Nakahashi Y, Maruyama S, Seki S, Hidaka S, Kuchida K
Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
J Anim Sci. 2008 Dec;86(12):3551-6. doi: 10.2527/jas.2008-0947. Epub 2008 Aug 15.
The percentage of MUFA to total fatty acids of beef differs among intermuscular, intramuscular, and subcutaneous fat even within an individual cow. Our objective was to investigate the variation of the percentage of MUFA by geometric and sectional change of marbling flecks in rib eye. Longissimus muscles of 8 Japanese Black steers from a common sire and a common maternal grand sire were used. Three slices (1 from rib roast and 2 from sirloin) from each animal were selected for analysis. Five marbling flecks from each slice were randomly taken to obtain the percentage of MUFA using gas chromatography. High-quality digital images of all slices were taken with a mirror-type camera. The area and location of each marbling fleck were calculated by image analysis. The marbling flecks were categorized by area [small <0.4 cm(2), medium 0.4 to 2.0 cm(2), large >2.0 cm(2)], by location (dorsal and ventral), and by slice section through the LM (front, middle, and back). The effects of classification according to the area, location, and slice section were statistically significant (P < 0.05) for the percentage of MUFA. Least squares means of the percentage of MUFA for marbling flecks of sizes small, medium, and large were 56.8, 58.4, and 60.2%, respectively, indicating that larger marbling flecks had greater MUFA (P < 0.05). Those of dorsal, ventral, front, middle, and back were 59.1, 57.8, 55.4, 59.9, and 60.1%, respectively. The percentages of MUFA of the marbling flecks located in the dorsal part were greater than those in the ventral part (P < 0.05). The percentages of MUFA from middle and back were greater than those from front (P < 0.01). We suggest that the area, location, and slice section of marbling would be the determining factors for the percentage of MUFA of marbling.
即使在同一头牛体内，牛肉中MUFA（单不饱和脂肪酸）占总脂肪酸的百分比在肌间、肌内和皮下脂肪之间也存在差异。我们的目标是通过肉眼可见的大理石花纹斑点的几何形状和截面变化来研究MUFA百分比的变化。使用了8头来自同一父系和同一母系祖父的日本黑牛的背最长肌。从每头牛中选取三片肉（一片取自肋排烤肉，两片取自里脊）进行分析。从每片中随机选取五个大理石花纹斑点，使用气相色谱法测定MUFA的百分比。用镜面式相机拍摄所有肉片的高质量数字图像。通过图像分析计算每个大理石花纹斑点的面积和位置。大理石花纹斑点按面积[小<0.4平方厘米，中0.4至2.0平方厘米，大>2.0平方厘米]、位置（背部和腹部）以及通过背最长肌的切片部位（前部、中部和后部）进行分类。根据面积、位置和切片部位进行分类对MUFA百分比的影响具有统计学意义（P<0.05）。小、中、大尺寸的大理石花纹斑点的MUFA百分比的最小二乘均值分别为56.8%、58.4%和60.2%，表明较大的大理石花纹斑点含有更多的MUFA（P<0.05）。背部、腹部、前部、中部和后部的MUFA百分比分别为59.1%、57.8%、55.4%、59.9%和60.1%。位于背部的大理石花纹斑点的MUFA百分比高于腹部的（P<0.05）。中部和后部的MUFA百分比高于前部的（P<0.01）。我们认为，大理石花纹的面积、位置和切片部位是大理石花纹中MUFA百分比的决定因素。
