Fruit peels are increasingly being used as functional foods nowadays. Peelings of twelve varieties of Persea americana fruits consumed in Cameroon were investigated for their phenolic compounds (polyphenols and flavonoids) using three solvents systems, water, ethanol: water (50 : 50 v / v ), and ethanol, and antioxidant activity using total antioxidant capacity (TAC), ferric reducing antioxidant power (FRAP), and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging methods. Total polyphenol, flavonoids, and antioxidant potential of the peels significantly varied with P. americana variety and also with the extraction solvents in the order ethanol > ethanol: water > water. Total phenolic content varied from 2407 (Fuerte florid) to 673 (Semil) mg GAE/g DM, respectively, while flavonoids varied from 986 to 119 mg QE/g DM for Fuerte florid and Hickson varieties, respectively. TAC, respectively, varied between 132.87 and 126.85 mg AAE/g DM with Hass and Semil varieties, respectively. The highest DPPH scavenging capacity was recorded for the ethanolic extract with Lula (86.33%) and the least for the aqueous extract with the Semil (30.11%) variety. With FRAP, the highest capacity was obtained with hydroethanolic extract of Fuerte florid (0.43 mg AAE/g DM) and the least for aqueous extract with the Semil (0.269 mg AAE/g DM) variety. In conclusion, varieties of avocado peels are a good source of antioxidants. Solvent extraction significantly affected the concentration of bioactive compounds but not the potency of the antioxidants. A weakly positive correlation but not significant between the quantity of polyphenol, flavonoid, and antioxidant capacity of avocado peelings was obtained in this study.

Aims: As the world nowadays is turning towards the research of biologically active natural compounds, this work aimed at assessing the antioxidant potential of compounds contained in the aqueous extracts of three common Cameroonian pharmacopoeia plants, namely Millettia laurenti (Wengé) seeds, Lophira alata (Azobé) leaves and Milicia excelsa (Iroko) barks and the associated bioactive compounds. Methodology: After being dried and ground, they were macerated in water and the polyphenols, tannins, flavonoids, and alkaloids quantified. The antioxidant potential of the extracts was evaluated through DPPH free radical scavenging, NO scavenging, phosphomolybdate method (TAC), and iron-reducing power (FRAP). Results: The mean concentrations obtained ranged between 527 and 1213 µg GAE/g DM for polyphenols, 0.39 and 0.65 µg GAE/g DM for tannins, 19.79 and 27.06 µg QE/g DM for flavonoids, 15.72 and 16.02 µg QuE/g DM for alkaloids. Aqueous extracts of Wengé (AE-WG) and Azobé (AE-AZ) exhibited the highest and significantly similar contents. AE-AZ presented the highest iron reducing power (0.015 µg AAE/g DM at 10 mg/mL) and NO scavenging (IC50=3.63 mg/mL) while AE-WG showed the highest DPPH scavenging activity (IC50 = 4.20 mg/mL) and total antioxidant capacity (0.39 µg AAE/g DM at 10 mg/mL). No significant correlation was observed between studied bioactive compounds and the different antioxidant responses except flavonoids and tannins with TAC (p<0.05). Conclusion: AE-AZ and AE-WG exhibited different antioxidant mechanisms and are therefore of high interest for potential use in the food industry and medicine with reserves to toxicological studies.

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Aims: Ginger (Zingiber officinale) is one of the most popular and widely used spice, known for its health benefits. This study aimed at assessing the potential impact of a Handcrafted dryer (HCD) on the quality of ginger in comparison to the most common drying methods. Methodology: Fresh ginger originating from 2 regions were dried using the following techniques: HCD; Air Drying (AD); Ventilator Oven (VO) at 50°C, 60°C and 80°C; Freeze Drying (FD) and Microwave drying (MD) at 700 and 900 W) methods. Dried products were ground and infused in hot water and the total flavonoid contents, and antioxidant potential through different mechanisms (DPPH radical, FRAP and TAC assays) as well as the sensory properties of the infusions were assessed. Results: TFC of the samples significantly varied with regard to the origin of the Ginger. Infusions deriving from the dried ginger from HCD and VO at 80°C exhibited the highest TPC, TFC and antioxidant activities. While the rise of temperature with VO led to an increase of TPC, it was rather a decrease that was observed with the rise of microwave power level but which did not have a significative effect on the antioxidant potential. No significant difference was noticed in the acceptance of infusions by consumers except MD samples, which received the lowest score by panelists. Conclusion: Heat-based processes appears to be useful in the optimization of the nutritional value of dried ginger, and HCD appropriate for farmers as it is easy and not expensive to put into practice.