猪肉成熟与冷藏过程对其热源性晚期糖化终末产物的影响机制

The accumulation of dietary advanced glycation end-products (AGEs) in the human body have been linked to several diseases. Although meat products are generally high in AGEs, there is a lack of study on the AGEs in meat products, especially on the formation of AGEs in meat during heating as affected by the physical and chemical changes of chilled meat during aging and cold storage process. In this proposed study for AGEs in chilled pork products, HPLC-MS/MS method with isotope labeled Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) as internal standards will be used to analyze free and protein-bound AGEs in pork. This study will provide a basic understanding of the effects of aging and cold storage of chilled pork on the amounts of AGEs in raw pork as well as on the levels of heat induced AGEs during the subsequent heat treatments (including pasteurization and commercial sterilization). In addition, the combined effects of cold storage and some commonly used meat additives on the amounts of AGEs in chilled ready-to-cook pork products before and after heat treatments will be evaluated. Finally, the underlying mechanism deciding the amounts of AGEs formed in raw and heat treated chilled pork and chilled ready-to-cook pork products will be examined based on the physical and chemical changes in pork due to lipid and protein oxidations etc. during cold storage. This proposed study makes it possible to effectively evaluate the combined effects of cold storage, meat additives and thermal processing on the AGEs levels of chilled meat products，which serves as the basis to help reduce the amounts of AGEs in meat products.

食源性晚期糖化终末产物（AGEs）在人体内的积累与多种疾病的发生相关。尽管肉类食品中AGEs的含量通常较高，但目前与肉中AGEs相关的研究较少，更未涉及冷却肉（畜肉）在成熟与冷藏期间的理化变化对其后续热加工中AGEs形成的影响机制。本项目拟以冷却猪肉为对象，采用HPLC-MS/MS结合羧甲基赖氨酸（CML）和羧乙基赖氨酸（CEL）的同位素内标物分析肉中游离态和结合态AGEs含量，探明成熟嫩化和冷藏过程对冷却肉的AGEs含量及其在后续加热处理（包括巴氏杀菌和商业灭菌）中AGEs形成的影响；明确冷却肉调理肉制品中常用辅料和冷藏过程对生肉及其加热处理后AGEs含量的影响机制；揭示冷却肉及其调理肉制品在冷藏期间的脂肪、蛋白质氧化等导致的理化变化与其加热前后AGEs含量的内在关联。本项目将全面阐明冷藏过程、加工辅料和热处理对最终熟食肉品中AGEs含量的影响机制，为降低肉品中的AGEs含量提供依据。

肉类食品中潜在危害物晚期糖化终末产物（AGEs）含量较高，但有关冷却肉的冷藏过程对其本底和热源性AGEs形成的影响机制尚未明确。本项目以冷却猪肉为对象，分析了猪肉冷藏和后续加热过程中典型AGEs（羧甲基赖氨酸，CML；羧乙基赖氨酸，CEL）、α-二羰基化合物（α-DCs，乙二醛和丙酮醛）、脂肪和蛋白质氧化等的变化，研究了常用辅料（NaCl、乙醇、香辛料、还原糖和非还原糖、有机酸、碱盐）对猪肉冷藏和热源性AGEs形成及相关理化指标的影响。结果表明：猪肉冷藏过程中，其α-DCs、硫代巴比妥酸（TBARS）、可溶性肽、和希夫碱含量以及色氨酸荧光强度逐渐增加，而肉中AGEs含量通常没有显著变化（酸、碱处理肉除外），但猪肉冷藏时间越长，其在后续加热过程中AGEs的产生量越多。说明猪肉冷藏过程发生的理化变化对其本底AGEs含量影响较小，但氧化过程产生的中间产物尤其是α-DCs会在加热条件下促进AGEs的形成。与空白对照猪肉相比，NaCl或乙醇的添加对热源性AGEs的形成无显著影响，而八角、小茴香、桂皮、草果提取液的添加可降低热源性CML的形成。葡萄糖、果糖、乳糖显著促进猪肉热源性CML和CEL的产生，蔗糖对热源性CML（P = 0.928）和CEL（P = 0.623）的产生均无明显影响，可作为理想的甜味剂用于肉制品生产。乙酸和柠檬酸对猪肉冷藏和加热过程中TBARS和希夫碱等的产生有抑制作用，对在冷藏过程中AGEs的产生无显著影响，但可使得热源性CML和CEL的产生量分别减少30% ‒ 54%和14% ‒ 48%，证明有机酸抑制热源性AGEs的形成与其抑制加热过程中脂肪氧化和美拉德反应初期产物的形成有关。碱盐（碳酸氢钠、三聚磷酸钠、焦磷酸钠）对猪肉冷藏过程CML的含量无明显影响（P = 0.989），但使得CEL的含量增加26% ‒ 53%。加热程度高的肉中热源性AGEs的形成受加热前猪肉冷藏期间的理化变化的影响较小。本项目探明了猪肉冷藏过程及调理肉制品中常用辅料对其本底及热源性AGEs的影响机制，为系统、有效地降低肉类食品从宰后到熟制过程中AGEs的形成提供了理论依据。

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