The push for non-thermal food processing methods has emerged due to the challenges associated with thermal food processing methods, for instance, high operational costs and alteration of food nutrient components. Non-thermal food processing involves methods where the food materials receive microbiological inactivation without or with little direct application of heat. Besides being well established in scientific literature, research into non-thermal food processing technologies are constantly on the rise as applied to a wide range of food products. Due to such remarkable progress by scientists and researchers, there is need for continuous synthesis of relevant scientific literature for the benefit of all actors in the agro-food value chain, most importantly the food processors, and to supplement existing information. This review, therefore, aimed to provide a technological update on some selected non-thermal food processing methods specifically focused on their operational mechanisms, their effectiveness in preserving various kinds of foods, as revealed by their pros (merits) and cons (demerits). Specifically, pulsed electric field, pulsed light, ultraviolet radiation, high-pressure processing, non-thermal (cold) plasma, ozone treatment, ionizing radiation, and ultrasound were considered. What defines these techniques, their ability to exhibit limited changes in the sensory attributes of food, retain the food nutrient contents, ensure food safety, extend shelf-life, and being eco-friendly were highlighted. Rationalizing the process mechanisms about these specific non-thermal technologies alongside consumer education can help raise awareness prior to any design considerations, improvement of cost-effectiveness, and scaling-up their capacity for industrial-level applications.

Maize-dependent populations in sub-Saharan Africa are continually exposed to aflatoxin poisoning owing to their regular consumption of this dietetic cereal. Being a staple in Kenyan households, consumption of maize-based meals is done almost daily, thereby exposing consumers to aflatoxicoses. This study assessed awareness levels, knowledge disparities, and perceptions regarding aflatoxin contamination at the post-harvest phase among farmers in the Rift Valley Region of Kenya. Households were randomly selected using a geographical positioning system (GPS) overlay of the agro-ecological zones within Uasin Gishu and Elgeyo Marakwet counties. Face-to-face interviews were conducted in 212 smallholder and large-scale farms. The study documented the demographic profiles of farmers and knowledge, awareness, and perceptions of aflatoxin contamination using a pre-designed structured questionnaire. Most farmers were familiar with aflatoxins and the adverse effects they present to health (61.32%). Almost all the farmers (94.37%) were aware of storage molds and food-spoilage fungi. However, few farmers adopted good post-harvest practices (PHPs), such as avoiding premature harvests (49.8%), using well-ventilated storage spaces (44.6%), grain sorting (30.5%), proper drying of maize (17.8%), and using hermetic bags for storage (30.5%). Conclusively, intensified farmer education is required to train farmers on good PHPs to protect their maize from aflatoxigenic fungi and aflatoxin accumulation.

The manuscript provides an overview of the nutritional, nutraceutical, sensory and quality characteristics of various legumes, cereals, fishes, fruits, and vegetables used in some African countries for the production of both traditional and innovative foods. Moreover, research studies on the application of diverse technological processes, such as milling, extrusion, baking, smoking, and solar drying, have been compiled and analyzed, shedding light on both conventional and emerging food technologies applied or potentially applicable in the same African regions. This review shows that various ingredients and/or final products present opportunities to be explored, offering potential strategies for their countries of origin. It emphasizes the importance of developing mechanisms to protect these products while contributing to the recognition of their quality and production models as key factors that add value. In fact, the review highlights that many of these food ingredients and products represent valuable opportunities for protection, e.g. with geographical indications, considering the already existing exploitation by several extra European Union countries (see Rooibos/Red Bush PDO from South Africa or Poivre de Penja PGI from Cameroon among others), which could represent an empowerment for small and medium local food producers also in view of export, helping African countries add value to their products and establish strong protection frameworks for their unique food heritage.

African leafy vegetables are rich in micronutrients that can help solve hidden hunger problems in Sub-Saharan Africa. However, their availability is limited due to seasonality and high post-harvest losses, which account for about 50%. In the field survey, we observed that wilted vegetables are usually discarded from the Morogoro Region, Tanzania markets. That loss also contributes to the loss of resources used to cultivate and transport the vegetables. Therefore, this study aimed to investigate the effect of the commonly used sun-drying method on the nutritional and sensory properties of fresh and wilted African nightshade and cowpea leaves. The common practice of handling fresh vegetables by vendors was adopted by putting the freshly harvested vegetables in an open basin at 24 ± 2°C for 3 days. Then, the stored vegetables were either sprayed or dipped in water to reduce the wilting rate. Next, the fresh and the wilted vegetables were dipped into hot water at 100°C for 7 min. Afterwards, the vegetables were sundried (22.5 ± 5.5°C) for three consecutive days. To study the effect of wilting, blanching, and sun drying fresh and dried vegetables were analysed for moisture, ascorbic acid, β-carotene, antioxidant activity and nitrate contents. Fresh and dried vegetables were used to prepare sauces using traditional recipes. The vegetable sauces were analysed for their sensory attributes using 30 semi-trained panellists. After drying, ascorbic acid contents, antioxidant activity and nitrate were reduced. The β-carotene significantly increased in the African nightshade and decreased in the cowpea leaves. Ascorbic acid ranged from 17.40 to 2.22 mg/100 g, antioxidant activity from 37.30 to 19.78, nitrate 230 to 10 mg/100 g and β-carotene from 96.38 to 79.49 mg/100. The sensory results showed relative acceptability among the sauces prepared from the fresh, fresh-dried and wilted-dried vegetables. In conclusion, blanching before drying reduced the water-soluble nutrient content but improved the sauces’ sensory scores of fresh and wilted vegetables. Therefore, reducing the post-harvest loss of African leafy vegetables is possible by drying the wilted vegetables and preparing the sauces with acceptable quality.

Sitophilus zeamais Motschulsky is the most important insect pest of stored maize in tropical regions. The objective of this study was to determine the practicality of periodic physical disturbance on S. zeamais mortality and its adoption by smallholder farmers in developing countries. In this experiment, treatments and control were arranged in a randomized block design with three replications and three storage times in three regions of Tanzania. Region was used as the blocking variable. A total of 108 clean 20-L plastic containers were each loaded with 10 kg of fresh white dent corn and 0.50 kg of maize infested with S. zeamais. For the treatment, containers were disturbed twice a day, whereas for the controls the containers were not disturbed until the end of storage. The overall mortality rate (%) after 30, 60, and 90 days of storage were 88%, 96%, and 98%, respectively. A statistically significant difference (p < 0.05) was observed for the number of live S. zeamais between the control and experimental treatments. Additionally, the number of live S. zeamais in the treatment significantly decreased as storage time increased. This study shows the potential of a feasible, simple, affordable, and effective method of protecting maize grain for small-holder farmers in developing countries without using chemicals.