カゼイン凝集クラスターの構造的特性とその物質包含系としての役割に関する研究

兵庫県立大学大学院201

カゼイン凝集クラスターの構造的特性とその物質包含系としての役割に関する研究

兵庫県立大学大学院201

Altering textural properties of fermented milk by using surface-engineered Lactococcus lactis

Lactic acid bacteria are widely used for the fermentation of dairy products. While bacterial acidification rates, proteolytic activity and the production of exopolysaccharides are known to influence textural properties of fermented milk products, little is known about the role of the microbial surface on microbe-matrix interactions in dairy products. To investigate how alterations of the bacterial cell surface affect fermented milk properties, 25 isogenic Lactococcus lactis strains that differed with respect to surface charge, hydrophobicity, cell chaining, cell-clumping, attachment to milk proteins, pili expression and EPS production were used to produce fermented milk. We show that overexpression of pili increases surface hydrophobicity of various strains from 3-19% to 94-99%. A profound effect of different cell surface properties was an altered spatial distribution of the cells in the fermented product. Aggregated cells tightly fill the cavities of the protein matrix, while chaining cells seem to be localized randomly. A positive correlation was found between pili overexpression and viscosity and gel hardness of fermented milk. Gel hardness also positively correlated with clumping of cells in the fermented milk. Viscosity of fermented milk was also higher when it was produced with cells with a chaining phenotype or with cells that overexpress exopolysaccharides. Our results show that alteration of cell surface morphology affects textural parameters of fermented milk and cell localization in the product. This is indicative of a cell surface-dependent potential of bacterial cells as structure elements in fermented foods

Agro-industrial Waste Upgrading via Torrefaction Process – A Case Study on Sugarcane Bagasse and Palm Kernel Shell in Thailand

In this research, the upgrading of agro-industrial wastes was investigated by using the torrefaction pretreatment technique. Two types of biomass waste, including sugarcane bagasse (SBG) and palm kernel shell (PKS), were used as raw materials. The operating conditions, i.e., torrefaction temperature and residence time, are between 225-300oC and 30-60 minutes. The findings show that, in terms of mass yield and calorific value of the solid product, the torrefaction temperature is a more sensitive parameter than the residence time. By increasing the torrefaction temperature from 225 to 300oC, the mass yields are dropped in the range of 28.79-31.57 wt.% and 28.00-29.88 wt.%, while the effect of holding time exhibits the mass yield decreasing only 3.12-5.90 wt.% and 1.53-3.41 wt.%, for SBG and PKS torrefaction, respectively. In terms of calorific value, higher heating values increase as torrefaction severity increases, varying in the range of 0.29-2.84 MJ/kg, with torrefaction temperature as the dominant factor. Regarding the calorific value, energy yield, energy gain, and energy-mass co-benefit index, the optimal operating conditions for SBG and PKS torrefactions are the same condition as 275oC for 90 minutes. SBG and PKS bio-coals obtained from torrefaction are promising solid fuels with high calorific value (about 23 MJ/kg), with an energy yield of 73.93-77.41%, relative to coal that could be further utilized for co-firing in thermal power plants

Agro-Industrial Waste Upgrading via Torrefaction Process – A Case Study on Sugarcane Bagasse and Palm Kernel Shell in Thailand

In this research, the upgrading of agro-industrial wastes was investigated by using the torrefaction pretreatment technique. Two types of biomass waste, including sugarcane bagasse (SBG) and palm kernel shell (PKS), were used as raw materials. The operating conditions, i.e., torrefaction temperature and residence time, are between 225–300 °C and 30–90 minutes. The findings show that, in terms of mass yield and calorific value of the solid product, the torrefaction temperature is a more sensitive parameter than the residence time. By increasing the torrefaction temperature from 225 to 300 °C, the mass yields are dropped in the range of 28.79–31.57 wt.% and 28.00–29.88 wt.%, while the effect of holding time exhibits the mass yield decreasing only 3.12–5.90 wt.% and 1.53–3.41 wt.%, for SBG and PKS torrefaction, respectively. In terms of calorific value, higher heating values increase as torrefaction severity increases, varying in the range of 0.29–2.84 MJ/kg, with torrefaction temperature as the dominant factor. Regarding the calorific value, energy yield, energy gain, and energy-mass co-benefit index, the optimal operating conditions for SBG and PKS torrefactions are the same condition as 275 °C for 90 minutes. SBG and PKS bio-coals obtained from torrefaction are promising solid fuels with high calorific value (about 23 MJ/kg), with an energy yield of 73.93–77.41%, relative to coal that could be further utilized for co-firing in thermal power plants

Enhanced Energy Recovery from Food Waste by Co-Production of Bioethanol and Biomethane Process

The primary objective of this research is to study ways to increase the potential of energy production from food waste by co-production of bioethanol and biomethane. In the first step, the food waste was hydrolysed with an enzyme at different concentrations. By increasing the concentration of enzyme, the amount of reducing sugar produced increased, reaching a maximum amount of 0.49 g/g food waste. After 120 h of fermentation with Saccharomyces cerevisiae, nearly all reducing sugars in the hydrolysate were converted to ethanol, yielding 0.43–0.50 g ethanol/g reducing sugar, or 84.3–99.6% of theoretical yield. The solid residue from fermentation was subsequently subjected to anaerobic digestion, allowing the production of biomethane, which reached a maximum yield of 264.53 ± 2.3 mL/g VS. This results in a gross energy output of 9.57 GJ, which is considered a nearly 58% increase in total energy obtained, compared to ethanol production alone. This study shows that food waste is a raw material with high energy production potential that could be further developed into a promising energy source. Not only does this benefit energy production, but it also lowers the cost of food waste disposal, reduces greenhouse gas emissions, and is a sustainable energy production approach

Effect of mixed light emitting diode spectrum on antioxidants content and antioxidant activity of red lettuce grown in a closed soilless system

Abstract Background Light spectra have been demonstrated to result in different levels of comfort or stress, which affect plant growth and the availability of health-promoting compounds in ways that sometimes contradict one another. To determine the optimal light conditions, it is necessary to weigh the vegetable’s mass against the amount of nutrients it contains, as vegetables tend to grow poorly in environments where nutrient synthesis is optimal. This study investigates the effects of varying light conditions on the growth of red lettuce and its occurring nutrients in terms of productivities, which were determined by multiplying the total weight of the harvested vegetables by their nutrient content, particularly phenolics. Three different light-emitting diode (LED) spectral mixes, including blue, green, and red, which were all supplemented by white, denoted as BW, GW, and RW, respectively, as well as the standard white as the control, were equipped in grow tents with soilless cultivation systems for such purposes. Results Results demonstrated that the biomass and fiber content did not differ substantially across treatments. This could be due to the use of a modest amount of broad-spectrum white LEDs, which could help retain the lettuce’s core qualities. However, the concentrations of total phenolics and antioxidant capacity in lettuce grown with the BW treatment were the highest (1.3 and 1.4-fold higher than those obtained from the control, respectively), with chlorogenic acid accumulation (8.4 ± 1.5 mg g− 1 DW) being particularly notable. Meanwhile, the study observed a high glutathione reductase (GR) activity in the plant achieved from the RW treatment, which in this study was deemed the poorest treatment in terms of phenolics accumulation. Conclusion In this study, the BW treatment provided the most efficient mixed light spectrum to stimulate phenolics productivity in red lettuce without a significant detrimental effect on other key properties