Evaluation of Cassava Postharvest Handling Practices in Gasuba and Goffa Districts of South Ethiopia Region

© The Author(s) 2025. Published by AMO Publisher. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https:// creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. Evaluation of Cassava Postharvest Handling Practices in Gasuba and Goffa Districts of South Ethiopia Region Gezahegn Demeke  South Ethiopia Agricultural Research Institute, Areka Agricultural Research Center, Department of food Science and Postharvest Technology Research, Areka, Ethiopia Article History: Received: 04.05.2025 Revised: 17.08.2025 Accepted: 14.11.2025 Published: 17.11.2025 Abstract The effect of cassava postharvest handling storage conditions on end product quality was evaluated. Cassava chips and flour samples were collected from Goffa and Gasuba locations. Composite flour samples were prepared and analyzed in quality evaluation laboratory. The result showed that moisture content ranged from 12.60% to 14.07% in control and chips collected from ware stores respectively. The water activity value ranged from 0.62 in control samples to 0.78 in flour sample that was prepared from ware store chips. Water absorption capacities of the flour samples increased with decreasing the moisture content in the samples ranging from 1.61 in chips from warehouses to 1.97 in control samples. No significant differences were observed in extent of total plate count among the collected samples. Relatively chips collected from ware stores exhibited higher (5.5 x 103 cfu/g) yeast and mold counts, and lower (8.6 x 102 cfu/g) in flour sample collected from retail market. In general, appropriate postharvest handling and processing of cassava roots (harvesting, peeling, washing, chopping, drying and milling) were found to be good practice to get good quality chips and flour in the area. Keywords: postharvest handling, cassava chips, product quality, food safety, quality deterioration. Suggested citation: Demeke, G. (2025). Evaluation of Cassava Postharvest Handling Practices in Gasuba and Goffa Districts of South Ethiopia Region. European Journal of Theoretical and Applied Sciences, 3(6), 128-133. https://doi.org/10.59324/ejtas.2025.3(6).12 Introduction Root and tuber crops play an important role in food system and livelihood mainly staple diets in South and Southwestern part of Ethiopia. Root and tuber crops produced and consumed in Ethiopia include enset, potato, taro, cassava, tannia, sweet potato, yams, and anchote (EIAR, 2015). Cassava (Manihot esculenta Crantz) is major carbohydrate source food and it is the fourth supplier of dietary energy in the tropics next to rice, sugar and maize. Nigeria, Thailand, Brazil and Indonesia are the main cassava producer countries in the world (FAO 2016). It contributes a lot in satisfying household food security in less developed nations. Cassava is a drought-tolerant, staple grown in tropical and subtropical areas where many people are afflicted with under nutrition, making it potentially valuable food source for developing countries. Cassava roots have more carbohydrate than potatoes and less carbohydrate than wheat, rice, yellow corn, and sorghum on a 100-g basis (Gil and Buitrago 2002, FAO 2002). Cassava roots have calcium, iron, potassium, magnesium, copper, zinc, and manganese contents comparable to those of many legumes, with the exception of soybeans. Therefore, formulation and consumption of different cassava food products are necessary to www.ejtas.com European Journal of Theoretical and Applied Sciences (ISSN 2786-7447) 2025 | Volume 3 | Number 6 129 improve the nutrition status of consumers and utilization of the crop. Agricultural products have good value in form of fresh product but there are challenges in marketing associated with transportation and storage facilities to maintain quality (Semeredin and Tsegaye, 2018). In areas with no postharvest handling and value addition, farmers often sell cassava at throw-away prices. In sub Saharan Africa problem related to root crop postharvest loss reaches 45-54% (Gustavsson et al., 2010). The losses are high after harvesting thus, processing of cassava can improve its utilization and minimizes its loss. Quality defect experience when the crop is processed with its bark, uneven moisture release due to size difference. High quality cassava flour can be obtained following its processing procedure (peeling healthy root, washing, grating, pressing, drying, milling, sifting, packaging and storage). Cassava can be utilized by formulating composite flour with component crops like cow pea and millet (Onyango, et.al, 2020). In Ethiopia, cassava is cultivated for long period and cassava flour blend injera which is prepared from cassava and teff flour is widely consumed (Shiferaw, et.al, 2022). Beside the production, studies on impact of ways of cassava processing and storage on product quality, food security and public health is nil. Short post-harvest shelf life of cassava leads to quality deterioration when appropriate measure is not taken after harvest. This research aims to investigate the impact of cassava way of handling, processing and storage on the quality of the product along postharvest chains in south Ethiopia. Materials and Methods Study Area Description The cassava product samples were collected from two zones of South Ethiopia region. Gassuba is selected from Wolaita zone and Goffa is selected from Gamo Goffa zone. Gassuba and Goffa are situated 362 and 511km distance from capital, Addis Ababa respectively. Gassuba is located 6° 43' 24"N and 37° 12' 28"E with altitude of 1305m above sea level. Goffa is located 6° 36' 42"N and 37° 33' 26"E with altitude of 1548m above sea level. Sample Collection and Preparation From the total 25 ware houses and 15 retailers engaged in marketing of cassava chips and flours, 9 samples were collected for each treatment using the equation for calculating the sample size and control sample was processed at laboratory (Onyeka et al., 2015). n=N/1+N(e)2 (1) Where, n is the sample size, N is the population size, and e is the level of precision. Cassava samples were collected from two sites namely Goffa and Gasuba, South Ethiopia region which are highly potential areas for cassava production. Random sampling method was undertaken to pick the samples from different sources. Both chips and flour samples were sampled from retail market, warehouse storages and cassava chips. Cassava flour obtained by following recommended cassava chips and flour processing techniques was used as control. The collected chips were milled using laboratory sample mill to get flour for further quality analysis. Finally the flour samples were then packed in airtight polythene bags for further qualitative analysis. Physico-Chemical Analysis Moisture content and water activity (aw) measurements Moisture content was determined by the method of the Association of Official Analytical Chemists’ (AOAC, 2000); the official method 925.10, by drying the samples in an oven until a constant weight will be obtained. The crucible with its content will be put into a drying oven at 105˚C for 5hr and placed in desiccators to cool. 5 grams of the samples were accurately weighed using digital electronic beam balance and were placed into a previously cleaned, dried and weighed glass crucible. The Samples along with the weighed dry glass crucible was put into the drying oven and dried at 105ºC and cooled in desiccators to room temperature until constant weight will be attained. Finally, the dried and cooled samples together with the crucible were www.ejtas.com European Journal of Theoretical and Applied Sciences (ISSN 2786-7447) 2025 | Volume 3 | Number 6 130 weighed to determine the percentage moisture content of the samples. The loss in weight expressed as a percentage of the initial weight of sample gave the percent moisture content and the water activity in cassava flours was measured using electric hydrometer. Water absorption capacity WAC was determined by the method reported by Sosulski. Twentyfive milliliters of distilled water was added to a sample of 3g flour (W1) in a weighed centrifuge tube (W2) and stirred six times for 1 min at 10min intervals. The mixture was centrifuged at 3000 rpm for 25 min and the clear supernatant was decanted and discarded. Pel lets were dried at 50°C for 25 min and the adhered drops of water were removed and reweighed (W3). The amount of water retained in the sample was recorded as weight gain and was taken as water absorbed. Water absorption capacity was expressed as the weight of water bounded by 100g dried flour. Yeast and mold count Composite sample (20g each) was prepared from collected samples for laboratory analysis. From ground sample 1g was measured diluted with distilled water to prepare sock solution for enumeration of yeast and mould. For each sample, 0.1ml of 101 to 105 dilutions were aseptically spread plated using a 90° sterile glass spreader on 90mm Petri dishes containing Dichloran 18% (mass concentration) glycerol agar (DG18) supplemented with chloramphenicol prepared in duplicates. The plates were incubated in an upright position with lids uppermost in an incubator at 25°C±1°C for 5 to 7 days. After incubation, colonies that grew on the plates were counted using colony counter. Colonies that appeared flat, fluffy with colored or with spore structures were enumerated as molds and expressed as colony forming units (cfu) per gram of the cassava sample. Total plate count Total plate counts were done according to AOAC, (1995). Initial product sample homogenates were prepared in sterile diluents in ratios of 1:10. For each homogenate, 1 ml will be aseptically diluted through a series of tubes containing 9ml sterile diluents. Approximately 1 ml of diluents of each tube will be spread plated on to plate count agar (PCA) and incubated for 48 hrs at 350C. Plates with less than 300 colonies were counted. The number of bacterial colonies will be expressed as colony forming units per gram (CFU/g) of the sample using the formula from International Dairy Federation method (IDF, 1996) as follows Log C=∑ x/n1+ (0.1n2)xd (2) Where C= Count CFU/g, x= Total number of colonies in all plates, n1= Number of plates from initial dilution where counts were made, n2= Number of plates from second dilution from where counting was done, d= Initial dilution of counting Statistical Analysis Data analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 25.0 (IBM Corp., Armonk, NY, USA). The mean was separated using LSD (p< 0.05). All statistical tests were two-tailed, and a p-value < 0.05 was considered statistically significant. Results and Discussion Moisture Content and Water Activity The moisture content and water activity range in this study deviates from the standards recommended for safe storage and consumption. To ensure microbiological stability, safe for storage and human consumption, moisture content of cassava flour should not exceed 11% or 13% and water activity of 0.6 and less (codex and East African standards). Samples collected from retail market and ware stores results shows disparities in compared to the permissible values but it ranged from 13.43% (cassava flour from retail market) to 14.07% (cassava chips sample from ware houses). Only cassava flour sample processed following standard cassava flour processing procedure at laboratory laid within the permissible range (12.6%) as indicated in table 1. The results showed non significance among cassava chips and flours collected from retail market and ware stores indicating the samples www.ejtas.com European Journal of Theoretical and Applied Sciences (ISSN 2786-7447) 2025 | Volume 3 | Number 6 131 were not handled in appropriate manner which leads to postharvest losses due to microbial action. Exposure to open air and unit operations like chopping and milling might minimized the moisture and water activity wherein microbial growth is hampered in lower moisture conditions in the products. Table 1. Physico-Chemical and Functional Property Analysis of Cassava Products Collected from Different Sources Treatment Sample source MC (%) aw WAC (mL/g) 1 Cassava flour from retail market 13.43±0.35b 0.63±0.01a 1.92±0.04b 2 Cassava chips from retail market 13.70±0.10b 0.63±0.01a 1.91±0.08b 3 Cassava chips from warehouses 14.07±0.71b 0.78±0.03c 1.61±0.03a 4 Cassava flour from warehouses 13.97±0.21b 0.73±0.01b 1.83±0.09b 5 Cassava flour control 12.60±0.27a 0.62±0.01a 1.97±0.09b Mean 13.55±0.64 0.678±0.07 1.85±0.14 CV 4.69 10.02 7.73 LSD 0.177 0.015 0.032 Note: MC=moisture content, aw= water activity, WAC= water absorption capacity, CV= coefficient of variance. The values are averages of duplicate readings (mean ± standard deviation). Means followed by different superscript letter within the same column indicate significant difference and means with the same superscript letters within the column are not significantly different at (p<0.05). Water Absorption Capacity Water absorption capacity describes flour to water association ability under limited water supply which is dependent on the power of aggregation between starch molecules (Aryee et al., 2006), the weak aggregation power between starch molecules causes the surface of its molecular to form a bond with water molecules become easier thus increase the rate of water absorption capacity. The water absorption capacities ranged from 1.61 mL/g (in cassava chips flour) to 1.97 mL/g (in control flour samples). Water absorption capacities of the flour samples increased with decreasing the moisture content in the samples. The study result in line with past reports which ranged between 1.13 mL/g and 2.01 mL/g (Aryee et al., 2006). Total Plate Count In this study the total plate count does not showed statistical differences among the analyzed samples. The decrease in moisture content at the same time reduced the water activity in flour samples, and as a result drop in total plate counts. High moisture content of the flours promotes the sustenance of the TPC and thus affects the quality of the flours. Total plate counts in the collected cassava flour samples were which were higher than total plate counts set by East African Standard (EAS 740:2010 specification for cassava flour), which should not exceed 5.00 log cfu/g for edible cassava flours Yeast and Mold Count The results of the total yeast and mold count in the flours collected from different sources are presented in Table 2. The yeast and mold counts of cassava chips and flour samples collected from different sources exhibited significant difference (P=0.05) from each other. The yeast and mold count ranged from 8.6 x 102 cfu/g to 5.5 x 103 cfu/g, with cassava flour sample processed at laboratory having the lowest count while the highest was recorded in processed and stored cassava chips from warehouses respectively. The higher value exceeded the recommended value in 5 folds which is too much. The presence of higher yeast and mold on cassava products could be due to improper handling during harvesting, processing/drying and storage. Moisture reabsorption in local ware stores where there is no ventilation which leads contamination by yeast and mold. Therefore, the detection could be ascribed to post harvest contamination from the processing www.ejtas.com European Journal of Theoretical and Applied Sciences (ISSN 2786-7447) 2025 | Volume 3 | Number 6 132 environment, temperature and increased water activity. According to the East African Standard (EAS 740:2010 specification for cassava flour), permissible limits of the microbial load which should not exceed 3.00 log cfu/g yeast and mold counts for edible cassava flours. Table 2. Microbial Quality Analysis of Cassava Products Collected from Different Sources Treatment Sample source TPC (Log CFU/g) YMC (Log CFU/g) 1 Cassava flour from retail market 3.102±0.02 2.932±0.01a 2 Cassava chips from retail market 3.195±0.02 2.982±0.01a 3 Cassava chips from warehouses 3.213±0.02 3.564±0.57b 4 Cassava flour from warehouses 3.195±0.02 2.886±0.01a 5 Cassava flour control 2.546±0.57 2.845±0.01a Mean 3.050±0.34 3.042±0.35 CV 11.18 11.44 LSD NS 0.581 Note: TPC= total plate count, YMC= yeast and mold count, CV= coefficient of variance. The values are averages of duplicate readings (mean ± standard deviation). Means followed by different superscript letter within the same column indicate significant difference and means with the same superscript letters within the column are not significantly different at (p<0.05). Conclusion Postharvest physiological deterioration is a common quality defect after harvesting cassava storage roots. The roots can be processed into chips or flour to reduce the postharvest losses. The quality of processed chips and flours has to meet minimum standards and thresholds for safe consumption of the products. Cassava flour is used as an integral part of staple foods like injera by blending with teff flour in the study areas. This study reveals that the tested parameters showed microbial amount that exceeds the standards. Higher microbial counts (both total plate count, and yeast and mold) recorded as the moisture and water activity of the samples increased. Proper drying of the chips to moisture content below recommendation is among critical unit operations to get quality chips and cassava flours. Therefore, appropriate postharvest handling practices have to be adopted to ensure quality and safety of end product. Acknowledgement I would like to thank Southern Ethiopia Agricultural Research Institute (SEARI) for providing financial support, and Areka agricultural research center and crop research work process for their sympathetic facilitation of field trips for sample collection and laboratory analysis. Conflict of interests The author declares no conflict of interest. References Aryee, F. N. A., Oduro, I., Ellis, W. O., & Afuakwa, J. J. (2006). The physicochemical properties of flour samples from the roots of 31 varieties of cassava. Food Control, 17(11), 916– 922. https://doi.org/10.1016/j.foodcont.2005.06.01 3 Buitrago, J. A., Ospina Patiño, B., Gil Llanos, J. L., & Aparicio, H. (2007). 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