Mycotoxins contamination in some agricultural food commodities seriously impact human and animal health and reduce the commercial value of crops. Mycotoxins are toxic secondary metabolites produced by fungi that contaminate agricultural commodities pre- or postharvest. Africa is one of the continents where environmental, agricultural and storage conditions of food commodities are conducive of Aspergillus fungi infection and aflatoxin biosynthesis. This paper reviews the commodity-wise aetiology and contamination process of aflatoxins and evaluates the potential risk of exposure from common African foods. Possible ways of reducing risk for fungal infection and aflatoxin development that are relevant to the African context. The presented database would be useful as benchmark information for development and prioritization of future research. There is need for more investigations on food quality and safety by making available advanced advanced equipments and analytical methods as well as surveillance and awareness creation in the region.

Increasing consumer awareness regarding the health benefits of different nutrients in food has led to the requirement of assessing the effect of food processing approaches on the quality attributes. The present work focuses on understanding the effects of ultrasound (US) processing, mild heat pasteurization (65˚C for 15 min), thermal pasteurization (80˚C for 15 min) and their combination on physicochemical, microbiological properties and nutritional quality of pineapple juice through 60 days of storage at room temperature. Ultrasound treatment showed significantly lower browning degree. Ultrasound followed by ultrasound combined with mild heat pasteurization (UMP) treatments was effective in retaining the total phenolic content of pineapple juice as compared to the thermal treatment or the untreated juice sample at room temperature during 60 days of storage. Thermal pasteurization (TP) followed by ultrasound combined with mild heat pasteurization (UMP) and ultrasound (US) treatment, in increasing order, was found to be effective in delaying microbial growth in pineapple juice. This study demonstrates that ultrasound combined with mild heat pasteurization treatments could be able to effectively inactivate the microorganisms and pectin methylesterase in pineapple juice whilst preserving relatively high amount of phenols.

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Contamination of foods with mycotoxins represents an important limit to the income of farmers and a major public health concern especially in tropical countries. Cassava represents an important part of the diet of many people in this part of the word and the most important smallholder crop in Africa. Fungal contamination of cassava products can occur at pre-harvest level or after, during processing, according to the conditions (moisture, temperature, competition with other microorganisms). Such fungal contamination can also lead to mycotoxin accumulation. The most common fungi found in cassava products belong to genera Rhyzopus, Aspergillus, Fusarium, Phoma and Penicillium. Their corresponding mycotoxins could also be found in cassava. However, until now, the correlation between the presence of Aspergillus flavus and its toxins aflatoxins remains unclear. In this review, we broadly report data about mycotoxins contamination of cassava (Manihot esculenta Crantz) and its derivatives, with a special emphasis on aflatoxins.

The scopoletin level in a cassava variety from Benin, BEN 86052, and the compounds effect on the growth of an Aspergillus flavus isolate from cassava chips were investigated. The influence on the biosynthesis of aflatoxins was also investigated. Scopoletin was quantified using high performance liquid chromatography. An in vitro test was used to evaluate the inhibitory effects of cassava flour extracts and pure scopoletin on growth and biosynthesis. The A. flavus isolate was genetically characterized to be an aflatoxin producer using polymerase chain reaction. Scopoletin was found in roots and chips with a level ranging from 4.9 to 242.5 mg/kg dry weight. Scopoletin induction was noticed after a peeling and drying process (6 days). Aflatoxin production by a strain of A. flavus holding the cluster Nor1, Omt1 and OmtB responsible for aflatoxin biosynthesis was inhibited by scopoletin and cassava flour at lower concentrations (0.024 mM). Scopoletin could be used on other commodities susceptible to mycotoxin contamination. PRACTICAL APPLICATIONS Scopoletin accumulated in cassava variety used for chips production. Scopoletin inhibited the production of aflatoxin by toxigenic Aspergillus flavus. The use of this compound on other crops susceptible to fungi infection and aflatoxin contamination could be investigated to reduce food spoilage and mycotoxin contamination.

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A new method that uses HPLC with a photochemical reactor for enhanced detection was developed and validated for the determination of aflatoxins in cassava flour. Samples were spiked with a mixture of four aflatoxins at 5, 10, and 20 g/kg mixed with either 1 or 5 g NaCl and extracted with methanolwater (80 20, v/v) by shaking for 10 or 30 min. An immunoaffinity column was used for cleanup. HPLC with postcolumn derivatization, for enhancement of aflatoxin fluorescence, and fluorescence determination were used for quantitation of the toxin concentration. The method was validated for recovery, linearity, and precision at the three concentrations tested. Recovery ranges were 5270, 6985, and 8089 for the spiking levels of 5.0, 10.0, and 20.0 g/kg, respectively. It appears that the amount of salt (NaCl) and the shaking time are critical factors in this method; optimal performance was obtained when 1 g salt was used and the shaking time was 10 min. The good linearity and precision of the method allowed baseline separation from interferences, e.g., coumarins.

Casuarina equisetifolia (L.) (Casuarinaceae) and Oxalis corniculata (L.) (Oxalidaceae), two medicinal plants used in Bénin were screened for their antifungal activity against six strains of the genus Aspergillus (Aspergillus fumigatus, Aspergillus flavus, Aspergillus terreus, Aspergillus parasiticus, Aspergillus ochraceus and Aspergillus nidulans). The antioxidant activity and phytochemical constituents were also examined. The extracts were screened for the presence of alkaloids, coumarin, anthracene derivatives, flavonoids, lignans, essential oils, naphtoquinones and terpenoids. The antifungal activity was carried out using agar diffusion method, while antioxidant activity was determined by the 2,2-diphenylpicrylhydrazine method. Phytochemical investigation revealed the presence of flavonoids, anthracenic derivatives, essential oil, pigments, terpene and triterpene in the leaves of O. corniculata and terpene and pigments in the fruits of C. equisetifolia. The antifungal activity of extracts is more marked on the sporulation (17.74 to 99.48%) than the mycelia development (7.69 to 65.71%). Methanol and hydro-ethanol extracts showed the best inhibitory percentage of DPPH radical (78 to 95%).