Total phenolic (polyphenols, flavonoids, and condensed tannins) contents and antioxidant property (DPPH, ABTS, FRAP) were evaluated in hexane (HE), acetone (AC), ethanol (ET), 70% (v/v) ethanol/water (EW), and powder extracts of Jatropha gossypifolia leaves using spectrophotometric methods. The lowest and highest contents of polyphenols (10.27 ± 0.36 and 21.23 ± 0.95 mg GAE/g), flavonoids (4.83 ±0.42 and 12.53 ±0.58 mg QE/g), and condensed tannins (3.03 ± 0.18 and 7.13 ± 0.12 mg CE/g) were recorded in powder and EW, respectively. EW exhibited the highest scavenging activities displayed by the lowest IC50 values (0.23±0.01 mg/mL DPPH and 0.2±0.03 mg/mL ABTS). Moreover, it recorded the highest reducing power (92.85±1.25 mg AAE/g), followed by HE (72.73±1.99 mg AAE/g) and AC (41.84±0.47 mg AAE/g). Relevant correlations were found between the polyphenols, flavonoids, condensed tannins and reducing antioxidant power (r = 0.986, p < 0.01; r = 0.958, p < 0.01; r =0.950, p < 0.05; respectively). Based on their phytochemical and antioxidant properties, PCA classified the five extracts into three distinct clusters. The results of this study indicate that EW contains powerful bioactive molecules with noteworthy antiradical and electron donating properties. Therefore, it may be a promising candidate in the search for natural compounds with therapeutic and food/crop preservative applications.

This article is focused on the production of biodiesel from the waste cotton seed oil (WCSO), after purification, as an alternative to fossil fuels. Waste oil was collected from Sodecoton, a factory producing cotton seed oil in the Far North Cameroon. The WCSO was subjected to purification using activated coal, followed by transesterification under basic conditions (potassium hydroxide (KOH)), using methanol and ethanol. Some physico–chemical properties of biodiesel, such as absorbance of waste and purified oil, density, viscosity, water content, acid value, and its energy content were determined. The result of treating the WCSO with activated coal indicated that purification efficiency of activated coal increased with the contact time and the mass of the absorbent. Absorbance results directly proved that activated coal removed unwanted components. In the same way, activated coal concentration and exposure time influenced the level of free fatty acids of WCSO. The yield of methyl ester was 97%, while that of ethyl ester was 98%. The specific gravity at 25 °C was 0.945 ± 0.0601. An evaluation of the lower calorific value (PCI) was done in order to study the energy content of biodiesel. This was found to be a value of 37.02 ± 3.05 MJ/kg for methyl ester and 36.92 ± 7.20 MJ/kg for ethyl ester. WCSO constitutes feedstock for high volume, good quality, and sustainable production of biodiesel, as well as a realistic means of eliminating the pollution resulting from the indiscriminate disposal of waste oils from both household and industrial users.

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Milk powder was substituted by 0, 10, 20, 30 and 40% (w/w) cocoa powder, and used for yoghurt production. Microbiological and physico-chemical analyses were carried out during fermentation and sensory profile of fermented products evaluated in comparison to plane commercial yoghurt. Adding cocoa powder induced an increase of the initial pH (p<0.05). A reduction (p<0.05) of the fermented products viscosity was observed with an increase in the amount of cocoa powder. Coagulation times increased with substitution level up to 20%. Under 20% substitutions, the products were accepted by the panellist with no significant difference with respect to the control.

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