Physical, chemical, and rheological properties of flour from accessions of Frafra potato (Solenostemon rotundifolius)

Abstract

Frafra Potato (FP) is a climate-smart crop facing extinction in the tropical regions of Africa due to inadequate information about its properties. This study determined the physicochemical, functional, and rheological characteristics of flours from ten FP accessions to gauge their suitability for culinary purposes. The flour yield from FP tubers ranged from 59.3 % (E134) to 69.3 % (E111). While FP flours (FPF) exhibited consistent colour across accessions, variations in paste clarity were noted, ranging from 5.2 % (E145 and Maa-Lana) to 8.6 % (WAAPP). The least gelation concentration varied from 8 % (WAAPP) to 12 % (E 82, 111, 132, 134, 145). Released accessions showed higher protein and ash content than unreleased ones. Mineral composition differed significantly among accessions, including iron, calcium, zinc, and phosphorus, each with varying bioavailability percentages. Vitamin A content also varied across accessions. Proteins common in tuber crops, such as lipoxygenase, patatin, sporamin, tarin, and protease inhibitors (Bowman-Birk PIs), were identified in FPF. Amino acid analysis revealed nineteen amino acids, including seven essentials. FPF characteristics included a bulk density of 0.9 g/ml, oil and water binding capacities of 3 g/g and 1.3 g/g respectively, a pH of 6.4, and titratable acidity of 0.5. All FP flours displayed standard non-Newtonian behaviour, exhibiting pseudoplastic properties. They also showed a type II sigmoidal sorption curve, indicating increased equilibrium moisture content with higher water activity. Moisture sorption studies predicted a safe storage maximum allowable moisture content. These findings have practical implications for flour packaging and storage. The study underscores the culinary potential of Frafra potato and its role in addressing food and nutrition security in Ghana and Sub-Saharan Africa.