Radical scavenging capacities of saba-narezushi, Japanese fermented chub mackerel, and its lactic acid bacteria

Narezushi (salted and fermented fish with rice) is a traditional Japanese food prepared using lactic acid-fermentation. In the current study, the antioxidant (2,2-diphenyl-1-picrylhydrazyl (DPPH−)) and superoxide anion radical (O2−) scavenging capacities of four saba-narezushi (fermented chub mackerel with rice) products were determined. Lactose utilizing, bile resistant, acidophilic and antioxidative lactic acid bacteria (LAB) were also screened from 182 isolates derived from narezushi samples for use as starters of fermented foods as well probiotics. Radical scavenging capacities varied by product, with viable cell counts ranging from 7.9 to 9.4 log CFU/g and lactic acid content ranging from 0.27 to 1.2 mmol/g. Of the LAB isolates examined, five (four Lactobacillus plantarum and one Leuconostoc mesenteroides) were identified that were able to ferment lactose, grow in MRS containing 3 g/L bile, grow in broth adjusted to pH 3.6, and scavenge DPPH− and/or O2− radicals. Two strains, Lb. plantarum 7FM10 and Ln. mesenteroides 1RM3, were able to grow and ferment in soybean milk and vegetable juice. These LAB also exhibited synergistic effects in milk fermentation, where samples containing both LAB showed a significant increase in O2− radical scavenging capacity.

► Saba-narezushi is a dish consisting of fermented chub mackerel with cooked rice. ► Five isolates with probiotic and antioxidative properties were selected. ► The isolates were identified as Lb. plantarum and Ln. mesenteroides. ► The isolates were able to ferment milk, soybean milk and vegetable juice. ► O2− radical scavenging was induced in the fermented foods.