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Inactivation of Pichia membranaefaciens in Soybean Paste by Dual-Frequency and Moderate Thermosonication
Jingya Qian1, Shubei Chen1, Shuhao Huo1
1School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China.
Abstract:
Dual-frequency and moderate thermosonication (TS, 300 + 300 W, 20 + 40 kHz, 25~60 °C) was employed to inactivate Pichia membranifaciens in soybean paste. The aim was to evaluate the effect of TS on the inactivation of P. membranaefaciens and on the quality of soybean paste. The Weibull model fitted the survival data of P. membranaefaciens in thermosonicated soybean paste well and a decrease of 5 log of P. membranaefaciens in soybean paste was obtained at TS50°C, TS55°C, TS60°C, and T65°C for 15.41, 7.49, 2.27, and 18.61 min. Scanning electron microscope observation revealed TS50°C damaged the cell structure, leading to the leakage of intracellular contents. The physicochemical properties of soybean paste treated by TS were more retained than in paste treated by heat. The GC-MS analysis indicated that the flavor components had increased after TS treatment, especially at TS50°C. In conclusion, TS can inactive P. membranaefaciens in soybean paste without causing significant changes in its physicochemical and flavor qualities.
Insights
Dual-frequency thermosonication effectively inactivates Pichia membranifaciens in soybean paste. This method preserves physicochemical and flavor qualities, offering a promising alternative to traditional heat treatments.
Area of Science:
- Food Science and Technology
- Microbiology
- Biotechnology
Background:
- Soybean paste quality is often compromised by microbial contamination, necessitating effective inactivation methods.
- Traditional pasteurization methods can negatively impact the sensory and nutritional attributes of soybean paste.
- Developing novel inactivation techniques that preserve quality is crucial for the food industry.
Purpose of the Study:
- To investigate the efficacy of dual-frequency thermosonication (TS) for inactivating Pichia membranifaciens in soybean paste.
- To assess the impact of TS on the physicochemical properties and flavor profile of soybean paste.
- To compare the effects of TS with conventional heat treatment on soybean paste quality.
Main Methods:
- Dual-frequency thermosonication (300 + 300 W, 20 + 40 kHz, 25–60 °C) was applied to soybean paste inoculated with Pichia membranifaciens.
- The Weibull model was used to analyze microbial survival data.
- Scanning electron microscopy (SEM) was employed to observe cell structure changes.
- Physicochemical properties and flavor components (GC-MS) were analyzed post-treatment.
Main Results:
- Thermosonication effectively reduced Pichia membranifaciens populations, achieving a 5-log decrease under various temperature conditions.
- SEM revealed that thermosonication damaged the yeast cell structure, causing intracellular content leakage.
- Thermosonication treatment resulted in better retention of physicochemical properties compared to heat treatment.
- GC-MS analysis indicated an increase in flavor components after thermosonication, particularly at 50°C.
Conclusions:
- Dual-frequency thermosonication is an effective method for inactivating Pichia membranifaciens in soybean paste.
- TS treatment preserves the physicochemical and flavor qualities of soybean paste better than conventional heat.
- Thermosonication presents a viable alternative for microbial control in soybean paste production, enhancing product quality.
