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A two-step hydrolysis of Japanese beech (Fagus crenata) was conducted by semi-flow treatment with hot-compressed water. The first treatment stage was conducted at 230degC/10 MPa for 15 min and the second at 270degC/10 MPa for 15 min. Hemicellulose and lignin were found to be hydrolyzed in the first stage, while crystalline cellulose was hydrolyzed in the second stage. The treatment solubilized 95.6% of the Japanese beech wood flour into water with 4.4% remaining as water-insoluble residue, which was composed mainly of lignin. Hydrolysis products from the first stage were xylose and xylo-oligosaccharides, glucuronic acid and acetic acid from O-acetyl-4-O-methylglucuronoxylan, and hydrolyzed monomeric guaiacyl and syringyl units and their dimeric condensed-type units from lignin. Products from the second hydrolysis stage were glucose and cello-oligosaccharides from cellulose. The dehydrated products levoglucosan, 5-hydroxymethylfurfural (5-HMF), and furfural, as well as fragmented products glycolaldehyde, methylglyoxal, and erythrose, were recovered in the first stage from hemicellulose, and to a greater extent in the second stage from cellulose. Furthermore, organic acids such as glycolic, formic, acetic, and lactic acids were recovered in both stages. Based on these lines of evidence, decomposition pathways of O-acetyl-4-O-methylglucuronoxylan and cellulose are independently proposed.

The goal of this work was to design mixed vegetable (vegetable-fruit) juices which are preserved by high pressure, have an increased content of bioactive substances, are made from locally available produce, and offer excellent nutrition and appealing taste. The new products were prepared on laboratory scale units and underwent nutritional, microbiological, and sensory evaluations. The basic composition, total polyphenol content, ascorbic acid content, and total antioxidant activity were determined.

Japanese beech (Fagus crenata) wood was treated in supercritical water at 380degC/30 MPa and 380degC/100 MPa. The hydrolysate (water-soluble portion) was found to contain the fragmented and dehydrated compounds of sugars and organic acids. Although organic acids are expected to be utilized for methane fermentation, the effects of the fragmented and dehydrated compounds of sugars on methane production are not known. The objective of this study is, therefore, to elucidate the potential of supercritical water treatment as a new pretreatment for methane production by evaluating the methane fermentability of the hydrolysate. From the methane fermentation tests for those model compounds with digested sludge, it is found that methane was produced not from the fragmented and dehydrated compounds but from the organic acids. The yield of methane from the hydrolysate obtained at 380degC/30 MPa was higher than that from the hydrolysate obtained at 380degC/100 MPa because the former contains more organic acids than the latter. The maximum yield of methane was seven times greater compared to the untreated wood, indicating that the supercritical water treatment is effective for enhancing the productivity of methane from wood.

Cellulose powders were pulverized by an ultra high-pressure counter-collision treatment in an aqueous suspension state, and then used in composites with vinyl polymers and graft copolymerized with methyl methacrylate using ceric ion initiator. The influence of freeze-drying methods after microfibrillation of cellulose was visualized by scanning electron microscopy (SEM). The coalescence of microfibrillar structures was observed to increase easily reflecting the freeze-drying conditions. While the degree of microfibrillation was unsatisfactory for use as fillers in preparing polymer-nanocellulose composites, the situation was found to be rectified with the use of a proper kneading technique. The roles of microfibrillated cellulose in processes producing bio-nano-composites suitable for practical uses were studied through SEM observations and measurements of physical properties. The characteristics of the successive graft copolymerization were studied through examining the monomer conversion and the grafting efficiency. The significant improvement in the grafting became apparent in response to the counter-collision pretreatment. Dynamic viscoelastic properties of the molded sheets of the grafted products were studied to measure the effects of the graft copolymerization compared with the corresponding physically blended material and neat poly(methyl methacrylate). The grafting reaction resulted in composites with much higher heat-resisting properties than those obtained for the latter two.

High-pressure technology is used as an alternative to heat processing because of its inactivating effect on microorganisms and enzymes. However, it can also alter the structure of other muscle proteins. The present study compares the effects of high pressure (300 MPa, 7°C, 20 min) on the proteolytic degradation and alterations in the myofibrillar proteins of sardine and blue whiting muscle. Also, muscle homogenates and enzyme extracts were pressurized in order to evaluate the high-pressure effects on unprotected proteolytic enzymes outside the whole muscle structure. Peak proteolytic activity was found to occur at 55°C in both species. The peak activity pH was pH 3 for the sardine and pH 8 for the blue whiting; the main enzyme families being aspartic proteases in the former and alkaline serine proteases in the latter. Pressurization lowered activity levels at the peak activity pH and temperature in the fish muscle (by 30.8% in the sardine and by 9.5% in the blue whiting) and also slightly in the enzyme extracts (by 16.8% in the sardine and by 19.4% in the blue whiting). The electrophoretic profiles disclosed higher protein degradation in the pressurized muscle. Overall, the observed changes in proteolytic activity can be attributed not only to the effect of high pressure on the enzymes, but also and mainly, to the effect on other muscle proteins.

The effects of technological treatments (freezing, pasteurisation, high-pressure treatment) on the concentration of isothiocyanates were observed in single-species vegetable juices prepared from cruciferous vegetables (broccoli, cauliflower, Brussels sprouts, white and red cabbage). The concentrations of sulforaphane and total isothiocyanates were studied relative to the temperature, action period, and time delay after juice pressing. Sulforaphane and total isothiocyanates were determined by HPLC. Sulforaphane concentration in various parts of fresh broccoli was also assessed. Antimutagenic activity of the juices (frozen, pasteurised, and high-pressure treated) was evaluated using the Ames test and the following mutagens: AFTB1 (aflatoxin B1), IQ (2-amino-3-methyl-3H-imidazo-[4,5-f]quinoline), and MNU (2-nitroso-2-methylurea). Clastogenicity inhibition of the mutagens, in response to broccoli juice, as well as of pure sulforaphane, was observed using an in vivo experiment (the micronucleus test). It was shown that in terms of sulforaphane content, it is best to let broccoli juice stand for 60 min after pressing and pH adjustment. Sulforaphane level does not change under heating to 60 deg C. Its concentration decreases considerably (compared to fresh juice) with heating to higher temperatures than 60 deg C. High-pressure treatment preserves mutagenic inhibition to the same degree as juices freezing.

An aqueous ribose-cysteine model system, heated at 140 deg C under supercritical carbon dioxide (SC-CO2) and supercritical nitrogen (SC-N2), was investigated with emphasis on the formation of volatile compounds. In general, SC-CO2 facilitated the overall intermediates accumulation while suppressing the advanced stage of browning. 3-Methyl-1, 2-dithian-4-one increased with increasing SC-CO2 pressure, and was always more concentrated than in the case of SC-N2-treatment. The formation of thiols, disulfides, and formyl substituted thiophenes was also promoted in SC-CO2-treated reaction products, while the effect of high pressure on the individual components followed different patterns. The reversible pH decrease and reinforced acid-base catalysis of 2, 3-enolisation by SC-CO2 could be attributed to the decreased browning and higher amounts of most intense meaty aromatic compounds.

High-pressure inactivation data were obtained for model working suspensions of Enterococcus faecium in saline solutions in pH range from 5.5 to 6.8, at water activity 0.99. The data were predicted for the pressure range of 450 MPa to 550 MPa, at the initial model suspension temperature 6-7 deg C prior to pressurising. The results indicate that E. faecium is a highly resistant organism under physiological pH values. With decreasing the substrate pH, the tolerance to the inactivation effects of high pressure decreased. The high-pressure inactivation proved ineffective for the above organism in the range of physiological pH values. The values for high-pressure inactivation model were specified and the calculated parameters of high-pressure inactivation were compared to the experimental data for the working suspensions of E. faecium in cow and human milks. As to cow milk, the predicted data showed some deviation from the model experimental results, while with human milk the model failed completely. High-pressure inactivation of E. faecium in human milk proved to be significantly more effective than that predicted by a model based on the saline solution.

Staphylococcus epidermidis, commonly found on the human skin, may contaminate human milk. High-pressure pasteurisation of human milk under normal temperature preserves the majority of its protective agents. The objective of this study was to acquire baroinactivation data and develop a model for model solutions of pH = 6.4 to 7.2 and water activity aw = 0.99 in which baroinactivation of Staphylococcus epidermidis takes place. Decontamination data manifested exponential kinetics and the resulting model was described by the following equations: Dp = Dp, ref x 10 (Pref - P)/Z, Z = -123.90 pH2 + 1635.54 pH - 5210.49; Dp, ref = -8.89 pH2 + 121.02 pH - 408.34. The developed model was verified using pasteurised human milk and UHT-treated skimmed cow milk. The agreement between the experimental data and model-based prediction was very good for human milk. The application of a pressure of 350 MPa for 10 min decreased the concentration of the working suspension of S. epidermidis in the model substrate by a minimum of five orders of magnitude.

The influence of the high pressure treatment of 300 MPa/200 s, possibly combined with antimicrobial additives, on the quality of liquid whole egg (LWE) in terms of rheology, foaming and emulsification properties, colour changes, and microbial quality was studied and compared to the characteristics of commercially available pasteurised liquid whole egg (65 deg C, 3 min). It can be concluded that the above-mentioned regime of LWE pressurisation did not deteriorate the functional properties of eggs and can be used, after the addition of some antimicrobial agents, as a preservation technique keeping the organoleptic and nutritive qualities of eggs.