Extracts from Hibiscus sabdariffa L. (roselle) have been used traditionally as a food, in herbal medicine, in hot and cold beverages, as flavouring or coloring agent in the food industry. In vitro and in vivo studies and trials provide evidence, but roselle is poorly characterised phytochemically due to the extraction processes. The optimization of the extraction of phenolic compounds and their antioxidant activities is still a hot topic. In this study, the effect of solute/solvent ratio (33, 40 and 50 mg/mL), extraction temperature (40, 50 and 60 °C) and extraction time (30, 60 and 90 min) was evaluated through the content of phenolic compounds and antioxidant activity. A response surface methodology through a Box–Behnken design was applied and model fit, regression equations, analysis of variance and 3D response curve were developed. The results showed that TPC, TFC, DPPH and FRAP were significantly influenced by temperature, extraction time and solvent/solute ratio. Thus, TPC, TFC, DPPH and FRAP varied from 5.25 to 10.58 g GAE/100 g DW; 0.28 to 0.81 g QE/100 g DW; 0.24 to 0.70 mg/mL; 2.4 to 6.55 g AAE/100 g DW respectively. The optimal experimental condition (41.81 mg/mL; 52.35 °C and 57.77 min) showed a significant positive effect compared to conventional methods. The experimental values at this extraction condition show that this optimization model is technologically, financially and energetically viable as it requires a reasonable concentration, time and temperature.

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Edible oils play an essential role in our diet. In addition to providing a nutritional function, they contribute to energy supply and are sources of essential fatty acids particularly linoleic and alpha-linolenic acids (Okparanta et al., 2018). They also participate in the supply and transport of fat-soluble vitamins including A (in terms of carotenoids), D, E, K, and other constituents of nutritional interest such as phytosterols or phenolic compounds especially for vegetable oils (Mengistie et al., 2018). This high nutritional potential of oils is due to their stability (Benmohamed et al., 2020).In Burkina Faso, vegetable edible oils are essentially made up of locally produced oils and imported ones. During 2009-2010, the demand for oil on the Burkinabe market was in the order of 60,000-65,000 tons,

(1) Background: Sorghum (Sorghum bicolor (L.) Moench) is a staple food cereal for most of the rural populations in sub-Saharan Africa. In Burkina Faso, a great diversity of sorghum cultivar is cultivated, but its nutritional potential still needs to be assessed. This study aims to characterize the physicochemical and nutritional profile of grains from 15 sorghum cultivars grown in Burkina Faso in order to identify the best ones for selection and breeding programs. (2) Methods: The physicochemical, nutritional, and antioxidant-activity characterizations of the grains were performed according to standard methods. (3) Results: The study shows significant differences between cultivars according to the physicochemical traits of the grains, such as 1000-grain weight, moisture, and germination rate. For nutritional parameters, the best contents of carbohydrates (79.36%), proteins (9.21%), and fats (4.40%) were recorded with cultivars V12, V8, and V11, respectively. The heavy grains are flouriest with high contents of carbohydrates with high ABTS antiradical activity. However, these grains have low contents of proteins and flavonoids. Those with high ash contents are the richest in amylose and phenolic compounds. Principal component analysis based on physicochemical and nutritional characteristics of sorghum grains identified four groups of varieties with specific characteristics. Group 1 (G1), which includes cultivars V1, V12, V13, V14, and V15, is characterized by a high weight of 1000 grains and mealy cultivars with relatively high total carbohydrate content and ABTS.+ antiradical activity. Group 2 (G2) includes cultivars V7, V9, and V11 and is characterized by cultivars with low 1000-grain weight, less floury but good germination rate, high protein, flavonoids, and relatively high antioxidant activity. Group 3 (G3) includes cultivars V3, V4, and V8 with relatively high ash, amylose, and polyphenol contents, while group 4 (G4), which includes cultivars V2 and V6, has high antioxidant activity and high fatty acid content. Conclusions: The study recorded a variation of physicochemical and nutritional characteristics of sorghum grain according to cultivars. The cultivars were divided into four groups. Among them, the group 1 cultivars have the best nutritional traits and could therefore be used in breeding and selection programs to improve the nutritional potential of sorghum.