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Open access

Martina Bevardi, Marinko Petrović, Ksenija Markov and Jasna Bošnir

Abstract

Mycotoxin patulin is one of the quality indicators for apple juice. Like other mycotoxins, it raises consumer health concerns. The issue of low quality is particularly relevant for apples provided by small producers, whose quality control may not be standardised. As sulphur dioxide (SO2) is common in fruit preservation against fungi, the aim of this study was to determine how efficient it is in degrading patulin in apple juices stored in real-life conditions. This included refrigerated (4 °C) and non-refrigerated warehouses/environments (30 °C) over 8, 10, 12, and 20 weeks of storage. Apple juice was diluted to 0.010 μg g-1, 0.050 μg g-1, and 0.100 μg g-1 of patulin. SO2 was added to each sample in the amounts of 250 μg mL-1 and 50 μg mL-1. Untreated juice samples for each patulin concentration served as controls under the same experimental conditions. Patulin content was determined with high performance liquid chromatography. The best degradation was observed with 250 μg mL-1 of SO2 at 30 °C regardless of the patulin baseline concentration. Although treatment with SO2 and refrigeration did not fully remove patulin, it was highly efficient over twelve weeks of storage. Our results suggest that patulin levels can be reduced between 33 and 100 % at 30 °C and up to 100 % at 4 °C.

Open access

Martina Bevardi, Jadranka Frece, Dragana Mesarek, Jasna Bošnir, Jasna Mrvčić, Frane Delaš and Ksenija Markov

Fungicides are the most common agents used in postharvest treatment of fruit and are the most effective against blue mould, primarily caused by Penicillium expansum. Alternatively, blue mould can be treated with antagonistic microorganisms naturally occurring on fruit, such as the bacterium Gluconobacter oxydans. The aim of this study was to establish the antifungal potential of the G. oxydans 1J strain isolated from apple surface against Penicillium expansum in culture and apple juice and to compare it with the efficiency of a reference strain G. oxydans ATCC 621H. The highest antifungal activity of G. oxydans 1J was observed between days 3 and 9 with no colony growth, while on day 12, P. expansum colony diameter was reduced to 42.3 % of the control diameter. Although G. oxydans 1J did not fully inhibit mould growth, it showed a high level of efficiency and completely prevented patulin accumulation in apple juice.