Chitosan is a biopolymer with high added value, and its properties are related to its molecular weight. Thus, high molecular weight values provide low solubility of chitosan, presenting limitations in its use. Based on this, several studies have developed different hydrolysis methods to reduce the molecular weight of chitosan. Acid hydrolysis is still the most used method to obtain low molecular weight chitosan and chitooligosaccharides. However, the use of acids can generate environmental impacts. When different methods are combined, gamma radiation and microwave power intensity are the variables that most influence acid hydrolysis. Otherwise, in oxidative hydrolysis with hydrogen peroxide, a long time is the limiting factor. Thus, it was observed that the most efficient method is the association between the different hydrolysis methods mentioned. However, this alternative can increase the cost of the process. Enzymatic hydrolysis is the most studied method due to its environmental advantages and high specificity. However, hydrolysis time and process cost are factors that still limit industrial application. In addition, the enzymatic method has a limited association with other hydrolysis methods due to the sensitivity of the enzymes. Therefore, this article seeks to extensively review the variables that influence the main methods of hydrolysis: acid concentration, radiation intensity, potency, time, temperature, pH, and enzyme/substrate ratio, observing their influence on molecular weight, yield, and characteristic of the product.

In this paper, natural deep eutectic solvents (NADESs) with lactic acid, glycine, ammonium acetate, sodium acetate, and choline chloride were prepared with and without the addition of water. NADES formation was evaluated using FTIR and Raman, where hydrogen bonds were identified between the hydroxyl group of lactic acid and the amino and carboxyl groups of glycine. Acetate and ammonium ions were also identified as forming bonds with lactic acid. The addition of water did not cause changes in the vibrational modes of the FTIR and Raman spectra but contributed to a reduction in NADES viscosity and density. Viscosity ranged from 0.335 to 0.017 Pa s⁻¹, and density ranged from 1.159 to 0.785 g mL⁻¹. The best results for the extraction of phenolic compounds from pitaya (dragon fruit) were achieved with an organic solvent (450. 41 mg 100 g⁻¹ dry bases-db) in comparison to NADESs lactic acid:glycine (193.18 mg 100 g⁻¹ db) and lactic acid:ammonium acetate (186.08 mg 100 g⁻¹ db). The antioxidant activity of the extracts obtained with the NADESs was not statistically different from that of the extract obtained with organic solvents.

The use of lignocellulosic biomass as a raw material for the production of lipids has gained increasing attention, especially in recent years when the use of food in the production of biofuels has become a current technology. Thus, the competition for raw materials for both uses has brought the need to create technological alternatives to reduce this competition that could generate a reduction in the volume of food offered and a consequent commercial increase in the value of food. Furthermore, the use of microbial oils has been studied in many industrial branches, from the generation of renewable energy to the obtainment of several value-added products in the pharmaceutical and food industries. Thus, this review provides an overview of the feasibility and challenges observed in the production of microbial lipids through the use of lignocellulosic biomass in a biorefinery. Topics covered include biorefining technology, the microbial oil market, oily microorganisms, mechanisms involved in lipid-producing microbial metabolism, strain development, processes, lignocellulosic lipids, technical drawbacks, and lipid recovery.

This study aimed to identify the volatile compounds in the fermented and dried cocoa beans conducted with three distinct inoculants of yeast species due to their high fermentative capacity: Saccharomyces cerevisiae, Pichia kudriavzevii, the mixture in equal proportions 1:1 of both species, and a control fermentation (with no inoculum application). Three starter cultures of yeasts, previously isolated and identified in cocoa fermentation in the municipality of Tomé-Açu, Pará state, Brazil. The seeds with pulp were removed manually and placed in wooden boxes for the fermentation process that lasted from 6 to 7 days. On the last day of fermentation, the almonds were packaged properly and placed to dry (36 °C), followed by preparation for the analysis of volatile compounds by GC-MS technique. In addition to the control fermentation, a high capacity for the formation of desirable compounds in chocolate by the inoculants with P. kudriavzevii was observed, which was confirmed through multivariate analyses, classifying these almonds with the highest content of aldehydes, esters, ketones and alcohols and low concentration of off-flavours. We conclude that the addition of mixed culture starter can be an excellent alternative for cocoa producers, suggesting obtaining cocoa beans with desirable characteristics for chocolate production, as well as creating a product identity for the producing region.

Natural deep eutectic solvents (NADESs) of choline chloride (ChCl) and fructose, glucose, citric and malic acid with different water concentration were prepared and characterized. The pH ranged from 2.34 to 7.38. An increase in the intensity at 3300 cm⁻¹ (FT-IR), by the interaction between the receptor and the hydrogen donor, occurred. The water content increased the intensity in the OH region without changing the vibrational mode. The same behavior occurred in Raman spectra. NADES without water showed a high density (1.234 to 1.375 g/mL) and viscosity (0.09991 to 0.46921 Pa·s). NADESs with 20% and 40% water were selected for extracting phenolic compounds from araza (Eugenia stipitata), using an ultrasonic system of bath, tip, and ethanol. Araza ethanol extract had a TPC (total phenolic compounds) of 325.19 mg GAE/g, and DPPH and ABTS of 12.00 and 291.31 µmolL⁻¹ Trolox g⁻¹. ChCl:citric acid (1:1) containing 40% water was the most efficient NADES in the tip ultrasound extraction: a TPC of 273.40 mg GAE/g; DPPH and ABTS of 31.55 and 204.9 µmolL⁻¹ Trolox g⁻¹; and an extraction yield of 84% related to ethanol. NADESs as solvents can be used directly by the food industry as a final product or ingredient, without purification, and proved to be versatile, with different properties.