Merialdi Giuseppe, Ramini Mattia, Parolari Giovanni, Barbuti Silvana, Frustoli Maria Angela, Taddei Roberta, Pongolini Stefano, Ardigò Paolo, Cozzolino Paolo
Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
Experimental Unit for Food Preserves Industry , Parma, Italy.
Ital J Food Saf. 2016 Apr 19;5(2):5564. doi: 10.4081/ijfs.2016.5564.
The objective of this study was to investigate growth and toxin production in the industrially manufactured Italian Parma ham. The study focuses on the Parma ham production phase identified as maximum risk to proliferation, . the transition from cold phase (salting and resting) to a phase carried out at temperature between 15 and 23°C (drying). A preliminary test was carried out in order to verify the capability of 6 strains (1 type A, 4 type B, and 1 type E strains) to grow in conditions of temperature, pH and NaCl concentration comparable to those of the beginning stage of ham drying. Five strains grew at 20°C and pH 6, four strains produced toxin when inoculated at a concentration equal to 10 cfu/mL at NaCl concentration of 4%, while when the inoculum concentration was 10 cfu/mL, NaCl concentration of 3% resulted the toxin-genesis limiting factor. An experimental contamination with a mixture of the 5 strains selected by the preliminary test was performed on 9 thighs inoculated at the end of the resting phase. The study was designed to evaluate the potential growth and toxin production in extremely favourable conditions for the bacterium. Type B proteolytic toxin was produced after 14 days of incubation at 20°C in 2 thighs characterised by high weight, low number of days of resting and anomalous physiochemical characteristics [one for very low NaCl concentration (1.59%), the other for elevated pH (6.27) and both for high water activity values (>0.970)]. The results of this research confirm that the cold resting step is a critical phase in the production process of Parma ham for the investigated hazard. Based on the present study, the long resting phase adopted in the manufacturing of Parma ham is proven effective to prevent the growth of , an event which could not otherwise be excluded if the hams were processed under less stringent technological conditions.
本研究的目的是调查工业化生产的意大利帕尔马火腿中的生长情况和毒素产生情况。该研究聚焦于帕尔马火腿生产阶段中被确定为增殖风险最大的阶段，即从冷阶段（腌制和静置）过渡到在15至23°C温度下进行的阶段（干燥）。进行了一项初步试验，以验证6株菌株（1株A型、4株B型和1株E型菌株）在与火腿干燥初始阶段相当的温度、pH值和NaCl浓度条件下生长的能力。5株菌株在20°C和pH值为6时生长，4株菌株在NaCl浓度为4%时以10 cfu/mL的接种浓度接种时产生毒素，而当接种浓度为10 cfu/mL时，3%的NaCl浓度成为毒素产生的限制因素。对9条在静置阶段结束时接种的大腿进行了由初步试验选择的5株菌株混合物试验性污染。该研究旨在评估在对该细菌极为有利的条件下的潜在生长和毒素产生情况。在20°C下孵育14天后，在2条大腿中产生了B型蛋白水解毒素，这2条大腿具有重量高、静置天数少和理化特性异常的特点[一条NaCl浓度极低（1.59%），另一条pH值升高（6.27），两条的水分活度值均较高（>0.970）]。本研究结果证实，对于所研究的危害，冷静置步骤是帕尔马火腿生产过程中的关键阶段。基于本研究，帕尔马火腿生产中采用的长时间静置阶段被证明可有效防止[细菌名称未给出]的生长，否则如果火腿在不太严格的工艺条件下加工，这一情况无法排除。
