Impact of freezing and thawing on the quality of meat: review

This comprehensive review describes the effects of freezing and thawing on the physical quality parameters of meat. The formation of ice crystals during freezing damages the ultrastructure and concentrates the solutes in the meat which, in turn, leads to alterations in the biochemical reactions that occur at the cellular level and influence the physical quality parameters of the meat. The quality parameters that were evaluated are moisture loss, protein denaturation, lipid and protein oxidation, colour, pH, shear force and microbial spoilage. Additionally mechanisms employed to mitigate the effects of freezing and thawing were also reviewed. These include the use of novel methods of freezing and thawing, ante and post mortem antifreeze protein inclusion and vitamin E supplementation, brine injection and modified atmospheric packaging.     

肉类冷冻解冻技术研究进展

冷冻肉因具有易贮藏、易运输、安全性高的优势而被肉类加工企业广泛使用,是肉类加工的主要原料,但是肉类在冷冻解冻过程中会发生一系列品质下降和损耗的现象,如重结晶、油烧、汁液流失和干耗等。因此在肉类加工中为了防止冷冻解冻时品质劣变有必要采用高效的冷冻解冻技术。本文综述了不同冷冻解冻技术(传统技术、高新技术)在肉类加工中的应用,为肉类的高效冷冻解冻技术的研究提供参考。     

浓厚味天然肉类提取物在速冻食品中的应用

主要阐述浓厚味的定义 ,浓厚味提取物的制备方法及呈味特点 ,各种风味料在冷冻食品中应用对比。     

影响肉类食品冷冻质量的因素

冷冻肉类食品在不同的冷冻条件下会有不同的品质变化。食品的冻结温度,冻结曲线,最大冰晶生成带速度,及冷冻中的玻璃化转变及转变温度,都对食品组织结构,对蛋白质的冻结变性,对食品的外观,风味,营养等都构成了直接的影响。     

Effect of freezing and mincing technique on microbial load of minced meat

This experiment was carried out to explain the variation between the use of either fresh or frozen meat cuts in manufacturing of minced meat; in this connection the role of the mincer and the hygienic condition of handling as well as of the temperature under which the raw material and product was handled should be investigated. The achieved results indicated that the minced meat manufactured from fresh meat has low microbial load as compared with that produced from frozen one. However, the mincing at butcher's shops may expose the meat to more sources of contamination than that minced at home (self-made mincing). The handling of raw meat either fresh or frozen in butcher's shops exposed the produced minced meat to high numbers of either spoilage or food poisoning microorganisms. The sources of contamination of produced minced meat were discussed.     

冻结与解冻处理对肉类品质影响的研究进展

冻藏是保藏肉类制品最重要的方式之一,在延长货架期方面起着重要的作用。虽然微生物和酶活性能够很好地被控制,但在冻藏过程中肉类品质的劣变仍然不可避免,并成为影响其商业价值的重要因素。本文概述冷冻、贮藏及解冻过程对肉类理化性质、微观结构及食用和加工品质的影响,如脂肪氧化,蛋白变性,微观组织改变,保水性、色泽和质构等品质下降,并总结现今行业中品质改善措施及技术开发现状,旨在为畜禽肉及水产类保鲜和品质控制提供参考。     

冻结与解冻处理对肉类品质影响的研究进展

冻藏是保藏肉类制品最重要的方式之一,在延长货架期方面起着重要的作用。虽然微生物和酶活性能够很好地被控制,但在冻藏过程中肉类品质的劣变仍然不可避免,并成为影响其商业价值的重要因素。本文概述冷冻、贮藏及解冻过程对肉类理化性质、微观结构及食用和加工品质的影响,如脂肪氧化,蛋白变性,微观组织改变,保水性、色泽和质构等品质下降,并总结现今行业中品质改善措施及技术开发现状,旨在为畜禽肉及水产类保鲜和品质控制提供参考。      

冰温保藏技术在生鲜肉保藏中的应用

生鲜肉营养丰富,但在加工、运输和储存过程中易受微生物和外界环境的影响发生腐败变质,因此保鲜方式极其重要。冰温保藏较传统冷藏技术可更加有效地延长产品的货架期,同时也不会因冻结而造成产品品质下降,因此近年来在生鲜肉的保藏逐渐受到关注。目前对冰温保藏技术在生鲜肉的应用还缺乏全面的综述,因此,本文以冰温保藏技术为研究对象,阐述了其原理以及在禽肉、畜肉、水产品保鲜中的应用研究进展,论述了冰温保藏技术在生鲜肉保藏中的应用前景,介绍了冰温保藏技术与真空、气调和生物保鲜剂相结合的保藏方式在生鲜肉中的应用研究进展,为冰温保藏技术能更好地应用于生鲜肉中提供一些思路和研究方向,以期为冰温保藏技术的推广应用提供参考。     

浅谈白条肉在冷却和冻结过程中的干耗

目前在猪肉的冷加工过程中,一般冷却肉的加工温度为0～15℃,冷冻肉的加工温度为-40～-15℃.肉类在冷加工过程中,由于表面层的水分蒸发,使肉类不断减重,这种减重的现象,称为"脱水",俗称"干耗".     

新型冷冻和解冻技术在肉类食品中的应用研究进展

冻藏是肉类食品的主要贮藏方式之一,而冷冻和解冻过程是影响冻藏食品品质的重要因素。传统的冷冻和解冻方法耗时长,极易导致营养成分的流失及品质的降低,已不能满足现代食品工业的发展需求。因此,发展能够较好地保持肉类食品品质的新型快速技术具有重要的意义。文中对目前先进的冷冻和解冻技术在肉类食品中的应用研究进行重点综述,分析了各技术现阶段存在的不足和未来的研究趋势,为肉类食品冷冻工业的实际生产提供相关指导。     

Structure of northern snakehead (Channa argus) meat: Effects of freezing method and frozen storage

This study was conducted to investigate the potential of cryogenic freezing with liquid nitrogen in the shelf-life extension of northern snakehead (Channa argus) and clarify the effects of temperature fluctuations after freezing on the quality attributes and tissue microstructure during frozen storage. The fish fillets were frozen by three methods including freezing using an ultra-low-temperature freezer (?80°C) to the core temperature of ?60°C (T1) or ?18°C (T2), or liquid nitrogen (T3) followed by storage at ?20°C for five months. Cryogenic freezing with liquid nitrogen postponed the decrease in pH and protein extractability. Temperature fluctuations after freezing might promote the accretion of ice crystals and resulted in the loss of tissue integrity and disorganization of myofibrils. The microstructural changes contributed greatly to the increased thawing loss and decreased resilience, as indicated by the enlarged extracellular spacing and the flakiness of myofibrils. Cryogenic freezing with liquid nitrogen showed no superiority in maintaining the microstructure of northern snakehead fillets, which was supposedly attributed to the cracking in tissue during freezing and the accretion of ice crystals during frozen storage.     

Determination of tetracyclines in meat using two phases freezing extraction method and HPLC-DAD

Food Analytical Methods - The protein binding of tetracyclines may cause the common extraction methods are not able to completely remove them from the proteins. To overcome this problem, we...     

An ultrastructural observation on charquis, salted and intermediate moisture meat products

Charqui meats are tropical intermediate moisture meat products containing 45% moisture and 15% salt with an A_w of 0.70–0.75. Light microscopic studies of a charqui derivative popularly known as Jerked beef (JB) demonstrated considerable shrinking of muscle cells and the formation of fluid channels. The area occupied by muscle cells in JB was diminished by 30–40% in comparison with control samples. At the ultrastructural level, A-bands including the M-line disappeared indicating proteins were lost during processing. Z-lines appeared to be fragmented. In the enlarged extracellular spaces, collagen fibers retained their banding patterns although an empty space was observed surrounding these fibers. The denaturation of myofibrillar proteins during processing and the osmotic pressure caused by salting create conditions for water movement from the myofibrillar compartments to the intermyofibrillar space, then to the extracellular matrix and ultimately to the meat surface.     

Effect of cooking methods and freezing storage on amino acids constituents of lamb meat

The flavour of cooked meat and the acceptability of frozen meat, especially those of lamb meat, are affected to a great extent by methods of cooking such as boiling or roasting. These methods of cooking degrade meat protein as an activity of proteolytic enzymes during storage. Amino acids contents, especially essential ones, decreased during freezing and storage in both selected muscles (Longissimus dorsi muscle and Biceps femoris muscle) under investigation. Roasting was favoured as a cooking method compared with boiling methods, as the latter proved lower amounts of essential amino acids [1–3].     

冷冻处理的熟制虾肉在保鲜条件下的货架期

以熟制克氏原螯虾(Procambarus clarkia)虾肉为原料,分别进行缓慢冷冻和快速冷冻处理后,于4℃下贮藏,通过感官评价、理化指标和微生物指标的测定,研究冷冻处理的熟制虾肉的货架期和品质。研究发现:快速冷冻处理虾肉的品质优于缓慢冷冻处理,但两者的货架期均为5d,6d为可接受的限值,未经冷冻处理的虾肉货架期为2d。感官评分值与TVB-N,MDA含量和菌落总数均有极显著的负相关,R2均在-0.947以上(P<0.01)。快速冷冻组虾肉在贮藏期间失重率和pH值稳定。TVB-N和菌落总数有望作为评价熟制虾肉品质的化学指标,TVB-N值为30mg/100g和菌落总数为6logcfu/g可作为熟制虾肉可接受的限值。冷冻处理有效的延长了熟制虾肉在4℃贮藏条件的货架期,可作为一种处理手段应用于熟制水产品的保鲜。     

Ice crystal growth of living onion epidermal cells as affected by freezing rates

The entire crystallization process and the effect of freezing rates on the temperature of spontaneous freezing (TSF) of living onion epidermal cells were analysed in this study. The cells, stained with iodine at a concentration of 1%, were frozen at three different freezing rates, i.e. 2, 1.2, and 0.5°C/min, and were thawed at 5°C/min. The higher freezing rate caused a higher TSF. Moreover, this article presents a method for determining whether a cell is inactivated by a plasmolysis experiment. The results of plasmolysis showed that the formation of ice crystals did not cause fatal mechanical damages to the cells, even when the freezing rate was as slow as 0.1°C/min. Finally, this article also demonstrated the grey-scale changes that occurred in the cells, as evidenced by an image processing technique. This further highlighted the ice crystal growth process and showed the ice crystal content at different locations inside the cells.     

Effects of raw binder system, meat cut and prior freezing on restructured beef

The effect of different meat cuts or previously frozen meat on processing properties of restructured beef bound with alginate or Fibrimex^TM was investigated. Inside rounds, chuck tenders, chuck clods and tri-tip were used to manufacture restructured logs. Steakettes manufactured with alginate had significantly (P<0.05) higher particle bind in the raw state but Fibrimex had greater bind between meat pieces after cooking. Choice of cut or use of previously frozen meat to manufacture restructured steakettes had no effect on any of the processing parameters measured. Steakettes made with Fibrimex were lighter, redder and yellower than those made with alginate. Redness and yellowness of steakettes decreased with retail storage time. However, the change in redness and yellowness over time was similar for both binders. Use of previously frozen meat resulted in a darker, less red steakette. When alginate was used to manufacture steakettes, cut had no affect on the acceptability of steakettes. However, when Fibrimex was used steakettes made from clod and tip were preferred by a consumer panel to steakettes made from tender and inside round.