Effect of the Degassed Status on the Quality and Microbial Control of Enoki Mushrooms (Flammulina velutipes) for Export to the U.S.

Abstract

The decline in the export of Korean enoki mushrooms (Flammulina velutipes) to the United States has been linked to rising dissatisfaction among consumers and concerns over microbial safety. This is primarily due to quality deterioration during the distribution process, leading to inadequate conditions for maintaining the freshness and safety standards of the mushrooms. In this study, we investigated the effects of pressed packaging (PP) and semi-pressed packaging (SPP) on the quality, sensory evaluation, and microbial control of enoki mushrooms for export to the United States during a simulated shipping period of three weeks at 4°C and a local distribution period of one week at 10°C. Common quality degradation factors such as the browning index (BI), respiration rate, off odors, browning, cap opening, stem elongation, total aerobic count, and environmental Listeria spp. count were identified for both PP and SPP during simulated shipping. There were also significant differences between PP and SPP regarding SSC, pH, and BI. The sensory evaluation showed that browning, cap opening, and stem elongation were significantly higher in SPP than in PP, making it difficult for semi-vacuum packaging to be commercialized for three weeks at 4°C and one week at 10°C. Regarding microbial safety, PP significantly suppressed the growth of harmful microorganisms such as the total aerobic count and environmental Listeria spp. count, providing an advantage with regard to preserving the quality. In conclusion, PP was more effective than SPP in suppressing the occurrence of harmful microorganisms and improving the respiration rate, BI, browning, cap opening, stem elongation, total aerobic count, and environmental Listeria spp. count outcomes, thus helping to maintain the safety and quality of enoki mushrooms during their distribution.