Immobilized α-amylase from Bacillus licheniformis: a potential enzymic time—temperature integrator for thermal processing

Biphasic and nth-order models were tested as to their usefulness to fit experimental inactivation data of Bacillus licheniformis α-amylase, immobilized on glass beads, and were discussed with respect to their suitability to characterize the considered enzymic system as a time—temperature integrator (TTI) to evaluate heat processes. Both isothermal and non-isothermal inactivation experiments were carried out. Model (kinetic) parameters (rate constant k, activation energy E_A and reaction order n) were estimated using a non-linear regression procedure. The results obtained, especially the activation energy of about 293 kJ mole^–1, indicated a potential use of this system as a TTI for heating processes in the temperature range of 96–108°C.     

A laboratory evaluation of a novel hot water cabinet for the decontamination of sides of beef

A hot water cabinet based on an idealized distributor design for the decontamination of sides of beef is described and a laboratory evaluation of this novel cabinet is reported.
Beef sides were inoculated with E. coli and exposed to mean water temperatures at the surface tissue ( T _f) of 83.5, 74.2, 66.0 and 44.5°C for 10 or 20 s. Mean log₁₀ reductions of bacteria for 10-s exposures were 2.23, 1.40, 0.91 and 0.2. For 20 s, reductions were 2.98, 2.14, 1.17 and 0.1. There was a significant ( P < 0.05) linear relationship between log reductions and T _f which varied with exposure time. At a T _f of 83.5°C with exposure times greater than 20 s, carcass bloom was judged to be permanently and adversely affected. At shorter times or with lower temperatures this did not occur.
Evaporative heat losses were well correlated with the pressure driving force ( r = 0.89) and gravity driving force ( r = 0.92) for air interchange between the cabinet and its surrounds.
The running cost using the distributor cabinet was one-third of that of an existing spray cabinet when compared at the maximum reduction of log 1.3 (95%) achieved by the spray cabinet. An additional advantage of the distributor cabinet is its constructional simplicity.     

酱油熟料的微波加压灭菌研究

采用微波加压灭菌酿造酱油熟料的技术方法是可行的,它具有时间短、灭菌效率高、微波功率和灭菌时间容易精确控制的优点,更容易在实现酱油孰料的完全灭菌的同时,最大限度地提高酱油孰料的消化率。     

黄酒灭菌技术追溯

灭菌是黄酒生产的关键工序之一.古代黄酒的加热杀菌技术经历了"温酒"、"烧酒"和"煮酒"3个发展阶段.目前,黄酒企业对瓶装酒采用高温(80～90℃)灭菌法;对成品酒的灭菌主要采用蒸汽加热方法.黄酒灭菌的创新技术有微波杀菌、脉冲强光杀菌和强磁脉冲杀菌技术.(孙悟)     

LEDs技术在果蔬杀菌保鲜领域应用研究进展

水果和蔬菜是人类饮食的重要组成部分,可为人体提供多种营养物质。然而,果蔬在采收、加工、贮藏等环节极易污染微生物,造成品质劣变,甚至引发食源性疾病。作为一种非热加工技术,发光二极管(LEDs)技术具有绿色环保、节能、寿命长等优点,在农业和食品领域具有广阔应用前景。综述LEDs技术在果蔬杀菌中应用,探讨LEDs技术的杀菌机理及影响因素,概括LEDs技术对果蔬主要品质的影响,并对该技术的发展趋势进行讨论分析。     

微波能对紫菜杀菌保鲜的研究

利用微波能对小包装紫菜进行杀菌保鲜研究。通过正交试验获得微波杀菌的最佳条件,并与常规高温灭菌法进行比较分析,结果表明,微波杀菌后细菌总数均低于对照组,且紫菜的主要营养成分蛋白质、碘的含量损失最少,保鲜期比常规灭菌法长。     

不同热处理过程中鲜食甜玉米类胡萝卜素含量变化研究

为研究加工热处理对鲜食甜玉米中主要类胡萝卜素组分的影响,以晶甜5号鲜食甜玉米为原料,采用高效液相色谱法分析速冻甜玉米烫漂条件、罐装甜玉米预煮和灭菌时间对甜玉米中常见类胡萝卜素变化的影响。结果表明：速冻甜玉米烫漂处理相同时间,蒸汽烫漂甜玉米籽粒中类胡萝卜素含量高于沸水烫漂,且随着烫漂时间的增加,类胡萝卜素的含量在两种烫漂方式下均逐渐下降。对于罐装甜玉米,在20 min内,预煮时间越短总类胡萝卜素含量越高,随着预煮时间增加,仅α-隐黄质含量有所增加,其余均逐渐下降,但预煮时间超过20 min后,总类胡萝卜素含量无明显变化;在10 min内,灭菌处理可以显著提高总类胡萝卜素含量,随着灭菌时间的增加,总类胡萝卜素含量、各种类胡萝卜素组分含量均呈下降趋势。     

即食调味鲅鱼产品开发及杀菌条件对其品质的影响

为开发一款即食调味鲅鱼产品,通过正交优化确定调味鲅鱼的最佳调味料配方,同时探究不同杀菌条件对产品品质的影响。结果表明:最佳调味配方为白砂糖添加量1 g,辣椒粉添加量2 g,麻椒油添加量2 g,五香粉添加量1.5 g;杀菌条件对调味鲅鱼质构和色差中的硬度、胶着度、咀嚼度和L值影响显著,当杀菌条件为115℃、20 min时,鲅鱼硬度为1405.33±45.30,L值为58.52±0.41,综合感官评分最高。结合菌落总数、感官评价、质构和色差综合分析,最佳杀菌条件为:115℃、20 min。     

辐照对花椒粉中微生物及抗氧化性的影响

花椒粉易受微生物的污染,采用50Co-γ射线对其进行辐照处理,研究不同剂量的灭菌效果及辐照对其抗氧化活性的影响.结果表明:花椒粉污染严重,其中菌落总数和大肠菌群分别为5.4×105 cfu/g和2.1×105 MPN/100 g.辐照后,随着剂量的升高,菌落数出现明显下降.15 kGy可以使其微生物指标达到辐照香辛料的卫生标准.其中,芽孢杆菌的D10值最高,耐辐照能力较强.贮藏期内,辐照也可有效抑制微生物增长,并延长花椒粉的货架期.通过对辐照后花椒粉抗氧化性进行检测,得出总还原力、DPPH·和·OH自由基清除率会随辐照剂量的升高出现明显下降,但贮藏过程中,辐照组与对照组之间抗氧化性的差异逐渐消失.