扩散型时间-温度指示器在预测奇异果品质中的应用

为了研究扩散型时间-温度指示器(time-temperature indicator,TTI)对奇异果品质的预测情况,分别研究了不同贮藏温度(5、10、15、20℃)下指示器的颜色变化和奇异果品质(失重率、可溶性固形物含量、VC含量和总酸度)变化情况,通过Arrhenius方程计算TTI反应和奇异果品质变化的活化能Ea值,并将指示器颜色变化与奇异果品质变化的Ea值进行比较,从而评估使用TTI预测奇异果品质的可能性。研究结果表明,贮藏温度及时间对TTI颜色和奇异果品质变化均有影响,贮藏温度越高,TTI颜色变化速度越快,奇异果失品质变化速度越快,同时TTI的RGB值减小速度越快。研究获得TTI的Ea值为37. 302 4 k J/mol,TTI颜色变化与奇异果品质变化的Ea差值在±25 k J/mol以内,因此可以将时间-温度指示器用于奇异果品质的预测,也表明了该指示器在食品品质预测方面具有应用潜力。     

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。     

动力学模型预测即食南美白对虾货架寿命

研究采用挥发性盐基氮(TVB-N)为即食南美白对虾的品质变化和货架寿命的指示指标,根据感官评定结果,确定TVB-N 值16.0mg/100g 为货架寿命终点。建立TVB-N 与贮藏时间(t)之间的一级动力学方程以及TVB-N 变化速率常数(k)与贮藏温度(T)之间的Arrhenius 方程,以预测在某一贮藏温度下即食南美白对虾的货架寿命理论值。求得Arrhenius 方程中TVB-N 变化反应的活化能Ea 为66.24kJ/mol,指前因子k0 为8.41 × 109。分别在15、37、42℃条件下下验证动力学模型的准确性,得到货架寿命预测值相比实际值的相对误差分别为10.45%、－ 4.72%、－ 0.87%。进一步通过Arrhenius 方程外推法求得真空包装的即食南美白对虾在20℃和25℃条件下下保藏的理论货架寿命分别为151.8d 和96.5d。     

不同包装方式对通江段木鲜银耳低温贮藏品质的影响

以新鲜银耳为原料,研究不同包装方式对其保鲜效果及贮藏品质的影响。采用PE膜打孔包装、PE膜不打孔包装和无包装方式贮藏于1℃和4℃条件下,定期测定贮藏期间的品质变化。结果表明,1℃贮藏期间,打孔、不打孔和无包装的鲜银耳的可溶性蛋白含量变化分别为40.86%、43.01%和45.16%;鲜银耳可溶性蛋白含量变化和白度变化率低于4℃贮藏条件。贮藏25 d时,1℃贮藏的PE膜打孔包装鲜银耳品质最佳,失重率23.76%、亨特白度43.45°、可溶性蛋白质含量0.55 mg/g、总糖含量3.39%、微生物的抑制情况显著好于其他处理。     

真空预冷毛豆冷藏期间色泽和失重率变化动力学模型构建

目的探究真空预冷毛豆贮藏过程中色泽和失重率变化规律及其动力学模型。方法将真空预冷毛豆贮藏在0、5、10℃温度条件下,研究其色泽L*、a*、b*、?E和失重率随贮藏时间的变化规律,采用动力学模型对指标进行分析,并结合Arrhenius方程建立基于色泽和失重率变化的预测模型。结果在实验条件下,贮藏温度越低,真空预冷毛豆的色泽和失重率变化速率越慢。不同贮藏温度下毛豆色泽和失重率变化符合零级动力学规律和Arrhenius方程,色泽L*、a*、?E和失重率的活化能Ea分别为27.78、49.70、30.55、54.32 kJ/mol,建立依赖于温度-时间的色泽和失重率动力学模型,验证表明其模型拟合度良好(r20.9)。结论动力学模型能够预测真空预冷毛豆贮藏期间色泽和失重率的变化,为毛豆冷藏期间色泽和失重率的变化提供理论依据。     

微冻罗非鱼片贮藏保质期预测研究

研究真空包装罗非鱼片在-4,2,8℃下的品质变化;测定pH、电导率、AW和TVB-N随贮藏时间变化的规律;确定用电导率值作为指示罗非鱼品质变化及保质期终点的指标;建立电导率与贮藏时间的一级动力学方程,电导率变化速率常数与贮藏温度问的Arrhenius方程.其中电导率反应活化能Ea=120.28 kJ/mol,指前因子k=4.35×1021.并通过试验得出当电导率达5.55 ms/cm时即为鱼片保质期的终点.     

梅州沙田柚贮藏期品质变化及动力学模型预测

研究了梅州沙田柚采后在298,293和288 K条件下主要品质指标变化规律。研究结果表明,随着贮存时间的延长,柚子的失重率、可溶性固形物、可溶性总糖和抗坏血酸含量基本呈下降趋势。线性回归分析表明,零级反应对抗坏血酸以及可溶性总糖含量的变化具有较高的拟合精度。在Arrhenius动力学方程基础之上,建立了梅州沙田柚抗坏血酸和可溶性总糖含量与贮存时间及贮存温度之间的零级化学反应动力学预测模型。并对其进行验证,相对误差小于10%,说明在此温度范围内,可根据贮藏时间对沙田柚品质变化进行预测。     

指示消费端食源性AGEs含量的美拉德反应型时间-温度指示器的研究

美拉德反应产生的晚期糖化终末产物(AGEs)与糖尿病及其并发症有潜在的关联性,因此,消费者需要一种便捷的可指示消费端食品中AGEs水平的动态标识,以指导日常合理的膳食,减少AGEs对人体健康的危害。建立了指示荧光性AGEs含量变化的美拉德反应型时间温度指示器(TTI),以指示食品模拟体系(赖氨酸/葡萄糖)在短时间加热过程中AGEs含量的变化。根据TTI活化能与食品质量变化匹配的原则,在恒温条件和变温条件下,通过计算荧光性AGEs和指示器的反应动力学参数,对TTI和荧光性AGEs变化进行匹配。结果表明:0.4 mol/L赖氨酸和0.3mol/L木糖溶于pH7.0磷酸缓冲溶液制成的美拉德反应型TTI在短时间加热过程中颜色变化明显,恒温条件下得到食品模拟体系中荧光性AGEs和美拉德反应型TTI反应活化能分别为118.18 kJ/mol和96.17 kJ/mol,两者活化能之差小于25 kJ/mol,并且在变温实验中得到两者有效温度之差小于1K,证明所构建的TTI可以用于指示食品模拟体系中荧光性AGEs的积累过程。     

综合稳定性指数法在菠菜贮存期预测中的应用

采用综合稳定性指数(General Stability Index,GSI)法结合Arrhenius方程,建立了菠菜品质预测和预存期预测模型.在5、15、25、35℃贮存环境中,以感官品质、失重率、维生素C含量为品质评价指标,计算综合稳定性指数,研究菠菜综合稳定性指数的反应动力学,建立了菠菜品质预测模型和贮存期预测模型.结果表明,菠菜综合稳定性指数的反应动力学符合零级动力学模型,活化能En为59.33kJ/mol,在20℃贮存条件下对菠菜品质预测模型进行验证,平均相对误差为9.38％,贮存期预测模型相对误差为8.89％.由此表明,综合稳定性指数法适用于菠菜品质和贮存期预测.     

采用挥发性盐基氮动力学模型预测低盐虾酱的货架寿命

本文采用挥发性盐基氮(TVB-N)为低盐虾酱的品质变化和货架寿命的指示指标,根据感官评定结果和SB/T 10525-2009,确定TVB-N值4.50 mg/g为货架寿命终点。建立TVB-N与贮藏时间(t)之间的一级动力学方程和TVB-N变化速率常数(k)与贮藏温度(T)之间的Arrhenius方程,以预测在某一贮藏温度下低盐虾酱的货架寿命理论值。求得Arrhenius方程中TVB-N变化反应的活化能Ea为63.69 kJ/moL,指前因子k0为2.76×109,TVB-N的变化速率常数k为2.76×109e-63690/RT。分别在15℃、30℃和37℃条件下验证动力学模型的准确性,得到货架寿命预测值与实际值的相对误差分别为9.79%、7.00%和-6.54%。进一步通过Arrhenius方程外推法求得低盐虾酱在23℃和27℃条件下保藏的理论货架寿命分别为155.8 d和107.2 d,预测结果与实际值之间能较好地符合。     

Guideline for proper usage of time temperature integrator (TTI) avoiding underestimation of food deterioration in terms of temperature dependency: A case with a microbial TTI and milk

Time-temperature integrators (TTIs) can be used to predict food deterioration. However, underestimation of the magnitude of deterioration is not desirable. This study aims to establish guidelines in terms of temperature dependency (Arrhenius activation energy, Ea) to avoid such underestimation by proper use of TTIs. A case study was executed with a microbial TTI and milk. The Ea of the TTI color change was 106 kJ/mol and those of milk deterioration factors aerobic mesophilic bacteria count, lactic acid bacteria count, ln lactic acid %, and pH were 101, 107, 122, and 145 kJ/mol, respectively. The deterioration factors with values of Ea larger than that of TTI, ln lactic acid %, LAB, and pH, were found to be underestimated as compared to their actual levels by prediction from TTI color change, leading to potential consumption of deteriorated milk.     

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.     

Systematic Application of Time Temperature Integrators as Tools for Control of Frozen Vegetable Quality

ABSTRACT: The application of Time Temperature Integrators (TTI) for quality monitoring and control of frozen vegetable products was studied. Kinetic modeling of characteristic shelf life indices of frozen green peas and white mushrooms was conducted from - 3 to - 20 °C. Effect of temperature on color and vitamin C changes was modeled by the Arrhenius and WLF equations and validated at dynamic temperature conditions. Temperature dependence expressed by the value of activation energy ranged from 79 to 155 kJ/mol. Response kinetics of 2 enzymatic TTI were also obtained and validated. Activation energies of response were 61 and 100 kJ/mol. Based on kinetics, suitable TTI predicted the product remaining shelf life at different temperature exposures from production to consumption.     

New enzymatic time–temperature integrator (TTI) that uses laccase

A new enzyme based TTI prototype was developed using an advantageous enzyme, laccase, which has simple discoloration kinetics and is widely available. The possibility for the laccase TTI to be a qualified TTI product was investigated and the color response variable, kinetics and Arrhenius parameters of the TTI were identified. The hue value was found to be highly correlated with the concentration of laccase reaction product and determined as the color response variable. The significance of kinetics and Arrhenius relationships were sufficient for the TTI prototype to meet the general requirements of TTI products. The activation energy of laccase TTI ranged from 43.9 to 46.9 kJ/mol. The results indicated that the laccase based TTI prototype could be useful as a new type of enzymatic TTI product.     

Use of time-temperature integrators and predictive modeling to evaluate microbiological quality loss in poultry products

The purpose of this study was to characterize the kinetics of the spoilage process of chicken drumsticks in order to evaluate the application of an enzyme process-based time-temperature integrator (TTI) as a continuous quality monitor of poultry products. Shelf life studies were conducted at several temperatures (3 to 20 degrees C) to characterize (i) the poultry spoilage process as a function of total aerobic bacteria and Pseudomonas species populations and (ii) the TTI chroma response function. Two types of poultry products were examined: ice-packed and chill-packed drumsticks. An enzyme-based TTI with a color change response from green to yellow was used. Activation energies for each of the poultry products and each of the bacterial populations were as follows: 21.8 +/- 1.6 kcal/mol (ca. 91.2 +/- 6.7 kJ/mol) for ice-packed drumsticks and total aerobic population, 18.8 +/- 4.5 kcal/mol ca. 78.7 +/- 18.8 kJ/mol) for ice-packed drumsticks and Pseudomonas spp., 17.0 +/- 2.3 kcal/mol (ca. 71.1 +/- 9.6 kJ/mol) for chill-packed drumsticks and total aerobic population, and 14.1 +/- 3.6 kcal/mol (ca. 59.0 +/- 15.1 kJ/mol) for chill-packed drumsticks and Pseudomonas spp. The activation energy calculated for the TTI, 19.1 +/- 1.8 kcal/mol (ca. 79.9 +/- 7.5 kJ/mol), was determined to be adequately close to that of the poultry spoilage process to make effective quality predictions possible. Initial bacteria levels on the chicken drumsticks were uniform and not judged as important limiting factors in the application of TTIs to poultry products. Because the poultry spoilage process was reasonably characterized on the basis of Arrhenius kinetics, there is further need to conduct validation studies to determine the ability of TTIs to provide a continuous quality monitoring system.     

Calibrations between the variables of microbial TTI response and ground pork qualities

A time-temperature indicator (TTI) based on a lactic acid bacterium, Weissella cibaria CIFP009, was applied to ground pork packaging. Calibration curves between TTI response and pork qualities were obtained from storage tests at 2 °C, 10 °C, and 13 °C. The curves of the TTI vs. total cell number at different temperatures coincided to the greatest extent, indicating the highest representativeness of calibration, by showing the least coefficient of variance (CV = 11%) of the quality variables at a given TTI response (titratable acidity) on the curves, followed by pH (23%), volatile basic nitrogen (VBN) (25%), and thiobarbituric acid-reactive substances (TBARS) (47%). Similarity of Arrhenius activation energy (Ea) could also reflect the representativeness of calibration. The total cell number (104.9 kJ/mol) was found to be the most similar to that of the TTI response (106.2 kJ/mol), followed by pH (113.6 kJ/mol), VBN (77.4 kJ/mol), and TBARS (55.0 kJ/mol).     

Time-Temperature Indicator using Phospholipid-Phospholipase System and Application to Storage of Frozen Pork

A novel time-temperature indicator (TTI) using phospholipid-phospholipase was developed to monitor quality change of frozen foods during storage. The ITI was more reliable than the lipase system and monitored quality changes of frozen pork during storage. The TTI was designed for reactions at sub-zero temperatures because the substrate emulsion would be stable at such temperatures. The TTI contained glycerol and sorbitol as anti-freeze reagents and was designed to show distinctive color changes according to pH by mixing bromothymol blue, neutral red, and methyl red. The TTI had an activation energy of 32.12 kcal/mol, suitable for many food reactions.     

Thermal Degradation Kinetics of Carotenoids and Visual Color of Papaya Puree

The degradation kinetics of carotenoids and visual color of papaya puree were investigated at selected temperatures (70 to 105°C). The concept of fractional conversion was applied to determine the kinetic parameters. The degradation of papaya color was based on change of Hunter a and b values and it was found that combination of Hunter (a × b) value adequately represented thermal color change. Degradation of carotenoids and visual color followed first order reaction kinetics. Dependence of the rate constant followed the Arrhenius relationship. The process activation energies for carotenoids and visual color were 20.56 and 32.59 kJ/mol respectively. Higher activation energy value indicated greater temperature sensitivity of visual color as compared to carotenoids. The degradation of pigment and visual color varied linearly. Visual color could therefore be used for on‐line quality control of papaya puree.