Anti-diabetic Effect of Fermented Loquat (Eriobotrya japonica Lindl.)

The loquats (Eriobotrya japonica Lindl.) have been well known for its medicinal effects on expectorants, diuretics and anti-edema. It was reported that loquats leaves contained large amounts of terpenoids and flavonoids with strong antioxidant, anti-inflammatory, and anticancer functions while loquats seed part exhibited hypoglycemic effect and anti-obesity (1). In this study, loquat fruits were fermented using Leuconostoc mesenteroides and/or Lactobacillus brevis (2%, w/v) for 3 days at 37 °C to reduce their strong sweetness and improve anti-diabetic effect. Fermented loquat fruits were evaluated their reducing sugar, corosolic acid contents by HPLC analysis, and anti-diabetic effect using a-glucosidase inhibition assay. As results of analysis, loquat fruits fermented by combined of Leuconostoc mesenteroides and Lactobacillus brevis showed the lowest content of reducing sugar (4,733 mg/100 g). The corosolic acid content, the representative anti-diabetic component, was increased by 47% (8.38 mg/100 g), compared to the control (no fermentation). The a-glucosidase inhibition of fermented loquat fruits was 61.8% ˜ 67.7%. Especially, loquat fruits fermented by Leuconostoc mesenteroides and Lactobacillus brevis showed 2.3 times higher inhibition of a-glucosidase compared those of control loquat fruits.

[1] Eun Kim, Min-Sook Kim, Dong-Young Rhyu, Oh-Jin Min, Hum-Young Baek, Yung-Jae Kim, and Hyeon-A Kim. Korean J. Food & Nutr. 2009. 22: 159˜165.1034.