Study on the microbial inactivation of whole hulless barley flour using a continuous instant pressure drop sterilizer

This work evaluated the microbial reduction and quality change of the whole hulless barley flour (WHBF) treated by a continuous instant pressure drop (CIPD) sterilizer. The microbial reduction of WHBF was proportional to steam-material ratio under the conditions of 165 degrees C, 0.2 MPa steam, and 0.2 MPa Laval nozzle, and the microbial reduction was 3.87 +/- 0.09 log cfu/g with the steam-material ratio of 3.0:1. The work was followed-up with the quality testing of CIPD, UV-C, hot air, and ozone treated WHBF. The microbial reduction of hot air, UV-C, and ozone treated WHBF was 3.98 +/- 0.09, 3.33 +/- 0.04, and 3.68 +/- 0.12 log cfu/g, respectively, while the CIPD treatment achieved similar bactericidal effect at a unit treatment time of 22 s. Moreover, there is no measurable quality degradation in CIPD treated WHBF compared with the untreated WHBF. These results showed CIPD sterilizer had a great potential for microbial inactivation of powdery foods industry.