Meat consumption and consumer attitudes in Japan: An overview.

Among Asian countries, Japan has the shortest history of eating meat in its food culture. It was only after 2007 that household fresh meat consumption surpassed fresh fish consumption in Japan. Although it was forecast that slowing population and economic growth would limit the demand for meat, household meat consumption in 2020 increased remarkably from that in 2019, perhaps due to COVID-19. Meat consumption has regional variations within Japan attributable to historical background. Japanese consumers prefer domestically produced meat and focus on the visual characteristics of meat, in particular marbling. Extrinsic factors such as information also contribute to Japanese consumers' meat choices more than the quality of the meat. Although Japanese consumers are concerned about the safety of meat, reassurance from appropriate inspection will restore their purchasing intention. Novel factors such as animal welfare and environment-friendly production are also recognized in Japan. Also notable is that wild animal meat consumption is beginning to increase in recent years.

Estimation of discrimination threshold for emulsified chicken oil in chicken broth.

Although fat content affects the texture and flavor of meat and meat products, the fat discrimination thresholds are unknown. This study aimed to elucidate the discrimination threshold of fat in meat products using broth from chicken thigh meat as a meat taste model. In Experiment 1, triangle tests were conducted between 1%, 0.2%, 0.04%, and 0.008% (w/v) chicken oil-supplemented broth and broth without chicken oil. The results indicated the discrimination threshold to be between 0.04% and 0.008% (w/v). In Experiment 2, similar triangle tests were conducted using oil supplementation at 0.1%, 0.0333%, 0.0111%, and 0.0037% to refine the discrimination threshold. Logistic regression analysis revealed that the discrimination threshold of emulsified chicken oil in chicken broth was 0.0387% (w/v). We demonstrated that chicken oil made a sensory difference in chicken broth at a low concentration and indicates that the chicken oil strongly affects the sensory characteristics of chicken broth.

11-Ketotestosterone is a major androgen produced in porcine adrenal glands and testes.

Porcine steroid hormone profiles have some unique characteristics. We previously studied human and murine steroidogenesis using steroidogenic cells-derived from mesenchymal stem cells (MSCs). To investigate porcine steroidogenesis, we induced steroidogenic cells from porcine subcutaneous preadipocytes (PSPA cells), which originate from MSCs. Using cAMP, adenovirus-mediated introduction of steroidogenic factor-1 (SF-1)/adrenal 4-binding protein (Ad4BP) induced the differentiation of PSPA cells into sex steroid-producing cells. Introducing SF-1/Ad4BP also induced the aldo-keto reductase 1C1 (AKR1C1) gene. Porcine AKR1C1 had 17ß-hydroxysteroid dehydrogenase activity, which converts androstenedione and 11-ketoandrostenedione into testosterone (T) and 11-ketotestosteorne (11KT). Furthermore, differentiated cells expressed hydroxysteroid 11ß-dehydrogenase 2 (HSD11B2) and produced 11KT. HSD11B2 was expressed in testicular Leydig cells and the adrenal cortex. 11KT was present in the plasma of both immature male and female pigs, with slightly higher levels in the male pigs. T levels were much higher in the male pigs. It is noteworthy that in the female pigs, the 11KT levels were >10-fold higher than the T levels. However, castration altered the 11KT and T plasma profiles in the male pigs to near those of the females. 11KT induced endothelial nitric oxide synthase (eNOS) in porcine vascular endothelial cells. These results indicate that 11KT is produced in porcine adrenal glands and testes, and may regulate cardiovascular functions through eNOS expression.

Assessment of the dynamics of sensory perception of Wagyu beef strip loin prepared with different cooking methods and fattening periods using the temporal dominance of sensations.

In this study, we assessed the relative sensory perception of Wagyu beef using temporal dominance of sensations (TDS), which is a dynamic sensory method that captures the "dominance of sensation" throughout food consumption. In addition, we checked the integrity of the TDS by comparing the TDS results with a physicochemical analysis. Strip loins were obtained from 24- and 28-month-old Japanese Black cattle ("Wagyu") and were cooked by grilling (yakiniku) or boiling (shabu-shabu). Temporal dominance of sensations was then used to evaluate the four types of samples. "Tender and/or soft," "juicy," "dry," "fat melting," "fat taste," "umami," "sweet taste," and "butter odor" were dominant in at least one of the sample types, with the yakiniku cooking method highlighting texture- and fat-related sensory characteristics, and the shabu-shabu cooking method highlighting flavor-related sensory characteristics. In addition, beef obtained from the 24-month-old Wagyu was significantly more "dry" than that of the 28-month-old cattle, reflecting their different cooking loss. Temporal dominance of sensations successfully demonstrated the dominant sensory perceptions of Wagyu beef prepared with different cooking methods and fattening periods.

Relative contribution of sensory characteristics for different types of pork loin, assessed by temporal dominance of sensations.

BACKGROUND: Sensory perception is a dynamic process occurring sequentially. The dynamic analysis of the perception of sensory characteristics in meat is important to understand complex meat sensory characteristics. Temporal dominance of sensations (TDS) is a dynamic sensory method that captures the 'dominance of sensations' throughout food consumption, and it is possible to calculate the relative contribution of various sensory characteristics by 'dominance rate' over time. The objective of this study was to assess the major sensory characteristics of the dynamic sensory perception of pork loin. Using the TDS, we evaluated pork loins derived from pigs with different genetic and feeding backgrounds. Moreover, we checked the integrity of the TDS by comparing the TDS results with a descriptive sensory analysis and a physico-chemical analysis. RESULTS: Seven types of pork loin were evaluated by TDS, and 'tender and/or soft,' 'tough and/or hard,' 'juicy,' 'dry,' 'fat melting,' 'smoothness,' 'sourness,' 'umami,' and 'beast odors' became dominant in at least one type of pork loin. The dynamics of the perception of pork sensory characteristics was also depicted by TDS. In addition, TDS and descriptive analysis demonstrated similarity in principal component analysis. CONCLUSION: TDS demonstrated the major sensory characteristics on the dynamic sensory perception of pork loin. © 2019 Society of Chemical Industry.

Descriptive Sensory Traits of Cooked Eggs Laid from Hens Fed Rice Grain.

Descriptive sensory characteristics of eggs produced by conventional corn-based feeding and unhulled whole rice grain-feeding were compared in two cooking procedures using a trained panel. Rice-feeding significantly decreased brothy and roasted odor in eggs cooked into half-cooked egg yolks, and decreased the creamy odor, smoothness and moisture of eggs cooked into custard puddings. However, a statistical interaction between rice-feeding and production farm was not observed in every sensory attribute. These findings indicated that replacing corn with unhulled whole rice grain in diets for laying hens alters the sensory attributes of eggs.

Differences in gene expression profiles for subcutaneous adipose, liver, and skeletal muscle tissues between Meishan and Landrace pigs with different backfat thicknesses.

Backfat thickness is one of the most important traits of commercially raised pigs. Meishan pigs are renowned for having thicker backfat than Landrace pigs. To examine the genetic factors responsible for the differences, we first produced female crossbred pig lines by mating Landrace (L) × Large White (W) × Duroc (D) females (LWD) with Landrace (L) or Meishan (M) boars (i.e., LWD × L = LWDL for Landrace offspring and LWD × M = LWDM for the Meishan offspring). We confirmed that LWDM pigs indeed had a thicker backfat than LWDL pigs. Next, we performed gene expression microarray analysis in both genetic lines to examine differentially expressed genes (DEGs) in energy metabolism-related tissues, subcutaneous adipose (fat), liver, and longissimus dorsi muscle tissues. We analyzed the annotation of DEGs (2-fold cutoff) to functionally categorize them by Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways. The number of DEGs in muscle tissues of both lines was much less than that in fat and liver tissues, indicating that DEGs in muscle tissues may not contribute much to differences in backfat thickness. In contrast, several genes related to muscle (in fat tissue) and lipid metabolism (in liver tissue) were more upregulated in LWDM pigs than LWDL pigs, indicating that those DEGs might be responsible for differences in backfat thickness. The different genome-wide gene expression profiles in the fat, liver, and muscle tissues between genetic lines can provide useful information for pig breeders.

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.

Classification and characterization of Japanese consumers' beef preferences by external preference mapping.

BACKGROUND: Over the past few decades, beef producers in Japan have improved marbling in their beef products. It was recently reported that marbling is not well correlated with palatability as rated by Japanese consumers. This study sought to identify the consumer segments in Japan that prefer sensory characteristics of beef other than high marbling. RESULTS: Three Wagyu beef, one Holstein beef and two lean imported beef longissimus samples were subjected to a descriptive sensory test, physicochemical analysis and a consumer (n = 307) preference test. According to consumer classification and external preference mapping, four consumer segments were identified as 'gradual high-fat likers', 'moderate-fat and distinctive taste likers', 'Wagyu likers' and 'distinctive texture likers'. Although the major trend of Japanese consumers' beef preference was 'marbling liking', 16.9% of the consumers preferred beef samples that had moderate marbling and distinctive taste. The consumers' attitudes expressed in a questionnaire survey were in good agreement with the preference for marbling among the 'moderate-fat and distinctive taste likers'. CONCLUSION: These results indicate that moderately marbled beef is a potent category in the Japanese beef market. © 2017 Society of Chemical Industry.

Dynamics of protein secretion during adipocyte differentiation.

The major functions of adipocytes include both lipid storage and the production of secretory factors. However, the type of proteins released from mouse 3T3-L1 cells during adipocyte differentiation remains poorly understood. We examined the dynamics of secreted proteins during adipocyte differentiation using mass spectrometry (MS) combined with an iTRAQ (®) labeling method that enables the simultaneous analysis of relative protein expression levels. A total of 215 proteins were identified and quantified from approximately 10 000 MS/MS spectra. Of these, approximately 38% were categorized as secreted proteins based on gene ontology classification. Adipokine secretion levels were increased with the progression of differentiation. By contrast, levels of fibril collagen components, such as subunits of type I and III collagens, were decreased during differentiation. Basement membrane components attained their peak levels at day 4 when small lipid droplets accumulated in differentiated 3T3-L1 cells. Simultaneously, peak levels of collagen microfibril components that comprise type V and VI collagen subunits were also observed. Our data demonstrated that extracellular matrix components were predominantly released during the early and middle stages of adipocyte differentiation, with a subsequent increase in the secretion of adipokines. This suggests that 3T3-L1 cells secrete adipokines after their ECM is constructed during adipocyte differentiation.

Simultaneous imaging of fat crystallinity and crystal polymorphic types by Raman microspectroscopy.

The crystalline states of fats, i.e., the crystallinity and crystal polymorphic types, strongly influence their physical properties in fat-based foods. Imaging of fat crystalline states has thus been a subject of abiding interest, but conventional techniques cannot image crystallinity and polymorphic types all at once. This article demonstrates a new technique using Raman microspectroscopy for simultaneously imaging the crystallinity and polymorphic types of fats. The crystallinity and ß' crystal polymorph, which contribute to the hardness of fat-based food products, were quantitatively visualized in a model fat (porcine adipose tissue) by analyzing several key Raman bands. The emergence of the ß crystal polymorph, which generally results in food product deterioration, was successfully imaged by analyzing the whole fingerprint regions of Raman spectra using multivariate curve resolution alternating least squares analysis. The results demonstrate that the crystalline states of fats can be nondestructively visualized and analyzed at the molecular level, in situ, without laborious sample pretreatments.

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.

The importance of subfragment 2 and C-terminus of myosin heavy chain for thick filament assembly in skeletal muscle cells.

In skeletal muscle cells, myofibrillar proteins are highly organized into sarcomeres in which thick filaments interdigitate with thin filaments to generate contractile force. The size of thick filaments, which consist mainly of myosin molecules, is strictly controlled. However, little is known about the mechanisms by which myosin molecules assemble into thick filaments. Here, we assessed the ability of each domain of myosin heavy chain (Myh) to form thick filaments. We showed that exogenously expressed subfragment 2 (S2) + light meromyosin (LMM) of Myh was efficiently incorporated into thick filaments in muscle cells, although neither solely expressed S2 nor LMM targeted to thick filaments properly. In nonmuscle COS7 cells, S2+LMM formed more enlarged filaments/speckles than LMM. These results suggest that Myh filament formation is induced by S2 accompanying LMM. We further examined the effects of Myh C-terminus on thick filament assembly. C-terminal deletion mutants were incorporated not into entire thick filaments but rather into restricted regions of thick filaments. Our findings suggest that the elongation of myosin filaments to form thick filaments is regulated by S2 as well as C-terminus of LMM.

CE-TOF MS-based metabolomic profiling revealed characteristic metabolic pathways in postmortem porcine fast and slow type muscles.

To determine key compounds and metabolic pathways associated with meat quality, we profiled metabolites in postmortem porcine longissimus lumborum (LL) and vastus intermedius (VI) muscles with different aging times by global metabolomics using capillary electrophoresis-time of flight mass spectrometry. Loading analyses of the principal component analysis showed that hydrophilic amino acids and ß-alanine-related compounds contributed to the muscle type positively and negatively, respectively, whereas glycolytic and ATP degradation products contributed to aging time. At 168h postmortem, LL samples were characterized by abundance of combinations of amino acids, dipeptides, and glycolytic products, whereas the VI samples were characterized by abundance of both sulfur-containing compounds and amino acids. The AMP and inosine contents in the VI were approx. 10 times higher than those in the LL at 4h postmortem, suggesting different rates of inosine 5'-monophosphate (IMP) accumulation by adenylate kinase 7 and 5'-nucleotidase, and subsequent different production levels of IMP and hypoxanthine between these two porcine muscles.

MicroRNA-33b downregulates the differentiation and development of porcine preadipocytes.

Sterol regulatory element binding transcription factor (SREBF) is a key transcription regulator for lipid homeostasis. MicroRNA-33b (miR-33b) is embedded in intron 16 of porcine SREBF1 and is conserved among most mammals. Here, we investigated the effect of miR-33b on adipocyte differentiation and development in porcine subcutaneous pre-adipocytes (PSPA). PSPA were transiently transfected with miR-33b, and adipose differentiation was then induced. Delayed adipose differentiation and decreased lipid accumulation were observed in miR-33b-transfected PSPA. Computational predictions suggested that miR-33b may target early B cell factor 1 (EBF1), an adipocyte activator of lipogenesis regulators such as CCAAT-enhancer binding protein alpha (C/EBPα) and peroxisome proliferator-activated receptor gamma (PPARγ). Both gene and protein expression of EBF1 were downregulated in miR-33b-transfected PSPA, followed by considerable decreases in the expression of C/EBPα and PPARγ and their downstream lipogenic genes. However, miR-33b transfection did not markedly affect mRNA and protein expression of SREBF1. We also investigated differences in the expression of miR-33b and lipogenic genes in subcutaneous fat tissues between 5-month-old crossbred gilts derived from Landrace (lean-type) and Meishan (fatty-type) boars. Landrace-derived crossbred gilts expressed more miR-33b and less lipogenic genes than did gilts derived from Meishan. Our results suggest that miR-33b affected the differentiation and development of PSPA by attenuating the lipogenic gene expression cascade through EBF1 to C/EBPα and PPARγ. The differential expression of miR-33b observed in crossbred gilts may in part account for differences in lipogenic gene expression and the fat:lean ratio between pig breeds.

Characterization and classification of Japanese consumer perceptions for beef tenderness using descriptive texture characteristics assessed by a trained sensory panel.

Meat tenderness is an important characteristic in terms of consumer preference and satisfaction. However, each consumer may have his/her own criteria to judge meat tenderness, because consumers are neither selected nor trained like an expert sensory panel. This study aimed to characterize consumer tenderness using descriptive texture profiles such as chewiness and hardness assessed by a trained panel. Longissimus muscles cooked at four different end-point temperatures were subjected to a trained sensory panel (n=18) and consumer (n=107) tenderness tests. Multiple regression analysis showed that consumer tenderness was characterized as 'low-chewiness and low hardness texture.' Subsequently, consumers were divided into two groups by cluster analysis according to tenderness perceptions in each participant, and the two groups were characterized as 'tenderness is mainly low-chewiness' and 'tenderness is mainly low-hardness' for tenderness perception, respectively. These results demonstrate objective characteristics and variability of consumer meat tenderness, and provide new information regarding the evaluation and management of meat tenderness for meat manufacturers.

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.

Differences in mRNA expression of calpains, calpastatin isoforms and calpain/calpastatin ratios among bovine skeletal muscles.

Messenger RNA (mRNA) expression of calpain-1 (µ-calpain), -2 (m-calpain), -3 (p94), small subunit (calpain-4; 28 kDa), and three types of calpastatin (CSTN) isoform were investigated for 10 skeletal muscles of Holstein cattle by real-time and/or semi-quantitative reverse transcription polymerase chain reaction. Noticeably, effect of muscle type was observed on 28 kDa expression (P < 0.001) with a tendency of higher 28 kDa expression in myosin heavy chain (MyHC)-2x-rich muscles compared to MyHC-slow-rich muscles. The CSTN-I and -III expression in Longissimus thoracis (LT) showed the lowest value among the muscles tested. Moreover, 28 kDa/CSTN-I ratio was higher in the diaphragm (DP), psoas major (PM), and LT than those in the lingual muscles (TN), masseter (MS) and pectoralis (PP) (P < 0.05). Calpain-1/CSTN I, calpain-2/CSTN I in LT and PM were higher than that in TN (P < 0.05). Calpain-3/CSTN-I and -III in LT and/or PM showed higher values than that in TN (P < 0.05). These results indicated that the calpain and CSTN expressions are regulated by muscle type, suggesting especially by muscle fiber type. Calpains/CSTN-I ratios, especially 28 kDa/CSTN-I, may account for higher extent of post mortem proteolysis previously observed in LT and PM muscles.

The effects of concentrations of lysine in media on differentiation of 3T3-L1 preadipocytes.

Intramuscular fat content is increased by feeding of low lysine diets in pigs. Reduction in dietary lysine intake results in low plasma lysine concentration and low cytosolic lysine concentration in skeletal muscles. From these observations, we hypothesized that low plasma lysine concentration in pigs fed on low lysine diets reduced supply of lysine from blood circulation to preadipocytes, and this limited supply of lysine might promote adipocyte differentiation in porcine muscles. In order to verify the hypothesis, we investigated the effects of low concentrations of lysine in culture medium on differentiation of 3T3-L1 preadipocytes. Low concentration of lysine suppressed lipid accumulation and messenger RNA (mRNA) expression and enzyme activity of fatty acid synthase. mRNA expressions of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) were lower in cells cultured in low lysine medium. On the other hand, mRNA and protein expressions of C/EBPß and C/EBPδ were not inhibited by low concentrations of lysine in culture medium. These results indicate that low lysine concentrations in culture medium inhibit differentiation of 3T3-L1 preadipocytes through inhibiting the mRNA expressions of PPARγ and C/EBPα.

Influence of different feeding systems on the growth performance and muscle development of Japanese Black steers.

This study investigated the growth performance and gene expression for muscle development between grass hay-fed (GH) and concentrate-fed (CT) steers. Daily gain and energy intake during the fattening period of the GH group were lower than those of the CT group. Analysis of C/EBPα, PPARγ2, myosin heavy chain (MHC), and myostatin gene expressions was performed by real-time PCR. Expressions of C/EBPα and myostatin in semitendinosus and longissimus lumborum (LL) muscles were higher in the CT group than in the GH group at the end of fattening. In LL muscle, MHC expression at the end of fattening was greater in the GH group than in the CT group. These results suggest that regulation of adipogenesis and myogenesis by the expression of genes involved in muscle development might have occurred in the skeletal muscle of the GH group by the feeding of grass hay and/or because of the low energy intakes.