Comparative Study of ɛ-Polylysine or Nisin Inhibition Kinetics of Lactococcus lactis and Spoilage Microorganisms in Fresh Flammulina velutipes Fruiting Bodies

Abstract

Flammulina velutipes is one of the most important edible mushrooms, which quickly decays with a short shelf life. However, little is known about the effect of ɛ-polylysine (ɛ-PL) or nisin on the survival of Lactococcus lactis (L. lactis) during the storage at constant temperatures. The objective of this study was to investigate the effect of ɛ-PL or nisin on the growth of L. lactis and background (BK) microorganisms in fresh Flammulina velutipes fruiting bodies (FVFB) and develop mathematical models to predict their growth behavior. The effect of ɛ-PL (0.15 and 0.30 g/kg) or nisin (0.10 and 0.20 g/kg) on the growth of L. lactis and BK microorganisms in FVFB was analyzed at 4, 16, and 20°C. The lag phase of L. lactis was extended, and the specific growth rate was decreased by increasing concentrations of ɛ-PL or nisin and lowering the temperature. The results showed that ɛ-PL or nisin could control the growth of L. lactis in FVFB. However, the growth of BK microorganisms was not affected by ɛ-PL or nisin. The growth of L. lactis and BK microorganisms could be successfully described by the reparameterized Gompertz and no lag phase models, respectively. Additionally, ɛ-PL or nisin could maintain the quality of FVFB by preventing weight loss, color-changing, and decreasing soluble solid content in FVFB at 4°C. These results suggest that ɛ-PL or nisin in combination with low temperature may inhibit the growth of L. lactis in FVFB and prevent the decrease in the quality of FVFB.

Recent advances in quality preservation of postharvest golden needle mushroom (Flammulina velutiper)

“…Additionally, ε‐PL or nisin could maintain the quality of F. velutiper by preventing weight loss and color change, and reducing the soluble solids content at 4 °C (Table 2). 28 …”

“…Freshly picked F. velutiper contains up to 90–95% water 22 . Flammulina velutiper lacks the protective tissue on its surface and has a high transpiration rate, providing a favorable environment for the growth of microorganisms, 28 which can damage fresh F. velutiper by destroying the intracellular matrix and reducing the central vesicles, leading to a partial collapse of the cell structure 22,28,29 . Water loss of F. velutiper is also related to its specific surface area and the temperature and humidity of the storage environment, affecting its freshness and flavor 30 .…”

“…22 Flammulina velutiper lacks the protective tissue on its surface and has a high transpiration rate, providing a favorable environment for the growth of microorganisms, 28 which can damage fresh F. velutiper by destroying the intracellular matrix and reducing the central vesicles, leading to a partial collapse of the cell structure. 22,28,29 Water loss of F. velutiper is also related to its specific surface area and the temperature and humidity of the storage environment, affecting its freshness and flavor. 30 During storage, the quality of F. velutiper gradually decreases, accounting for 4.1% weight loss due to the loss of water during respiration, causing significant tissue shrinkage, 25 and a reduced commercial value with a quality loss above 5%.…”