Physicochemical properties as indicators of sensory characteristics of jidori and broiler chicken meat.

To improve the eating quality of chicken, the physicochemical properties were examined, which serve as indicators for breeding. Thigh meat was collected from 384 chickens from seven and nine types of the jidori (free-range local traditional pedigree chickens) or broiler chickens, respectively. The principal component analysis of the physicochemical values of the jidori and broilers were arranged as different groups in the score plot. The results of multiple regression analysis of the sensory characteristics and physicochemical properties of thigh meat indicated that the tenderness decreased with the higher crude protein content and cooking loss in the jidori and increased with lower cooking loss and higher moisture and ether extract content in the broiler. The juiciness of the jidori decreased as the moisture content decreased, and that of the broiler decreased as the cooking loss and crude protein content increased. The umami of both the jidori and broiler was improved by increasing the 5'-inosinic acid content. Therefore, it was suggested that the physicochemical properties, which serve as indicators of the eating quality of chicken, differed between the jidori and broiler, and that the general biochemical components, cooking loss and 5'-inosinic acid content may serve as breeding indicators.

Relationship between refractive index and fatty acid composition by gas chromatography and near-infrared fiber-optic method in bovine fat.

The causes of the difference in fatty acid composition between gas chromatography (GC) and near-infrared fiber-optic method (NIR) in bovine fat and their countermeasures were studied using absolute values of refractive index. Using intermuscular fat from 45 crossbreeds, refractive index was measured by using a refractometer, and saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were measured by NIR and GC. The correlation coefficients between GC and NIR in SFA and MUFA, as well as those between refractive index and GC or NIR (in SFA and MUFA), were all greater than or equal to 0.8 (p < 0.01). In samples with 3% or more difference between GC and NIR in SFA and MUFA, GC and NIR values were often located in opposite directions to the regression lines with regard to refractive index. GC reanalysis on these samples slightly increased the correlation coefficient between GC and refractive index and reduced the difference between GC and NIR by 1%-2%. Results indicate that measurement errors in GC and NIR are related to their more than 3% difference, and GC reanalysis based on refractive index may improve its accuracy.