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.

Most pyrolysis reactors require small sizes of biomass particles to achieve high-quality products. Moreover, understanding the usefulness of high-pressure systems in pyrolysis is important, given the operational challenges they exhibit specific to various biomass materials. To actualize these aspects, the authors first checked previous reviews involving pyrolysis on different biomass and different conditions/situations with their respective objectives and subsections. From these already existing reviews, the team found that there has not been much emphasis on high-pressure fast pyrolysis and its potential in biomass conversion, showing that it is a novel direction in the pyrolysis technology development. Therefore, this review aims to shed more light on high-pressure fast pyrolysis, drawing from (a) classification of pyrolysis; (b) reactors used in fast pyrolysis; (c) heat transfer in pyrolysis feedstock; (d) fast pyrolysis parameters; (e) properties/yields of fast pyrolysis products; (f) high pressure on pyrolysis process; (g) catalyst types and their application; and (h) problems to overcome in the pyrolysis process. This review increases the understanding regarding high-pressure fast pyrolysis. An attempt has been made to demonstrate how high-pressure fast pyrolysis can bring about high-quality biomass conversion into new products. It has been shown that fluidized bed (bubbling and circulating) reactors are most suitable and profitable in terms of product yield. The high-pressure, especially combined with the fast-heating rate, may be more efficient and beneficial than working under ambient pressure. However, the challenges of pyrolysis on a technical scale appear to be associated with obtaining high product quality and yield. The direction of future work should focus on the design of high-pressure process reactors and material types that might have greater biomass promise, as well understanding the impact of pyrolysis technology on the various output products, especially those with lower energy demands. We propose that the increase of process pressure and biomass particle size decrease should be considered as variables for optimization.

More still needs to be learned regards the relative contamination of heavy metals and pesticide residues, particularly those found in widely consumed Nigerian food crops like cereals, vegetables, and tubers. In this current study, the heavy metals and pesticide residues detectable in widely consumed Nigerian food crops were respectively quantified using atomic absorption spectroscopy (AAS) and gas chromatography (GC). Specifically, the widely consumed Nigerian food crops included cereals (rice, millet, and maize), legume (soybean), tubers (yam and cassava), as well as leaf (fluted pumpkin, Amaranthus leaf, waterleaf, and scent leaf) and fruit vegetables (okro, cucumber, carrot, and watermelon). Results showed that the detected heavy metals included arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), and nickel (Ni), whereas the pesticide residues included Aldrin, Carbofuran, g-chlordane, Chlorpyrifos, DichloroBiphenyl, Dichlorodiphenyldichloroethane (DDD), Dichlorodiphenyltrichloroethane (DDT), Dichlorvos, Endosulfan, Heptachlor, Hexachlorobenzene (HCB), Isopropylamine, Lindane, t-nonachlor, and Profenofos. Across the studied food crops, the concentrations of heavy metals and pesticides were varied, with different trends as they largely fell below the established maximum permissible limits, and with some exceptions. Our findings suggest there could be a somewhat gradual decline in the concentration of the heavy metals and pesticide residues of these studied food crops when compared to previously published reports specific to Nigeria. To help substantiate this observation and supplement existing information, further investigations are required into the concentration of these heavy metals and pesticide residues specific to these studied food crops at other parts of the country.

Mycotoxins like aflatoxins, ochratoxins, patulin, citrinin, deoxynivalenol (DON), fumonisins, trichothecenes, etc., produced by molds (Aspergillus avus, A. parasiticus, Penicillin spp, etc.) could occupy such grains as peanuts, millet, sunower, cassava, beans, sesame, sorghum, maize, etc. In order to either eliminate and or reduce the levels of mycotoxins, as well as detection limits, there are a number of grain processing techniques that have been reported in the literature. In this article, an overview of the effectiveness of grain processing methods to eliminate mycotoxins was performed. Specifically, the grain processing techniques considered include: extrusion, alkaline cooking, flaking, roasting, frying, baking, milling, cooking, cold plasma, cleaning, trimming, sorting, as well as chemical treatments like the use of sodium hydroxide, citric acid, sodium bisulfite and ammonia. Overall, while most methods seem effective in reducing some mycotoxins over others, more studies are required to identify how these methods particularly their combinations would elevate the removal/degradation of mycotoxins in grains, particularly to safer levels.

Economic development and population growth lead to the increased production of chicken manure, which is a problematic organic waste in terms of its amount, environmental threats, and moisture content. In this study, hydrothermal carbonization, an emerging way of waste disposal, was performed on chicken manure to produce an energy-rich material called hydrochar. The effects of hydrothermal carbonization temperature (180, 240, 300 °C) and process time (30, 90, 180 min) were summarized. Proximate and ultimate analysis, as well as low and high heating values were applied both on raw material and derived hydrochars. Additionally, the performance of the process was examined. The obtained results show that hydrothermal carbonization is a feasible method for chicken manure disposal and valorization. Although the process time did not influence the fuel properties of chicken manure considerably, a higher temperature led to a significantly higher heating value, reaching 23,880.67 ± 34.56 J × g−1 at 300 °C and 180 min with an improvement of ~8329 J × g−1 compared with raw chicken manure (15,551.67 J × g−1). Considering the energy gain value, the hydrochar derived at 240 °C in 30 min had the best result. Moreover, the energy consumption for this process was relatively low (124.34 ± 8.29 kJ × g−1). With its still feasible fuel properties and high heating value of 20,267.00 ± 617.83 kJ × g−1, it was concluded that these parameters of chicken manure hydrochar are the most beneficial and present a potential alternative for conventional fuel.

The paper presents the influence of different curing conditions—wet, dry, and protection against water evaporation (PEV)—on selected properties of concretes with different amounts of recycled concrete aggregate (RCA) previously subjected to atmospheric CO2 sequestration. Two types of cement were used, Portland cement and blast-furnace slag cement. The study was performed in laboratory conditions (at the temperature of 20 ± 1 °C and relative humidity of about 60%), according to currently applicable test procedures for most of the measured characteristics of concrete. Additionally, the eco-efficiency indexes (bi and ci) as well as the eco-durability S-CO2 index were calculated. It was found that dry conditions cause the properties of concrete to deteriorate, especially concrete made of blast-furnace slag cement, while PEV allows the achievement of results comparable to wet conditions. Moreover, for series with the highest amounts of coarse recycled aggregate and after longer periods of curing, the difference between the effects of wet curing and protection against water evaporation disappears. The eco-efficiency and eco-durability indexes approach confirms the beneficial effect of blast-furnace slag cement used as a binder, but on the condition of using a proper way of curing.

In this research, biochar (BC) made from the brewer’s spent grain at temperatures of 300, 450, and 600 °C was produced and subjected to the anaerobic digestion of the brewer’s spent grain. BC shares of 2, 5, 10, and 50% concerning total solids of the substrate were tested at three substrate-to-inoculum ratios of 0.5, 1.0, and 2.0, respectively. The anaerobic digestion process was performed at 37 °C and took 30 days. For anaerobic digestion, biomethane production was recorded and used for kinetics parameter determination according to the first-order model. After the process, process residues (digestate) were analyzed for fertilizing potential. The biomethane yield differs from 264 to 325 mL×gvs−1, while kinetics parameters were 292.7–344.7 mL×gvs−1, 0.08–0.11 d−1, and 24–42.5 mL×(gvs×d)−1, for ymax, k, and r, respectively. The main factors affecting biomethane production were substrate-to-inoculum ratio and BC share. No specific effect between BC types on biomethane yield was found. An increase in BC share from 2% to 50% concerning specific SIR results in biomethane production improvement in the range of 1.8% to 10%. The main factors affecting the quality of digestate (nutrients) were the quality of the used inoculum and the quantity of the used substrate. The research results were complex and showed that the final effect of BC supplementation depends not only on BC properties, but also on process operational parameters and the quality of the used feedstock.

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