Evaluation of the mineral and antioxidant contents of fermented and extruded green plantain enriched with soyabean

Abstract

This research evaluated the impact of fermentation and extrusion on the mineral content and antioxidant properties of green plantain enriched with soybean. The problem addressed was the low mineral content and limited antioxidant capacity of plantain, which reduces its nutritional value. To enhance nutrient density and bioactive functionality, unripe plantain was blended with soybean at ratios of 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 (green plantain:soybean). Each blend was divided into untreated control, spontaneously fermented, extruded and fermented–extruded samples. Microbial, mineral, and antioxidant analyses were conducted using standard methods. Fermented samples were dominated by lactic acid bacteria, notably Limosilactobacillus fermentum, Levilactobacillus brevis, Lacticaseibacillus rhamnosus, and Lactobacillus delbrueckii, indicating active biochemical transformation. Fermentation significantly increased ferric reducing antioxidant power (FRAP) and enhanced 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity compared with raw and solely extruded samples. The highest antioxidant activity occurred in fermented-extruded blends, reflecting the synergistic effects of microbial enzymatic hydrolysis and thermal-mechanical disruption in releasing bound phenolics and bioactive compounds. Processing significantly (P < 0.05) increased iron, magnesium, potassium, calcium, and zinc contents, demonstrating improved mineral bioavailability. The distinctive contribution of this research is the combined processing strategy, which enhanced micronutrient retention and antioxidant stability. These findings support the production of nutrient-dense complementary and functional foods for small and medium-scale processors under controlled fermentation and extrusion conditions