Survival of Trichinella spiralis in cured meat products

Processing of meat is one possible approach to control meat-borne parasites. Processing methods such as freezing, cooking and irradiation are recommended for the control of Trichinella in pork, horse or game meat if specific technical conditions are fulfilled. Curing is a widely used preservation process influencing product characteristics such as shelf life, food safety, and taste. As curing methods are characterized by high parameter variability and predictions about inactivation of parasitic stages in raw meat products are difficult, curing and smoking are not recommended for Trichinella control. The objective of this study was to investigate the survival of T. spiralis in cured raw sausages taking into account water activity (a_w-value), pH value, temperature, and time. For this purpose, four different types of sausage (Knackwurst, vacuum packed Knackwurst, short ripened salami, long ripened salami) were produced using T. spiralis infested batter. After production, the sausages were stored at product specific conditions for up to 35 days. During storage, pH value and a_w-value of the sausages were monitored over time. Further, sausages of each type were digested using the magnetic stirrer method and the viability of the isolated larvae was assessed using a previously published larval motility test as a proxy for viability and infectivity of Trichinella larvae. In this context, we also introduce a three-level rated infectivity score (RIS) with a clear categorization scheme allowing the assessment of the infectivity of larvae. Based on the RIS, larvae isolated from the salamis were regarded as potentially infective until day 2 (short ripened salami) or day 3 (long ripened salami) post ripening, whereas in Knackwurst, potentially infective larvae were still found by day 8 post ripening. In contrast potentially infective larvae were detected in vacuum-packed Knackwurst until day 24 post ripening. Finally, using the RIS approach, data from previously published studies were collected and subjected to a correlation analysis to identify matrix factors linked to short Trichinella inactivation times.