Search

Copyright of China Condiment is the property of China Condiment and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polylactic acid (PLA) plastic waste has significant potential for methane production in anaerobic digestion, but its slow degradation rate hinders efficient fermentation. Pre-treatment of PLA plastic waste can enhance anaerobic fermentation efficiency, promoting resource utilization. PLA plastic cup sample was pre-treated by irradiation with 60Co-γ ray to study the changes of PLA molecular structure and soluble substance content under the irradiation with absorbed doses of 0, 20, 40 and 60 kGy. And the effect of ionizing irradiation on the anaerobic fermentation performance of PLA samples was investigated by the proteolytic enzyme enzymatic digestion experiments and the changes of anaerobic fermentation gas production. The results showed that the lactic acid content in the supernatant of PLA samples irradiated by 60Co-γ ray increased slightly with the increase of absorbed dose in the range of 0~60 kGy. The molecular structure of the samples did not change significantly, but their crystallinity and molecular weight decreased significantly. The lactate concentration and mass loss of the irradiated samples increased significantly during the enzymatic digestion process compared to the unirradiated samples. Specifically, The PLA sample with an absorbed dose of 60 kGy reached its maximum lactate concentration on the 4th day, which was 17.4% higher than that of non irradiated samples. The mass loss increased over time, which was 68.7% higher than that of non irradiated samples on the 7th day. The irradiated samples took significantly less time to reach gas production equilibrium in anaerobic fermentation, and the total gas production increased by 3.0%. The results indicate that γ-ray irradiation has potential application as a pretreatment technology for PLA plastics, and this study can provide a theoretical reference for the resourceful disposal of PLA plastics.

This study was conducted to investigate the effects of 60Co γ-radiation and electron-beam irradiation on the color of dried chili products through comparative analysis of the color difference, non-enzymatic browning index, color value, and R/Y value. The experiment included different doses (0, 3, 7, and 16 kGy) and different storage times (0 and 30 d). The results revealed that when no storage time elapsed (0 d), the a* value decreased by 13% in the dried chili samples treated with a 60Co γ-ray dose of 16 kGy; the non-enzymatic browning value increased by 12%, and the R/Y value decreased by 16%. Moreover, the a*, b*, and L* values of the samples treated with electron beams at 7 kGy were significantly lower than those treated with 60Co γ-rays. Furthermore, increasing the dosage of either the 60Co γ-rays or electron beam resulted in large color differences and small non-enzymatic browning values for the chili powder samples stored for 0 d. Notably, at a dose of 16 kGy, ΔE* of the chili powder treated with 60Co γ-rays was higher than that of the powder subjected to electron-beam treatment. By contrast, the non-enzymatic browning value of the 60Co γ-ray-treated sample was significantly lower than that of the electron-beam-treated sample. After 30 d of storage, ΔE* of the chili powder samples treated with a 7 kGy dose of either 60Co γ-rays or electron beam was significantly higher than that recorded for the other dosage groups. Further, ΔE* was the highest for the samples treated with a 7 kGy dose of 60Co γ-rays. In conclusion, the impact of electron beams on the color of the dried chili products was less than that of the 60Co γ-rays. Furthermore, the effect of irradiation on the color of the chili powder was stronger than that on the color of the dried chilis.

Cordycepin is a major bioactive compound found in Cordyceps sinensis that exhibits a broad spectrum of biological activities. Here a Paecilomyces hepiali OR-1 strain was initially isolated from plateau soil for the bioproduction of cordycepin. Subsequently, strain modification including 60Co γ-ray and ultraviolet irradiation were employed to increase the cordycepin titer, resulted in a high-yield mutant strain P. hepiali ZJB18001 with the cordycepin content of 0.61 mg/gDCW, showing a 2.3-fold to that from the wild strain (0.26 mg/gDCW). Furthermore, medium screening based on Box-Behnken design and the response surface methodology facilitated the enhancement of cordycepin yield to the value of 0.96 mg/gDCW at 25 °C for 5 days in submerged cultivation with an optimized medium composition. The high cordycepin yield, rapid growth rate and stable genetic characteristics of P. hepiali ZJB18001 are beneficial in terms of costs and time for the industrialization of cordycepin production. [ABSTRACT FROM AUTHOR]