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Summary: The objective of this study is to explore the feasibility of sequential hydrothermal and alkaline pretreatment in improving enzymatic hydrolysis and sugar production of coconut pulp residue for bioethanol production. Hydrothermal pretreatment with the different heating duration of 20, 40, 60 minutes yielded 32.27, 27.51, and 26.72 g/L of total sugar, respectively. After posttreatment with 1%, 2%, and 3% alkaline treatment, the further increment of almost 90% on sugar production was observed. Compared to the single pretreatment, the combination of hydrothermal and alkaline pretreatment significantly affected the enzymatic hydrolysis. The optimum condition for efficient hydrolysis was 40 minutes hydrothermal pretreatment, followed by 1% NaOH posttreatment. At these conditions, the total and reducing sugar was 257.14 ± 0.92 and 102.86 ± 0.82 g/L and the maximum ethanol achieved was 27.19 g/L on the 48 hours of fermentation with efficiency and ethanol productivity of 51.83% and 0.57 g/L/h, respectively. [ABSTRACT FROM AUTHOR]

The processing of Citrofortunella mircocarpa fruit juice generates large volume of solid waste, causing disposal problem. Several studies have demonstrated that wastes from agricultural and food processing industries such as fruit and vegetable peels contain high amount of polysaccharides that can be transformed into useful chemicals, including lactic acid, through fermentation. Lactic acid is widely used in various industries, such as in the manufacture of biodegradable plastic, and the demand for this chemical justifies the search of renewable feedstock for its biotechnological production. This study aimed to produce lactic acid from C. microcarpa fruit waste biomass through fermentation with Lactobacillus plantarum. The hydrolysate from C. microcarpa fruit waste was prepared, inoculated with different amounts of L. plantarum cell suspension, and incubated for three days. Lactic acid production was monitored daily. The lactic acid produced from the fermentation was recovered as calcium lactate and lactic acid crystals. The identity of the crystals was evaluated using Fourier transform infrared spectroscopy (FTIR) spectroscopy and paper chromatography. The highest lactic acid production was observed in fermentation mixtures containing the highest number of L. plantarum cells. Within three days of fermentation, the amount of lactic acid production increased with increasing period of incubation. Partial characterization of the crystals recovered from the fermentation mixtures by FTIR spectroscopy showed that the peaks in the spectrum were consistent with the chemical structure of lactate. Paper chromatography results likewise confirmed that the crystals are lactate. C. microcarpa fruit waste can afford lactic acid when fermented with L. plantarum. The results of the study may serve as basis for the development of technology for the utilization of C. microcarpa fruit waste biomass as renewable resource for industrial production of lactic acid. [ABSTRACT FROM AUTHOR]