Effect of ultraound on protein extraction, functionality, and antinutrients of sovent-defatted sacha inchi (Plukenetia volubilis L.) flour

Abstract

Chronic-degenerative diseases, such as obesity, diabetes, hypercholesterolemia, and cancer represented more than 75% of global deaths of year 2020 before the COVID- 19 pandemic. In this regard, malnutrition is one of the major driving factors. Proteins are key macronutrients involved in several biological process, nevertheless there are still several low- and middle-income countries where populations do not have access to high quality proteins. On the other hand, the highly consumed animal proteins also contribute to the previously mentioned health problems due to its contents of cholesterol and saturated fatty acids. Furthermore, Sacha Inchi is an underutilized ancient Inca crop, whose edible seeds are high in oil (45-51%) especially polyunsaturated fatty acids, protein (25-28%), and an array of important phytochemicals. After oil extraction or removal, normally by mechanical pressing of seeds, the residue is a protein-rich flour. Interestingly, the Sacha Inchi pressed cake has been previously reported to be rich in essential amino acids, predominantly tryptophan a fundamental precursor of neurotransmitters. Nevertheless, there are several protease inhibitors previously characterized from vegetable protein matrices. Thus, the objective of this work was to evaluate the efficiency of ultrasound to extract Sacha Inchi protein, while reducing its anti- nutrients content without affecting its protein quality. In this work, a 55% extraction yield of protein from solvent-defatted Sacha Inchi flour was achieved using ultrasound (15 minutes, at 1 cycle with an amplitude of 100%) under alkaline conditions (pH 11). Moreover, all the treatments assayed resulted in significative reductions of trypsin inhibitors (less than 20% of their original content); meaning that all the ultrasound- assisted protein extracts obtained herein were safe for human consumption. Likewise, alkaline extracts showed important increases on their essential amino acids, especially Tryptophan (3.4-3.8 grams/ 100 grams of protein). Regarding the in vitro protein digestibility, all the ultrasound-assisted under alkaline conditions protein extracts had significantly better protein digestibility (>82%) compared to other pulses and plant-based proteins. Finally, the techno-functional properties suggested that protein extracted from Sacha Inchi using ultrasound could be used as an adequate ingredient in formulation of functional foods and nutraceuticals, especially beverages.