Effect of lactic acid fermentation of onions (Allium cepa) on the composition of flavonol glucosides

Abstract

Fermentation of red onions inoculated with Lactobacillus plantarum S1 (starter treatment) resulted in acid production to pH 4.5, after 48 h of incubation at 19°C, which has proven to be adequate for proper preservation. In the presence of erythromycin (starter + antibiotic), acidification to pH 5.2 resulted, which was similar to that of the uninoculated control. The bacterial population was about 10 8 CFU mL )1 of brine after 3 days for the three treatments, suggesting that in the starter + antibiotic treatment, the antibiotic effectively suppressed the activity of the starter but not the native flora. Before lactic fermentation, the red onions contained 297.4 mg of total quercetin (Q) per kg wet weight, which consisted of 58.3%, 41.6% and 0.1% in quercetin diglucoside (Qdg), quercetin monoglucoside (Qmg) and free Q, respectively. For the starter treatment, Qdg decreased to 41.8% and 18.3% at 48 and 72 h, respectively, and a substantial amount of free Q had accumulated. The fermentation substantially increased the proportion of Qmg, which may have a positive effect as fractions containing higher ratios of Qmg to Qdg have been reported to have higher antioxidant activity.

Change in Flavonoid Composition and Antioxidative Activity during Fermentation of Onion (Allium cepa L.) by Leuconostoc mesenteroides with Different Salt Concentrations

“…Onion has been used as an ingredient in fermented vegetable foods such as kimchi and pickles. Previously published reports presented data concerning the effect of LAB fermentation on flavonoids in onion (Bisakowski and others ; Millet and others ). However, investigations on change in individual flavonoid contents during LAB fermentation have not yet been performed.…”

“…Therefore, it is inferred that Q glucosides transform into their aglycone forms by the β‐glucosidase produced from L. mesenteroides during fermentation. That is, fermentation by L. mesenteroides increased Q content in onion through the enzymatic cleavage of the main Q glucosides, such as Q3,4′G and Q4′G (Bisakowski and others ; Yang and others ). However, no previous studies have investigated the specific changes in flavonoid composition during fermentation comprehensively.…”

Development of New Products: Probiotics and Probiotic Foods

“…The latter vary as a function of the microflora of the raw material, the temperature and the storage conditions [160]. Currently fermented cabbage, olives, cucumbers, carrots, lettuce, peas, corn, tomatoes, onions, pickles, radishes, Brussels sprouts, etc.…”

Antioxidant changes of leek (Allium ampeloprasum var. porrum) during spontaneous fermentation of the white shaft and green leaves

“…This evolution could not be seen for our results, primarily because of the limited data, but the increase of kaempferol 3‐ O ‐glucoside, kaempferol, quercetin and (hydro)ferulic acid after fermentation can indicate such an evolution. Bisakowski et al . also noticed a substantial increase in the proportion of quercetin monoglucoside upon fermentation of onion.…”