Impact of State of Ripeness and Culinary Treatments on the Hypoglycemic, Antioxidant, and Nutritional Properties of Two Varieties of <i>Solanum aethiopicum</i> L. Fruit

Abstract

The aim of this study was to characterize two varieties of Solanum aethiopicum according to their ripeness stage and culinary treatments. Green and red fruits from the local variety (V1) and the modern variety (V2) were subjected to steaming and boiling, resulting in 24 samples. These samples were used to assess the phytochemical, nutritional, antioxidant, and hypoglycemic properties of S. aethiopicum using standard methods. The results showed that all the samples had high fiber content, with the highest fiber content found in the pulps of each variety (26.76 ± 0.16%DM for V1 and 30.82 ± 0.10%DM for V2). The results also showed that culinary treatments reduced the antinutrient (phytates, oxalates, and tannins) content. The presence of minerals in the samples, such as iron and zinc, varied, with iron contents ranging between 2.27 ± 0.01 and 7.48 ± 0.03 mg/100 g, and zinc contents ranging between 1.02 ± 0.01 and 21.97 ± 0.32 mg/100 g. The red samples showed higher total phenol content before culinary treatment in both varieties, with a value of 101.01 ± 1.04 mg GAE/g; however, a significant decrease was observed after the two cooking methods. The samples also showed the ability to reduce Fe 3+ to Fe 2+ and to scavenge DPPH free radicals. The ability of S. aethiopicum extracts to inhibit the α‐amylase enzyme showed inhibition percentages above 50% in the selected samples in vitro. Furthermore, in vivo, the oral glucose tolerance test showed that the extracts exhibited hypoglycemic activity, as the samples effectively regulated glycemic peaks compared with the negative control. In conclusion, the steamed, skin‐on fruits of the local variety of S. aethiopicum exhibited the best nutritional, antioxidant, and hypoglycemic properties.