Acid hydrolysis of Musa paradisiaca and Citrus sinensis residues for the production of glucose syrups

ABSTRACT Several agro-industrial residues can be utilized for the extraction of sugars through chemical reactions. This study evaluated the extraction of total sugars and reducing sugars from banana (Musa paradisiaca) and orange (Citrus sinensis) peel residues using acid hydrolysis. It also investigated if there is a difference between the concentration of sugars present, and analyzed the effect of different sulfuric acid concentrations and reaction times. A completely randomized 2 × 4 × 2 experimental design was used to evaluate two types of waste, exposed to four concentrations of sulfuric acid (4, 6, 8 and 10% V/V) at reaction times of 2 and 4 hours. This amounted to 16 treatments with three repetitions. The experimental units consisted of borosilicate glass flasks, half submerged in a bath of vegetable oil and assembled in a rapid cooling tower from which the analyzed glucose syrups were obtained. The orange peel residues showed the highest values of reducing sugar extraction with 8% sulfuric acid concentration, presenting mean of 16.46 mg L-1 ± SE = 0.591 and optimal hydrolysis reaction time of 2 hours. With 4 hours reaction time, the extraction of reducing sugars was higher in orange peel residues compared to banana peel residues. Both residues proved to be suitable for sugar extraction, presenting a valuable opportunity for utilization in regions where they are readily available. They can be employed in fermentation processes for bioethanol production.