In the context of a biorefinery, lignocellulosic materials represent an important source of raw material for the bioconversion of cellulose, hemicellulose, and lignin into value-added products, such as xylose for fermentation, oligosaccharides, and bioplastics for packaging. Among the most abundant lignocellulosic materials in Brazil, sugarcane bagasse biomass stands out, as it is rich in cellulose and hemicellulose. In this context, through an experimental design, this study developed a robust enzyme cocktail containing xylanases and accessory enzymes to complete the hydrolysis of xylan from sugarcane bagasse, obtaining a low xylose yield and concentration (9% and 1.8 g/L, respectively, observed in experiment number 16 from the complete hydrolysis of a xylan assay), a fermentable sugar that is important in the production of second-generation ethanol, and a high xylooligosaccharides (XOS) yield and concentration (93.1% and 19.6 g/L, respectively, obtained from a xylooligosaccharides production assay); in general, xylan has prebiotic activities that favor an improvement in intestinal functions, with immunological and antimicrobial actions and other benefits to human health. In addition to completely hydrolyzing the sugarcane bagasse xylan, this enzymatic cocktail has great potential to be applied in other sources of lignocellulosic biomass for the conversion of xylan into xylose and XOS due to its enzymes content, involving both main chain and pendant groups hydrolysis of hemicelluloses.

A significant part of fruit production is wasted annually, a material of high value without use, causing environmental and social damage. These residues from agro-industrial processes, or those that can no longer be used in the market, can be recycled and generate value-added products by pretreatments/hydrolysis. One of the important pretreatments is acid hydrolysis, which can produce xylooligosaccharides (XOS) from biomass, a product of great commercial value in the food and pharmaceutical markets, mainly due to its prebiotic potential. Bananas, oranges, and guava generate a large volume of waste and represent much of Brazil’s fruit production. The dilute acid hydrolysis resulted in XOS production of 37.69% for banana peel, 59.60% for guava bagasse, 28.70% for orange bagasse, and 49.64% for restaurant residue. XOS were quantified by a liquid chromatograph system with a Bio-Rad Aminex HPX-87C column. The results show that, for this type of material and hydrolysis, the ideal conditions to produce XOS are high temperature, low time, and high acid concentration for banana peel residue (160 °C, 15 min, and 3% H₂SO₄), low temperature, low time, and high acid concentration for guava bagasse (100 °C,15 min and 3% H₂SO₄), high temperature and acid concentration with low time for orange bagasse (160 °C,15 min and 3% H₂SO₄) and high temperature and time and high acid concentration for restaurant waste (160 °C, 55 min and 3% H₂SO₄). This study identified acid hydrolysis conditions that maximized XOS production with a low amount of xylose production using agro-industrial and food residues, also showing the high potential of the chosen residues through the high yields of XOS production.

Dekkera bruxellensis is one of the most important contaminant yeasts of alcoholic fermentation. The use of propolis, which can selectively target contaminating yeasts without affecting the starter one, Saccharomyces cerevisiae, could be a useful nonconventional strategy for controlling the growth of contaminant yeasts. The objective of this research was to evaluate four samples of propolis produced by Apis mellifera honeybees from different regions of Argentina as antimicrobial agents against the growth of D. bruxellensis and S. cerevisiae. Hydroalcoholic extracts of propolis were prepared with ethanol:water (70:30 v/v), and the specific absorbance and final concentration of the samples were evaluated. A qualitative in vitro assay in solid medium was performed with different propolis concentrations, and the evaluation of yeast growth was based on a qualitative scale. A quantitative in vitro assay in liquid medium was also performed to assess the yeast cell number, using two different propolis concentrations. The cell number of D. bruxellensis decreased 1.52 and 1.85 log cycles with the two propolis extracts utilised at a concentration of 4.5 mg mL-1 while the cell number of S. cerevisiae decreased 0.48 and 0.76 log cycles with the same samples of propolis. The results from both assays demonstrated the selectivity of propolis use on the yeast species, leading to a higher inhibition of D. bruxellensis growth. This indicates a good potential for using propolis at the concentration of 4.5 mg mL-1, as a nonconventional strategy to control the growth of D. bruxellensis without significantly affecting S. cerevisiae, the yeast starter of ethanol fermentation.