BACKGROUND: Soursop (Annona muricata L.) is an underutilized tropical and subtropical fruit with high nutritional and therapeutic benefits. This fruit is faced with enormous post-harvest losses due to its high perishability. This work was aimed to optimize the pectinase-assisted extraction conditions of soursop juice using Doehlert design and to study the effect of pectinase on its pectin structure. RESULTS: The predicted models were validated for all the responses studied and the regression coefficients ranged from 0.905 to 0.987 (P ≤ 0.05). An incubation time of 172 min, enzyme concentration of 0.04% (w/w) and incubation temperature at 42.9°C were found to be the optimal conditions for soursop juice extraction, which resulted in 75.20%, 3.74, 7.35°Brix, 87.06%T, and 0.44% MAE for soursop juice yield (%), pH, total soluble solids (TSS) (°Brix), clarity (%T) and titratable acidity (% malic acid equivalent, MAE), respectively. Morphologically, untreated soursop pulp presented a non-uniform spherical surface; enzyme hydrolyzed soursop exhibited ruptured and wrinkled surface; meanwhile for the different pectin obtained, untreated soursop pectin depicted porous surface and enzyme hydrolyzed soursop pectin showed whirling rough surface. Fourier-transform infrared (FTIR) confirmed the presence of similar chemical group stretching and vibrations in commercial pectin and soursop pectin. CONCLUSION: Under the optimum conditions, the numerical predictions were similar to the experimental data obtained, thus confirming the validity of the models. Application of enzyme treatment caused the breakdown of pectin structure as illustrated by scanning electron microscopy (SEM) and FTIR analyses. Supporting information may be found in the online version of this article.

In Cameroon, agrofood waste biomass such as peels of Musa paradisiaca and Musa acuminate is being valorized using various traditional processing methods to produce a traditional functional food salt, potash, locally called nikkih. Nikkih has been reported to have varying physicochemical and functional properties, which negatively affect the quality and stability of food prepared using it. This work aims at evaluating the effect of traditional process methods on the physicochemical and functional properties of nikkih produced from these peels in view of the optimization of the process. The peels were preprocessed using two methods: boiling at 90oC before drying and direct drying of raw samples. All samples were dried and combusted to ash at varying temperatures of 250oC, 300o C, and 350oC and times of 30 min, 60 min, and 90 min. The ash obtained was dissolved in varied volumes of water, filtered to obtain the nikkih. Yellow achu soup was prepared through the dry gum method using water and read palm oil, with nikkih as emulsifier. The physicochemical and functional properties of nikkih on yellow achu soup were evaluated using standard methods. The ash yield ranged from 10.62 ± 0.12% to 7.10 ± 0.05%, with the raw samples combusted at 3000C and 2500C having the highest and lowest values respectively. The pH of nikkih ranged from 10.95 ± 0 to 12.01 ± 0.056 while potash content ranged from 32.45 ± 0.905% to 72.29 ± 1.31%, with the highest and lowest values obtained from the raw sample combusted at 2500C and the boiled samples combusted at 3500C respectively. Alkaline content ranged from 61.7 ± 0.141% to 52.8 ± 0.141%, with boiled M. acuminate combusted at 3500C having the highest value and the lowest from raw M. paradisiaca combusted at 2500C. The foaming capacity and foam stability ranged from 6.9 ± 0.01% to 16.07 ± 2.51% and from 3.20 ± 0.07% to 11.205 ± 2.39% for M. acuminate and M. paradisiaca respectively. The emulsification index ranged from 85.62 ± 0.09% to 86.67 ± 1.141% after 24 hrs and from 26.0 ± 0.94% to 27.02 ± 2.390% after 48 hrs, with the highest value from the raw M. acuminate combusted at 350oC and the lowest from that combusted at 3000C. The potash source, pretreatment method, combustion conditions, and dilution factors all had an effect on the physicochemical and functional properties of nikkih.

This study aims at bringing to light the preservative potential of essential oils of Thymus vulgaris, Cinnamomum zeylanicum and Mentha piperita in the stabilisation of lipids against oxidation. The essential oils were extracted by hydrodistillation and chemical composition were analysed by gas chromatography coupled with mass spectrometry. In vitro antioxidant potentials of the essential oils were tested by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H 2 O 2) methods. The effects of essential oils on palm olein during accelerated storage for 20 days were carried out using the Shaal Oven test and indices of oxidation were measured. Essential oil of T. vulgaris was the most active oil with respect to the DPPH and H 2 O 2 tests. T. vulgaris and C. zeylanicum showed varying degree of inhibition to palm olein oxidation within 20 days of storage at 60°C. Essential oils of T. vulgaris and C. zeylanicum at a concentration of 300 ppm showed comparable results to that of tert-butyl hydroquinone (TBHQ) applied at the recommended dose of 200 ppm. Palm olein samples treated with the essential oils did not show rancid characteristics at the end of storage. These essential oils significantly stabilised palm olein during accelerated storage conditions and may be exploited for use as preservatives in food products.

Agricultural production, agro-industrial food processing, distribution and consumption generate high Amounts of varied food by-products and waste which place a heavy burden on the environment and cause losses to the food industry. The most common disposal methods of food wastes are the use of landfills and incineration, which lead to several environmental, social, and economic issues. However, many of these by-products and wastes have been reported to be higher than the final product in terms of nutritional or functional properties, making them potential raw materials for application in the agro-food industry. Together with the recent sustainable development goals of food security, environmental protection, and energy efficiency, these are the key reasons why food waste valorization is necessary. Valorization of food waste within the bio-economy approach offers an economical and environmental opportunity that can serve as a solution to the issues faced with the conventional disposal methods. Traditionally, in Africa, especially in Cameroon, food by-products and waste have been valorized into a range of products for application in food and food preparation, including food additives and spices, food emulsifiers and stabilizers, food salts and nutraceuticals. Traditional Waste valorization methods could achieve sustainable development in technologically underdeveloped countries by going beyond improving agro-food waste management to the production of useful biochemicals, food ingredients and food products, which can be referred to as value added products from waste. In addition, the processing and conversion of these agro-food by-products and waste generated in the poor regions of the world for the production and formulation of novel foods and biochemicals will directly benefit the local communities by reducing environmental pollution and increasing income in the food industry. This review aims at providing insight into current trends in food waste valorization using traditional methods in an African country such as Cameroon. This paper presents the variety and type of food waste within the food chain that can be valorized into various products using traditional methods. Furthermore, a series of examples of key food waste valorization schemes and value added products as case studies to demonstrate the advancement in traditional bioconversions are described, bringing out the opportunities and challenges for the Cameroon bioeconomy.

The aim of this study was to determine the optimum malting conditions, for rice beer production, of seven cultivars of local rice (Oryza sativa L.) cultivated in the North and Far North Regions of Cameroon. Characteristic tests prior to malting (thousand corn weight, germinative energy, germinative capacity and starch content) of the cultivars (NL36, NL56, ITA306, ITA300, BKN, IR46, NL60) were determined using analytical methods described by The American Society of Brewing Chemists (ASBC). The best cultivars used for the experimental design were NL36 and ITA300, having starch contents greater than 60% DM, germinative energies and capacities greater than or equal to 96%. A Box-Behnken Design was used to investigate the influence of the steeping duration (24-48 h), germination duration (4-7 days), and kilning temperature (45-50°C) on the diastatic power and reducing sugar content of NL36 and ITA300 malt. The optimum malting conditions for maximum diastatic power of NL36 malt (38.47 WK) and reducing sugar content (16.79 g/100 g DM) were: steeping duration of 40 h, germination duration of 4 days, and kilning temperature of 50°C with a desirability value of 0.94. The optimal conditions for a maximum diastatic power of ITA300 malt (39.097 WK) and reducing sugar content (10.34 g/100 g DM) were: steeping duration of 43 h, the germination duration of 5 days, and kilning temperature of 50°C with a desirability value of 0.97. Although rice malt has a low diastatic power compared to barley and sorghum malt, it contains limit dextrinase and α-glucosidase, which can act synergistically with α and β-amylases. These rice cultivars can be used as the main cereal for beer production, or as adjuncts to enhance the enzyme potential of sorghum or maize malt.

This study aimed to evaluate the antifungal activity of essential oils of Thymus vulgaris L., Cinnamomum zeylanicum B. and Mentha piperita L. on some saprophytic fungi. Essential oils were extracted by hydro-distillation, and chemical composition was analysed by gas chromatography coupled with mass spectrometry (GC-MS). T. vulgaris had as major components, Thymol (35.12%), pcymene (25.36%) and γ-terpinene (12.48%). E-B-Caryophyllane (21.82%), E-Cinnamaldehyde (13.03%) and eugenol (12.15%) were primary in C. zeylanicum. Menthol (33.59%), menthone (18.47%) and α-pinene (8.21%) were primary in M. piperita. Applying the micro-atmospheric method, essential oils were tested against Rhizopus oryzae Went & Prins, Rhizopus stolonifer Ehrenb, Aspergillus tamarii Taka, Aspergillus parasiticus Speare, Aspergillus flavus Link and Talaromyces purpureogenus purpureogenum. The minimum inhibitory concentrations were 3 to 8, 5 to 16 and 13 to 23 μL/75mL air space for T. vulgaris, C. zeylanicum and M. piperita, respectively. Means of percentage inhibition were compared through one-way ANOVA by the Tukey test. Scanning electron microscopy revealed fungal cell wall deformation after exposure to essential oil vapour. These essential oils can be exploited as alternatives to synthetic food preservatives.

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