Efficacy of sodium metabisulphite for control of Aspergillus flavus and aflatoxin B1 contamination in vitro and in chilli powder and whole red chillies

Chillies are an important spice in many regions of the world. During production and processing phases, they prone to infection by mycotoxigenic fungi, especially Aspergillus Section Flavi species contamination with aflatoxins. There is significant interest controlling aflatoxin B1 (AFB1) such spices ensure remain below legislative limits for human consumption. This study initially examined potential efficacy sodium metabisulphite (NaMBS, up 5000 mg/L) control growth AFB1 flavus strains vitro on a chilli-based medium modified 0.93–0.995 water activity, aw). Subsequent studies NaMBS stored naturally contaminated chilli powder whole red chillies, or when inoculated A. at 0.70, 0.80, 0.90, 0.95 aw 30 °C 20 days. was effective three different levels examined. No occurred >500–1250 mg/L. only produced 0.98 complete inhibition ≥1250 mg/L preservative °C. The ED50, ED90 varied conditions. In situ dry chillies (naturally + conidial inoculum flavus) showed that 0.70 0.80 aw, treatments 1000 2000 resulted spices. However, under wetter conditions 0.90 powder, −/+ inoculum, were above limits, even days storage Stored reduction populations, NaMBS. Control achieved treatment after 10 storage. Studies commercial laminated sheets containing immobilised slow release SO2 properties significantly reduced fungal populations effectively controlled packaged chillies.