Department of Food and Environmental Sciences, Food Chemistry, University of Helsinki, Helsinki, Finland.
J Agric Food Chem. 2011 May 25;59(10):5435-43. doi: 10.1021/jf104995j. Epub 2011 Apr 28.
The present work aimed to study the relationship between protein carbonylation and the loss of water-holding capacity (WHC) occurring during frozen storage of porcine muscles. Pork samples corresponding to two different muscle types, glycolytic M. longissimus dorsi (LD) and oxidative M. psoas major (PM), and subjected to two different premincing, minced (MINCED) and intact pork pieces (INTACT), and packaging, vacuum packaged (VACUUM) and packed in oxygen-permeable bags (OXYGEN), procedures were frozen (-18 °C/12 weeks) and analyzed at sampling times upon thawing (weeks 1, 4, 8, and 12) for the relative amount of specific protein carbonyls, α-aminoadipic and γ-glutamic semialdehydes (AAS and GGS, respectively), and their ability to hold water using two different techniques. The formation of protein carbonyls occurred concomitantly with the loss of WHC, and both phenomena were found to be more intense in LD muscles and in MINCED and OXYGEN pork samples. The loss in WHC was from ca. 10 to 30% in 12 weeks, depending on the method of determination. Plausible mechanisms by which protein carbonylation may decrease the WHC of pork samples are thoroughly discussed in the present paper. Besides the likely impact of protein carbonylation in the water-myofibrillar protein relationships, the implication of AAS and GGS in further reactions including plausible cross-linking would explain the decrease of these semialdehydes by the end of frozen storage and would reinforce their liability in the loss of WHC of porcine muscles. The exact nature of these reactions, however, should be investigated in further studies.
本研究旨在探讨蛋白质羰基化与猪肌肉冷冻储存过程中持水力（WHC）丧失之间的关系。研究选取了两种不同类型的肌肉：糖酵解的背最长肌（LD）和氧化的腰大肌（PM），并进行了两种不同的前处理：切碎（MINCED）和完整猪肉块（INTACT），以及两种不同的包装：真空包装（VACUUM）和透气包装（OXYGEN）。猪肉样品在-18°C下冷冻（12 周），并在解冻后的不同时间点（第 1、4、8 和 12 周）进行分析，以测定特定蛋白质羰基、α-氨基己二酸和γ-谷氨酰半醛（AAS 和 GGS）的相对含量，以及使用两种不同技术测定的持水力。研究发现，蛋白质羰基的形成与持水力的丧失同时发生，并且这两种现象在 LD 肌肉、MINCED 和 OXYGEN 猪肉样品中更为明显。在 12 周的时间里，WHC 的损失约为 10%至 30%，具体取决于测定方法。本文深入讨论了蛋白质羰基化可能降低猪肉样品持水力的潜在机制。除了蛋白质羰基化可能对水-肌原纤维蛋白关系的影响外，AAS 和 GGS 的存在及其在进一步反应中的可能交联，解释了这些半醛在冷冻储存结束时的减少，并强调了它们在猪肌肉持水力丧失中的责任。然而，这些反应的确切性质应该在进一步的研究中进行调查。
