Liu Wenjie, Lanier Tyre C, Osborne Jason A
James Ford Bell Technical Center, General Mills, 9000 Plymouth Ave. N, Minneapolis, MN 55427, United States.
Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Box 7624, Raleigh, NC 27695, United States.
Meat Sci. 2016 Jan;111:67-77. doi: 10.1016/j.meatsci.2015.08.018. Epub 2015 Aug 29.
Fat- and nonfat-containing meat gels structurally became coarser and porous by partial substitution of whey protein isolate for myofibrillar protein, creating a weaker texture plus greater cook loss (CL: fat+water) and expressible water (EW). Microstructure examinations revealed a tendency for fat to coalesce during cooking of the more coarse-structured gels. This tendency was unaffected by fat pre-emulsification prior to addition, arguing against a strong role of an interfacial protein film in stabilizing fat. Instead, a gel structure with evenly distributed small pores leads to lower CL and EW, thus controlling both water- and fat- holding since fat cannot readily permeate small water-filled hydrophilic pores. Only when large pores or continuous fissures are structurally present can water be released, allowing liquid fat to also migrate and coalesce. This changes the current paradigm of understanding regarding the mechanism of fat/water-holding in comminuted meat products: gel capillarity (gel structure), not fat emulsifying ability of protein, is the likely determining factor.
通过用乳清蛋白分离物部分替代肌原纤维蛋白,含脂肪和不含脂肪的肉凝胶在结构上变得更粗糙且多孔,从而产生更弱的质地,以及更大的蒸煮损失(CL:脂肪+水)和可表达水(EW)。微观结构检查显示,在结构更粗糙的凝胶烹饪过程中,脂肪有聚集的趋势。这种趋势不受添加前脂肪预乳化的影响,这表明界面蛋白膜在稳定脂肪方面没有起到重要作用。相反,具有均匀分布的小孔的凝胶结构会导致较低的CL和EW,从而控制持水和持脂能力,因为脂肪不易渗透到充满水的小亲水性孔隙中。只有当结构上存在大孔或连续裂缝时,水才会释放出来,使液态脂肪也能迁移和聚集。这改变了目前关于碎肉制品中脂肪/水保持机制的理解范式:凝胶毛细作用(凝胶结构),而非蛋白质的脂肪乳化能力,可能是决定性因素。