The life cycle of Hyalomma scupense (Acari: Ixodidae) under laboratory conditions.

The life cycle of Hyalomma scupense on rabbit hosts was investigated under laboratory conditions. Hy. scupense exhibited one- and two-host life cycles of 163.2 and 161.4 days, respectively. The incubation of eggs required an average period of 52 days, which was the longest period among the four developmental stages. The average time for pre-feeding of larvae was 3.5 days. It took 20 days for larvae to become engorged nymphs and 52.3 days to become engorged females. The duration of the pre-feeding, feeding, pre-oviposition, and oviposition stages of female adults was 2.3, 13.5, 27.5, and 27.9 days, respectively. The average weight of engorged females was 390.0 mg (ranging from 129.3 mg to 828.6 mg), which was 28.95 times the weight of unfed females. There was a positive relationship between the weight and the number of eggs laid by engorged females (r = 0.927). The reproductive efficiency index (REI) was 8.63.

Optimizing food waste hydrothermal parameters to reduce Maillard reaction and increase volatile fatty acid production.

The occurrence of the Maillard reaction and melanoidins formation during the hydrothermal treatment of food waste can reduce the yield of volatile fatty acids (VFA); however, few studies have investigated the adverse effects of the Maillard reaction. This study identified the impact of hydrothermal treatment parameters on hydrolysis and melanoidins formation and optimized the hydrothermal treatment conditions to enhance VFA production by minimizing the impact of the Maillard reaction. A response surface methodology was employed to optimize the hydrothermal treatment parameters and VFA production was evaluated. Results showed that temperature, reaction time, and pH were significant interacting factors with respect to hydrolysis and melanoidins formation while the C/N ratio and moisture content of food waste had little impact. The optimal conditions for hydrothermal treatment (temperature of 132 °C, reaction time of 27 min, and a pH of 5.6) enhanced VFA production by 22.1%. Under optimal hydrothermal treatment conditions, a higher initial C/N ratio further increased VFA production.

Influence of melanoidins on acidogenic fermentation of food waste to produce volatility fatty acids.

Few studies on hydrothermal treatment (HT) of food waste (FW) considered the impact of melanoidins formation due to Maillard reaction on acidogenic fermentation. Here, the effects of different melanoidins doses on volatile fatty acid (VFA) production were investigated. Results showed that the solubilization and degradation of proteins can be inhibited by the presence of melanoidins. At the high-dose melanoidins, VFA production from FW was reduced by 12%. Besides, the bovine serum albumin degradation rate declined 22% with the high-dose melanoidins effectively identified their inhibition effect. However, the unaffected carbohydrates utilization led to insignificant VFA disparity at lower doses of melanoidins, because carbohydrates contributed the major VFA yield. The consumption of substrates due to melanoidins formation mainly caused VFA reduction, which contributed to 82% of substantial VFA loss. Therefore, controlling the formation of melanoidins may help the application of HT and enhance the resource recovery from FW.

Characteristics of acidogenic fermentation for volatile fatty acid production from food waste at high concentrations of NaCl.

This study explored the effects of NaCl on volatile fatty acid (VFA) production from food waste by acidogenic fermentation. The production and composition of VFAs, and the microbial community in acidogenic fermentation were investigated at four different NaCl concentrations: 10, 30, 50, and 70 g/L, and at 0 g/L (control). The highest VFA production was 0.542 g/g dry weight of food waste at 10 g/L NaCl, and about 23% lower but still high at 70 g/L NaCl. Interestingly, as NaCl concentration increased, the residence time of lactic acid in the reactor increased, and the maximum production also increased. The type of acidogenic fermentation also changed from butyric acid to propionic acid as the NaCl concentration increased. Microbial community analysis showed that a large number of propionibacteria were present at the end of fermentation, indicating their high tolerance to NaCl.