Study on the effect of bacteria-reducing treatment before drying on microorganism and quality of porphyra porphyra
The high aerobic plate count (APC) of dried laver or nori affect the microbial safety of seaweed foods, the post-drying decontamination effect of dried laver was limited. The pre-drying decontamination of laver by the slightly acidic electrolytic water (SAEW), ozonated water, and UV treatments was compared in this study. The average APC and coliform in untreated laver were 6.73 and 4.16 Log CFU/g, respectively. The APC of laver treated in SAEW (100 ppm, 30 mins), ozonated water (1 mg/L, 30 mins) and by UV (5 cm, 30 mins) decreased by 1.61, 2.26 and 1.84-2.24 Log CFU/g, respectively, and the coliform decreased by 1.27, 2 and 3.65 Log CFU/g, respectively. The changes of color, VC, VE and protein content were not significant except for ozonated water treatment. Compared with untreated group, species richness of laver decreased after all treatments, and increased after drying; Species diversity of laver decreased after treated by ozonated water, and decreased for ozonated water and SAEW combined group and UV group after drying. The above results showed microbiological control of laver before drying was helpful to improve the quality and safety of dried laver.