Issue 6: Nigerian Journal of Postharvest Research
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Articles in This Issue
Assessment of Pesticide Handling Practices, Safety Awareness, and Management Behaviours among Grain Handlers in Dawanau Market, Kano State. Nigerian Journal of Post-Harvest Research, 3(6), 1-7
Pesticide misuse in Kano State poses a threat to both human health and agricultural trade. This is partly because grain handlers often lack training and overlook safer integrated pest management (IPM) practices. A purposive multi stage sampling technique was employed to select 120 pesticide handlers across 12 market commodity lines, and the collected data were analysed using SPSS and Microsoft Excel. Findings reveal critical gaps in pesticide handling at Dawanau Market, Kano. Although 64.2% use protective gear and 61.7% follow dosage instructions, 57.5% rarely use manuals, and 51.7% mix solutions incorrectly. Limited access to personal protective equipment, illiteracy, and poor exposure response highlighted the need for improved training and stricter regulation. Despite this, nearly half lacked formal training in pesticide use, pointing to a significant training gap. Approximately 81.7% of pesticides used were purchased from licensed vendors and stored properly; however, some handlers still stored them within living spaces, posing health risks. Preliminary awareness of first-aid procedures was evident, whereas understanding of safety label signals demonstrated variability. To address these, tailored training programs, supportive policy measures, and greater engagement in professional organisations are essential. Implementing these measures will help protect the health of handlers and the environment, while also boosting the quality and marketability of agricultural produce from Dawanau Market, Kano State.
Effect of Standard Fish Processing Practices on Livelihood Status of Fish Processors in Delta and Edo States, Nigeria. Nigerian Journal of Post-Harvest Research, 3(6), 17-26
Usage of improved fish processing methods appears to be relatively low compared to traditional methods. Hence, this research aimed to investigate the effect of the utilisation of Standard Fish Processing Practices (SFPP) on the livelihood status of fish processors in Delta and Edo States. Users and non-users of SFPP were sampled. Sampling of users involved a random selection of 70% from the trained 90 fish processors per state to give a sample size of 63 respondents per state and 126 users for the two states, while the snowballing technique was employed to select 63 non-users per state and 126 non-users for the two states to give a total sample size of 252 respondents for the research. Data used for this research were sourced using an interview schedule and analysed using descriptive statistics and a t-test. The results revealed that the majority (77.8%) of SFPP users had a high livelihood status, whereas a high percentage (63.5%) of non-users had a low livelihood status. Additionally, users of SFPP reported a better health status (19.95±3.29) compared to non-users, who had a poorer health status (52.50±8.15). Additionally, the majority (96.8%) of SFPP users were food secure, while 86.5% of non-users were food insecure. Vulnerability to poverty was low for 90.5% of SFPP users, whereas 80.0% of non-users showed high vulnerability to poverty. The study concluded that the usage of SFPP has significantly improved the livelihood status of fish processors in the study area. The study therefore recommends that agricultural extension agencies strengthen their efforts to disseminate SFPP to non-users.
Functional Properties, Hydrolysis and Estimated Glycemic Indices of Processed Orange and Creamed Coloured Skinned Sweet Potatoes. Nigerian Journal of Post-Harvest Research, 3(6), 50-62
In the present work, orange-coloured sweet potatoes (OCSP) and cream coloured skinned sweet potatoes (CCSP) were processed using the following methods: steaming (with or without peeling), roasting, boiling (with or without peeling), and frying. The functional and pasting properties, colour (L* a* b*∆E*), hydrolysis, and estimated glycemic indices (eGI), as well as the glycemic loads (GL) of the processed sweet potatoes, were studied. Results revealed that processing methods increased the swelling capacities, water absorption capacities, and bulk densities of sweet potato flours, with steaming (with or without peel) having the highest values. Processing methods reduced lightness (L*). They increased the yellowness (b*) of the sweet potato flours, while well visible colour differences (∆E*) were observed in the processed samples compared to the control (RAW – OC and RAW – CC). Processing reduced the HI, eGI, and GL of the sweet potatoes; the lowest values of these parameters were observed in the roasted samples. In this study, roasting was observed to provide significant nutritional benefits, making it a suitable dietary regimen for individuals who require low- to medium glycemic index (GI) foods.
Physicochemical Characteristics of Hydrocolloids Extracted from Peels and Flesh Flour of Selected Root and Tuber Crops in South-Eastern Nigeria. Nigerian Journal of Post-Harvest Research, 3(5), 71-78.
Plant-based hydrocolloids are widely used in food, cosmetic, and pharmaceutical industries for their natural thickening and stabilizing properties. With rising demand for clean-label and functional ingredients, root and tuber hydrocolloids offer a sustainable solution. Hence, the study analysed the physicochemical properties of hydrocolloids extracted from the peels and flesh flour of specific root and tuber crops grown in south eastern Nigeria. Hydrocolloids were extracted from flour of Trifoliate yam (Dioscorea dumentorum), aerial yam (Dioscorea bulbifera), water yam (Dioscorea alata), white yam (Dioscorea rotundata), cocoyam (Colocasia esculenta), white and yellow fleshed sweet potato (Ipomoea batatas). The hydrocolloids were tested to determine the proximate composition, functional properties, gelation temperature, and pH levels. The findings revealed significant differences (P < 0.05). Moisture contents of flesh and peel samples ranged from 3.635% to 9.791%. Ash content from 0.60% to 6.10%. Crude fibre from 0.363 to 5.425 %, Carbohydrate from 82.294 % to 94. 406%. Functional properties results recorded highest values of 1.441(water yam peel) in swelling index, 4.200 % (water yam flesh) in foaming capacity, 78.805 % (yellow fleshed sweet potato flesh) in solubility, 2.205 (white yam peel) in oil absorption capacity, 2.505 (trifoliate yam flesh) in water absorption capacity, 69.310 % (cocoyam flesh) in emulsifying capacity, 75.615; 0.561; 0.766 (white fleshed sweet potato flesh) in freeze thawing stability, bulk density and tapped density. The highest values of gelation temperature and pH were observed in cocoyam peel (83 °C) and aerial yam peels (7.6). The potential of these hydrocolloids lies in their use as natural and sustainable ingredients in food formulations.
Biopesticidal effect of Onion Peel, Ginger and Alligator pepper Extracts against Penicillium spp, Aspergillus flavus, Grain Damage and Weight Loss of Stored Maize and Cowpea. Nigerian Journal of Post-Harvest Research, 3(6), 79-90
The overreliance on synthetic pesticides for stored-grain protection presents environmental and health concerns, highlighting the need for safer plant-based alternatives. This study evaluated the biopesticidal efficacy of onion peel, ginger, and alligator pepper formulations against storage fungi and insect pests (Sitophilus zeamais and Callosobruchus maculatus) infesting maize and cowpea. The plant materials were prepared as powders, aqueous extracts, and hexane oil extracts. Phytochemical screening and GC–MS profiling confirmed phenolics, alkaloids, flavonoids, glycosides, and tannins, with decanal (11.53%) in ginger, dodecadiene (7.01%) in onion peel, and octadecanoic acid (31.96%) in alligator pepper identified as major constituents. Antifungal activity was assessed via radial mycelial inhibition at five concentrations (0.2–1.0 g), while insect bioefficacy was evaluated at 1.0–3.0 g/50 g grain over 60 days. The aqueous extract of alligator pepper showed the strongest antifungal effect, restricting A. flavus and Penicillium spp. growth to 1.0 cm after 24 hours. Ginger aqueous extract at 3.0 g/50 g reduced maize grain damage and weight loss to 1.20 ± 0.20% and 1.33 ± 1.15%, compared with 38.42 ± 4.62% and 12.66 ± 8.33% in untreated controls (p < 0.05). Ginger oil extract at 3.0 g/50 g lowered cowpea damage (10.96 ± 1.00%) and weight loss (0.60 ± 0.20%) relative to controls (32.75 ± 8.86% and 7.78 ± 2.10%). Overall, ginger and alligator pepper extracts exhibited potent antifungal and insecticidal activity, demonstrating strong potential as sustainable, cost-effective botanical alternatives for integrated postharvest management of stored grains in tropical regions.
Insecticidal Efficacy of Onion and Garlic Peel Extracts for Sweet Potato Preservation. Nigerian Journal of Post-Harvest Research, 3(6), 8-16
This study examined the insecticidal activity of onion and garlic peel extracts as a control method for sweet potato beetles, Cylas formicarius, infesting sweet potatoes after harvest. The primary objective of this study was to extract bioactive compounds from onion and garlic peels using a column chromatographic technique. The extracts were bioassayed against five C.formicarius adults in various concentrations: 0.01 g/0.25 kg, 0.02 g/0.25 kg, and 0.04 g/0.25 kg. Methanolic extract of onion peel being the most effective was subjected to isolation using column chromatography packed with silica gel of 60-120 mesh, employing a gradient elution technique. The elution started from 100% hexane and gradually incorporated 10% ethyl acetate until a 10% methanol in ethyl acetate solution. TLC was used to monitor similar fractions collected, and the combined fractions were then subjected to Prep-TLC until a pure compound, known as OM-15, was obtained. The results revealed that onion peel methanolic extract (OMH) caused 93.3% mortality 96 h postexposure. In contrast, garlic peel methanolic extract (GMH) caused 73.3% mortality, but hexane garlic peel extract caused 80% mortality 96 h postexposure, and the pure compound showed mortality of 60% on Cylas formicarius 96 h postexposure. It can be concluded that the methanolic extract of onion peels was more effective than the ethyl acetate and hexane extracts, and is not statistically different from the standard insecticide (cypermethrin) at P < 0.05 significant level. The extracts are eco-friendly and potent against Cylas formicarius, providing a scientific rationale for incorporating their development into biopesticides.