Macauba Acrocomia aculeata side streams: An emerging source of innovative proteins and soluble fibers

Abstract: Macauba palm (Acrocomia aculeata) is a perennial and fructiferous palm tree native to Latin America currently considered a promising alternative for vegetable oil production. With an estimated oil yield of 5 tons per hectare per year, Macauba palm shows productivity potential similar to palm oil (Elaeis guineensis), but with a reduced risk of rainforest clearance. Both Macauba kernel and pulp render economically attractive oils. After oil extraction, the kernel meal (MKM) offers a protein concentration between 30-50%, whereas the pulp meal (MPM) has a dietary fiber content of 40-50%, both currently underutilized and thus an emerging source of valuable proteins and fibers. Therefore, the present work aimed to recover Macauba kernel proteins and pulp soluble fibers to produce food ingredients and leverage the sustainable use of Macauba fruits. For this, integrated process solutions for the downstream fractionation of Macauba proteins and fibers were developed. In the case of MKM, oil extraction was optimized and sieve fractionation (SF) was used to produce protein concentrates. For MPM, aqueous extraction was used to produce a soluble fiber concentrate.

De-oiling of Macauba kernels, comprising cold pressing, milling, and hexane extraction, followed by SF yielded a protein concentrate with 65% protein content, with improved gelling and emulsion stabilization properties compared to MKM.

Optimized aqueous extraction of Macauba soluble fibers comprising single-extraction in demineralized water at 60 °C, followed by precipitation in ethanol, resulted in a recovery rate of soluble dietary fibers of 89%. The obtained concentrate presented a soluble fiber content of 73% with negligible amounts of insoluble fibers. The soluble fiber concentrate presented versatile functionality, with an oil binding capacity of 4.2 mL/g, an emulsifying capacity of 913 mL/g, 95% of foaming stability, and shear-thinning behavior, thus with high application potential in food applications.

Therefore, the downstream fractionation of Macauba side streams resulted in sustainable and functional protein- and soluble fiber concentrates. Altogether, the exploitation of Macauba oil and the conversion of side streams from oil processing into functional ingredients can promote the sustainable use of Macauba fruits, and fuel the development of a value chain for the sustainable production of food ingredients.