A comprehensive characterisation of mezquite seeds Algarroba as a source of galactomannans of interest to the food industry

Abstract

The mezquite “algarroba” fruit, produced by species of the Neltuma genus in the Gran Chaco Americano region, has historically been used by indigenous communities to produce flour. In Paraguay, the value chain surrounding it is still in its infancy, but there is growing interest in its full utilisation. The seeds, which are commonly discarded as biowaste, contain galactomannans with technological properties that make them a potential natural alternative to commercial hydrocolloids. This study aimed to characterise the physical properties and chemical composition of Neltuma chilensis seeds from the Paraguayan Chaco and evaluate their potential as a source of dietary fibre and galactomannans. Physical parameters (weight, dimensions and colour) as well as moisture content, protein, lipid, dietary fibre and mineral content were determined using official methods (AOAC). Available carbohydrates, total sugars and caloric value were also quantified. Galactomannans were extracted with isopropanol using two treatments. Mannose and galactose were quantified using liquid chromatography with a refractive index detector (HPLC/RID). The results revealed high levels of dietary fibre (47.39 ± 2.25 g/100 g) and protein (27.55 ± 2.92 g/100 g) in the seeds, as well as notable concentrations of phosphorus, potassium, and magnesium. No statistically significant differences were observed in the mannose/galactose ratio (1.38 ± 0.02) between the treatments used (p < 0.05). Beyond their composition, the technological potential of these seeds supports their use in functional foods that could contribute to digestive and metabolic health. This work provides novel evidence for the revaluation of this traditionally underutilised by-product, in line with strategies for functional nutrition, waste reduction, and the development of a sustainable bioeconomy in the Paraguayan Chaco.