基于滴液粘性流动的冷鲜牛肉保水机制研究

Drip loss is the most commonly indicator used to describe water-holding capacity of chilled beef. And the drip channel is a necessary condition to increase drip loss. With ageing, the muscle structure breaks and debris begins to fall within the microtubes creating hindrances and slowing down the flow of drip. Contemporaneously with the formation of hindrances is the increase in the amount of soluble or suspended finer particles in the drip water resulting in a more viscous drip that flow even slower within the microtubes. Nonetheless, few researchers have clarified the fundamental mechanism of water-holding capacity based on viscous flow of drip water in chilled beef. This project is intended to be determined by measuring pressure, drip viscosity, sarcomere length and pore size of drip channel to construct the viscous flow model of the elastic microtube. And the change law of the drip flow was analyzed in chilled beef during postmortem aging. Then we determine the interaction force in the drip loss components of chilled beef including electrostatic force, hydrogen bond, ionic bonds and surface hydrophobicity to reveal the interaction force law of chilled beef based on viscous flow. Through the determination of the interaction force including electrostatic force, hydrogen bond, ion bond and surface hydrophobicity in the components of drip water in chilled beef, the interaction force law of chilled beef based on viscous flow was revealed. The distribution of water in chilled beef was determined by low field nuclear magnetic resonance (LF-NMR), near-infrared spectroscopy and Raman spectroscopy. The mechanism of dripping viscous flow was clarified from three levels including the drip flow, interaction force and water distribution in chilled beef. The purpose of the study was to develop theoretical system of water-holding capacity in beef, and provide scientific basis for improving and reasonable utilization of beef meat.

滴水损失是描述冷鲜肉保水性最常用的指标，滴水通道是产生滴水损失的必要条件。宰后滴水损失中可溶性或悬浮颗粒含量增加，导致滴液(Drip water,滴水损失液)粘性改变，然而，滴液的粘性流动对冷鲜肉保水性变化的影响机制缺乏研究。本项目拟通过测定压力、滴液粘度、肌节长度和滴水通道孔径尺寸构建弹性微管粘性流动模型，解析宰后成熟过程中冷鲜牛肉滴液流量变化规律；通过测定冷鲜牛肉滴液中的相互作用力(静电作用力、氢键、离子键和表面疏水性)，揭示基于滴液粘性流动的冷鲜牛肉相互作用力规律；通过低场核磁共振(LF-NMR)、近红外光谱和拉曼光谱检测，确定冷鲜牛肉中不同状态水分分布规律。从冷鲜牛肉成熟过程中滴液流量、相互作用力和水分分布三个层面，阐明冷鲜牛肉中粘性流动对滴水损失影响的机制，为丰富牛肉保水性机制理论体系，改善及合理利用肉质提供科学依据。

保水性是牛肉重要的加工品质，明确冷鲜牛肉在成熟过程中保水性的差异和变化规律，有助于采取相应的措施控制汁液损失。本研究分析了冷鲜牛肉成熟过程中的食用品质变化并测定了不同部位冷鲜牛肉的相互作用力。通过测定低场核磁共振以及近红外光谱和拉曼光谱检测，直观揭示了冷鲜牛肉中不同状态水分分布规律，建立了冷鲜牛肉水分含量快速检测的模型。通过模型的构建对传统物理学上的管道流动模型进行改进，建立了应用于冷鲜牛肉上的滴液粘性流动模型。并结合代谢组学对宰后成熟过程中差异代谢物及代谢通路进行富集分析，为牛肉保水性保持和控制技术的开发提供理论基础。主要研究结果如下：.在成熟过程中不同部位牛肉的保水性均呈现显著降低后升高的趋势（P<0.05），且背最长肌与腰大肌的保水性显著高于半膜肌（P<0.05）。DSC结果显示，成熟期间腰大肌的TmaxPeakⅠ由55.03℃显著降低至54.14℃（P<0.05），TmaxPeakⅡ为63.56℃，显著低于背最长肌和半膜肌（P<0.05）。核磁共振中自由水的比例呈现先迅速下降后上升再下降的趋势。近红外光谱模型交叉验证后的预测性为0.62；拉曼光谱测定可知，拉曼强度呈明显的先上升后下降的趋势，这可能与宰后肌肉蛋白质肽链变化有关。通过建立滴液流动模型，对冷鲜牛肉的汁液流失进行较为精准的预测。通过代谢组学对鉴定出的差异代谢物进行筛选和功能注释，将25种差异代谢物富集到18个代谢通路中，主要包括溶酶体过程（bta04142）、果糖和甘露糖代谢（bta00051）、嘌呤代谢（bta00230）和氨基糖和核苷酸代谢（bta00520）。这些生物过程可能通过影响肌肉所参与的生物学过程，进而影响肌肉的保水性。.该项目的研究结果不仅可科学揭示不同部位冷鲜牛肉宰后成熟品质差异现象，而且可将牛肉保水性理论研究从整体肌肉粗放层次提升到基于相互作用力、水分分布、滴液流量变化及代谢组学变化规律的多层次多维度视角，以期为全面阐明宰后不同部位牛肉保水性机制提供新视角，为分割牛肉市场价值和加工特性的提高提供理论依据。

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