Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, via Brecce Bianche, Ancona, Italy.
Department of Agricultural, Forest, and Food Science, University of Turin, Largo Paolo Braccini 2, Grugliasco, Torino, Italy.
Food Res Int. 2022 Apr;154:110990. doi: 10.1016/j.foodres.2022.110990. Epub 2022 Feb 12.
The use of fish flesh to produce fermented sausages is uncommon, especially in European countries where fermented sausages are mainly obtained using mammalian meat. In the present study, the microbiota naturally occurring in novel fermented fish sausages, handcrafted using marine fish species caught in the Mediterranean Sea, was studied. To this end, fish sausages were subjected to physico-chemical analyses (including histamine quantification). Microbiological traits of sausages were studied via viable counting and metataxonomic analysis. Sausages were also subjected to the detection of genes encoding histidine decarboxylase of both Gram-positive (hdcA) and -negative (hdc) bacteria. The results of histamine quantification showed different contents among fish sausage samples. Moreover, the presence of the hdcA gene was below the detection limit in all the samples, whereas the hdc gene was detected only in samples from batch 2, characterized by high levels of Enterobacteriaceae. In the analysed samples, viable lactic acid bacteria, coagulase-negative staphylococci, and eumycetes were detected. Bacterial composition displayed the highest frequency of Latilactobacillus sakei, whereas eumycetic composition displayed the highest frequency of Kurtzmaniella zeylanoides. In order to select potential adjunct cultures for product improvement, 60 lactic acid bacteria (22 isolates of L. sakei and 38 of Latilactobacillus curvatus) were isolated from sausage samples and characterized for: i) the presence of the hdcA gene; ii) the production of exopolysaccharides (EPS); iii) the presence of genes involved in the production of EPS; iv) the production of bacteriocins against Listeria innocua. None of the isolates tested positive for the presence of the hdcA gene. Moreover, 39 out of 60 isolates showed the formation of mucoid colonies, thus attesting the production of EPS. Interestingly, 56 out of 60 isolates were positive for the gene epsD/E, whereas 37 out of 60 isolates were positive for the gene epsA, all these genes encoding the production of heteropolysaccharides. Of note, the EPS production capability and the absence of hdcA gene could represent a starting point for future selection of the isolates as autochthonous adjunct cultures to improve texture, sensory traits and safety of the fermented fish sausages under study. None of the L. sakei or L. curvatus isolates exerted a bactericidal effect against L. innocua.
利用鱼肉来生产发酵香肠并不常见，特别是在欧洲国家，发酵香肠主要使用哺乳动物肉制成。在本研究中，研究了使用在地中海捕获的海洋鱼类手工制作的新型发酵鱼香肠中自然存在的微生物群。为此，对鱼香肠进行了理化分析（包括组氨酸定量）。通过活菌计数和代谢分类分析研究了香肠的微生物特性。还检测了编码革兰氏阳性（hdcA）和阴性（hdc）细菌组氨酸脱羧酶的基因。组胺定量的结果表明，鱼香肠样品之间的含量不同。此外，所有样品中hdcA 基因的存在都低于检测限，而 hdc 基因仅在批次 2 的样品中检测到，该批次的肠杆菌科含量较高。在所分析的样品中，检测到了活菌数乳酸杆菌、凝固酶阴性葡萄球菌和真核生物。细菌组成显示出最高频率的拉氏乳杆菌，而真核生物组成显示出最高频率的库尔特兹曼氏酵母。为了选择用于产品改进的潜在辅助培养物，从香肠样品中分离了 60 株乳酸菌（22 株拉氏乳杆菌和 38 株卷曲乳杆菌），并对其进行了以下特征分析：i）hdcA 基因的存在；ii）胞外多糖（EPS）的产生；iii）参与 EPS 生产的基因的存在；iv）对无毒李斯特菌的抑菌素生产。没有分离株检测到 hdcA 基因的存在。此外，60 个分离株中有 39 个表现出粘液状菌落的形成，从而证明了 EPS 的产生。有趣的是，60 个分离株中有 56 个为 epsD/E 基因阳性，60 个分离株中有 37 个为 epsA 基因阳性，所有这些基因都编码异多糖的产生。值得注意的是，EPS 产生能力和 hdcA 基因的缺失可能成为未来选择作为发酵鱼香肠天然辅助培养物的起点，以改善研究中发酵鱼香肠的质地、感官特性和安全性。没有一株拉氏乳杆菌或卷曲乳杆菌对无毒李斯特菌表现出杀菌作用。
