Characterization of Mineral Composition and Nutritional Value of Acacia Green Pods

Abstract

The Acacia genus is considered one of the most invasive taxa in some habitats, namely coastal dunes, maritime calcareous soils, fresh lands in the valleys, mountainous areas, and the banks of watercourses and roadsides. In Portugal, the severity risk is very high, so this study aimed to evaluate the nutritional and mineral contents of the green pods as a potential source for livestock feeds and soil fertilizer because, as far as we know, there is no use for this species. The seven different species of Acacia (Acacia mearnsii Link, Acacia longifolia (Andrews) Willd, Acacia melanoxylon R. Br., Acacia pycnantha Bentham, Acacia dealbata Link., Acacia retinodes Schlecht, and Acacia cyclops A. Cunn. ex G. Don fil) were evaluated. The results showed that Acacia green pods have a high protein, fibre and minerals content, especially in potassium (K), calcium (Ca) and magnesium (Mg). All species present a different profile of the studied parameters, suggesting different potentials for their future use. Near-infrared spectroscopy was a potential tool to predict the earlier quality of the Acacia green pods to better select the raw material for the different applications.

First Chemical Profile Analysis of Acacia Pods

“…The band at 1352 cm −1 can be assigned to the C-N stretching band from the amides or amines [36][37][38]. This observed band can be due to the high protein content of acacia pods [42,43]. The peak at 1159 cm −1 could be attributed to the contribution of various vibrations, which can include C-O stretching bands from secondary alcohols, symmetric stretching vibration of carboxylic acid groups, C-C Stretching in glycosidic linkages, and C-O-C alkyl-substituted ether and esters [38,44].…”

“…The diverse distribution of the Acacia species in Portugal required the establishment of distinct geographic zones for gathering samples. The unripe green pods of A. dealbata, A. melanoxylon, A. cyclops, A. retinodes, A. longifolia, A. pycnantha, and A. mearnsii were collected in May 2021 in different regions of Portugal according to the scheme presented in [43]. After collecting the pods, they were left at room temperature until fully dry.…”