Michiyo Motoyama

Changes in the amounts of water-soluble umami-related substances in porcine longissimus and biceps femoris muscles during moist heat cooking

Time course changes in amounts of glutamic acid, total free amino acid, inosine monophosphate (IMP), and 2%-trichloroacetic acid-soluble oligopeptides in whole, muscle only, and cooking juice during wet-heat cooking in pork longissimus and biceps femoris muscles were investigated because the movements of umami-relevant substances during cooking treatment had not previously been clarified in detail. The amounts of glutamic acid, total free amino acid, and IMP significantly (P<.05) decreased and increased in muscle and cooking juice during 180min of cooking, respectively. The whole amounts of glutamic acid and total free amino acid remained unchanged during cooking treatment. The whole amount of IMP, however, increased significantly at 10min of cooking (P<.05) and was maintained after the 10-min period. The extramuscular oligopeptides amount increased significantly in response to the cooking treatment (P<.05). The intramuscular amount of oligopeptides decreased at 30min of cooking but increased significantly (P<.05) after 60min. The whole meat oligopeptides amount increased significantly during a 180-min cooking treatment (P<.05). These results indicate that glutamate, total free amino acid, and IMP were released from the muscle during cooking, and that IMP levels increased in the initial phase of cooking. In addition, oligopeptides increased during wet-heat cooking of pork muscles.

Differentiation of Animal Fats from Different Origins: Use of Polymorphic Features Detected by Raman Spectroscopy:

Food safety requires the development of reliable techniques that ensure the origin of animal fats. In the present work, we try to verify the efficacy of using the polymorphic features of fats for discriminating animal-fat origins. We use Raman spectroscopy to collect the structural information of fat crystals. It is shown that a single Raman band at 1417 cm−1 successfully differentiates pork fats from beef fats. This band is known to be characteristic of the β‘-polymorph of fats. Pork fats show this band because they contain the β’-polymorph after rapid cooling to 0 °C. In beef–pork-fat mixtures, this band is not detected even in the presence of 50% pork fat; an addition of beef fat to pork fat is likely to produce a mixed fat with a completely different polymorphic behavior. This method seems to have the potential to detect beef products contaminated with pork-adipose tissue.

Radiocesium distribution in the tissues of Japanese Black beef heifers fed fallout-contaminated roughage due to the Fukushima Daiichi Nuclear Power Station accident.

This study examined the accumulation and tissue distribution of radioactive cesium nuclides in Japanese Black beef heifers raised on roughage contaminated with radioactive fallout due to the accident at the Fukushima Daiichi Nuclear Power Station on March 2011. Radiocesium feeding increased both (134)Cs and (137)Cs levels in all tissues tested. The kidney had the highest level and subcutaneous adipose had the lowest of radioactive cesium in the tissues. Different radioactive cesium levels were not found among parts of the muscles. These results indicate that radiocesium accumulated highly in the kidney and homogenously in the skeletal muscles in the heifers.

Genomic structural analysis of porcine fatty acid desaturase cluster on chromosome 2

Fatty acid composition is an economically important trait in meat-producing livestock. To gain insight into the molecular genetics of fatty acid desaturase (FADS) genes in pigs, we investigated the genomic structure of the porcine FADS gene family on chromosome 2. We also examined the tissue distribution of FADS gene expression. The genomic structure of FADS family in mammals consists of three isoforms FADS1, FADS2 and FADS3. However, porcine FADS cluster in the latest pig genome assembly (Sscrofa 10.2) containing some gaps is distinct from that in other mammals. We therefore sought to determine the genomic structure, including the FADS cluster in a 200-kbp range by sequencing gap regions. The structure we obtained was similar to that in other mammals. We then investigated the porcine FADS1 transcription start site and identified a novel isoform named FADS1b. Phylogenetic analysis revealed that the three members of the FADS cluster were orthologous among mammals, whereas the various FADS1 isoforms identified in pigs, mice and cattle might be attributable to species-specific transcriptional regulation with alternative promoters. Porcine FADS1b and FADS3 isoforms were predominantly expressed in the inner layer of the subcutaneous adipose tissue. Additional analyses will reveal the effects of these functionally unknown isoforms on fatty acid composition in pig fat tissues.

Qualitative and Quantitative Comparisons of Texture Characteristics between Broiler and Jidori-niku, Japanese Indigenous Chicken Meat, Assessed by a Trained Panel

The texture of jidori-niku (Japanese indigenous native chicken meat) was characterized and compared with those of Chunky broiler chicken meat. Experiment 1: A qualitative sensory test using jidori-niku and broiler breast (pectoralis major, PM), thigh (biceps femoris, BF) and sasami (deep pectoral) meat cooked to the end-point temperature 75°C by steam-heating was administered to a trained sensory panel (n=16–17) for the selection of descriptive texture items from ISO5492 texture words. By the correspondence analysis, the characteristics of ‘chewiness,’ ‘hardness’ and ‘springiness’ were found to be different between jidori-niku and broiler: they likely characterize jidori-niku texture. Experiment 2: Texture characteristics in the three above-mentioned muscles in jidori-niku and broiler were compared quantitatively using the three above-mentioned texture items by the trained sensory panel. Sensory chewiness and hardness were the highest in the broiler PM and second highest in the jidori-niku BF, whereas sensory springiness was the highest in the jidori-niku BF. These results suggest that jidori-niku-like texture was characterized as a springy texture as compared to broiler meat.

Effects of Cooking End-point Temperature and Muscle Part on Sensory 'Hardness' and 'Chewiness' Assessed Using Scales Presented in ISO11036:1994

Texture and ‘tenderness’ in particular, is an important sensory characteristic for consumers’ satisfaction of beef. Objective and detailed sensory measurements of beef texture have been needed for the evaluation and management of beef quality. This study aimed to apply the sensory scales defined in ISO11036:1994 to evaluate the texture of beef. Longissimus and Semitendinosus muscles of three Holstein steers cooked to end-point temperatures of 60°C and 72°C were subjected to sensory analyses by a sensory panel with expertise regarding the ISO11036 scales. For the sensory analysis, standard scales of ‘chewiness’ (9-points) and ‘hardness’ (7-points) were presented to the sensory panel with reference materials defined in ISO11036. As a result, both ‘chewiness’ and ‘hardness’ assessed according to the ISO11036 scales increased by increasing the cooking end-point temperature, and were different between Longissimus and Semitendinosus muscles. The sensory results were in good agreement with instrumental texture measurements. However, both texture ratings in this study were in a narrower range than the full ISO scales. For beef texture, ISO11036 scales for ‘chewiness’ and ‘hardness’ are useful for basic studies, but some alterations are needed for practical evaluation of muscle foods.

Relationship between water-holding capacity and intramuscular fat content in Japanese commercial pork loin

Objective The relationship between water-holding capacity (WHC) and intermuscular fat (IMF) was studied in Japanese commercial pork. Methods Longissimus muscles of pigs (n = 62), obtained from two meat packing plants, were analyzed for IMF content, moisture content, drip loss, cooking loss, and pH. Pairwise relationships among these traits were determined using correlation analyses. Results IMF content was significantly correlated with moisture content (r = −0.88; p<0.01) and pH (r = 0.32; p<0.05), but not with drip loss (r = −0.23; p = 0.07) or cooking loss (r = −0.10; p = 0.42). In contrast, drip loss was significantly (and negatively) correlated with pH (r = −0.57; p<0.01). Conclusion IMF content was not significantly correlated with WHC in pork, and so ultimately, we consider pH to be one of the most important factors influencing WHC in pork meat.

Changes in Thiamin Contents in Porcine Muscles and Liver during Growth

Changes in the thiamin contents in three types of porcine muscle and porcine liver during growth were investigated. The muscular thiamin content was lower at the newborn stage than at fetal stage, and increased after the weaning period. The liver thiamin content, however, remained unchanged from the fetal stage to 5 months old. The changes in thiamin contents were different between Landrace and Meishan pigs.