低水分食品(LMF)中的油在热加工期间对细菌具有保护作用。然而,这种保护作用加强的情况仍不清楚。本研究旨在了解油暴露于细菌细胞的哪一步(接种,等温失活,或回收和枚举步骤)中的LMF可以增强它们的耐热性。选择花生粉(PF)和脱脂PF(DPF)作为富油无油LMF模型。肠炎沙门氏菌噬菌体30型(S.将肠炎)接种到代表不同油暴露阶段的四个指定PF组中。对其进行等温处理以获得耐热性参数。在恒定的水分含量下(aw,25°C=0.32±0.02)和受控aw,85°C(0.32±0.02),肠炎链球菌在富油样品组中表现出显著高的(p<0.05)D值。例如,PF-DPF和DPF-PF组中肠炎沙门氏菌的耐热性值分别为D80°C,分别为138.22±7.45min和101.89±7.82min;然而,DPF-DPF组的D80℃为34.54±2.07min。热处理后的油添加也有助于计数中受损的细菌恢复。例如,D80°C,D85°C,DFF-DPF油组的D90°C值分别为36.86±2.30,20.65±1.23和7.91±0.52min,分别,分别在34.54±2.07、17.87±0.78和7.10±0.52min时高于DPF-DPF组。我们证实,在所有三个阶段中,油保护了PF中的肠炎S.热处理,和回收平板中的细菌细胞。
The oil in low-moisture foods (LMFs) shows protective effects on bacteria during thermal processing. However, the circumstances under which this protective effect strengthens remain unclear. This study aimed to understand which step of the oil exposure to bacterial cells (inoculation, isothermal inactivation, or recovery and enumeration step) in LMFs can enhance their heat resistance. Peanut flour (PF) and defatted PF (DPF) were selected as the oil-rich and oil-free LMF models. Salmonella enterica Enteritidis Phage Type 30 (S. Enteritidis) was inoculated into four designated PF groups representing different oil exposure stages. It was isothermally treated to obtain heat resistance parameters. At a constant moisture content (aw,25°C = 0.32 ± 0.02) and controlled aw,85°C (0.32 ± 0.02), S. Enteritidis exhibited significantly high (p < 0.05) D values in oil-rich sample groups. For instance, the heat resistance values of S. Enteritidis in the PF-DPF and DPF-PF groups were D80°C of 138.22 ± 7.45 min and 101.89 ± 7.82 min; however, the D80°C in the DPF-DPF group was 34.54 ± 2.07 min. The oil addition after the thermal treatment also helped injured bacterial recovery in the enumeration. For instance, the D80°C, D85°C, and D90°C values in the DFF-DPF oil groups were 36.86 ± 2.30, 20.65 ± 1.23, and 7.91 ± 0.52 min, respectively, which were higher than those in the DPF-DPF group at 34.54 ± 2.07, 17.87 ± 0.78, and 7.10 ± 0.52 min. We confirmed that the oil protected S. Enteritidis in PF in all three stages: desiccation process, heat treatment, and recovery of bacterial cells in plates.