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 ( a w) 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, a w, natural flora, and inoculated Bacillus cereus spores. Surface temperatures were considerably higher than temperatures inside the powder, especially at low a w; 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 a w 0.5 and 0.8, resulting in unsatisfactory spore reduction. However, at a w 0.8, the load of the natural flora was reduced ( P < 0.05). In a w 0.96 powder, areas with high remaining a w displayed a reduction >6 log 10 CFU/g for B. cereus ( P < 0.05). In addition, no microbial counts of the natural background flora were observed in the paprika.