SUMMARY
Folic acid (Vitamin B9) involved in numerous metabolisms. Folate deficiency is responsible for some negative health problems. The fermentation of foodstuffs to produce rich content of folic acid beverages using lactic acid bacteria (LAB) is an effort to overcome the health issues. This study aimed to determine the effect of banana juice fermentation using LAB on the folic acid content of the banana juice. Banana juice was fermented for 48 hours at 37oC with monoculture of Lactobacillus plantarum and mixed LAB cultures of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Bifidobacterium bifidum and Bifidobacterium breve. The changes of folic acid characteristics were observed every 8 hours during 0 – 48 hours of fermentation, as well as the change in pH, total acid, soluble protein, and reducing sugar. The identification of folic acid monomers was conducted at the most optimal condition of the fermentation by using LC-MS. The result showed fermentation affect the folic acid content, pH, total acid, reducing sugar and soluble protein of banana juice. During fermentation, pH of the sample decreased with the increasing of total acid. Reducing sugar and soluble protein content tended to fluctuate. Optimal condition for folic acid enhancement was obtained by 32 hours of fermentation with mixed LAB, in which it yielded folic acid 34.07 µg/mL, pH .,00, total acid 0.51%, reducing sugar 119.17 mg/L, dissolved protein 0.43 mg/mL. Folic acid identification on the optimal condition revealed that it was dominated by compound with a molecular weight of 441.49 Dalton.Keywords: banana, fermentation, folic acid, lactic acid bacteriaABSTRAKAsam folat (Vitamin B9) terlibat dalam berbagai metabolisme. Kekurangan folat bertanggung jawab atas beberapa masalah kesehatan. Fermentasi bahan pangan untuk menghasilkan minuman kaya asam folat menggunakan bakteri asam laktat (BAL) merupakan upaya untuk mengatasi masalah kesehatan akibat defisiensi folat. Penelitian ini bertujuan untuk mengetahui pengaruh fermentasi jus pisang menggunakan BAL terhadap kandungan asam folat jus pisang. Jus pisang difermentasi selama 48 jam pada suhu 37oC dengan kultur tunggal Lactobacillus plantarum dan kultur campuran BAL yaitu Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Bifidobacterium bifidum dan Bifidobacterium breve. Perubahan karakteristik asam folat diamati setiap 8 jam selama 0-48 jam fermentasi. Selain itu, diamati pula perubahan pH, total asam, protein terlarut dan gula pereduksi. Identifikasi monomer asam folat dilakukan pada kondisi fermentasi paling optimum dengan menggunakan LC-MS. Hasil penelitian menunjukkan bahwa fermentasi dapat mempengaruhi kandungan asam folat, pH, total asam, gula pereduksi dan protein terlarut dari jus pisang. Selama fermentasi, pH sampel menurun diikuti dengan peningkatan total asam. Nilai gula pereduksi dan protein terlarut cenderung berfluktuasi. Kondisi optimum peningkatan kandungan asam folat diperoleh pada fermentasi menggunakan mix kultur LAB selama 32 jam dengan kandungan asam folat 34,07 mg/mL, pH 4,00, total asam 0,51%, gula pereduksi 119,17 mg/L dan protein terlarut 0,43 mg/mL. Identifikasi monomer asam folat pada kondisi optimum fermentasi didominasi senyawa dengan berat molekul 442,49 Dalton (Da).Kata kunci: asam folat, bakteri asam laktat, fermentasi, pisang