Biocontrol of Penicillium nordicum Growth and Ochratoxin A Production by Native Yeasts of Dry Cured Ham

Abstract

Twelve yeast strains isolated from the surface of Italian typical dry-cured hams, belonging to D. hansenii, D. maramus, C. famata, C. zeylanoides and H. burtonii species, and previously selected for their ability to grow in dry-cured ham-like substrates, were screened for antagonistic activity against a toxigenic strain of P. nordicum and inhibition of ochratoxin A (OTA) biosynthesis. On average, yeast inhibitory activity was lowered by increasing fungal inoculum and enhanced by NaCl presence. In the assay conditions, H. burtonii and C. zeylanoides were the most effective, both in inhibiting P. nordicum growth and OTA production. D. hansenii was the species with the lowest inhibitory activity, especially in the absence of salt. OTA production dropped from the range < LOD − 5000 ppb in P. nordicum control plates to the range < LOD − 200 ppb in yeast-added plates. OTA production increased in the presence of NaCl in P. nordicum control plates, while salt enhanced inhibition against OTA production in yeast-added plates.

Ecology of moulds during the pre-ripening and ripening of San Daniele dry cured ham

“…The inhibition was maintained until the end of ripening (8 months). These data confirm the results obtained in a screen for antagonistic activity against a toxigenic strain of P. nordicum and inhibition of OTA biosynthesis conducted by Virgili et al (2011). According to our data and the data of the above authors, it was suggested that bioprotective cultures might be used to inhibit the growth of OTA producing moulds during preripening and ripening of dry cured hams.…”

“…They were used as biocontrol agents in cereals (Druvefors & Schnurer, 2005), fruits (Guinebretiere, Nguyen-The, Morrison, Recich, & Nicot, 2000) and in coffee (Masoud & Kaltoft, 2006). The biological control of OTA producing moulds by microbial antagonists to improve food safety without affecting the sensory quality and properties of dry cured ham was investigated (Virgili et al, 2011). In particular, the growth of native yeasts such as Debaryomyces, Candida and less frequently Cryptococcus, Rhodosporidium and Rhodotorula, "in vivo" and "in vitro" seems to inhibit the growth of moulds (Sànchez-Molinero & Arnau, 2006;Virgili et al, 2011;Wang et al, 2006).…”

“…A bioprotective technique was used. The antagonistic potential of yeast and non-OTA producing moulds against toxigenic moulds has been considered for different food matrices (Virgili et al, 2011). They were used as biocontrol agents in cereals (Druvefors & Schnurer, 2005), fruits (Guinebretiere, Nguyen-The, Morrison, Recich, & Nicot, 2000) and in coffee (Masoud & Kaltoft, 2006).…”

“…The biological control of OTA producing moulds by microbial antagonists to improve food safety without affecting the sensory quality and properties of dry cured ham was investigated (Virgili et al, 2011). In particular, the growth of native yeasts such as Debaryomyces, Candida and less frequently Cryptococcus, Rhodosporidium and Rhodotorula, "in vivo" and "in vitro" seems to inhibit the growth of moulds (Sànchez-Molinero & Arnau, 2006;Virgili et al, 2011;Wang et al, 2006). For this reason, some of these yeasts could be used as starter cultures to protect dry cured ham from OTA producing moulds.…”

“…was used to evaluate bioprotective cultures consisting of Penicillium nalgiovense, Candida famata (as suggested by Virgili et al, 2011) and Saccharomycopsis fibuligera. In this case, OTA-producing fungi were co-inoculated with suspensions of bioprotective cultures at 100 spores or UFC/cm2.…”