Advancing solutions to cut postharvest losses in Nigeria and beyond.

Maize is highly vulnerable to infestation by the maize weevil (Sitophilus zeamais). The widespread use of synthetic insecticides in pest management has raised significant environmental and health concerns, necessitating the exploration of sustainable, plant-based alternatives. This study evaluated the insecticidal, repellent, and emergence inhibition of methanolic extracts from Aframomum melegueta, Pterocelastrus tricuspidatus, and Bryophyllum pinnatum against Sitophilus zeamais in stored maize. Standard phytochemical and antioxidant analytical techniques were used to assess the insecticidal efficacy of the plant extracts. Phytochemical screening revealed that A. melegueta possessed the highest phenols (10.65 mg/100g) and tannins (3.83 mg/100g) contents, while P. tricuspidatus recorded the highest flavonoids (3.90 mg/100g), saponins (1.44 mg/100g), and cardiac glycosides (8.31 mg/100g) levels. B. pinnatum showed the highest alkaloid content (7.85 mg/100g). Antioxidant activity assessed by DPPH radical scavenging showed strong activity across all extracts, with A. melegueta exhibiting the highest activity (74.13%). Bioassay results demonstrated a concentration and time-dependent mortality in S. zeamais, with B. pinnatum showing the highest mortality of 83.33% at 5% after 36 h, while P. tricuspidatus achieved 76.67% at 2%. Repellency assays showed that all extracts significantly deterred insect presence, with P. tricuspidatus exhibiting superior repellency even at lower concentrations. Additionally, adult emergence inhibition was most pronounced at 10%, with P. tricuspidatus and B. pinnatum recording 0.00% emergence within 12 and 24 hs, respectively. These findings highlight the potential of these plant extracts as eco-friendly insecticides. Their rich phytochemical composition, potent antioxidant properties, and strong bioactivity support their application in postharvest grain protection and integrated pest management (IPM) strategies.

The evaluation of acute toxicity of three slow-release pelletised edible essential oils (SRPEEOs) extracted from clove (Syzygium aromaticum (L. Merr. and L. M. Perry), West African black pepper (WABP), (Piper guineense Schumach. and Thonn.) and Ginger (Zingiber officinale Roscoe) on the bean bruchid, Callosobruchus maculatus (F.) infesting cowpea, pigeon pea, Bambara groundnut, Lima and Soya beans. The research was conducted under laboratory conditions at the Faculty of Agriculture, Nasarawa State University, Keffi, Nigeria. Evaluation of the SRPEEOs on susceptibility and lethal concentration (LC50) was conducted using 0.25, 0.5, 0.75, and 1.0 g/5 g legumes. The treatments were replicated three (3) times, and the experiments were laid out in a complete randomised block design. Data analyses were conducted using Statistix 10, an analytical software package, in a two-way factorial analysis. All data were transformed before analysis. The results of the LC50 showed that WABP SRPEEO caused the highest mortality of bruchids (LC50: 1 g/5 g) compared to 0.25, 0.5, and 0.75 g/5 g for clove and ginger, respectively. The three SRPEEOs were very effective in conferring protection on the legume varieties against infestation by the bruchid and can also serve as an alternative to synthetic pesticides. However, SRPEEOs from WABP proved to be more effective and can thus repel colonisation of legumes by the cowpea seed bruchid.

Food is lost and wasted to varying extents across all stages of the food value chain and for all types of food, negatively impacting food security. In Nigeria, it has been revealed that a significant quantity of food is lost both before and after storage, with losses of up to 20-30% of all grains, 30-50% of roots and tubers, and a larger proportion of fruits and vegetables. Despite the Nigerian government's primary agricultural policy being to achieve food security and self sufficiency, the agricultural sector has steadily deteriorated over the years due to inadequate government attention. One of the primary causes of food insecurity, particularly in developing countries like Nigeria, is high postharvest losses and waste resulting from inadequate food processing and storage facilities, as well as negligence or a deliberate decision to discard food. This paper reviews the basic concept of food loss and waste, examines food security and the Nigerian situation, and discusses the challenges to food sufficiency, the implications and potential benefits of food loss, as well as some possible approaches to reducing food loss and waste in Nigeria. Thus, reducing food loss and waste is one of the leading global strategies for achieving a sustainable food future. Practical and cost-effective approaches could be implemented to attain mid-term gains once put into place. The review recommends the development of a food loss and waste measurement protocol and increased investments in reducing postharvest losses in Nigeria.

Postharvest losses significantly constrain the steady market supply of plantain; thus, bio-based preservatives are increasingly employed as sustainable alternatives to chemical agents for extending its shelf life. This study evaluated the effects of bio based coatings on plantain quality during a 15-day storage period. Mature green plantains were treated with gum arabic cinnamon extract coating (A), gum arabic clove extract coating (B), gum arabic bay leaf extract coating (C), gum arabic alone (D), untreated (E) and gum arabic shea butter coating(F). Treatment B recorded the highest weight loss of 28%. Although there was a decline in the moisture content of all treatments, treatment D showed optimal retention (65.660%). Treatments A (6.24) and F (6.153) maintained pH stability, while C and D exhibited acidification (4.87 and 5.25, respectively). Vitamin C levels increased across treatments (12.5–18.7 mg/100 g), although β-carotene degraded substantially. Treatment F demonstrated the highest starch content (58.228±0.002 mg/100 g) and potassium (8.54 mg/100 g). Treatments A, B, and C resulted in reduced bacterial populations, while treatments A and B achieved complete fungal inhibition. Treatment C recorded 33.33% decay incidence despite antimicrobial activity. Panelists rated F highest in colour (7.45), appearance (7.30), odour (6.90), texture (7.60), and general acceptability (7.75). Results demonstrate that gum arabic-shea butter coatings optimized overall quality and consumer acceptability, while cinnamon and clove formulations provided superior antimicrobial protection. These composite coatings offer sustainable alternatives for extending plantain shelf life under tropical conditions.

This study assesses the susceptibility of 31 legume varieties to Callosobruchus maculatus, a significant pest of these globally important, protein-rich staple crops, which are crucial for food security in sub-Saharan Africa. Field surveys and market visits across Northern Nigeria yielded 31 cowpea varieties, which were subsequently collected and evaluated for their susceptibility to Callosobruchus maculatus infestation. Physical attributes, including seed length, width, thickness, weight, density, volume, sphericity, porosity, surface area, and moisture content, were measured. The samples were then artificially infested with C. maculatus to assess resistance. Data analysis, including hierarchical data analysis, dendrogram clustering, histograms, and correlation analysis, was employed to reveal patterns and groupings of cowpea varieties based on physical traits. Distinct groupings of cowpea varieties emerged from the study, with smaller seed dimensions forming a cluster that included pigeon pea, Azuki beans, Achi Shiru, Farin Akidi, and Bakin Akidi. Another cluster, representing medium to large-seeded varieties, comprised 573-1-1, Kidney Beans, Shamjir Brown, and Zebra Beans. Overall, Farin Akidi exhibited the highest susceptibility to C. maculatus, followed by Agwugwu and Zebra Beans. In contrast, Lima Black, Lima Silver, and Kaki beans demonstrated the most substantial resistance. The study found negative correlations between pest resistance and seed traits, such as thickness, diameter, surface area, and weight, indicating their role in resistance. These findings provide valuable insights for breeders to develop more resilient cowpea varieties, thereby enhancing storage, adaptability, and genetic diversity, which supports global food security.

Onion (Allium cepa) derivatives contain bioactive compounds with antioxidant and antimicrobial properties that may improve product quality. This study evaluated the effects of onion juice (OJ) and onion chaff (OC) on the sensory, proximate, and microbial characteristics of smoked Clarias gariepinus to assess their performance in enhancing fish quality. Onions weighing 1kg were washed and blended to a paste, the pulp was transferred through a muslin cloth (1mm mesh-size) to obtain the juice by squeezing, leaving the chaff as a waste residue Thirty freshly harvested C. gariepinus (average weight 1kg) were divided into three groups of ten fish, each treated with OJ, OC, and untreated controls. All samples were smoked using a modified smoking kiln and stored at room temperature for eight weeks. Proximate composition, microbial characteristics and sensory attributes were analysed using standard procedures. Results indicated that OC-treated fish recorded higher proximate values, which differed significantly (p<0.05) from those of OJ-treated samples. Protein content decreased slightly across treatments, from 62.38% to 60.25% (OC), 60.09% to 58.05% (OJ), and 59.43% to 55.84% (control), while ash and moisture contents increased. Sensory evaluation revealed higher scores for OJ-treated fish in taste (7.90), appearance (8.05), aroma (7.80), texture (7.80), and overall acceptability (8.10) compared to OC-treated fish. Microbial organisms isolated showed varied characteristics. These findings suggest that onion derivatives enhance the sensory, nutritional, and microbial properties of smoked fish. Onion juice performed slightly better than onion chaff, suggesting its potential as a natural quality enhancer for smoked C. gariepinus.

Postharvest losses of fruits and vegetables remain high in Nigeria due to continued reliance on traditional sun drying and limited access to electricity-powered dryers. This study presents the modification and performance evaluation of the parabolic-shaped solar dryer (PSSD) integrated with a secondary heat source and an improved airflow system, designed to address the limitations of conventional dryers in maintaining optimal drying conditions during nighttime and cloudy weather. The modified dryer was compared with an existing, non-modified unit under no-load and load conditions, using 190 kg of tomatoes as test material. Temperature, relative humidity, drying rate, colour change and moisture content were monitored during evaluation. Und both conditions, the modified dryer achieved higher internal temperatures and lower relative humidity compared to the non-modified dryer and ambient air, resulting in improved drying efficiency and overall performance. Drying curves exhibited an initial warming-up phase followed by a falling-rate period, with a peak drying rate of 36.6 kg/day observed in the modified dryer. A safe final moisture content of 12.3% was achieved in 96 hours, compared with 120 hours and 13.9% (dry basis) in the non-modified dryer. Colour analysis revealed a decrease in L* (Lightness), a* (Redness), and b* (yellowness) for both systems; however, overall colour difference (ΔE) was consistently lower in the modified dryer (≈18.9) than in the non-modified dryer (≈23.2), indicating superior colour retention. The modification enhanced thermal performance, drying efficiency, and quality preservation, demonstrating its potential to reduce postharvest losses in tomatoes and promote sustainable drying technologies for smallholder farmers.

Postharvest handling of fruits and vegetables in tropical regions faces significant challenges due to unpredictable weather. This review critically examines the application of conventional cold storage techniques in the postharvest management of tropical horticultural produce, considering the constraints that affect their performance and the environmental factors influencing the storage of tropical fruits and vegetables. Particular attention is given to the technical limitations of these systems when deployed under tropical conditions. The study systematically examined findings from peer-reviewed literature on various conventional cooling applications, offering a comprehensive overview of their performance and limitations. Furthermore, it explores the integration of solar powered refrigeration systems to enhance energy efficiency and promote technological innovation in off-grid cooling. Findings from this review underscore research gaps and highlight the need to develop advanced, climate resilient cold storage configurations tailored to the unique challenges of tropical environments. Specifically, integrating solar-powered refrigeration units with thermal energy storage (TES) compartments into conventional cooling systems for the storage of fruits and vegetables.

Banana (Musa acuminata) is a vital staple food, but it suffers from high postharvest losses due to rapid ripening and poor processing. This study designed and evaluated a low-cost solar dryer for banana flour production to reduce postharvest losses. The dryer, constructed using local materials with surfaces of aluminium foil paper and aluminium tall-list (aluminium alloy 6061 (Magnesium and Silicon) drying, incorporated solar-powered fans for forced convection. It is backed with a tall black aluminium list to trap solar radiation. Experiments compared five treatments in quadruplicate: aluminium foil paper without a fan (T1), aluminium tall-list without a fan (T2), aluminium foil with a fan (T3), aluminium tall-list with a fan (T4), and open air drying (control, T5). Economic analyses were performed to assess the economic viability of the drying systems. Results revealed that there was no significant difference between treatments T1, T2, T3 and T4, which performed better than the control. Aluminium surfaces enhanced heat retention, with internal temperatures reaching 53.1 °C in T1 compared to ambient (30 °C). Fan-assisted drying reduced drying time by 50% compared to natural convection, while aluminium surfaces alone (T2) also outperformed the control. Passive dryers (T2) are optimal for short-term return on investment (26-day Payback Period (PBP). Fan-assisted dryers (T4) maximise long term profitability (4.760,000M CFA net profit). The study concludes that solar assisted drying with aluminium surfaces and forced convection significantly improves efficiency, offering a cost-effective solution for small-scale processors in tropical regions. Future research should explore hybrid designs for further optimisation.