Enzymatic hydrolysis of orange bagasse and effect of filtration on lactic acid fermentation

Along with the general trend of reducing waste in the agro-industrial sector, new methods are sought to utilize side or waste products. With this purpose, we examined the utilization of orange bagasse (OB) for Ca-lactate production via enzymatic hydrolysis and fermentation. The hydrolysis of OB was carried in both dried and fresh forms with cellulolytic and pectinolytic enzymes to obtain a reasonable amount of fermentable sugars for further lactic acid fermentation. A novel industrial approach was studied to increase the hydrolysis yield by reusing the former hydrolysate media. Meanwhile, lactic acid fermentation was performed with optimal OB hydrolysate by Lactobacillus delbrueckii subsp. bulgaricus OZZ4 and Lactobacillus plantarum OZH8. One of the main problems in OB utilization via fermentation was the inhibition observed on microorganisms. It was found that either by drying of the biomass prior to enzymatic hydrolysis or by filtration of the hydrolysate prepared with fresh biomass could be done in order to overcome the inhibitory effects. After treatments, lactic acid with yields around 0.95 g/g and levels of 45 g/L was produced with the fermentation of OB hydrolysate.