冷却牛肉保鲜技术的进展

为了改善新鲜牛肉不易保存、运输和销售的缺陷,综合概括了冷却牛肉保鲜技术,继而对常用的气调保鲜、辐照保鲜、保鲜剂保鲜、复合保鲜及延缓褪色等技术进行了较详细介绍。     

冷却牛肉质量评定系统开发

本文以计算机视觉系统为基础 ,以面向对象的C ++程序语言为开发工具 ,综合运用人工神经网络、模糊评价、模式识别等理论 ,在VC6 0开发平台上 ,编制了高效实用的图像处理软件 ,开发出冷却牛肉新鲜度和嫩度指标的质量自动评定系统。操作人员能够方便地运用键盘和鼠标对系统直观的图形化界面进行操作 ,使得本系统具有方便、灵活的特点 ,便于推广应用     

冷鲜牛肉的优势腐败菌及其消长规律

冷鲜牛肉的腐败与微生物的种类和数量密切相关。对冷鲜牛肉的初始菌相和不同贮藏温度条件下菌相及pH的变化规律进行研究,结果表明:假单胞菌和乳酸菌是冷鲜牛肉初始菌相中的主要微生物;假单胞菌和热死环丝菌是冷鲜牛肉的优势腐败菌;不同贮藏温度下细菌总数达到107 cfu/g的时间为2～8 d,pH的变化范围为5.6～6.8。     

不同包装材料对冷鲜牛肉品质的影响

采用感官评分、菌落总数、挥发性盐基氮、pH值为指标,研究保鲜袋、聚酯袋、铝箔复合袋三种不同包装材料对冷鲜牛肉在0～4℃条件下品质的影响。实验结果显示,在相同的冷藏条件下,聚酯袋包装的牛肉品质最佳,保鲜效果最好,铝箔复合袋包装的牛肉保鲜效果次之,保鲜袋包装的牛肉保鲜效果最差。     

In-Plant evaluation of a lactic acid treatment for reduction of bacteria on chilled beef carcasses.

The effectiveness of a lactic acid treatment consisting of spraying a 4% L-lactic acid solution (55 degrees C at source) on chilled beef carcasses to reduce bacterial populations was tested in a commercial slaughter environment. All carcasses had been treated with a proprietary decontamination treatment composed of a hot water spray followed by a lactic acid spray prior to chilling. Bacterial groups used to indicate reductions included aerobic plate count (APC), total coliform count, and Escherichia coli count, and samples were examined from the brisket, the clod, and the neck regions of 40 untreated and 40 treated carcass sides. Depending on the carcass surface region, APCs were reduced by 3.0 to 3.3 log cycles. Log coliform and E. coli counts were consistently reduced to undetectable levels. The small reductions observed for coliforms are attributable to counts on untreated carcasses already being near the lower detection limit of the counting method. The percentage of samples with detectable numbers of coliforms (positive samples) on untreated carcasses ranged from 52.5 to 92.5%, while 0.0% of the samples collected from treated carcasses contained detectable coliforms. Percent E. coli-positive samples ranged from 7.5 to 30.0% on untreated carcasses and 0.0% after treatment of carcass sides. These results indicate that a hot lactic acid spray with increased concentration and time of application may be effectively implemented for an additional decontamination treatment of chilled beef carcasses prior to fabrication.     

感官评价优化冷却牛肉可食性涂层的研究

研究以大豆分离蛋白、豌豆淀粉和三乙酸甘油酯为主要原料的可食性涂层对冷却牛肉感官品质的影响。以冷却牛肉的感官评价值为响应值,采用响应面分析方法优化可食性涂层的最佳配方。实验结果显示,当可食性涂层中大豆分离蛋白含量为3.00g/100mL、豌豆淀粉含量为4.90g/100mL和三乙酸甘油酯为1.49g/100mL时,冷却牛肉的感官品质最佳,并且显著优于未包装的冷却牛肉,验证实验表明预测值与真实值相对偏差仅为2.4%,为可食性涂层在冷却肉保鲜中的应用提供了理论支持。     

包装方式对冷鲜牛肉保鲜效果的影响

采用真空包装、热收缩膜包装、保鲜剂配合热收缩膜包装冷鲜牛肉,对其贮藏期间的质量变化进行研究。结果表明:对照组在第10d色泽变暗、表面发粘、肉质松散、有异味,挥发性盐基氮为20.35 mg/100g、菌落总数为1.6×106CFU/g;试验组Ⅰ、Ⅱ、Ⅲ在16d、19d、25d挥发性盐基氮分别为20.16 mg/100g、21.22 mg/100g、19.02 mg/100g,菌落总数分别为1.1×106CFU/g、1.2×106CFU/g、3.2×106CFU/g,已超过标准要求。保鲜处理有效地提高了冷鲜牛肉的货架期,其中采用热收缩膜配合复合保鲜剂的保鲜效果最好(25天)。     

响应面分析法优化冷鲜牛肉可食性涂层的研究

采用响应面分析法优化冷鲜牛肉可食性涂层的组成,有效延长其货架期。研究以冷鲜牛肉的硫代巴比妥酸值为考察对象,采用响应面分析法研究由大豆分离蛋白、豌豆淀粉和三乙酸甘油酯制备的可食性涂层对冷鲜牛肉品质的影响,进一步对响应面分析优化结果进行实验验证,两者误差为7.3%,证明响应面分析法的结果真实可靠。因此,冷鲜牛肉可食性涂层的最佳组成为大豆分离蛋白(3.00%)、豌豆淀粉(3.24%)和三乙酸甘油酯(1.21%)。     

HACCP在冷却牛肉生产中控制微生物的应用

根据危害分析与关键控制点系统原理,对冷却牛肉加工过程中主要环节可能存在的微生物危害进行分析,确立关键控制点、关键限值、监控方法及纠偏措施,构建规范的HACCP质量管理体系,从而有效消除、预防或最大限度地降低冷却牛肉生产过程中的微生物危害,确保产品质量。     

真空包装牛肉冷藏过程理化和微生物变化

将牛肉真空包装贮藏在4℃条件下,每3 d测定其p H、挥发性盐基氮（TVB-N）、菌落总数,并利用聚合酶链式反应-变性梯度凝胶电脉（PCR-DGGE）技术来研究其贮藏过程的菌相变化。结果表明:4℃条件下,真空包装冷却牛肉菌落总数在12 d超过6.0 lg cfu/g,p H在贮藏21 d时超过6.0,TVB-N在贮藏18 d时超过25 mg/100 g,根据理化指标结果显示可知真空包装冷却牛肉贮藏期为12 d;贮藏初期主要存在苍白杆菌、巨球菌、Bosea vestrisii;贮藏末期主要含有成团泛菌、乳酸杆菌、热死环丝菌、慢生根瘤菌属、广布肉杆菌、美洲爱文氏菌、拉恩氏菌、肠杆菌。      

冷鲜牛肉复合天然减菌剂的筛选及优化

使用天然减菌剂保鲜冷鲜牛肉能提高冷鲜牛肉产品的市场竞争力。该文以细菌总数及假单胞菌数、乳酸菌数为指标,比较了乳酸、植酸、壳聚糖、溶菌酶和乳酸链球菌素(Nisin)对冷鲜牛肉的保鲜效果,并用正交试验优化了复合减菌剂的配方。结果表明,Nisin的抑菌效果最佳,植酸和溶菌酶的抑菌效果次之。Nisin和植酸2种减菌剂之间存在协同减菌作用,由它们组成的复合减菌剂的最佳配比为Nisin∶植酸(3∶1),最佳使用量为0.15%的质量分数。     

Curdlan协同Alcalase嫩化生鲜调理牛肉工艺优化

以新鲜牛肉为原料,分析不同浓度的Curdlan及Alcalase对生鲜调理牛肉剪切力、蒸煮损失及感官品质的影响,并研究该体系下肌浆蛋白质及肌原纤维蛋白质的分解情况,优化生鲜调理牛肉嫩化加工工艺。结果表明:体系中Curdlan对生鲜调理牛肉剪切力、蒸煮损失及感官品质均有显著的影响(P0.05),但是对牛肉中蛋白质无明显的分解作用;Alcalase对肌原纤维蛋白质及肌浆蛋白质有明显的分解作用。另外,不同的Curdlan及Alcalase添加量对生鲜调理牛肉的剪切力、蒸煮损失均有显著的影响(P0.05);并且Curdlan、Alcalase对生鲜调理牛肉感官品质有显著的促进作用;通过响应曲面试验二次回归法优化生鲜调理牛肉工艺,得到工艺条件为Curdlan添加量5.43 mg/g,Alcalase添加量4.29 U/g,腌制时间73.4 h,以该工艺进行验证实验后得到产品剪切力为(0.960±0.006)kg,蒸煮损失为(19.96±0.36)%,感官评分为92.81±0.75,与理论值相比,相对误差小于5%,该工艺准确可靠,可以用于生鲜调理牛肉的嫩化加工处理。     

中草药防腐剂在冷却牛肉中的保鲜应用研究

研究了三组中草药防腐剂结合两种包装对冷却牛肉的防腐保鲜效果,对冷却肉的微生物、感官品质和理化指标三方面进行了检测。结果显示,紫丹参提取液在维持冷却牛肉在贮藏期间的感官品质、微生物和理化指标上效果明显,均优于未经保鲜液处理的对照。复配液FP2保鲜效果要好于复配液FP1和紫丹参提取液,复配液FP2结合抗菌PE[T200-4＋负离子粉]3‰～5‰纳米薄膜包装可使冷却牛肉贮存至15d时仍符合国家二级鲜肉标准。     

冷鲜牛肉嫩度的影响因素和嫩化技术

主要论述了冷鲜牛肉嫩度的影响因素,诸如性别和年龄、肌内脂肪和胶原蛋白含量等,同时嫩化技术得到了重点阐述,其包括了排酸成熟、机械法、电刺激等。希望为冷鲜牛肉的生产、品质的改善提供理论依据和技术支持。     

气调包装对冷却牛肉货架期的影响

冷却肉的货架期直接影响着其销售情况。本文用不同的气调成分:0.5%CO/60.4%CO2/39.1%N2(CO组)、62.8%CO2/37.2%N2(无氧组)、69.9%O2/30.1%CO2(高氧组)和真空(真空组)包装冷却牛肉,并在1±1℃下贮藏。结果显示,CO组在贮藏28d时在保持鲜红颜色的同时,鲜度仍在国标规定的范围内;高氧组第一周可以保持颜色鲜红,但第二周已有较强的脂肪氧化异味,且颜色开始褐变;无氧组和真空组处理的冷却肉在28d时虽然可保持鲜度在国标范围内,但此两组处理的色泽在28d时呈灰褐色或暗紫色,不是消费者所喜爱的鲜红色。     

The effects of non-vacuum packaging systems on drip loss from chilled beef

This study investigated drip loss in chilled beef (hot-boned m. longissimus lumborum (LL)) under conventional packaging systems, in which a vacuum is applied, and non-vacuum packaging systems. The use of vacuum during the packaging process (vacuum packaging, CO(2) atmosphere packaging) was associated with increased drip. Drip was lower in heat-shrunk vacuum packaging than in non-shrunk vacuum packaging. A slow vacuum onset had no effect on drip formation, or may have increased it. The extent of pressure reduction (vacuum; range 0-1 atm) did not significantly affect drip formation, although the standard vacuum pressure (0 atm) tended to cause more drip loss than higher pressures. The three non-vacuum anaerobic packaging systems tested were: flushed with carbon dioxide without the pressure being reduced below atmospheric (Flush), or the same system with no CO(2) flush but a proprietary oxygen absorber added (Scavenger), or a combination of both (Flush/Scavenger). Storage was at -1.5 °C for up to 20 weeks. The Flush and Flush/Scavenger systems had considerably lower drip loss than the CAP standard system (6.4%, 6.5%, and 9.1% respectively); the Scavenger system had the lowest drip loss (5.2%). Drip losses generally increased with storage period, irrespective of packaging system. All non-vacuum packaging systems except the Flush system had very low oxygen levels (<0.l% v v ). The Flush system had considerably higher levels of oxygen (0.9%) with associated browning of meat samples. All packaging systems gave a hygienic shelf-life of at least 16 weeks. At 16 weeks, microbial numbers were highest (5 × 10(6)) in the Scavenger system. The meat from all packaging systems was acceptable to taste panels even after 16 weeks of storage at -1.5 °C. There were no significant differences between any of the packaging systems for any of the sensory attributes tested. The packaging systems with the best all round performance were the Flush/Scavenger and the Scavenger systems, depending on the storage-life required.     

壳寡糖与茶多酚复合保鲜剂对冷鲜牛肉的保鲜效果

以冷鲜牛肉为研究对象,通过分析菌落总数、大肠杆菌、L*(亮度)、a*(红度)、高铁肌红蛋白值(metmyoglobin,met Mb)、肉糜脂肪氧化程度(meat fat oxidation degree,TBARS)、挥发性盐基氮(total volatile basic nitrogen,TVB-N值)、硬度以及汁液流失率等指标,研究了0. 06 g/100mL壳寡糖和不同浓度茶多酚复配对冷鲜牛肉的保鲜效果。结果表明,使用复合保鲜剂,比单独使用壳寡糖可以更好地抑制冷鲜牛肉中菌落总数、大肠菌群、MetMb%、TBARS、TVB-N、硬度和汁液流失率的上升,以及L*、a*的下降。0. 06 g/100mL壳寡糖与0. 3g/100mL茶多酚复配时,保鲜效果最佳,可将冷鲜牛肉的货架期由单独壳寡糖处理的20 d延长至25 d。     

减菌液涂布方法对冷鲜牛肉贮藏品质的影响

为筛选冷鲜牛肉加工时较优的减菌液涂布方法,分别将25℃、0.1%(w/w)的乳酸链球菌素(Nisin)、植酸、壳聚糖、溶菌酶和乳酸等天然减菌剂以喷涂法和浸渍法处理牛肉,考察4℃下贮藏10d后牛肉的p H值、蒸煮损失率、TBAS值、剪切力等理化指标和细菌总数的变化。结果表明:浸渍法比喷涂法更能保持冷鲜牛肉的嫩度,降低蒸煮损失率,减轻脂肪氧化和抑制细菌的生长,从而更适合做冷鲜牛肉保鲜剂的涂布方法。