Ethanol production by repeated batch and continuous fermentations of blackstrap molasses using immobilized yeast cells on thin-shell silk cocoons

A thin-shell silk cocoon (TSC), a residual from the silk industry, is used as a support material for the immobilization of Saccharomyces cerevisiae M30 in ethanol fermentation because of its properties such as high mechanical strength, light weight, biocompatibility and high surface area. In batch fermentation with blackstrap molasses as the main fermentation substrate, an optimal ethanol concentration of 98.6 g/L was obtained using a TSC-immobilized cell system at an initial reducing sugar concentration of 240 g/L. The ethanol concentration produced by the immobilized cells was 11.5% higher than that produced by the free cells. Ethanol production in five-cycle repeated batch fermentation demonstrated the enhanced stability of the immobilized yeast cells. Under continuous fermentation in a packed-bed reactor, a maximum ethanol productivity of 19.0 g/(L h) with an ethanol concentration of 52.8 g/L was observed at a 0.36 h⁻¹ dilution rate.     

The effect of myofibrillar/sarcoplasmic protein ratios on the properties of round scad muscle protein based film

The effect of the ratios of myofibrillar protein (MP) to sarcoplasmic protein (SP) from round scad (Decapterus maruadsi) muscle on the properties of the resulting films was investigated. Tensile strength (TS) of films decreased with increasing SP content (p < 0.05). Films prepared from MP/SP ratio of 10:0 (w/w) exhibited the highest TS (p < 0.05). Elongation at break (EAB) of films prepared with SP content greater than 30% had the decreased EAB (p < 0.05). Water vapor permeability (WVP) of films increased when SP content increased up to 20% and decreased with increasing SP content up to 30% (p < 0.05). Solubility of films decreased but protein solubility increased with increasing SP contents (p < 0.05). The a*-value and ΔE* of film increased with increasing SP content. Films with all MP/SP ratios exhibited the negligible transmission to the light in UV range. Therefore, it is suggested that the type and ratio of proteins in fish muscle, both SP and MP, influenced the properties of film from round scad muscle. Results suggested that the removal of sarcoplasmic protein from fish muscle by thorough washing was an effective means to improve the mechanical properties as well as color of the fish muscle protein-based film.     

Properties of protein-based film from round scad (Decapterus maruadsi) muscle as influenced by fish quality

The properties of film prepared from round scad (Decapterus maruadsi) stored in ice for different times were investigated. Degradation of myosin heavy chain (MHC) was more pronounced with the coincidental increase in total volatile base and trimethylamine contents as the storage time increased (P<0.05). Regardless of storage time, no changes in tensile strength (TS) and elongation at break (EAB) of resulting films prepared from unwashed mince were observed (P>0.05). For the films prepared from washed mince, TS decreased, whereas EAB increased when the storage time of fish increased (P<0.05). However, films prepared from washed mince showed the greater mechanical properties with the lower film solubility and protein solubility than did those from mince (P<0.05). Generally, films prepared from fish stored in ice for a longer time became less transparent, darker and more yellowish. The electrophoretic study revealed that similar protein patterns were observed between films, irrespective of storage time of fish and washing. Therefore, the quality of fish did not show the marked impact on the mechanical property of the resulting films, while washing likely affected the film forming ability.     

Round scad protein-based film: Storage stability and its effectiveness for shelf-life extension of dried fish powder

Storage stability of different round scad (Decapterus maruadsi) protein-based films including (1) control film without palm oil and chitosan, (2) film with 25% palm oil (glycerol substitution) and (3) film with 25% palm oil and 40% chitosan (protein substitution) was investigated. During storage (54% relative humidity, 28-30 °C), tensile strength (TS) of the films without and with 25% palm oil or 25% palm oil in combination with 40% chitosan increased continuously, while elongation at break (EAB) decreased markedly when storage time increased up to 8 weeks (p < 0.05). No changes in water barrier properties were observed throughout the storage time up to 4 weeks (p > 0.05). Film solubility slightly increased but protein solubility decreased continuously during storage (p < 0.05). All films became darker and more yellowish as storage time increased. When round scad muscle protein-based films were used to cover dried fish powder, the samples covered with the film containing 25% palm oil and 40% chitosan showed lower thiobarbituric acid reactive substances (TBARS) and yellowness than other samples during the extended storage up to 21 days (p < 0.05). No differences in moisture content of all samples covered with different films were noticeable (p > 0.05), except those covered with HDPE, which had the lowest moisture content. Thus, round scad protein-based film incorporated with palm oil and chitosan could be a promising packaging material to prevent lipid oxidation in oil enriched foods.     

A Modified-Simplified MPPT Technique for Three-Phase Single-State Grid-Connected PV Systems

Nowadays, the single state inverter for the grid-connected photovoltaic (PV) systems is becoming more and more popular as they can reduce circuit complexity resulting in less power losses of the inverter. This paper focuses on the use of model predictive control (MPC) to control a 3-phase and 2-level single-state grid-connected inverter in order to regulate the PV maximum power point (MPP). The algorithm of MPC scheme was done to measure the simultaneous current signal including predicting the next sampling current flow. The reference current (I_d*) was used to control the distribution of electrical power from the solar cell to the grid. To be able to control the maximum power point tracking (MPPT) when the sunlight suddenly changes, so that a developing MPPT based on estimation current perturbation and observation (ECP&O-MPPT) technique was used to control the reference current. This concept was experimented by using MATLAB/Simulink software package. The proposed technique was tested and compared with the old technique. The simulation results showed that the developed MPPT technique can track the MPP faster when the light changes rapidly under 1,000 W/m², 25°C standard climatic conditions. The MPPT time was 0.015 s. The total harmonic distortion (THD) was 2.17% and the power factor was 1.     

Properties of a protein-based film from round scad (Decapterus maruadsi) as affected by muscle types and washing

The effects of muscle types and washing on the properties of a protein-based film from round scad (Decapterus maruadsi) mince were investigated. Washing resulted in an increase in the protein content with a coincidental decrease in the fat content of mince, especially from whole muscle and dark muscle. Among all types of muscle (ordinary, dark and whole muscle), the ordinary muscle rendered the film with the highest tensile strength (TS) (p < 0.05). TS of films from washed mince was greater than that of films prepared from unwashed mince for the same type of muscle used (p < 0.05). Nevertheless, the water vapour permeability (WVP) of films from unwashed mince was higher than that of films prepared from washed mince (p < 0.05). Films from washed mince had higher solubility but lower protein solubility than those from unwashed mince (p < 0.05). Regardless of washing, films from ordinary muscle showed the highest L^∗-value (p < 0.05). However, films prepared from dark muscle were more yellowish than those prepared from other muscles, as evidenced by the greater b^∗-value. Films from round scad mince and washed mince had excellent barrier properties to UV light at the wavelength of 200–280 nm. Generally, films from round scad mince had a lower preventive effect on visible light transmission than had those from unwashed mince. Among films from all muscles, those prepared from dark muscle exhibited the highest barrier to visible light transmission (p < 0.05). Therefore, the properties of films from round scad meat were governed by muscle type as well as by washing.     

Protein Modification via Nitrile Oxide−Dehydroalanine Cycloaddition: Formation of Isoxazoline Ring on the Protein Backbone

Here we describe a novel catalyst-free 1,3-dipolar cycloaddition bioconjugation approach for chemical modification of proteins. The dehydroalanine (Dha)-containing protein reacts with nitrile oxides generated in situ through 1,3-dipolar cycloaddition in fully aqueous-buffered systems. This leads to the formation of a new isoxazoline ring at a pre-defined site (Dha) of the protein. Furthermore, the 1-pyrene isoxazoline-installed annexin V acts as a fluorescent probe, which successfully labels the outer cellular membranes of human cholangiocarcinoma (HuCCA-1) cells for detection of apoptosis.