Screening of West Cameroonian edible plant-based mucilage for the production of improved protein-polysaccharide conjugates

Abstract

In developing countries, blending the powders of locally utilized edible plants for mucilage extraction can be a way to address the growing demand for more viscous and soluble cost-effective hydrocolloids. This study aimed to identify mucilaginous edible plants exploited in the western region of Cameroon in order to enhance the viscosity and water solubility of their mucilages. A semi-administered questionnaire facilitated a comprehensive ethno-nutritional survey. Powders (200 μm) from mucilaginous plants available were defatted, oven dried, and used to produce crude extracts in a water bath (50 °C, 1 h, 2 cycles), with distilled water (1:10, m/v), followed by triple filtration (60 μm, 25 °C) and double centrifugation (2900 g, 20 min). The apparent viscosity of these crude extracts was recorded (spindle 2#, 600 s−1, 60 rpm) at 25 °C, and compared to a 0.2% (m/v) xanthan gum solution (in distilled water). The best plant powders were blended (5 blends) for use under an alkaline condition (pH 10, 0.025 M) for optimal liquid mucilage production and its corresponding powder named hibisanua, derived by coagulating the liquid mucilage (4 °C, 96% ethyl alcohol), oven drying (45 °C), powdering, and sieving (200 μm). Some rheological parameters were determined. FTIR and SEM analysis were carried out with the mucilage hibisanua. Out of 300 surveyed participants, 120 (40%) from 17 ethnicities use the identified plants. Thirty species were found, spanning 27 genera and 19 botanical families. Hibiscus esculentus (okra) pods, Triumfetta annua (nkui) bark, and Corchorus olitorius (lalo) leaves are commonly used in traditional food processing. However, only okra (9.23 Pa s) and nkui (5.54 Pa s) liquid mucilage viscosities were similar to xanthan, making their defatted powders interesting. The validated plant powder mixture (F2) thus comprised 10% nkui and 90% okra (w/w). Their crude extract of concentration 1.51% (w/v) showed the highest dynamic viscosity (23.05 Pa s), not significantly different (p ≥ 0.05) from the control. The resulting dry mucilage with a yield of 215.8 mg/g F2 had the highest solubility (83.05%) with a specific viscosity of 11.519 Pa s upon a desirability of 0.73. All polysaccharides’ solutions exhibited pseudoplastic characteristics and shear-thinning behaviour. A concentrated solution (1.51%) of hibisanua had a rheologic index (0.742) and viscous relaxation time (69.25 s) comparable to xanthan gum. Its structural analysis revealed functional group and morphological changes, typical of highly physical gelling pectic mucilages. These findings support the formulated plant powder approach and the use of its mucilage in the food and pharmaceutical industries.