真空泠却技术在熟肉制品工业化生产中的应用研究

真空冷却技术是依据较高温度的含水物料在密封环境中真空的条件下通过水分迅速蒸发使物料自身得到迅速降温冷却的原理，这项快速蒸发冷却技术过去仅局限应用在蔬菜和鲜花的冷却保鲜等领域中，本课题研究真空冷却技术应用在熟肉制品生产的冷却工艺中，实验结果表明：相同的熟肉产品从95℃冷却到20℃，真空冷却比传统自然冷却速度快20倍以上，该技术可有效防止微生物在产品中的污染和增殖，提高产品的质量和安全性，延长产品货架期。研究同时就真空冷却技术对产品失水率的影响作了探讨。     

食品加工业中极具应用潜力的真空冷却技术

真空冷却是在真空下水分快速蒸发的预冷技术 ,可用于食品尤其适于叶类蔬菜的冷却。本文介绍了真空冷却技术的原理、在食品加工中的优缺点及其在水果、蔬菜、肉制品、鱼制品、调味品和焙烤食品中的应用     

真空冷却技术在熟肉制品加工中的应用

真空冷却是一种快速蒸发冷却技术,近年来广泛应用于食品工业,在熟肉制品中的应用也逐渐增多。本文介绍了真空冷却技术的原理、优点,以及影响熟肉制品真空冷却的因素。     

真空冷却的原理及应用

真空冷却技术的原理是将被冷却的产品放在真空冷却室内,通过真空泵抽去空气以造成一个低压环境,使产品内部的水分得以蒸发;由于蒸发吸热,导致产品本身的温度降低。真空冷却实现了农产品和食品冷却过程中温度均匀、清洁,不会受到污染,能使食品的品质得到很好的保证。而且由于处理时间短,不产生局部干燥、脱水现象。同时又由于预冷过程时间短,相应设备运转能耗和费用与传统的制冷设备明显降低,另外还可以大大的减少由于预冷时间长导致周围环境渗透的热量所增加的负荷。目前,真空冷却技术在熟食制品中的应用主要是：熟肉、焙烤食品、豆制品、调味品、中式快餐及其它一些需要从高温快速冷却到常温的食品。     

食品加工业中极具应用潜力的真空冷却技术

真空冷却是在真空下水分快速蒸发的预冷技术，可用于食品尤其适于叶类蔬菜的冷却。本文介绍了真空冷却技术的原理、在食品加工中的优缺点及其在水果、蔬菜、肉制品、鱼制品、调味品和焙烤食品中的应用。     

不同冷却方法对馒头贮藏过程品质的影响

通过对馒头采用自然冷却、冷风冷却和真空冷却3种冷却方法,并在4℃的条件下对产品进行贮藏,研究面食品质的变化。结果表明,相对于其他冷却方法,真空冷却将馒头从85℃冷却至20℃所用时间最短,仅为900s,冷却速率高,产品质量损失大,失重率可达到1.683%;冷却后产品硬度、黏性、咀嚼性较大,但粘结性和回弹性方面3种冷却方式没有明显差异;亮度L*偏小,红度a*偏大,黄度b*差异不明显。真空冷却能够有效抑制微生物生长,从而延长食品的保存期。     

食品真空冷却技术的应用研究

以六种不同类型的固体类熟食品在专用实验装置上进行了真空冷却技术的应用研究。结果表明,在真空冷却过程中,熟食品内部孔隙中溶质水的蒸发是一质量传递过程,利用质量传递系数的预测性无量纲方程:dm\dt=KmKSV(P-P')算出预期的质量传递值,与实验数据比较其误差仅为4%,说明所提出模型的正确性,从理论上探讨了真空冷却后,产品失水量的评估和感官质量问题。     

真空冷却技术的研究进展

真空冷却是一种快速冷却技术,它被广泛应用在花卉、水果、蔬菜和食品的冷却降温。本文综述了真空冷却技术在花卉、果蔬和熟肉中的应用研究现状以及目前真空冷却技术理论研究的进展。总结出目前真空冷却技术研究中存在的一些问题,并提出了今后真空冷却的研究方向。     

真空冷却技术在蛋糕制品冷却中的应用研究

采用真空冷却技术对新鲜出炉的蛋糕进行冷却处理,分别考察了冷却终温、冷却终压、水分添加量等因素对蛋糕品质的影响。实验结果表明在真空冷却终温20℃、冷却终压1800Pa和水分添加量5%的条件下能最大程度保持蛋糕的品质,在总体感官上与自然冷却样品无显著差异;与传统自然冷却的150min相比,真空冷却将250g蛋糕由81℃冷却至20℃仅需11min,且样品中心与表面温差不超过1℃。     

真空泠却技术的研究进展

真空冷却是一种快速冷却技术，它被广泛应用在花卉、水果、蔬菜和食品的冷却降温。本文综述了真空冷却技术在花卉、果蔬和熟肉中的应用研究现状以及目前真空冷却技术理论研究的进展。总结出目前真空冷却技术研究中存在的一些问题，并提出了今后真空冷却的研究方向。     

不同冷却方式对熟制馄饨品质的影响

通过真空冷却、鼓风冷却以及自然冷却3种方式对熟制馄饨进行冷却处理,并在4℃的条件下对产品密封储藏,研究随储存时间的延长,3种不同冷却方式处理的馄饨产品品质的变化情况。结果表明:与常规冷却方式相比较,真空冷却的冷却速率高(P<0.05),冷却失重率大(P<0.05);真空冷却的产品L*值偏小,a*值偏大(P<0.05);硬度和咀嚼性较大、弹性较低(P<0.05),但粘结性、黏性、回复性方面3种冷却方式没有显著差异。随着储藏时间的延长,真空冷却能显著降低馄饨产品的菌落总数、TBA值和pH值(P<0.05),减缓产品品质的劣变。     

熟食豆制品的真空冷却工艺研究

研究真空冷却工艺对熟食豆制品品质的影响,并与传统风冷做比较。对其冷却时间、水分含量、质量损失、感官、质构以及色泽进行研究。实验结果表明,真空冷却条件下,将产品的表面温度和中心温度从90℃冷却到5℃,只需19min,而传统风冷方式在冷却40min 后表面温度降到15℃,中心温度仍为42℃。而在感官评定、质构分析和色泽上,两种冷却方式可以达到相同的效果。     

冷却方式对熟制腊肉品质的影响

利用真空冷却、混合冷却（自然冷却＋真空冷却）、自然冷却和鼓风冷却4 种冷却方式将熟制腊肉的中 心温度从60 ℃冷却至25 ℃,研究腊肉在4 ℃下贮藏期间的品质变化。并对冷却样品的冷却速率、质量损失率、质 构、色泽、气味、感官得分进行分析及对比。结果显示,理化指标方面,相对其他冷却方式,真空冷却和混合冷却 能够减少微生物污染,从而延长货架期;混合冷却不仅能够缩短冷却时间,提高产品口感,还能够达到延长货架期 的目的。     

不同盐水注射量下西式火腿真空预冷过程中水分存在形式及孔隙结构变化规律

真空预冷技术在低温熟肉制品的降温方面扮演着极其重要的角色。本实验以真空预冷前后不同盐水注射量（质量分数10%、20%、30%、40%）下的西式火腿水分存在形式和孔隙结构参数为研究对象,并利用偏最小二乘回归分析探讨真空预冷的降温机理。结果表明,10%盐水注射量样品整体平均降温速率（0.94 ℃/min）显著高于20%（0.76 ℃/min）、40%（0.68 ℃/min）和30%（0.56 ℃/min）盐水注射量样品（P＜0.05）。真空预冷过程中不同盐水注射量样品的结合水、束缚水和自由水弛豫峰面积均呈下降趋势,但束缚水驰豫时间却始终维持不变。真空预冷可使不同盐水注射量的样品均获得更宽范围的孔径分布、更大的孔隙率和平均孔径等。载荷图分析结果显示,真空预冷过程中各降温段平均速率与孔隙结构和水分存在形式中的部分参数（束缚水弛豫时间和弛豫面积、累计孔隙体积和累计孔面积、平均孔径及孔曲率和渗透率等）存在着极强的相关性。变量重要性投影值分析结果表明,束缚水较自由水、结合水对降温速率的影响更大。此外,平均孔径、渗透率和孔曲率等孔隙结构指标要比单纯的孔隙率指标对降温速率影响更明显。     

真空冷却与常规冷却方式对白煮牛肉品质影响的比较

本实验研究了真空冷却方式与冷风冷却,自然冷却方式对白煮牛肉品质的影响。样品中心温度从80℃冷却到10℃以下,与冷风冷却(120min)室温冷却(240min)相比较,真空冷却(24min)冷却速率较高。与常规冷却方式相比较,真空冷却的冷却损失较高,剪切力较大,硬度较大,弹性较低,色泽较差。感观分析表明,真空冷却样品总体可接受性不及常规冷却样品。微生物检测表明,真空冷却能显著降低菌落总数,减少细菌增殖,保证样品的卫生质量。     

Effect of cooking and cooling method on the processing times, mass losses and bacterial condition of large meat Joints

This study compares the heating and cooling times of and mass losses from meat joints in three systems: convective air, water immersion and pressure/vacuum. Cooling times were compared with the UK Department of Health (DoH, 1989) guidelines which state that joints should be cooled to 10°C or below in less than 150 min.
Five types of joint were used: 50-mm thick (0.94kg) slabs of beef m. semitendinosus, 2.7kg rolled beef forequarter and silverside, 6.4kg rolled turkey and 7.1kg boned-out ham joints. Six replicates of all joints were cooked from 5 to 75°C (beef), 80°C (ham) or 85°C (turkey) and then cooled to a maximum internal temperature of 10°C.
Average cooking times for convection, immersion and pressure were 263, 278 and 135 min, respectively. Average cooling times for convection, immersion and vacuum were 433, 298 and 50 min, respectively. Vacuum cooling times did not depend on joint size but may have been affected by porosity of the meat. The DoH guidelines could be achieved by immersion or vacuum methods when cooling the small beef slabs but only vacuum cooling was sufficiently rapid when cooling the larger joints.
Mass losses due to pressure cooking (mean 37.4%) were greater than those during convection heating (28.9%). Vacuum cooling resulted in an average mass loss of 8.2% but losses were smaller after convection cooling (2.5%). Average total viable counts (log10 no. of bacteria cm⁻²) after processing and 12h storage were 1.0 at both the surface and interior.     

Feasibility assessment of vacuum cooling of cooked pork ham with water compared to that without water and with air blast cooling

To optimise vacuum cooling for application in the meat industry, an improved cooling method, i.e. vacuum cooling with water (or immersion vacuum cooling), was designed to cool cooked pork ham (2.2 ± 0.2 kg). It was found that the cooling time of vacuum cooling with water was significantly shorter than that of traditional air blast cooling (P < 0.05). For the cooling loss, vacuum cooling with water was significantly lower (6.99%) than that of vacuum cooling without water (13.71%) (P < 0.05). Significant differences in physical and chemical attributes were also observed for ham processed by vacuum cooling with and without water (P < 0.05). Therefore, for a certain size of pork ham, vacuum cooling with water could be an effective method to meet safety guidelines and obtain compatible quality attributes with air blast cooling.     

Developments of mathematical models for simulating vacuum cooling processes for food products – a review

Vacuum cooling is a rapid cooling method widely used in cooling some food products. Simulating the vacuum cooling process with mathematical models helps to acquire a more intuitive understanding and optimize the whole cooling process. However, there is no review summarizing the mathematical models of vacuum cooling. In this review, heat and mass transfer process during vacuum cooling, types of mathematical models for vacuum cooling, and numerical methods including finite difference method, finite element method and finite volume method used for process simulation are introduced in details. The food products used in numerical simulation study of vacuum cooling generally include liquid food, vegetables and cooked meat. The ranges of application of various numerical methods are also discussed. Moreover, heat and mass transfer coefficients have a great influence on the accuracy of the model, and are generally provided by the literature. The investigations presented in this review invariably demonstrate that mathematical modeling can provide good prediction of key information of vacuum cooling process, and has a great potential to improve vacuum cooling process in the food industry. However, more efforts are still needed to realize the industrial translation of laboratory results.     

Effect of rapid and conventional cooling methods on the quality of cooked ham joints

Three cooling regimes, vacuum (VC), blast (BC) and slow cooling (SC), were compared for their effect on cooling rate, weight loss and quality of large cooked ham joints. Vacuum cooling reduced the cooling rate (70-4°C) significantly (P<0.05) in comparison to the other methods; mean cooling times for cooked hams (5-6 kg) were 1.9 h for VC, 11.7 for BC and 14.3 for SC. However, VC gave an increased chill loss (P<0.05) of ca. 11% compared to ca. 4% for the other methods due to evaporative moisture loss. Sensory panels found that VC hams were tougher and less juicy (P<0.05). Shear force measurements and texture profile analysis also showed the vacuum cooling to have a toughening effect on the cooked ham. While vacuum cooling had an adverse effect on quality and yield, it was the only one that conformed to recent safety guidelines for cooked meat joints of a reduction in temperature to 5°C inside 10 h. The cooling conditions used do not reproduce full-scale industrial practice, however, the effects found serve as an indicator of the potential benefits and drawbacks of vacuum cooling for cooked meat joints.     

Vacuum cooling of meat products: current state-of-the-art research advances

Vacuum cooling (VC) is commonly applied for cooling of several foodstuffs, to provide exceptionally rapid cooling rates with low energy consumption and resulting in high-quality food products. However, for products such as meat and cooked meat products, the higher cooling loss of vacuum cooling compared with established methods still means lower yields, and important meat quality parameters can be negatively affected. Substantial efforts during the past ten years have aimed to improve the technology in order to offer the meat industry, especially the cooked meat industry, optimized production in terms of safety regulations and guidelines, as well as meat quality. This review presents and discusses recent VC developments directed to the cooked meat industry. The principles of VC, and the basis for improvements of this technology, are firstly discussed; future prospects for research and development in this area are later explored, particularly in relation to cooling of cooked meat and meat products.