Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, 310018, PR China.
Graduate School of Agricultural Science, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo, 060-8589, Japan.
Food Microbiol. 2022 Dec;108:104104. doi: 10.1016/j.fm.2022.104104. Epub 2022 Aug 9.
In this study, we found the inhibitory effect of d-Tryptophan (d-Trp) on the bacterial growth and spoilage potential of P. fluorescens and S. baltica. The effectiveness of d-Trp in bacterial growth inhibition was highly dependent on environmental NaCl concentrations. The growth/no growth models were developed to clarify the relationship between salt and d-Trp concentrations for optimal growth-inhibitory effect. It showed that higher levels of NaCl (>3.5%) with d-Trp (>15 mM) are required for growth inhibition. The d-Trp treatment combined with NaCl also retarded the psychrotrophic growth and reduced the respiratory active bacteria at low temperature, indicating that the inhibitory effect of d-Trp might be associated with the tolerance to osmotic and cold stress. Furthermore, the treatment d-Trp combined NaCl (artificial seawater) on salmon fillets was investigated. During refrigerated storage, the d-Trp treated salmon fillet either inoculated with S. baltica or P. fluorescen maintained remained a relatively low level of total volatile basic nitrogen (TVBN) (below 30 mg N/100 g during 8-days storage) and delayed increase of low total viable bacteria counts (TVC) with a longer lag phase of 2 days.
在这项研究中，我们发现 D-色氨酸（d-Trp）对荧光假单胞菌和嗜冷海洋小球菌的生长和腐败潜力有抑制作用。d-Trp 对细菌生长的抑制效果高度依赖于环境 NaCl 浓度。建立了生长/非生长模型，以阐明盐和 d-Trp 浓度之间的关系，以达到最佳的生长抑制效果。结果表明，需要更高水平的 NaCl（>3.5%）和 d-Trp（>15 mM）才能抑制生长。d-Trp 处理与 NaCl 联合处理还能延缓低温下的嗜冷生长，并减少呼吸活性细菌，表明 d-Trp 的抑制作用可能与对渗透压和低温胁迫的耐受有关。此外，还研究了 d-Trp 联合 NaCl（人工海水）处理三文鱼鱼片。在冷藏过程中，无论是接种嗜冷海洋小球菌还是荧光假单胞菌的经 d-Trp 处理的三文鱼鱼片，总挥发性碱性氮（TVBN）含量均保持在较低水平（在 8 天的储存期内低于 30mgN/100g），并且低总活菌数（TVC）的增加也被延迟，滞后期延长了 2 天。
