A combined mechanical grinding-deep eutectic solvent strategy for the deconstruction of carbohydrates-rich fruit by-products

The efficient recovery of carbohydrates from fruit by-products is limited by their restricted accessibility, as they are embedded within the complex cell wall matrix. Overcoming this barrier requires particle-size reduction, matrix disruption and selection of appropriate solvent. Recently, natural deep eutectic solvents (NADES) have emerged as promising sustainable alternative for polysaccharide recovery. However, their high viscosity can hinder mass transfer and consequently extraction yield. This study investigates the combination of NADES with grinding to enhance cell wall carbohydrates accessibility in lemon peel and apple pomace. Vibratory ball grinding was performed in presence of three chloride-based NADES: lactic acid (CCLA), malic acid (CCMlic), and malonic acid (CCMnic). Combining grinding with CCLA and CCMlic significantly increased mass yields, up to four-fold, reaching a maximum of 9.0%. This increase was associated to increased surface area and mechanical energy input by impact, as supported by modelling. In contrast, CCMnic showed limited efficiency with yields up to 4.3%, likely due to weaker solvent-matrix interactions. Compositional analyses revealed the co -extraction of polysaccharides with other components, including lignin (3.0 to 15%). Additionally, the initial disruption degree of the fruit by-product was identified as a critical factor for polysaccharides recovery.