Delgado Josué, Rondán Juan J, Núñez Félix, Rodríguez Alicia
Food Hygiene and Safety, Meat and Meat Products Research Institute, Faculty of Veterinary Science, University of Extremadura, Cáceres, Spain.
Food Quality and Microbiology, University Institute for the Research in Agrifood Resources-INURA, University of Extremadura, Badajoz, Spain.
Int J Food Microbiol. 2021 Feb 2;339:109016. doi: 10.1016/j.ijfoodmicro.2020.109016. Epub 2020 Dec 8.
Dry-fermented sausages are prone to be colonised by Penicillium nordicum, which is one of the main ochratoxin A (OTA)-producing species. Its ability to produce this mycotoxin on dry-fermented sausages has been reported. However, the influence of the conditions of a traditional processing of a Spanish dry-fermented sausage and the intrinsic physicochemical parameters of this product such as water activity (a) and pH on OTA production has not been studied yet. Thus, the aim of this study was to evaluate the influence of traditional processing (interaction of relative humidity (RH) x temperature x ripening days) on the evolution of pH and a during maturation of dry-fermented sausage "salchichón" and its relationship with OTA synthesis by P. nordicum. The expression of otapks and otanps genes, both involved in the biosynthesis of the mycotoxin, was also assessed. For this, 27 raw sausages were inoculated with P. nordicum and ripened for 26 days in a drying chamber (3 days at 5 °C and 84% RH, 17 days at 12 °C and 84% RH, and 6 days at 12 °C and 80% RH). From results, although it seems that the pH slightly influenced on OTA biosynthesis, the a had a great impact on this mycotoxin production. In fact, the two highest OTA concentrations found coincided with a dramatic rise of the a value (0.92 a) by day 18 of incubation when the RH of the drying chamber was still 84% and at the end of the incubation time when the a decreased noticeably (0.87 a). The expression of the otapks and otanps genes correlated with the OTA produced by P. nordicum. Results from this work confirm that the traditional processing of Spanish dry-fermented sausages favours itself OTA synthesis by P. nordicum. Our findings may help in informed decision-making in relation to RH/temperature of drying chambers and shortening of the ripening process. This may be then effectively incorporated into the hygienic production system in the framework of HACCP together with other measures including the use of Penicillium nalgiovense as protective culture or the monitoring of otapks gene expression, and a during the processing of dry-fermented sausages. All these strategies together may put ochratoxigenic Penicillia at a disadvantage and minimise OTA contamination risks in dry-fermented sausages.
干发酵香肠容易被北欧青霉定殖，北欧青霉是产生赭曲霉毒素A（OTA）的主要菌种之一。已有报道称其在干发酵香肠上产生这种霉菌毒素的能力。然而，西班牙干发酵香肠传统加工条件以及该产品的内在理化参数（如水活性（a）和pH值）对OTA产生的影响尚未得到研究。因此，本研究的目的是评估传统加工（相对湿度（RH）×温度×成熟天数的相互作用）对干发酵香肠“salchichón”成熟过程中pH值和水活性（a）变化的影响，以及其与北欧青霉合成OTA的关系。还评估了参与霉菌毒素生物合成的otapks和otanps基因的表达。为此，27根生香肠接种了北欧青霉，并在干燥室中成熟26天（5℃和84%RH下3天，12℃和84%RH下17天，12℃和80%RH下6天）。从结果来看，虽然pH值似乎对OTA生物合成有轻微影响，但水活性（a）对这种霉菌毒素的产生有很大影响。事实上，发现的两个最高OTA浓度分别与培养第18天a值急剧上升（0.92 a）时相吻合，此时干燥室的RH仍为84%，以及在培养结束时a值显著下降（0.87 a）时。otapks和otanps基因的表达与北欧青霉产生的OTA相关。这项工作的结果证实，西班牙干发酵香肠的传统加工有利于北欧青霉自身合成OTA。我们的研究结果可能有助于在干燥室的RH/温度以及缩短成熟过程方面做出明智的决策。然后，这可以与其他措施（包括使用纳吉奥青霉作为保护培养物或监测otapks基因表达以及干发酵香肠加工过程中的水活性（a））一起有效地纳入HACCP框架下的卫生生产系统。所有这些策略共同作用可能会使产赭曲霉毒素的青霉菌处于劣势，并将干发酵香肠中OTA污染风险降至最低。
