀粉酶;耐高温α-淀粉酶对马铃薯粉的最佳作用条件为60U/g的加酶量,处理温度85℃,处理时间30min。     

耐高温α-淀粉酶特性的研究

耐高温α-淀粉酶是在高温下具有最适反应温度的α-淀粉酶。本文对地衣芽孢杆菌所产耐高温α-淀粉酶的最适反应温度、热稳定性、最通反应 pH 以及 pH 稳定性等进行了系统的研究,为该酶的广泛应用提供了理论基础。     

添加耐高温α-淀粉酶对马铃薯糊化的影响

马铃薯粉的糊化起始温度为65.5℃;马铃薯粉糊化醪最高粘度高达21Pa·s,糊化过程中须添加耐高温α-淀粉酶;耐高温α-淀粉酶对马铃薯粉的最佳作用条件为60U/g的加酶量,处理温度85℃,处理时间30min。      

用于食品智能包装的时间温度指示器的开发与性能测试研究进展

时间温度指示器（time-temperature indicator, TTI）作为实时监测食品温度历史的有效工具,在确保食品质量安全、减少食品浪费方面具有广阔的前景。当前已形成了物理型、化学型、生物型和复合型等多种类型的TTI用于食品智能包装,产品应用于海鲜、肉制品、乳制品和果蔬等不同类型食品。本文研究总结了近年来国内外TTI的开发及商业化应用情况,重点对纳米型、微生物型、酶型、美拉德型4种TTI的工作原理和研究进展进行了综述,同时梳理分析了TTI与食品的匹配性原则、变温环境下产品适用性、可靠性测试方法以及欧盟、美国和韩国等国外法规对TTI的食品安全要求,最后提出了未来TTI发展面临的一些挑战,开发高适用性、高可靠性、高稳定性、安全低价的产品,是实现TTI商业化应用的有效途径。     

用于监测食品新鲜度的时间-温度指示器研究现状

随着人们对食品新鲜度的要求越来越高,时间-温度指示器(time-temperature indicator,TTI)作为有效的监测工具已被应用于预估各类生鲜食品的剩余货架期.TTI是用于记录食品时间和温度历史的装置,它是利用时间和温度的累积效应产生的不可逆现象所实现的,有助于确保食品的质量和安全,但是由于其成本高、性能...     

Development of a time-temperature integrator system using Burkholderia cepacia lipase

A time-temperature integrator (TTI) is a device used to show a time-temperature dependent change that reflects the temperature history and quality status of the food to which it is attached. An enzymatic TTI system based on the reaction between Burkholderia cepacia lipase and tricaprylin, which causes a pH change, was developed. The temperature dependence of the response rate of this new lipase-type TTI was modeled using the Arrhenius equation, and the estimated activation energy was calculated as 70.61±11.10 kJ/mol (±95% confidence interval). The TTI response was validated under dynamic storage conditions with independent variable temperature experiments, and a good agreement was obtained between the predicted and measured values.     

Time temperatüre integration for chilled food shelf life monitoring using enzyme‐substrate systems

Abstract

Time Temperature Integrators (TTI) are simple devices to monitor temperature exposure history and relate it to food shelf life behaviour. Four colorimetric enzyme reaction systems are proposed as the basis for TTI use and results for their kinetic characterisation under isothermal conditions are presented. Nonisothermal experiments have shown that the proposed system response reflected accurately the dynamic nature of the environment temperature. The reliability of the proposed TTI systems was demonstrated by a case study on chilled fish shelf life prediction after storage temperature abuse.     

Modelling pH evolution and lactic acid production in the growth medium of a lactic acid bacterium: application to set a biological TTI

Time temperature integrators or indicators (TTIs) are effective tools making the continuous monitoring of the time temperature history of chilled products possible throughout the cold chain. Their correct setting is of critical importance to ensure food quality. The objective of this study was to develop a model to facilitate accurate settings of the CRYOLOG biological TTI, TRACEO. Experimental designs were used to investigate and model the effects of the temperature, the TTI inoculum size, pH, and water activity on its response time. The modelling process went through several steps addressing growth, acidification and inhibition phenomena in dynamic conditions. The model showed satisfactory results and validations in industrial conditions gave clear evidence that such a model is a valuable tool, not only to predict accurate response times of TRACEO, but also to propose precise settings to manufacture the appropriate TTI to trace a particular food according to a given time temperature scenario.     

Extended study on the influence of z-value(s) of single and multicomponent time-temperature integrators on the accuracy of quantitative thermal process assessment

The possibilities and limitations of single- and multicomponent time-temperature integrators (TTIs) for evaluating the impact of thermal processes on a target food attribute with a Ztarget value different from the zTTI value(s) of the TTI is far from sufficiently documented. In this study, several thousand time-temperature profiles were generated by heat transfer simulations based on a wide range of product and process thermal parameters and considering a Ztarget value of 10 degrees C and a reference temperature of 121.1 degrees C, both currently used to assess the safety of food sterilization processes. These simulations included 15 different Ztarget=10 degrees CF121.1 degrees C values in the range 3 to 60 min. The integration of the time-temperature profiles with ZTTI values of 5.5 to 20.5 degrees C in steps of 1 degrees C allowed generation of a large database containing for each combination of product and process parameters the correction factor to apply to the process value FmultiTTI, which was derived from a single- or multicomponent TTI, to obtain the target process value 10 degrees CF121.1 degrees C. The table and the graph results clearly demonstrated that multicomponent TTIs with z-values close to 10 degrees C can be used as an extremely efficient approach when a single-component TTI with a z-value of 10 degrees C is not available. In particular, a two-component TTI with z1 and z2 values respectively above and below the Ztarget value (10 degrees C in this study) would be the best option for the development of a TTI to assess the safety of sterilized foods. Whatever process and product parameters are used, such a TTI allows proper evaluation of the process value 10 degrees CF121.1 degrees C.     

Development of an Enzymic Time Temperature Integrator for Sterilization Processes Based on Bacillus licheniformis α-amylase at Reduced Water Content

ABSTRACT: The thermal stability of Bacillus licheniformis α-amylase at low moisture content was studied, based on isothermal experiments performed in a temperature range 113 to 125 °C. The thermal inactivation was monitored by measuring the decrease in thermal denaturation enthalpy and/or the decrease in enzymic activity on pnitrophenyl-α-D-maltoheptaoside, or on starch as a substrate. Based on enthalpy readings, an enzymic system with a z-value of 10.4 °C was observed when using a relative humidity of 81% at 4 °C. A theoretical study showed that this system could be used as a Time Temperature Integrator (TTI) to monitor the safety of sterilization processes of numerous food products.     

扩散型时间温度指示器在表征奇异果品质中的适用性

目的评估本研究所用时间温度指示器(time-temperature indicators,TTI)在奇异果品质监测中的应用情况。方法分别研究了4种贮藏温度下该TTI的颜色变化和奇异果品质变化情况。通过阿伦尼乌斯方程计算TTI颜色反应和奇异果品质变化的活化能Ea值,将TTI颜色变化活化能值与奇异果品质变化的活化能值进行比较,评估使用TTI表征奇异果品质的可行性。结果 TTI颜色和奇异果品质受贮藏温度及时间的影响。贮藏温度越高,TTI颜色和奇异果品质变化速度越快,TTI的RGB值减小速度越快。结论此TTI能够用于奇异果品质的表征,说明其在食品品质表征方面具有一定的应用潜力。     

超高压对酱料食品中微生物指标的影响

由于超高压杀菌技术实现了常温或较低温度下杀菌和灭酶,保证了食品的营养成分和感官特性,因此被认为是一种最有潜力和发展前景的食品加工和保藏新技术。广泛的应用于含液体成分的固态食品或液态食品的杀菌。本实验尝试以酱料食品为样本,研究超高压杀菌技术对半固体膏状调味品的微生物卫生指标的影响,探讨非热力抑菌技术在半固体膏状调味品生产的应用。分别对压力、保压时间、温度进行单因素实验,结果为300MPa为最佳压力,20min为最佳保压时间,32℃为最适温度。