Effect of infrared heating on quality and microbial decontamination in paprika powder

Infrared radiation (IR) was explored as a technique for decontaminating paprika powder. The effect of water activity (aw) and IR heat flux on paprika temperature and water loss were measured during near- or medium-IR heating. Paprika was evaluated in terms of colour, aw, natural flora, and inoculated Bacillus cereus spores. Surface temperatures were considerably higher than temperatures inside the powder, especially at low aw; greater differences were observed with medium- than with near-IR. Surface darkening was observed, though the overall colour was not considerably affected. IR effectively removed water from paprika, especially at aw 0.5 and 0.8, resulting in unsatisfactory spore reduction. However, at aw 0.8, the load of the natural flora was reduced (P < 0.05). In aw 0.96 powder, areas with high remaining aw displayed a reduction >6 log10 CFU/g for B. cereus (P < 0.05). In addition, no microbial counts of the natural background flora were observed in the paprika.