Postharvest losses of bulb onion (Allium cepa L.) in selected sub-counties of Kenya

Inappropriate postharvest practices such as unsuitable harvesting methods and inadequate curing in bulb onion lead to losses. Postharvest losses in bulb onion contribute to food and nutrition insecurity. Although Kenya has suitable environmental conditions for bulb onion production, its productivity is low, which is attributed to pre- and postharvest factors. Information on bulb onion postharvest losses and their causes in the country is scanty which limits development of postharvest losses reduction strategies. Therefore, this study was carried out in three major bulb onion growing sub-counties of Kenya namely Mt. Elgon, Buuri and Kajiado East to determine postharvest practices, causes and factors influencing postharvest losses of bulb onion. A multi-stage sampling design was used to select the study areas and a total of 166 respondents were randomly selected. Face-to-face interviews were conducted using a structured questionnaire to collect information on postharvest handling practices, postharvest loss levels and their causes at farm level. Data were subjected to descriptive and logistic regression analysis using Statistical Package for Social Scientists (SPSS) software version 2.0. Results indicated that 68% of the respondents were males and with an average age of 40 years in the three sites. Forty eight percent of the respondents used leaves toppling, and 25% used drying of upper leaves as maturity indices. About 42% of the respondents used machete (panga) as a harvesting tool which significantly (P<0.05) influenced postharvest losses. Seventy seven percent of the respondents indicated that up to 30% postharvest losses occurred at farm level. Forty percent of the respondents indicated that bulb onion rots caused 10 % loss at farm level. The level of education, and mode of transport (bicycles and donkeys) significantly (P<0.05) influenced postharvest losses. It was concluded that the postharvest losses at farm level was 30% and were mainly caused by rotting. Socio-economic characteristics and postharvest handling practices nfluenced bulb onion losses at farm level. Development of postharvest losses reduction strategies on bulb onions focusing on alleviating rotting through appropriate postharvest handling practices at farm level was recommended

Effects of traditional processing techniques on the nutritional and microbiological quality of four edible insect species used for food and feed in east Africa

Published online: 4 May 2020Edible insects are increasingly being considered as food and feed ingredients because of their rich nutrient content. Already, edible insect farming has taken-off in Africa, but quality and safety concerns call for simple, actionable hazard control mechanisms. We examined the effects of traditional processing techniques—boiling, toasting, solar-drying, oven-drying, boiling + oven-drying, boiling + solar-drying, toasting + oven-drying, toasting + solar-drying—on the proximate composition and microbiological quality of adult Acheta domesticus and Ruspolia differens, the prepupae of Hermetia illucens and 5th instar larvae of Spodoptera littoralis. Boiling, toasting, and drying decreased the dry matter crude fat by 0.8–51% in the order: toasting > boiling > oven-drying > solar-drying, whereas the protein contents increased by 1.2–22% following the same order. Boiling and toasting decreased aerobic mesophilic bacterial populations, lowered Staphylococcus aureus, and eliminated the yeasts and moulds, Lac+ enteric bacteria, and Salmonella. Oven-drying alone marginally lowered bacterial populations as well as yeast and moulds, whereas solar-drying alone had no effect on these parameters. Oven-drying of the boiled or toasted products increased the aerobic mesophilic bacteria counts but the products remained negative on Lac+ enteric bacteria and Salmonella. Traditional processing improves microbial safety but alters the nutritional value. Species- and treatment-specific patterns exist

Aflatoxin and fumonisin mycotoxins contamination along the maize value chain in the eastern Democratic Republic of Congo

Aflatoxin and fumonisin contamination was assessed in different samples along the maize value chain in different territories of South Kivu province. Kabare and Ruzizi Plain were chosen as they represent two different agroecological areas where maize is mostly produced. Twelve districts and one town were selected across the province. The stakeholders were randomly selected, and 215 maize (139 maize grain and 76 maize flour) samples were taken for laboratory analysis. The Q + kit was used to determine the total aflatoxins and fumonisins. Three categories of maize were examined: freshly harvested dry maize, stored maize (maize stored for 3 months ±1.5 month) and market maize. Aflatoxin was found in 100% of the maize samples with the least content of 0.3 μg/kg detected in freshly harvested dry maize with mean 3.2+0.3 and levels ranging from 0.3 to 18.5 μg/kg. The average level of aflatoxin in stored grain samples was 97.9±182 μg/kg within a range of 1.16 to 841.5 μg/kg, and the mean level of aflatoxin in stored flour was 148.9±164.5 μg/kg with levels ranging from 2.05 to 905.1 μg/kg. The mean level of aflatoxin maize collected from the market was 95.1 ±164 μg/kg, with levels ranging from 1 to 823.2 μg/kg. Almost all the maize flour collected from the three areas had a high contamination level that exceeded the maximum tolerable limit of 10 μg/kg. Fumonisin was detected in all samples. However, the levels of fumonisin do not follow a specific trend with the duration of storage. The freshly harvested dry maize concentration was 2.4±5.1 μg/g, with levels ranging from 0.03 to 20.9μg/g. About 37% of freshly harvested maize samples contaminated by fumonisin exceeded the maximum tolerable limit of 4 μg/kg. There was a difference between total fumonisin in grain and flour; the average level of fumonisin in stored maize grain was 1.4±0.9 μg/g with levels ranging from 0.18- 4.7 μg/g while in flour, the level was 2.1±1.3 μg/g with levels ranging from 0.3-4.5 μg/g. Almost all the maize samples collected from the three areas had a degree of contamination that did not exceed the maximum tolerable limit of 4 μg/g. These results indicate that the two mycotoxin levels, particularly aflatoxin, were high in the different samples collected at specific nodes. Therefore, preventing mycotoxins accumulation in maize by post-harvest prevention of contamination and growth of toxigenic moulds by promoting proper grain drying and storage should be encouraged among the actors of the maize value chain.&nbsp

Effect of triple-layer hermetic bagging on mould infection and aflatoxin contamination of maize during multi-month on-farm storage in Kenya

Field trials were conducted in small-scale farmers' grain stores in an aflatoxin endemic region to assess the effect of storing maize in triple layer hermetic (PICS™) bags on aflatoxin contamination. Shelled maize grain was purchased from farmers, and filled into PICS bags, woven polypropylene (PP) and jute bags and kept in the farmers' own stores for 35 weeks. Grain moisture content, total mould count and mould incidence levels were examined at onset and after every 7 weeks during the 35 weeks of storage. Aflatoxin contamination was examined at onset, and after 14, 28 and 35 weeks. Ambient temperature and r.h. in the trial site and in all the bags, as well as oxygen and carbon dioxide levels in the PICS bags were also monitored. Initial moisture content (m.c.) of maize varied from farmer to farmer and ranged between 12.4 and 15.0%. The m.c. of maize stored in PICS bags remained significantly higher (P 14% increased profusely in the three types of bags. Our findings demonstrate that storing maize in PICS bags can prevent accumulation of aflatoxin in rural farmers' stores if grain moisture is <14%

Low permeability triple-layer plastic bags prevent losses of maize caused by insects in rural on-farm stores

Participatory on-farm trials were conducted to assess effectiveness of Purdue Improved Crop Storage (PICS™) bags for storage of maize in small-scale farmers’ stores in rural villages in eastern Kenya. A PICS bag is a three-layered hermetic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Jute, woven polypropylene or PICS bags were filled with shelled maize grain, purchased from the participating farmers, and the three sets of bags kept in the farmers’ own stores for 35 weeks. Oxygen and carbon dioxide levels in the PICS bags were monitored, as well as the temperature and relative humidity in all the bags. Grain moisture, live insect population, grain damage and weight loss were examined at intervals of seven weeks. Oxygen and carbon dioxide composition demonstrated that PICS bags are capable of sustaining good air-barrier properties under farmer storage conditions. Moreover, moisture content of maize stored in PICS bags did not change throughout the storage period whereas the moisture content of maize stored in polypropylene and jute bags decreased significantly in the final 14 weeks. Maize stored in PICS bags remained free from insect infestation and the weight loss due to insect damage was below 1 %. On the contrary, polypropylene and jute bags permitted profuse build-up of insect populations. At 35 weeks, grain damage reached 77.6 % and 82.3 % corresponding to 41.2 % and 48.5 % weight loss in the polypropylene and jute bags respectively. These findings demonstrate that PICS bags are effective in controlling losses caused by storage pests under farmer storage conditions

Evaluation of mycotoxin content in soybean (Glycine max l.) grown in Rwanda

Soybean is a critical food and nutritional security crop in Rwanda. Promoted by the Rwandan National Agricultural Research System for both adults and as an infant weaning food, soybean is grown by approximately 40% of households. Soybean may be susceptible to the growth of mycotoxin-producing moulds; however, data has been contradictory. Mycotoxin contamination is a food and feed safety issue for grains and other field crops. This study aimed to determine the extent of mycotoxin contamination in soybean, and to assess people’s awareness on mycotoxins. A farm-level survey was conducted in 2015 within three agro-ecological zones of Rwanda suitable for soybean production. Soybean samples were collected from farmers (n=300) who also completed questionnaires about pre-and post-harvest farm practices, and aflatoxin awareness. The concentration of total aflatoxin in individual soybean samples was tested by enzymelinked immunosorbent assay (ELISA) using a commercially-available kit. Other mycotoxins were analyzed using liquid chromatography-mass spectrometry (LCMS/ MS) on 10 selected sub samples. Only 7.3% of the respondents were aware of aflatoxin contamination in foods, but farmers observed good postharvest practices including harvesting the crop when the pods were dry. Using enzyme-linked immunosorbent assay (ELISA), only one sample had a concentration (11 μg/kg) above the most stringent EU maximum permitted limit of 4 μg/kg. Multi-mycotoxins liquid chromatography-mass spectrometry (LC-MS/MS) results confirmed that soybeans had low or undetectable contamination; only one sample contained 13μg/kg of sterigmatocystine. The soybean samples from Rwanda obtained acceptably low mycotoxin levels. Taken together with other studies that showed that soybean is less contaminated by mycotoxins, these results demonstrate that soybean can be promoted as a nutritious and safe food. However, there is a general need for educating farmers on mycotoxin contamination in food and feed to ensure better standards are adhered to safeguard the health of the consumers regarding these fungal secondary metabolites.Key words: soybean, safety, mould, aflatoxin, mycotoxins, sterigmatocystine, ELISA, LC-MS/MS, Rwand

Agronomic practices influence the infection of an oats cultivar with Fusarium langsethiae

Fusarium langsethiae, a toxigenic fungus known to contaminate small-grain cereals with type A trichothecene mycotoxins, HT-2 and T-2 was described as a new species in 2004. HT-2 and T-2 are some of the most potent Fusarium toxins in eukaryotes, capable of inhibiting protein synthesis. The epidemiology of F. langsethiae is not well understood and with the intent of the European Commission to set maximum levels of contamination of cereals with these toxins, importance is currently placed in trying to understand the fungal infection process and its favorable growth conditions. A field study was carried out to investigate the effect of artificially inoculated oats straw, ploughing and minimum tillage with and without incorporated crop debris (straw) on infection and mycotoxin production by F. langsethiae on oats cultivar Gerald. The results indicated that cultural field practices had effects on the infection of oats by F. langsethiae. Fusarium langsethiae DNA was quantified in significantly larger amounts (p0.05) on oat infection by F. langsethiae as quantified by DNA concentration. HT-2+T-2 quantification and analysis, gave no good evidence that either inoculation or cultural practice had any significant influence on the concentration of mycotoxins in the samples (p>0.05), but samples from minimum tillage with incorporated straw plots resulted in 2.5 times more HT-2+T-2 toxins than samples from ploughed with removed straw. These findings indicate the importance of tillage and crop debris management in the mitigation in an effort to prevent F. langsethiae infection, colonization and possible contamination of oats with HT-2 and T-2 toxins

Review article: Artificial inoculum and inoculation techniques commonly used in the investigation of Fusarium head blight in cereals

© 2014 Akadémiai Kiadó, Budapest. Fusarium head blight (FHB) is a disease of small-grain cereals that has a proven negative impact on crop yield, quality and food safety. In this regard, it is one of the most studied diseases of small-grain cereals worldwide. This paper reports the commonly used artificial sources of inoculum and inoculation techniques employed in the study of FHB epidemiology. Spore suspensions and grain spawn are the most popular forms of artificial inoculums. Spray inoculation technique is more commonly used than the point inoculation technique for delivering the inocula to the target sites. Spray inoculation has an advantage over point inoculation in that it can be used to detect both Type I and II resistances to FHB, point inoculation can only detect Type II resistance to FHB. Grain spawn is the commonest soil-surface inoculum used in the study of FHB. Its advantage lies in the fact that it is capable of propagating inoculum over a long period of time compared to other methods. It can also detect the five types of resistances reported (Types I, II, III, IV and V). In order to gain further information regarding the epidemiology of FHB, researchers need to explore other potential sources of artificial inoculum