title: Study on PotentialClostridium BotulinumGrowth and Toxin Production in Parma Ham.
abstract: The objective of this study was to investigateClostridium botulinumgrowth and toxin production in the industrially manufactured Italian Parma ham. The study focuses on the Parma ham production phase identified as maximum risk toC. botulinumproliferation,i.e. the transition from cold phase (salting and resting) to a phase carried out at temperature between 15 and 23°C (drying). A preliminaryin vitrotest was carried out in order to verify the capability of 6C. botulinumstrains (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. FiveC. botulinumstrains grew at 20°C and pH 6, four strains produced toxin when inoculated at a concentration equal to 103cfu/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 5C. botulinumstrains selected by the preliminaryin vitrotest 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 proteolyticC. botulinumtoxin 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 ofC. botulinum, an event which could not otherwise be excluded if the hams were processed under less stringent technological conditions.
authors: Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
authors: Giuseppe
authors: G
authors: Merialdi
authors: Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
authors: Mattia
authors: M
authors: Ramini
authors: Experimental Unit for Food Preserves Industry , Parma, Italy.
authors: Giovanni
authors: G
authors: Parolari
authors: Experimental Unit for Food Preserves Industry , Parma, Italy.
authors: Silvana
authors: S
authors: Barbuti
authors: Experimental Unit for Food Preserves Industry , Parma, Italy.
authors: Maria Angela
authors: MA
authors: Frustoli
authors: Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
authors: Roberta
authors: R
authors: Taddei
authors: Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
authors: Stefano
authors: S
authors: Pongolini
authors: Institute for Experimental Veterinary Medicine of Lombardy and Emilia Romagna , Brescia, Italy.
authors: Paolo
authors: P
authors: Ardigò
authors: Department of Public Health, Parma Local Health Unit , Parma, Italy.
authors: Paolo
authors: P
authors: Cozzolino
keywords: Botulism; Dry cured ham; Toxinogenesis