Characterization and antioxidant activity of peel extracts from three varieties of citrus sinensis

High volume of postharvest materials including peels from citrus fruits is periodically generated, which contributes to environmental pollution. Investigating the chemical composition cum antioxidant property of these 'wastes' would be instructive in achieving value addition in the food and pharmaceutical value chain. On this premise, this study carried out phytochemical screening and antioxidant activity of three (3) commonly cultivated citrus varieties namely Citrus sinensis 'valencia', Citrus sinensis 'washinton' and Citrus sinensis 'thompson navel'. The peels were extracted using ethanol and hexane in a Soxhlet extractor and thereafter subjected to phytochemical and Gas Chromatography/Mass Spectrometry (GC/MS) analyses, ferric ion reducing antioxidant power (FRAP), hydrogen peroxide scavenging and cupric ion reducing antioxidant capacity (CUPRAC) assays to evaluate their antioxidant potentials. Results show that Citrus sinensis peel extracts contain alkaloids, flavonoids, phenols, phytosterols, diterpenes, tannins and glycosides. GC/MS analysis identified about 48 compounds in each extract; with the predominant bioactive compounds being limonene (16.5%), ascorbic acid (17.7%), stearic acid (26.3%), linalool (4.7%), linoleic acid (16.18%), palmitic acid (15.23%), pentadecyclic acid (1.1%). Ethanol and hexane extracts of Valencia exhibited higher FRAP (9.09 ± 0.13) and CUPRAC (2.04 ± 0.06) values while the ethanol extract of Ibadan sweet demonstrated greater hydrogen peroxide scavenging activity (1.39 ± 0.00). Citrus peels are rich in bioactive compounds with excellent antioxidant activity and may serve as potential sources of natural antioxidants for food products or pharmaceutical formulations.

Improved storage mitigates vulnerability to food-supply shocks in smallholder agriculture during the COVID-19 pandemic

Millions of smallholder farmers in low-income countries are highly vulnerable to food-supply shocks, and reducing this vulnerability remains challenging in view of climatic changes. Restrictions to limit the spread of the COVID-19 pandemic produced a severe supply-side shock in rural areas of Sub-Saharan Africa, including through frictions in agricultural markets. We use a large-scale field experiment to examine the effects of improved on-farm storage on household food security during COVID-19 restrictions. Based on text message survey data we find that the prevalence of food insecurity increased in control group households during COVID-19 restrictions (coinciding with the agricultural lean season). In treatment households, equipped with an improved on-farm storage technology and training in its use, food insecurity was lower during COVID-19 restrictions. This underscores the benefits of improved on-farm storage for mitigating vulnerability to food-supply shocks. These insights are relevant for the larger, long-term question of climate change adaptation, and also regarding trade-offs between public health protection and food security.

Post-harvest losses of fruits and vegetables in supply centers in Salvador, Brazil: Analysis of determinants, volumes and reduction strategies

Food losses and waste are a global problem, with an estimated 1.3 billion tons lost annually. In Brazil, fruit and vegetable losses amount to approximately 30% and occur in the processing, handling and storage stages. Thus, this study aimed to evaluate the post-harvest losses of fruits and vegetables in the Central Supply (CEASA) of Salvador, Brazil, its determinants and potential solutions to minimize the problem. A cross-sectional, descriptive and quantitative study was carried out in which data were collected by observing the operation of the supply units, registration in a field notebook, and administering a questionnaire to sellers that covered four main dimensions: socioeconomic profile of vendors; hygienic-sanitary conditions; characteristics of acquisition, storage and commercialization of products; and measures used by sellers to reduce losses. Many inadequacies were found, including the transportation and reception of products and their commercialization. Regarding hygiene, there were flaws in the care of the environment, the products and the food handlers. At most sites (75%), there were problems with infrastructure. The loss was estimated to be on the order of 9.5 tonnes/week, especially bananas, papayas, tomatoes, peppers and lettuce. The main causes of loss were exceeding volume in purchases, storage without refrigeration and careless handling by consumers and vendors. Strategies to reduce losses included price reduction, donation practices and consumption by sellers. The study indicates the need for improvements both in the infrastructure and in the hygienic care, management and post-harvest conservation of the fruits and vegetables.

Effect of edible gum Arabic coating on the shelf life and quality of mangoes (Mangifera indica) during storage

This study evaluated the effect of treatment with gum Arabic edible coatings on shelf life and quality parameters of mangoes during 20 days at room temperature. Apple variety of mangoes of uniform size were obtained from small holder farms in Makueni County, Kenya and dipped in various concentrations of gum Arabic solutions [0, 10, 15 and 20% (w/v)] for 1 h, ensuring the coating solution uniformly covered the surface. Control fruits were dipped in distilled water only. The fruits were then air-dried on trays, packed in cardboard boxes and stored at room temperature (23 ± 2 °C) and normal relative humidity (45-60%). Changes in weight loss, ascorbic acid content, ß-carotene, total soluble solids (TSS), titratable acidity (TA) and pH were determined using standard methods. Gum Arabic coatings (all levels) significantly (p < 0.05) reduced weight loss, delayed increase in TSS and development of ß-carotene, while retaining ascorbic acid in the mangoes during storage compared to the controls. Gum Arabic treatments resulted into higher TA that corresponded with low pH in the mangoes compared to the control. Ripening was slower with gum Arabic treatments and a shelf life of 15 days was obtained for gum Arabic-treated mangoes compared to less than 10 days for the control. Gum Arabic coatings demonstrated gas and water vapour barrier properties, hence extending the shelf life of mangoes while maintaining quality. Gum Arabic treatment can therefore serve as an alternative preservation method for mangoes at farm and transit levels without affecting quality parameters; giving farmers more revenue and reducing post-harvest losses.

The fungal threat to global food security

Fungi threaten the security of food supply to human populations on several fronts. They destroy up to 30 % of crop products through disease and spoilage processes, while mycotoxin-producing fungi and opportunistic pathogens endanger food safety. Control of these fungi is vital for improving food security, but current measures are inadequate and further challenges due to human-population growth and climate change are escalating. Investment and innovation in research on strategies to control fungal growth, harnessed through international, inter-disciplinary collaboration across socio-economic boundaries, provides one key to rising to this challenge.

A methodological approach for the on-site quantification of food losses in primary production: Austrian and German case studies using the example of potato harvest

In the last decade, in many European Countries more and more measures have been initiated aiming at the prevention of food losses and wastes along the entire value chain. In order to evaluate or monitor such important measures it is crucial to obtain quantitative information on generated food waste amounts, subsequently enabling the quantitative evaluation of the measure's outcomes and efficiency. Currently there is a paucity of quantitative information, particularly on food losses that are directly generated during harvesting processes. Up to date, no method is available or standardised aiming at the in-situ or on-site quantification of food losses during harvest. Using the example of the potato harvest, this study presents a practical approach for determining potato losses. To test the applicability of the developed method, on-site measurements were conducted directly on the field at five different locations in Austria and Germany. Our method enables the quantification of food losses based on defined areas along the harvested potato rows, where the analyser manually collects potatoes during their harvest. Hereby, two types of potato losses needs to be considered: non-harvested, under-sized potatoes that remain under the earth and the harvested ones, which are rejected on-site because of quality requirements regarding their size, shape, and state of health. Our study shows that between 1 and 9% of field losses (based on yield potential) can be generated during the potato harvest. In future, this method may be the basis for standardised protocols in order to be able to derive cultivar-specific benchmarks and, consequently, to develop measures for preventing food losses. In general, more case studies and evidence-based ground-up measurements on other cultivars and for other regions are needed focusing on the on-site quantification of post-harvest losses.

Review: Food loss and waste in Sub-Saharan Africa

The research, development practitioner, and donor community has begun to focus on food loss and waste - often referred to as post-harvest losses (PHL) - in Sub-Saharan Africa. This article reviews the current state of the literature on PHL mitigation. First, we identify explicitly the varied objectives underlying efforts to reduce PHL levels. Second, we summarize the estimated magnitudes of losses, evaluate the methodologies used to generate those estimates, and explore the dearth of thoughtful assessment around "optimal" PHL levels. Third, we synthesize and critique the impact evaluation literature around on-farm and off-farm interventions expected to deliver PHL reduction. Fourth, we suggest a suite of other approaches to advancing these same objectives, some of which may prove more cost-effective. Finally, we conclude with a summary of main points.