Microwave-assisted extraction of soluble sugars from banana puree with natural deep eutectic solvents (NADES)

Over-ripe bananas serve as a good source for non-starch polysaccharides (NSP), which can be used as a functional food ingredient and represent an opportunity for waste utilization. However, ripe banana contains a large amount of sugars, which are undesirable and need to be removed. Traditional extraction methods using alcoholic solvents have many drawbacks. This study aims to use natural deep eutectic solvents (NADES) as new and eco-friendly solvents for the extraction of soluble sugars from ripe bananas. Thirty NADES were characterized and screened, and four of them were selected as most appropriate solvents to remove soluble sugars from banana puree with the help of microwave-assisted extraction. The effects of temperature, time, and quantity of water added to NADES were evaluated. In all cases, NADES were shown to be more effective than conventional solvents (water and ethanol). Among the four NADES, malic acid:beta-alanine:water (1:1:3, molar ratio) with 30 g/100 g of water (25 °C, 30 min) was found to be the most effective in the extraction of soluble sugars from banana puree. Thus, NADES can be considered a highly efficient extraction medium for fruits (such as bananas) and can replace conventional extractions using harsher organic solvents like ethanol.