Modelling Fungal Growth, Mycotoxin Production and Release in Grana Cheese

Abstract

No information is available in the literature about the influence of temperature (T) on Penicillium and Aspergillus spp. growth and mycotoxin production on cheese rinds. The aim of this work was to: (i) study fungal ecology on cheese in terms of T requirements, focusing on the partitioning of mycotoxins between the rind and mycelium; and (ii) validate predictive models previously developed by in vitro trials. Grana cheese rind blocks were inoculated with A. versicolor, P. crustosum, P. nordicum, P. roqueforti, and P. verrucosum, incubated at different T regimes (10–30 °C, step 5 °C) and after 14 days the production of mycotoxins (ochratoxin A (OTA); sterigmatocystin (STC); roquefortine C (ROQ-C), mycophenolic acid (MPA), Pr toxin (PR-Tox), citrinin (CIT), cyclopiazonic acid (CPA)) was quantified. All the fungi grew optimally around 15–25 °C and produced the expected mycotoxins (except MPA, Pr-Tox, and CIT). The majority of the mycotoxins produced remained in the mycelium (~90%) in three out of five fungal species (P. crustosum, P. nordicum, and P. roqueforti); the opposite occurred for A. versicolor and P. verrucosum with 71% and 58% of STC and OTA detected in cheese rind, respectively. Available predictive models fitted fungal growth on the cheese rind well, but validation was not possible for mycotoxins because they were produced in a very narrow T range.

Risk assessment of ochratoxin A in food

“…Considering that the transfer of OTA from feed to ruminants milk is negligible, due to the hydrolytic activity of rumen bacteria, the OTA occurrence in cheese is very likely due to environmental contamination leading to fungal growth on the cheese surface (Kure and Skaar, 2019 ). Although the common fungi growing on cheese surface have been reported as non‐OTA producers (Lund et al., 1995 ), the growth of uncontrolled moulds during ripening and ageing may occur causing spoilage and possibly mycotoxin production (Ropars et al., 2012 ; Camardo Leggieri et al., 2020 ). Very recently, the possible migration of OTA from the crust as far as 1.6 cm in depth was demonstrated in French semi‐hard Comté cheese following artificial inoculation with OTA‐producing strains (Coton et al., 2019 ).…”

Ochratoxin A and Sterigmatocystin in Long-Ripened Grana Cheese: Occurrence, Wheel Rind Contamination and Effectiveness of Cleaning Techniques on Grated Products

“…However, since STC and OTA occurrence in cheeses is related to environmental conditions of cheese ripening warehouses, it is of great importance to control toxigenic mould development during cheese storage. In order to reduce mould contamination of cheese, it is necessary to systematically take preventative measures aimed at mitigating mould growth, such as frequent cleaning of wheels [ 2 ]; however, since fungal spores have an airborne spread, the dispersion of spores in the warehouse can increase, with further contamination of wheels, already micro-damaged on the surface by the cleaning technique [ 3 ].…”

“…As a matter of fact, fungi belonging to several genera (Penicillium , Aspergillus , Cladosporium , Geotrichum , Mucor , Trichoderma Acremonium , Alternaria , Aureobasidium , Botrytis , Epicoccum , Eurotium , Exophiala , Fusarium , Gliocladium , Lecanicillium , Rhizopus and Wallemia ) have already been identified as being responsible for cheese spoilage [ 2 ]. Among these genera, several species are able to not only optimally grow in environmental conditions similar to those used for cheese ripening (15–25 °C) [ 3 ], but also to produce toxic secondary metabolites known as mycotoxins [ 4 ]; therefore, mould growth on cheese surface could be a concrete risk for consumers’ health.…”

Distribution of mycotoxins during manufacture and storage of cheeses – A review

“…Penicillium roqueforti, used in the manufacture of blue cheeses, in some conditions, can produce large levels of ROQ-C. Also, PAT, penicillic acid, penicillin roquefort toxin (PR toxin) and MPA can be produced by this fungus (Ansari and H€ aubl 2016;Camardo Leggieri et al 2020). P. camemberti, used to manufacture white cheeses, is responsible for producing cyclopiazonic acid (CPA).…”