Long-term storage under pressure in deep sea improved the microbiological safety and physical properties of whale meat.

This study aimed to clarify the effects of deep-sea pressure storage on the quality of whale meat, especially microbiological safety and physical properties, to examine the effectiveness of deep-sea storage for long-term aging of whale meat. Microbiological safety, physical properties, color and appearance, water content, water activity, and pH of whale meat were examined after storage in the deep sea at depths of 2200-6000 m (22-60 MPa) for 4 months. During storage under high pressure at a depth of >4000 m (40 MPa), the growth of aerobic bacteria was inhibited in whale meat. The toughness of whale meat stored in deep sea at a depth of >4000 m became significantly tender than that before deep-sea storage. Long-term storage of whale meat under high pressure and low-temperature conditions in the deep sea at a depth of >4000 m was clarified to improve the microbiological safety and tenderness of whale meat.

Integrated Transcriptome Analysis of miRNAs and mRNAs in the Skeletal Muscle of Wuranke Sheep.

MicroRNAs (miRNAs) are regarded as important regulators in skeletal muscle development. To reveal the regulatory roles of miRNAs and their target mRNAs underlying the skeletal muscle development of Wuranke sheep, we investigated the miRNA and mRNA expression profiles in the biceps femoris of these sheep at the fetal (3 months of gestation) and 3- and 15-month-old postnatal stages. Consequently, a total of 1195 miRNAs and 24,959 genes were identified. Furthermore, 474, 461, and 54 differentially expressed miRNAs (DEMs) and 6783, 7407, and 78 differentially expressed genes (DEGs) were detected among three comparative groups. Functional analysis demonstrated that the target mRNAs of the DEMs were enriched in multiple pathways related to muscle development. Moreover, the interactions among several predicted miRNA-mRNA pairs (oar-miR-133-HDAC1, oar-miR-1185-5p-MYH1/HADHA/OXCT1, and PC-5p-3703_578-INSR/ACTG1) that potentially affect skeletal muscle development were verified using dual-luciferase reporter assays. In this study, we identified the miRNA and mRNA differences in the skeletal muscle of Wuranke sheep at different developmental stages and revealed that a series of candidate miRNA-mRNA pairs may act as modulators of muscle development. These results will contribute to future studies on the function of miRNAs and their target mRNAs during skeletal muscle development in Wuranke sheep.

Toughness Variations among Natural Casings: An Exploration on Their Biochemical and Histological Characteristics.

We investigated the mechanical, biochemical, and histological properties of hog and sheep casings produced in different countries to elucidate the responsible factors for the toughness quality of natural casings. The toughness and collagen characteristics of sheep and lamb casings were also investigated to elucidate the effect of animal slaughter age on the relationships between connective tissue and the mechanical properties of natural casings. The results showed that the main component of hog and sheep casings was collagen with many layers of sheets. The contents of collagen, elastin, and proteoglycan in hog and sheep casings were similar. The toughest Chinese casings (p < 0.01) possessed a significantly lower heat solubility of collagen (p < 0.01), and a different size and arrangement of collagen fibers. Sheep casings were significantly tougher than lamb casings (p < 0.01). Compared with lamb casings, sheep casings had a significantly low heat-labile collagen content, a low heat solubility of collagen, a large size of collagen fibers, and a high pyridinoline concentration (p < 0.01). Therefore, the high thermal and structural stability of collagen in aged animals may contribute to the enhanced mechanical properties of casings.

Structural modification of myofibrillar proteins by high-pressure processing for functionally improved, value-added, and healthy muscle gelled foods.

The texture, yield, and organoleptic properties of comminuted meat products are closely related to the structure and functionality of myofibrillar proteins (MP). To enhance functional properties of MP, high hydrostatic pressure (HHP) has been widely utilized to modify the structure of MP through protein denaturation, solubilization, aggregation or gelation. This modification depends on the protein system (specie, type and formulation) and HHP condition (pressure intensity, pressurizing gradient, duration time, temperature, pressure/temperature and the sequence of application). However, there remains a lack of a systematic summary of structural changes and structure-function relationship of MP in response to various HHP conditions. Hence, this review first explored the profound knowledge on the structural and functional changes of MP induced by HHP based on previous works and recent progress. Second, to meet the growing demand for economical, nutritional and healthy meat products, recent applications of HHP on the manufacture of low salt, low phosphate and/or low fat gel-type meat products, as well as value-added and texture-modified meat products were highlighted. Finally, future considerations were presented to facilitate progress in this area and to enable HHP as an efficient strategy in tailoring the manufacture of functionally improved, value-added and healthy muscle gelled foods.

Relationships among muscle fiber type composition, fiber diameter and MRF gene expression in different skeletal muscles of naturally grazing Wuzhumuqin sheep during postnatal development.

The aim of this study was to determine the relationships among muscle fiber-type composition, fiber diameter, and myogenic regulatory factor (MRF) gene expression in different skeletal muscles during development in naturally grazing Wuzhumuqin sheep. Three major muscles (i.e. the Longissimus dorsi (LD), Biceps femoris (BF) and Triceps brachii (TB)) were obtained from 20 Wuzhumuqin sheep and 20 castrated rams at each of the following ages: 1, 3, 6, 9, 12 and 18 months. Muscle fiber-type composition and fiber diameter were measured using histochemistry and morphological analysis, and MRF gene expression levels were determined using real-time PCR. In the LD muscle, changes in the proportion of each of different types of fiber (I, IIA and IIB) were relatively small. In the BF muscle, a higher proportion of type I and a 6.19-fold lower proportion of type IIA fibers were observed (P < 0.05). In addition, the compositions of type I and IIA fibers continuously changed in the TB muscle (P < 0.05). Moreover, muscle diameter gradually increased throughout development (P < 0.05). Almost no significant difference was found in MRF gene expression patterns, which appeared to be relatively stable. These results suggest that changes in fiber-type composition and increases in fiber size may be mutually interacting processes during muscle development.

Technological demands of meat processing-An Asian perspective.

A rapid increase in the economy, population, industrialization, and urbanization of Asian countries has driven the fast development of their meat industries over recent decades. This consistent increase in meat production and consumption in Asia has been the major cause for the development of the global meat industry. Meat production methods and consumption are very diverse across different regions and countries in Asia, and thus, it is impossible to cover the technological demands of all Asian countries in this review. Here, we have mainly highlighted the differences in meat production methods and consumption in Asia during recent decades and the meat technology demands of three east Asian countries, namely China, Korea, and Japan, and one south Asian country, India. A brief introduction of the meat industry, in particular the production and consumption trend in these countries, is provided in this article. The technology demands for fresh and processed meat products are then reviewed.

Pork Loin Treated with High Hydrostatic Pressure as a Food Processing Technology: Subacute Toxicity of the Freeze-Dried Powder and Cytotoxicity of the Methanol Extracts.

High hydrostatic pressure (HP) treatment is used in food processing owing to its sterilization effect. Meat or meat products are sterilized and become tender by HP processing. Therefore, the variety of HP-processed meat products has increased worldwide. However, little is known about the safety of HP-processed meat products. The aim of this study was to determine the effects of HP processing and HP combined with 0.4 M sodium carbonate treatment (HP-Na) on pork loins and to evaluate the subacute toxicity and cytotoxicity of these processing methods. In an in vivo study, we performed 90- and 180-day feeding tests in mice and did not detect any adverse effects in HP-processed and HP-Na-processed pork loins. In addition, we evaluated the cytotoxicity of HP-processed meats, and did not observe any obvious toxicity associated with pork loin extracts in vitro. These results suggest that HP is not associated with risk factors during processing.

Application of High-Pressure Treatment to Enhancement of Functional Components in Agricultural Products and Development of Sterilized Foods.

In 1988, the late Prof. Rikimaru Hayashi had first proposed "Use of High Pressure in Food", introducing his views, i.e., "heat and pressure are independently capable of transforming the state of a substance, and such state transforming factors are only heat and pressure in nature." Sc. D. Masaru Nakahara stated in his note that he had been impressed by the unique starting point of Prof. Hayashi's idea. Prof. Hayashi had explored some good method for food processing without using heat, so he alternatively thought of high-pressure treatment (Hayashi R (1989) Use of high pressure to food processing and preservation. In: Hayashi R (ed) Use of high pressure in food. San-Ei Publishing Co, Kyoto, pp 1-30; Nakahara M (1990) Water and ions at high pressure: their fundamental properties relevant to the pressure treatment to food. In: Hayashi R (ed) Pressure-processed food--research and development. San-Ei Publishing Co, Kyoto, pp 3-21). Since the start-up of Japanese research group of high pressure in biological field (the present "Japanese Research Group of High Pressure Bioscience and Biotechnology (JHPBB)") and "International Association of High Pressure Bioscience and Biotechnology (IAHPBB)", we have continued to research into the industrial use of high-pressure treatment over a period of 25 years to realize our dream, that is, the same as Prof. Hayashi's dream. Although heat and pressure were found to be independent factors capable of transforming the state of a substance, use of heat has been overwhelmingly more frequent in food processing up to now. However, the pressure treatment has the advantages of instantaneous transmission, uniform distribution in vessels, and ability of inducing uniform change in quality. The high-pressure treatment does not cause cleavage of the covalent bond in the substance, thereby lessening the decomposition of nutrients, the generation of offensive smell, and the production of abnormal materials when compared with the heat application. In addition, energy consumption in the high-pressure treatment is less than that in the heat treatment. For the reasons mentioned above, the high-pressure treatment has thus been regarded as suitable for future food processing, and much attention has been paid to the researches of high-pressure treatment again. Then, we reviewed the previous researches in which little interest had been taken because of imperfectness of non-heat sterilization. Surprisingly, we discovered some novel findings about the effect of high-pressure treatment, that is, pressure history on the subsequent event. Then, we decided to present two theses on the themes, "Application of High-pressure Treatment to Enhancement of Functional Components in Agricultural Products" and "Application of High-pressure Treatment to Development of Sterilized Foods".

Evaluation of changes in the taste of cooked meat products during curing using an artificial taste sensor.

The purpose of this study was to assess an evaluation method using an artificial taste sensor, in comparison with chemical analysis and sensory evaluation of the taste of meat during curing. Samples of Canadian pork were treated with salt, nitrite and phosphate. Curing time ranged from 0 to 168 h. In the sensory evaluation, there were no significant differences in the all characteristic items at 72-h cured sample compared to the 0-h sample. Some of the characteristic items for the 168-h sample (umami, overall taste, richness and overall palatability) showed significant difference (P < 0.05) compared to the 0-h sample. Taste sensor analysis indicated that the sensor outputs of bitterness and saltiness were significantly correlated with curing time (R = 0.98 and 0.97, respectively), and total free amino acids (R = 0.91 and 0.96, respectively). The sensor output of bitterness was significantly correlated (R = 0.96) with the sum of amino acids corresponding to bitter taste. The increase in the chemical components contributing to bitterness and/or saltiness was indicated as the cause of the characteristic taste. Taste sensor analysis may be applicable as a qualitative method for evaluating taste characteristics generated during the curing of manufactured cooked meat products.

Formation of macromolecule complex with Bacillus thuringiensis Cry1A toxins and chlorophyllide binding 252-kDa lipocalin-like protein locating on Bombyx mori midgut membrane.

P252, a 252-kDa Bombyx mori protein located on the larval midgut membrane, has been shown to bind strongly with Bacillus thuringiensis Cry1A toxins (Hossain et al. Appl Environ Microbiol 70:4604-4612, 2004). P252 was also shown to bind chlorophyllide (Chlide) to form red fluorescence-emitting complex Bm252RFP with significant antimicrobial activity (Pandian et al. Appl Environ Microbiol 74:1324-1331, 2008). In this article, we show that Cry1A toxin bound with Bm252RFP and Bm252RFP-Cry1A macrocomplex, with both antimicrobial and insecticidal activities, was formed. The insecticidal activity of Bm252RFP-Cry1Ab was reduced from an LD50 of 1.62 to 5.05 µg, but Bm252RFP-Cry1Aa and Bm252RFP-Cry1Ac did not show such reduction. On the other hand, the antimicrobial activity of Bm252RFP-Cry1Ab was shown to retain almost the same activity as Bm252RFP, while the other two complexes lost around 30% activity. The intensity of photo absorbance and fluorescence emission of Bm252RFP-Cry1Ab were significantly reduced compared to those of the other two complexes. Circular dichroism showed that the contents of Cry1Ab α-helix was significantly decreased in Bm252RFP-Cry1Ab but not in the other two toxins. These data suggested that the reduction of contents of α-helix in Cry1Ab affected the insecticidal activity of the macrocomplex but did not alter the antimicrobial moiety in the macrocomplex of Bm252RFP-Cry1Ab.

Effects of a high-pressure treatment on bovine gamma globulin and its reduction in allergenicity.

The effects of a high-pressure treatment on the IgE-specific binding activity and structural changes to bovine gamma globulin (BGG), a beef allergen, were investigated. The allergenicity of pressure-treated BGG was also evaluated. We found that the IgE-specific binding activity and allergenicity of BGG were decreased by the high-pressure treatment. Almost no significant change in secondary structure was apparent for pressurized BGG, but a change in the tertiary structure was detected. The decreased IgE-specific binding activity and allergenicity of pressurized BGG were probably due to changes in the tertiary structure caused by pressurization. The results of this study suggest that a high-pressure treatment would be an effective food-processing technique to reduce the allergenicity of BGG.

Bombyx mori midgut membrane protein P252, which binds to Bacillus thuringiensis Cry1A, is a chlorophyllide-binding protein, and the resulting complex has antimicrobial activity.

The epithelial cell membrane 252-kDa protein (P252) isolated in our laboratory from Bombyx mori midgut was shown to bind strongly with Cry1Aa, Cry1Ab, and Cry1Ac toxins of Bacillus thuringiensis (15). In the current paper, P252 was shown to bind with chlorophyllide (Chlide) to form red fluorescent protein (RFP) complex, termed Bm252RFP, with absorbance and fluorescence emission peaks at 600 nm and 620 nm, respectively. P252 at a concentration of 1 microM is shown to bind with about 50 microM Chlide in a positively cooperative reaction to form Bm252RFP under aerobic conditions and in the presence of light at 37 degrees C. Various parameters influencing this reaction have been optimized for efficient in vitro chemical synthesis of Bm252RFP. Circular dichroism spectra revealed that P252 is composed of a beta-structure (39.8% +/- 2.2%, based on 5 samples) with negligible contribution of alpha-helix structure. When bound to Chlide, the beta-structure content in the complex is reduced to 21.6% +/- 3.1% (n = 5). Since Chlide had no secondary structure, the observed reduction suggests significant conformational changes of P252 during the formation of Bm252RFP complex. Bm252RFP had antimicrobial activity against Escherichia coli, Serratia marcescens, B. thuringiensis, and Saccharomyces cerevisiae with 50% effective concentrations of 2.82, 2.94, 5.88 microM, and 21.6 microM, respectively. This is the first report ever to show clear, concrete binding characteristics of the midgut protein to form an RFP having significant antimicrobial activity.

Changes in the immunogold electron-microscopic localization of calpain in bovine skeletal muscle induced by conditioning and high-pressure treatment.

Changes in the localization of calpain in conditioned and pressurized bovine skeletal muscles were investigated by immunogold electron-microscopy. In the muscle immediately after thawing (control), the relative distributions of colloidal particles statistically calculated by counting the colloidal particles were about 65% and 35% in the I-band/Z-disk and A-band regions, respectively. In the muscle conditioned for 7 days, distribution of colloidal particles was more than two times greater in both the I-band/Z-disk and A-band regions than in the control muscle. Almost no change in either the absolute concentration or relative distribution of the colloidal particles was detectable during further storage. In the muscle exposed to a pressure of 100 MPa or 200 MPa, slightly more immunogold was detected in the sarcomere than in that of the control muscle. Increasing pressure up to 300 MPa enabled high-density particles to be seen throughout the sarcomere. Conversely, few particles were detected in the sarcomere of the muscle exposed to 400 MPa. These electron-microscopic observations were confirmed from the statistical analysis as with the conditioned muscles. It was clear from the results obtained that the pressure-induced changes in calpain localization were much more pronounced than those from conditioning.

Effects of a high-pressure treatment on the activity and structure of rabbit muscle proteasome.

The effects were assessed of high hydrostatic pressure on the activity and structure of rabbit skeletal muscle proteasome. The pressure effects on the activity were measured by the amount of fluorometric products released from synthetic substrates under pressure and from fluorescein isothiocyanate (FITC)-labeled casein after releasing the pressure. The effects on the structure were measured by fluorescene spectroscopy under pressure, and by circular dichroism (CD) spectroscopy and surface hydrophobicity after releasing the pressure. The optimal pressure for the hydrolyzing activity of synthetic peptides was 50 MPa. The degradation of FITC-labeled casein increased linearly with increasing pressure applied up to 200 MPa, and then markedly decreased up to at 400 MPa. The changes in the tertiary structure detected by fluorometric measurement were irreversible, whereas the changes in the secondary structure were small compared with those by heat treatment. The pressure-induced activation of proteasome therefore seems to have been due to a little unfolding of the active sites of proteasome.