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.     

Color Degradation Kinetics of Spinach, Mustard Leaves, and Mixed Puree

ABSTRACT: The kinetics of color degradation of spinach, mustard leaves, and mixed (mustard:spinach:fenugreek = 1:0.75:0.25) puree were investigated at temperatures between 75 and 115 °C. Color degradation was studied in respect to both visual green color (Hunter -a value) and total color [L × (-a) × b]. Degradation of color followed 1st-order reaction kinetics. Temperature dependence of the degradation rate constant obeyed the Arrhenius relationship with activation energies ranging between 19.71 and 41.64 kJ/mol. Higher activation energy value indicated greater temperature sensitivity of mustard leaves than spinach and mixed puree. Activation energies for visual green color were consistently higher than that for total color. Visual green color could therefore be used for on-line quality control of spinach, mustard leaves, and mixed puree during thermal processing.     

A Fraction Conversion Kinetic Model for Thermal Degradation of Color in Red Chilli Puree and Paste

The kinetics of degradation of color was evaluated using a fraction conversion model during thermal treatment of red chilli puree at 60, 70, 80 and 90°C (up to 20 min) and storage of red chilli paste at 5, 25 and 37°C (up to 6 mo). Red chilli puree was subjected to heat treatment at different temperatures in a well-stirred water bath. Test samples were removed from the bath at selected time intervals (0-20 min after come-up), cooled immediately and analysed for color using a Hunterlab colorimeter. Chilli paste was prepared by a standard formulation by adding common salt (8%) and the required volume of citric acid to bring the pH to 4.0. The paste was thermally processed at 85°C for 15 min, filled into glass bottles and stored at selected temperatures for 6 mo. Red chilli color was expressed as a tristimulus combination value (L·a·b) as well as the total color difference (ΔE). The fraction conversion model adequately described the kinetic changes in both color values during thermal treatment of puree and storage of puree. The process activation energies were 24.2 and 24.8 kJ/mol, respectively, for ΔE and L·a·b during the thermal treatment, and during the storage the respective values were 24.1 and 25.0 18;kJ/mol. Up to the end of the 6-mo storage, the paste was microbiologically stable with no major changes in other physico-chemical characteristics.     

Color and Texture Change Kinetics in Ripening Bananas

Kinetics of color and texture changes in ripening bananas were investigated as a function of storage temperature (10, 16, 22, 28 °C). Color was evaluated in terms of L, a and b values as well as the total color difference (ΔE) representing the residual deviations from the ripe stage. Puncture force (PF) was used to evaluate the texture properties of banana. The results indicated that the time dependence of L, ΔE and PF values followed a logistic model, while a and b values were well described by a simple zero-order and fraction conversion models, respectively. The Arrhenius equation adequately described the temperature dependence of the reaction rate constants for both color and texture parameters, from which the activation energies and rate constant at reference temperature 15 °C were obtained. There were significant linear correlations between color parameters (L, a, b, ΔE) and texture parameter (PF).     

不同颜色大蒜品质分析

以打破休眠期的大蒜为原料,制备白色、绿色和黄色3种颜色大蒜,对其总酚含量、还原糖含量、自由基清除率、风味及味道进行测定,探究不同颜色大蒜的营养价值、抗氧化能力及感官品质的差异。结果表明,不同颜色大蒜的营养价值、抗氧化能力及感官品质存在显著差异。新鲜白色大蒜中含有较多总酚,绿蒜次之,黄蒜中最少。还原糖含量恰恰相反,黄色大蒜含量最高。不同颜色大蒜都具有较好的清除自由基能力,清除自由基能力强弱为新鲜白色大蒜>绿色大蒜>黄色大蒜。风味分析中,氮氧化合物(W5S)和硫化物(W1W)的感应器具有明显响应值变化,且响应值大小排序为黄色大蒜>绿色大蒜>新鲜白色大蒜。而味觉上,咸味、甜味、酸味、苦味上存在明显差异。绿色和黄色大蒜保持较好酸味,同时甜度下降。新鲜白色大蒜可以较好维持咸味和苦味。     

超高压对菠菜浆贮藏期间颜色变化的影响

为探究超高压技术（HHP）处理菠菜浆的颜色品质在不同贮藏条件下的变化规律,对HHP处理样品的CIEL’a’6’颜色进行测定。结果表明,HHP处理菠菜浆在处理后和贮藏期与传统热处理菠菜浆相比其颜色品质更好。在4~C下进行贮藏,HHP处理样品的一a‘值和h。值均显著高于热处理样品,并且在贮藏期阀基本保持不变;￡_’值在HHP处理后显著增加,在贮藏过程中亦基本保持不变,色泽更为明亮。在27。C下进行贮藏,HHP处理样品的一a’值和h。值均显著高于热处理和未处理样品,并在贮藏期间呈下降趋势;上’值在贮藏过程中呈现曲折上升的趋势。因此,HHP处理菠菜浆的表观绿色在冷藏和室温贮藏条件下均要好于传统热处理。HHP处理可以在一定程度上保持绿色菠菜浆的颜色品质,减缓其颜色品质的劣变。     

Green Pea and Garlic Puree Model Food Development for Thermal Pasteurization Process Quality Evaluation

Development and selection of model foods is a critical part of microwave thermal process development, simulation validation, and optimization. Previously developed model foods for pasteurization process evaluation utilized Maillard reaction products as the time–temperature integrators, which resulted in similar temperature sensitivity among the models. The aim of this research was to develop additional model foods based on different time–temperature integrators, determine their dielectric properties and color change kinetics, and validate the optimal model food in hot water and microwave‐assisted pasteurization processes. Color, quantified using a^* value, was selected as the time–temperature indicator for green pea and garlic puree model foods. Results showed 915 MHz microwaves had a greater penetration depth into the green pea model food than the garlic. a^* value reaction rates for the green pea model were approximately 4 times slower than in the garlic model food; slower reaction rates were preferred for the application of model food in this study, that is quality evaluation for a target process of 90 °C for 10 min at the cold spot. Pasteurization validation used the green pea model food and results showed that there were quantifiable differences between the color of the unheated control, hot water pasteurization, and microwave‐assisted thermal pasteurization system. Both model foods developed in this research could be utilized for quality assessment and optimization of various thermal pasteurization processes.     

Influence of Steeping Solution and Storage Temperature on the Color Change of Garlic

ABSTRACT:  The objective of this study was to investigate the browning of garlic under different steeping conditions and storage temperatures. The brown indices of steeped garlics showed lowest values (7.3 and 7) in 25% and 50% EtOH at 7 d of storage. The degree of browning of steeped garlics was lowest (10.2 in 25% EtOH and 10.4 in 50% EtOH) in the samples soaked for 8 h at 13 d of storage. As the storage temperature was increased from 10 to 40 °C, the brown indices of garlics revealed an increasing trend relative to storage time regardless of steeping treatment. Overall, the kinetic parameters showed relatively low  R ² and irregular reaction constants, but the  k_o  values showed an increasing trend with temperature under a zero-order model. The highest polyphenol content within the garlic bulbs was seen in controls (without steeping treatment, 588.9 μg/g), than 0% EtOH (water, 392.5 μg/g), than 25% EtOH (211.3 μg/g), and finally 50% EtOH (155.6 μg/g). The polyphenol oxidase activity of garlic showed a similar trend to that of polyphenol content. However, the texture properties of garlics steeped with 25% and 50% did not change.
Practical Application: The garlic color preferred by consumers is a creamy-white, but this is susceptible to enzymatic browning when pre-peeled and chopped. When garlic was steeped in the 25% and 50% alcohol, the browning of garlic was prevented during storage.     

Chemical Characteristics and Storage Stability of Pickled Garlic Prepared Using Different Processes

Three processes for preparing peeled pickled garlic were studied: (P) packing directly with an acidified brine, followed by pasteurization (90°C, 8 min); (B) blanching with hot water (90°C, 15 min) before packing, followed by a preservation treatment (pasteurization, preservatives + refrigeration); and (MB) same as B, except that microwave blanching was used (120g garlic cloves, 825W, 1.5 min). All products were microbiologically stable but fructans were hydrolyzed during storage at 27°C. A green pigment was also apparent in (P). Products from (B) or (MB) had better quality than that from (P). Most stable and best quality products resulted from the blanching treatments and water blanching resulted in the product with best color.     

水性色浆在文化纸调色中的应用

该文研究了水性色浆(颜料蓝PB、颜料紫PV)在文化纸调色中的应用,与国外水性色浆对比表明,颜料蓝PB、颜料紫PV在文化纸调色中具有色泽鲜艳、耐光耐热性好、性价比高等优势。     

蒜泥绿变影响因素及控制方法

研究大蒜品种、贮藏温度、pH 值、氧化剂以及还原剂等因素对蒜泥绿变的影响及其控制方法。结果表明：蒜泥的绿变与大蒜品种无关,对pH 值十分敏感;添加适量还原剂(抗坏血酸)对蒜泥绿变有一定的抑制作用,而添加氧化剂(双氧水)可促进蒜泥绿变,但是在一定的浓度以上,氧化剂或还原剂对绿变的影响都是有限的;低温贮藏能促进蒜泥的绿变,而高温贮藏则能抑制蒜泥的绿变。     

热破碎番茄浆贮藏期间非酶褐变动力学分析

探讨热破碎番茄浆在贮藏过程中非酶褐变的规律,以期为番茄浆的贮藏提供指导。在0、25℃和37 ℃条件对其进行了5个月的贮藏研究,并对产品中与非酶褐变相关的指标总氨基酸、总糖、维生素C(VC)、5-羟甲基糠醛(HMF)和褐变度(BD)的变化分别应用零级、一级、联合动力学模型进行了拟合分析。结果表明：联合动力学模型较零级、一级动力学模型能更好地解释热破碎番茄浆贮藏过程中非酶褐变的动态变化。25℃和37 ℃贮藏过程中,热破碎番茄浆中HMF含量和BD的变化呈线性关系,同时颜色指标亮度L*、红值a*、黄值b*是HMF的函数,可用联合动力学方程表示。较高的贮藏温度(25℃和37℃)对热破番茄浆中总氨基酸、总糖、VC、HMF含量、BD以及颜色指标(亮度L*、红值a*、黄值b*)影响显著(P＜0.05),较低温度(0℃)贮藏条件下,HMF含量、褐变度BD及颜色指标变化不明显(P＞0.05)。表明高温贮藏显著降低热破碎番茄浆的品质,而低温贮藏可有效保护热破碎番茄浆的品质。     

哈姆林橙汁在贮藏过程中的理化指标及色泽变化

以哈姆林橙汁为研究对象,分析了哈姆林橙汁在不同贮藏条件下VC、还原糖与色泽的变化。结果表明：在不同贮藏条件下,抗坏血酸含量均呈现明显下降趋势。温度越高,VC降解越快,冻藏和避光有助于减缓VC的降解速率,而还原糖含量则先上升后下降。果汁颜色随着贮藏时间的延长品质逐渐变差,L*值,b*值和c*值随着贮藏时间的延长和贮藏温度的升高呈下降趋势。a*值随着贮藏时间的增加而上升, 在同一贮藏时期,a*值随着贮藏温度的升高而增大。     

南极磷虾肉糜冷藏过程中蛋白水解酶的稳定性及自溶特性

以总蛋白酶活力为指标,研究3 种自制南极磷虾肉糜（虾肉糜）5 ℃冷藏过程中蛋白水解酶的稳定性,并以蛋白质组分、汁液流失率为指标,结合感官评价,研究其自溶特性。结果表明：在冷藏过程中,虾肉糜所含的消化腺蛋白酶稳定性较高,未充分漂洗的虾肉糜受到持续的水解;虾肉糜的自溶特性主要表现为盐溶性蛋白、碱溶性蛋白的降解和水溶性蛋白的增加,且汁液流失率增大和感官品质劣化。未漂洗虾肉糜的自溶现象尤为显著,不宜冷藏保存,而2 次漂洗虾肉糜在冷藏过程中自溶特性不显著,虽然存在一定的蛋白质组分变化和汁液流失率增加现象,但感官品质未大幅下降,因而适宜于短时间内在5 ℃进行冷藏保存。     

不同冻藏温度对金枪鱼肉肉色变化的影响

以黄鳍金枪鱼背部肌肉为研究对象,测定不同的冻藏温度(-18℃,-25,-55℃)对肌肉颜色(a*值)、高铁肌红蛋白的含量、脂肪氧化的影响。结果表明:随着冻藏时间的延长,a*值呈下降趋势;高铁肌红蛋白含量增加、脂肪氧化值增加;在不同的冻藏温度下,肌肉a*值变化显著(p<0.05);冻藏温度越低,a*值,脂肪氧化值变化越小,肌红蛋白氧化成高铁肌红蛋白的量越少。     

红葡萄柚番茄红素和色泽热降解动力学及降解机制

对红葡萄柚中番茄红素和色泽进行热降解动力学研究。结果表明,不同温度条件下番茄红素和色泽降解均为一级降解动力学,确定红葡萄柚汁中番茄红素含量与色泽可用线性关系C/C_0=1.770 7(a~*/a_0~*)+0.801 2来表示;纯化后番茄红素含量与色泽在70、80、90℃条件下的线性关系分别为:70℃:C/C_0=1.856(a~*/a_0~*)-0.841 5;80℃:C/C_0=1.714(a~*/a_0~*)-0.711 8;90℃:C/C_0=1.492 1(a~*/a_0~*)-0.467 2。高效液相色谱-二极管阵列在线监测发现番茄红素热降解途径为:加热促使全反式番茄红素向单顺式异构体进行转变,继续加热导致全反式和单顺式异构体转变为双顺式异构体,而加热过程中双顺式异构体也可转变为单顺式异构体或发生降解,从而造成总番茄红素含量的下降。     

Development of a High Sensory Quality Garlic Paste

ABSTRACT: Different processes of preparing garlic paste were studied. All methods involved the addition of antioxidant agents (AA): sodium bisulfite and citric acid; a sanitation step (SS) was optional. Sodium hypochlorite and citric acid and 3 pH values (3.0, 3.5, or 4.0) were evaluated. The paste had a shelf life of approximately 60 d and high sensory quality. The combination of the 2 unit operational procedures, SS and AA, and a pH of 4.0 provided the paste with the best chemical and sensory properties during storage at room temperature (20 ± 2 °C): intense pungent character, intense garlic odor and flavor, and white-yellowish color.     

Freezing Rate and Frozen Storage Effects on Color and Sensory Characteristics of Pineapple Fruit Slices

This study was carried out to evaluate the influence of freezing process (cold room –18°C and air-blast freezer –50°C) and frozen storage (–18°C for 0 to 12 mo) on color and sensory quality of pineapple fruit slices (Smooth Cayenne and Red Spanish cultivars). L, –a and +b color parameters showed differences (P ≦ 0.05) with cultivar, but not with freezing rate. No differences (P ≥ 0.05) were found in sensory analysis (color and appearance) between the cultivars, frozen at different rates, compared to fresh product, or after 1 yr frozen storage. The two cultivars are suitable for freezing.