Growth and fumitremorgin production by Neosartorya fischeri as affected by food preservatives and organic acids

Abstract

The effects of potassium sorbate, sodium benzoate, sulphur dioxide and citric, malic and tartaric acids on growth and fumitremorgin production by a heat‐resistant mould, Neosartorya fischeri, cultured on Czapek yeast autolysate agar (CYA) were studied over a 32‐day incubation period. Colonies were examined, and extracts of agar and mycelia were analyzed for mycotoxin content using high performance liquid chromatography (HPLC). Growth of N. fischeri always resulted in production of the fumitremorgins verruculogen and fumitremorgin A and C. Growth on CYA (pH 3.5) was highly repressed by potassium sorbate and sodium benzoate; 75 mg/1 completely inhibited germination of ascospores. Sulphur dioxide was less inhibitory; growth occurred on CYA containing 100 but not 200 mg/1. Growth of N. fischeri was significantly reduced when the pH of CYA was reduced from 7.0 to 4.5 to 3.5 to 2.5. Citric, malic and tartaric acids promoted growth and fumitremorgin production when supplemented to CYA (pH 2.5). These observations indicate that growth and fumitremorgin production by N. fischeri are influenced by pH and type of acid present and can be controlled by small amounts of preservatives.

Note: Influence of different heating media on thermal resistance of Neosartorya fischeri isolated from papaya fruit

“…Fruits and fruit-based products are natural growth media for different kinds of micro-organisms. Several mycotoxinproducing spoilage molds from fruits and their products have been reported Roland and Beuchat 1984;Nielsen et al 1989). The occurrence of spoilage outbreaks due to heat-resistant molds has been reported in many fruit products (Put and Kruiswijk 1964;King et al 1969;Beuchat and Rice 1979 ;Hocking and Pitt 1984;Scott and Bernard 1987;Beuchat and Pitt 1992).…”

Shelf life study of some Nigerian fruit juices inoculated with ascospores ofNeosartorya spp.

“…Complete inhibition of growth on solid medium (pH 3.5) at 25 ~ C with 100 mg/1 sodium benzoate has been reported for ascospores of a strain ofN. fischeri [13]. The pH values of these fruit juices were fairly close to 3.5.…”

“…Some strains of N. fischeri produce mycotoxin of the fumitremorgins group [7, 13-14] which cause tremors, convulsion and death in animals [13]. The fungi could, therefore, pose public health problems in processed fruit products in developing countries.…”

Comprehensive antifungal investigation of natural plant extracts against Neosartorya spp. (Aspergillus spp.) of agriculturally significant microbiological contaminants and shaping their metabolic profile

“…caramelization, evaporation and densification 17 . The importance of stopping the contamination not only concerns food spoilage, but also consumers’ health, as these potentially toxigenic fungi can produce mycotoxins such as fumitremorgin C, verruculogen and fischerin 18 – 20 . However, due to chemical fungicide overuse the European Union has launched the “Farm to Fork” strategy 21 .…”