Issue 4: Nigerian Journal of Postharvest Research
Articles in This Issue
Evaluation of a Low cost Storage System for Shelf-life Extension of Fresh Onions. Nigerian Journal of Post-Harvest Research, 3(4), 1-10
Onions, a major commercial vegetable crop, suffer losses during off-season storage due to sprouting and weight loss. This study examined the impact of different storage systems on the storability of onion bulbs under three storage conditions: a conventional onion storage system (COSS), the Nigerian Stored Products Research Institute's (NSPRI) solar storage system (NSCSS), and a low-cost onion storage system (LCOSS). 2,500 kg of fresh red onions were procured, sorted, and stored for a period of six months, between March and September. Samples were taken randomly every month to analyse their physical and chemical changes. Descriptive statistics and ANOVA were performed on the data recorded using SPSS at a significant difference of (p<0.05). It was observed that when relative humidity increases, particularly over 50%, there is a corresponding rise in the percentage weight loss of the stored onion. An average weight loss of 73.3%, 71.2%, and 85.6% was recorded at the end of the experiment for LCOSS, NSCSS, and COSS, respectively. A significant increase (p<0.05) in total polyphenols from 5.50 ± 0.55 GAE (mg/g) in all storage systems was observed during the study, with a steady increase (approximately 28.9%) in OSS, which is 37.7% higher than in other systems at the end of storage time. However, ascorbic acid declined significantly, with less than 50% retained beyond the third month. The dietary energy value decreased significantly (p<0.05) by 62.2%, 22.7%, and 32.8% in NSCSS, LCOSS, and Conventional, respectively. The study showed that LCOSS reduced sprouting. However, there is a need to modify both NSCSS and LCOSS to minimise weight loss.
Awareness and Utilisation of Improved Postharvest Technologies in Nigeria. Nigerian Journal of Post-Harvest Research, 3(4), 11-22
Postharvest losses substantially challenge global food security, particularly in low and middle income countries. Recognising the criticality of leveraging improved/new postharvest technology to address these losses, this study assesses the gap between available postharvest technologies and their awareness and use among farmers in Osun State. The study adopts a cross-sectional research design. With the assistance of the Agricultural Development Program officers in Osun state, a total of 126 farmers were randomly selected from the three agricultural zones in the state. The survey instrument was a structured questionnaire designed to investigate awareness, provisions, use, and challenges of postharvest technologies. The result revealed an increased awareness (34.7%) and use of improved storage technologies (mainly PICS and hermetic drums) over other technologies. Very few respondents are aware of ventilated plastic crates (5.5%), multi-crop dryer machines (4.5%), evaporating coolant systems (3.4%), and cold chain technology (3.0%). Moreover, high cost is a major hindrance, not only to adoption but also to the continuous use of some postharvest technologies. The substantial role of extension officers in providing and disseminating knowledge about new technology was evident. The study recommended strengthening extension services at all governance levels to create targeted awareness on lesser-known postharvest technologies such as ventilated plastic crates and multi crop dryers. Additionally, private and public sector-backed subsidies, microcredit facilities, and cooperative financing models should be introduced to address high costs and ensure sustained adoption of postharvest technologies.
Assessment of Drying Methods for Shelf Life Extension and Nutritional Composition of Tomato Fruits. Nigerian Journal of Post-Harvest Research, 3(4), 23-31
The high moisture content of tomato fruits limits their storage and availability. This study evaluated the role of drying in extending shelf life and its effect on nutritional quality. Fresh samples (10 kg) were processed by sun-drying (36–40 °C, 7 days) and oven-drying (50 °C, 17 h). Proximate, mineral, and vitamin contents were analysed using standard laboratory methods. Dried samples were packaged in aluminium foil and stored for 12 weeks in a dry cabinet. After this storage period, post-storage analyses were conducted. Drying was observed to significantly reduce moisture and increase ash, fibre, protein, and carbohydrates (p ≤ 0.05). Sun-dried tomatoes retained higher ash (5.90 ± 0.44 %), fibre (3.07 ± 0.04 %), protein (7.01 ± 0.01 %), and carbohydrates (75.12 ± 0.01 %), while oven-dried samples had higher fat (1.09 ± 0.04 %) and moisture (13.00 ± 0.10 %) (p≤0.05). After storage, moisture, ash, and fibre levels declined, whereas protein and carbohydrate levels increased. Mineral analysis revealed a decrease in phosphorus, sodium, calcium, and iron after drying, while nitrogen, magnesium, and zinc levels increased. Oven-dried samples preserved higher nitrogen (2.52 ± 0.02%), potassium (166.07 ± 0.0001 mg/100g), and iron (0.44 ± 0.02 mg/100g) levels (p ≤ 0.05). Vitamins A, C, folate, β-carotene, and lycopene declined significantly after drying. Oven-drying retained more vitamin C (10.03 ± 0.02 mg/100 g), β-carotene (14.28 ± 0.04 mg/100 g), and lycopene (28.19 ± 0.002 mg/100 g) (p≤0.05). Storage further reduced the levels of calcium, sodium, and lycopene. Drying effectively extended the shelf life of tomato fruits, and oven-drying better preserved sensitive micronutrients, supporting its use in small- and medium-scale processing.
The Effects of Processing and Varieties on Vitamins and Antioxidants of Sesame (Sesamum indicum L.). Nigerian Journal of Post-Harvest Research, 3(4), 32-38.
Sesame is rich in dietary nutrients; however, varietal selection and processing methods can alter its nutritional composition. Hence, in 2023, three sesame varieties (White Benue, Cameroon White, and E8) were cultivated for a duration of four months at Osun State University, using established agronomic practices. Following the harvest, standard analytical methods were employed to assess the variations in vitamin and antioxidant levels arising from processing. The Ferric Reducing Antioxidant Power (FRAP) was notably highest in the E8 variety, at a value of 17.80 mg/mL, and was lowest in Cameroon White, with a value of 17.30 mg/mL. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH) was significantly highest in White Benue at 44.8%, while Cameroon White recorded the lowest at 41.0%. Vitamin C content was significantly greater in raw sesame flour (4.11 mg/100 g) compared to roasted sesame flour (1.37 mg/100 g). Vitamin A was also higher in raw sesame flour (0.13 mg/100 g) and significantly reduced in roasted sesame flour (0.08 mg/100 g). Similarly, Vitamin E levels were significantly higher in raw sesame flour (2.44 mg/100 g) and lower in roasted flour (2.08 mg/100 g). The antioxidant activity, measured via DPPH assays, indicated that the raw sesame flour had a significantly greater value (51.61%) than the roasted sesame flour (34.35%). Raw sesame flour possesses superior nutritional content; however, if heat treatment is necessary, it should be applied mildly to avoid damaging the beneficial compounds in the sesame flour.
Design and Performance Evaluation of a Low-Cost Dryer for Reducing Postharvest Banana Losses and Supporting Flour Processing in Smallholder Systems. Nigerian Journal of Post-Harvest Research, 3(4), 39-53
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.
Assessment of Farmer Awareness and Adoption of Biotechnology Based Post-Harvest Loss Mitigation in Southwest Nigeria. Nigerian Journal of Post-Harvest Research, 3(4), 53-59
This study assessed the awareness and adoption of biotechnology-based post-harvest loss mitigation strategies among crop farmers in Southwest Nigeria. A descriptive survey design was employed, and data were collected from 400 farmers using a multi-stage sampling procedure and a validated 4-point Likert-type questionnaire (Cronbach's α = 0.82). Descriptive statistics, Pearson correlation, multiple regression, and one-sample t tests were used for analysis at a 0.05 significance level. Findings indicated a moderate level of awareness (overall mean = 2.46) but low adoption (overall mean = 2.27) of biotechnology innovations, including genetically modified crops, bio-preservatives, and biopackaging. The correlation analysis revealed a weak but statistically significant negative relationship between awareness and adoption (r = −0.1136, p < 0.05), indicating that higher awareness does not necessarily lead to increased adoption. Regression results showed that socio-economic (education, credit access) and institutional factors (extension services, input access) had positive but statistically insignificant effects. At the same time, membership in an association exhibited a negative influence. The one-sample t-test revealed that only technical difficulties (mean = 2.60) exceeded the 2.50 benchmark, indicating that constraints were generally moderate rather than severe. These results highlight the disconnect between awareness and adoption, which is shaped more by affordability, technical barriers, and institutional weaknesses than by lack of knowledge. The study concludes that enhancing adoption requires integrated interventions beyond awareness creation, including input subsidies, farmer training, credit access, and stronger extension systems to translate awareness into practice and reduce post-harvest losses.
Antifungal Activity and In Silico Study of Phyllanthus Amarus Ethanolic Leaf Extract against Pests of Stored Grains. Nigerian Journal of Post-Harvest Research, 3(4), 60-76
The persistence of synthetic pesticides in the environment and their toxic residues in food pose significant health risks, necessitating the pursuit of safe and eco-friendly green alternatives in postharvest management of stored grains. The antifungal efficacy of Phyllanthus amarus ethanolic leaf extract against Aspergillus flavus, Fusarium spp., and Penicillium spp. in stored maize and cowpea was evaluated in this report. The extract was screened for the presence of phytoconstituents. The results revealed the presence of phenols, tannins, flavonoids, alkaloids, and other bioactive compounds, while the GC-MS analysis identified 18 specific compounds. Antifungal activity was assessed using an in vitro food poisoning assay and in vivo storage studies. The results of the in vitro assay showed 85.3% inhibition against A. flavus, 83.7% against Fusarium spp., and 81.5% for Penicillium spp. The positive control demonstrated significantly lower inhibition, confirming the efficacy of P. amarus bioactive compounds. In vivo storage studies showed that the extract maintained fungal counts at 1.2–1.8 × 10⁶ cfu/g, whereas untreated samples reached 8.5 × 10⁶ cfu/g for A. flavus. Four phytoconstituents from the GC-MS result of the ethanolic extract of the Phyllanthus amarus leaves were docked against lanosterol 14-alpha demethylase (4LXJ), with Propiconazole as the standard ligand. Hinokinin was identified as the hit ligand, exhibiting the highest binding affinity compared to the other ligands. The outcome of this study suggests that P. amarus is a promising bio-preservative for grain storage, and its antifungal activity is attributed to the activity of the phytoconstituents, with hinokinin serving as the lead compound.
Assessment of Constraints of Fish Processing and Storage Technologies among Fish Processors and Marketers in Delta State. Nigerian Journal of Post-Harvest Research, 3(4), 77-83
This study examined the assessment of constraints of fish processing and storage technologies among processors and marketers in Delta State, Nigeria. The objectives were to describe the socio-economic characteristics of respondents, assess their awareness of fish processing and storage technologies, and identify the most frequently used technologies and associated constraints. A total of 180 respondents were selected through simple random, snowball, and purposive sampling techniques, and data were collected using structured questionnaires. Analysis was conducted using frequency counts, percentages, and mean rankings. Results revealed that 61.7% of respondents were female, 81.1% were married, and the mean household size was five persons. About 47.2% had secondary education, while 42.8% sourced capital from cooperatives. Locally fabricated smoking kilns were the most commonly used (34.4%), but were constrained by cuts, burns, and stressful use. For modern smoking kilns, high cost and poor access to improved technologies were the most critical challenges. The study concludes that although modern technologies such as the NSPRI smoking kiln and iced fish box offer improved efficiency and product quality, their adoption remains low due to high costs, limited awareness, and poor accessibility. It is recommended that government agencies, research institutes, and development partners intensify efforts in developing and disseminating affordable and user-friendly technologies, strengthening extension services, providing financial support, and implementing gender-sensitive policies to reduce post-harvest losses and improve the livelihoods of small-scale fish processors in Delta State.