Disinfestation techniques for major cereals: A status report

Current status of phosphine resistance in Indian field populations of Tribolium castaneum and its influence on antioxidant enzyme activities

Resistance to phosphine is widely reported in several stored product insect pests globally. However, knowledge of its prevalence and the association of antioxidant enzymes with phosphine resistance is limited. Herein, we assessed the levels of phosphine susceptibility and estimated the antioxidant enzyme activities viz., superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT) in selected Indian populations of red flour beetle Tribolium castaneum (Herbst). Dose-response probit assays revealed that the LC50 values ranged from 0.038 to 1.277 mg L-1 showing 2.11 to 70.94-fold resistance to phosphine compared to susceptible check. Activities of antioxidant enzymes varied significantly between the T. castaneum populations following phosphine exposure. The magnitude of SOD activity ranged from 8.77 to18.82 U mg-1 protein, while, the activities of POX and CAT varied between 52.42 and 408.32 and 61.11 to 247.49 µM H2O2 reduced min-1 mg-1 of protein, respectively. The correlation analysis revealed a significant positive association of SOD (r = 0.89) and POX (r = 0.98) with increased resistance ratio, while the CAT (r = - 0.98) is negatively linked with resistance to phosphine. A principal component analysis identified phosphine resistance was closely associated with POX and SOD activities but was unrelated to the CAT activity. Our results throw light on the varied association of antioxidant enzyme activities in response to phosphine fumigation in field populations of T. castaneum. Further studies on the biochemical and molecular basis of phosphine stress in insects may help to devise suitable strategies to safeguard storage commodities and ensure a sustainable environment.

Identification of odorant receptors of Tribolium confusum in response to limonene repellent activity

Tribolium confusum is an important storage pest showing significant resistance to various chemical pesticides, development of botanical pesticides is an effective strategy to resolve above problem and decrease utilization of chemical pesticides. Present study attempts to explore the molecular mechanism about the repellent activity of limonene. When treatment concentration of limonene was 200.00 μg/cm2, the repellent level remained at grade V after 24 hours. Our study showed that limonene could be distinguished by T. confusum antenna with a maximal electroantennography test value of 0.90 mV. Simultaneously, 88 upregulated and 98 downregulated genes were sequenced in limonene-repellent T. confusum, and RT-qPCR analysis showed that four down-regulated and one up-regulated OR genes play an important role in the response to limonene. The repellent rate was decreased by 22.13% mediated with a knockdown of dsTconOR93, while the EAG value of the female and male adults was reduced to 0.26 mV (49.06%) and 0.20 mV (54.05%), respectively. In conclusion, limonene had a strong repellent activity against T. confusum and TconOR93 gene was determined to be a major effector in perception of limonene. This study provides a basis for the development of limonene as a novel botanical pesticide for the control to storage pests, which will reduce the utilization of chemical pesticides and postpone the development of resistance.

Protection of postharvest grains from fungal spoilage by biogenic volatiles

Fungal spoilage of postharvest grains poses serious problems with respect to food safety, human health, and the economic value of grains. The protection of cereal grains from deleterious fungi is a critical aim in postharvest grain management. Considering the bulk volume of grain piles in warehouses or bins and food safety, fumigation with natural gaseous fungicides is a promising strategy to control fungal contamination on postharvest grains. Increasing research has focused on the antifungal properties of biogenic volatiles. This review summarizes the literature related to the effects of biogenic volatiles from microbes and plants on spoilage fungi on postharvest grains and highlights the underlying antifungal mechanisms. Key areas for additional research on fumigation with biogenic volatiles in postharvest grains are noted. The research described in this review supports the protective effects of biogenic volatiles against grain spoilage by fungi, providing a basis for their expanded application in the management of postharvest grains.

Human ectoparasitosis by mites of the genus Pyemotes Amerling 1861 (Acarina: Pyemotidae)

The mites of the family Pyemotidae Berlese (1897) are a large family of ectoparasitoids arthropods, known as pathogen for humans since the 18^th century and responsible for the so-called "straw itch" or "grain itch" in granary and dock workers. The identified species of the genus Pyemotes are divided into two groups: the scolyti group (P. scolyti, P. parviscolyti and P. dimorphus) and the ventricosus group (P. tritici and P. ventricosus). The first group is characterized by nonvenomous mites usually parasitizing bark beetles; the ventricosus group includes species associated with a large number of hosts (Coleoptera, Lepidoptera, Hymenoptera, Diptera and Rhynchota), parasitizing all host stages, often highly poisonous and responsible for itchy skin lesions for humans. Several species of Pyemotes mites can be pathogenic to humans, especially in spring and summer and in indoor environments, where worm-eaten wood or infested foodstuffs are present. The most frequent clinical feature is the "strophulus," characterized by small erythematous, edematous, and papular lesions centered by a tiny vescicle evolving into a small erosion covered by crust, or by a central hemorrhagic punctum. Other less frequently observed clinical features are urticaria-like lesions, erythematous excoriated papular and pustular lesions, and rarely scabies-like eruptions. The parasitological diagnosis together with the environmental disinfestation and removing of each substrate infested by insects parasitized by Pyemotidae is mandatory to definitely solve Pyemotes dermatitis.

Low-pressure ozone injection system: relationship between reaction kinetics and physical properties of grains

BACKGROUND

The ozonation of grains in a closed system at low pressure is a strategy with the potential for treating packaged products. Research is necessary to characterize the reaction kinetics of ozone in this type of injection system so that it is possible to design chambers and determine the ozone concentrations suitable for commercial-scale applications. The objective of this study was therefore to characterize the low-pressure ozone injection system in relation to the physical properties of the grains and determine possible changes in their quality. Samples (5 kg each) of common beans, cowpea beans, corn, popcorn kernels, paddy rice, and polished rice were exposed to ozone in a 70 L hypobaric chamber. Initially, the internal pressure of the chamber was reduced to 500 hPa. Then, ozone was injected at a concentration of 32.10 g m^-3 at a volumetric flow rate of 1 L min^-1 until reaching a pressure of 1000 hPa. To relate the decomposition of ozone to the grains that were being evaluated, different physical properties were determined, and quality analysis was conducted.

RESULTS

Ozone gas half-life outside and inside the package depended on the grain type. Ozone decomposition was quickest in polished rice and slowest in common beans. The half-life of the different grains ranged from 17.8 to 52.9 and 16.4 to 52.9 min, outside and inside the package, respectively. Considering the physical properties, specific surface (Ss), surface area (SA), and sphericity (φ) exhibited a significant correlation with the decomposition rate constant (k) of ozone. However, the variables volume (V), permeability (K), porosity (ε), and specific mass (ρ) showed no correlation with k.

CONCLUSION

The physical properties of grain influenced the reaction kinetics of ozone gas during the low-pressure injection process. Ozone gas injection at low pressures did not alter the quality attributes of the grains under study. © 2022 Society of Chemical Industry.

Advances in Environmentally Friendly Techniques and Circular Economy Approaches for Insect Infestation Management in Stored Rice Grains

Rice (Oryza sativa L.) is a staple food for about half of the world's population. Therefore, it is important to search for solutions that minimise losses and production costs for producers and ensure food quality and safety for consumers. Improved methods for the detection and monitoring of hidden infestations are useful for adopting infestation control measures. Chemical methods are used to prevent rice losses due to infestations; changing this situation, however, is of the utmost importance, as it harms the environment and human health. The management of infestation by controlled storage conditions, namely temperature and atmosphere composition and the use of current fossil-based packaging with modified atmospheres, is well recognised. The use of environmentally friendly solutions is promising, but it is necessary to perform a life-cycle assessment and cost analysis to evaluate their effectiveness. According to the principles of circular economy, the integration of the best-selected treatments/solutions for insect management, along with the use of biopackaging from rice by-products are recommended. This review describes the methods of detection and control of infestation as well as several promising alternatives to chemical treatments; however, more research is needed in order to obtain effective technological solutions that can be applied at an industrial scale.

A Scientometric Review of Grain Storage Technology in the Past 15 Years (2007-2022) Based on Knowledge Graph and Visualization

Food storage helps to ensure the food consumption needs of non-agricultural populations and to respond to major natural disasters or other emergencies, and the application of food storage technology can reduce post-harvest food losses. However, there are still obvious shortcomings in coping with large grain losses. Therefore, quantitative analysis of the research hotspots and evolutionary trends of grain storage technology is important to help the development of grain storage technology. This article uses the Web of Science database from 2007 to 2022 as a data sample with the help of CiteSpace software to analyze the basic situation, research hotspots, and evolutionary trends to draw a series of relevant knowledge maps. Visual analysis revealed that the number of publications had grown rapidly since 2015. First, the Journal of Stored Products Research, Journal of Economic Entomology, and Journal of Agricultural and Food Chemistry, with citation frequencies of 929, 536, and 453, should be focused on in order to keep up with the latest research developments in this field. The United States, China, and Brazil occupy dominant positions in relation to grain storage technology studies in general. Purdue University, Kansas State University, and Agricultural Research Institute ranked the top three in terms of the number and centrality of publications. In terms of research hotspots, the centrality of temperature, insects, carbon dioxide, and quality were 0.16, 0.09, 0.08, and 0.08. It shows that the field of grain storage technology in recent years has focused on grain storage temperature, pest control, and grain storage quality research. From the perspective of the evolution trend, the life cycle of emergent words lasts for several years, after which the strength of emergent words slowly decreases and is replaced by new emergent words. Mortality was the first keyword to appear and remained from 2007 to 2011, indicating that research on fumigants and their toxicity, as well as pest mortality under air fumigation and chemical fumigation conditions, became more popular during this period. In recent years, new terms have emerged that had never been used before, such as "grain quality" (2019-2022) and "stability" (2020-2022). We can find that people pursue food quality more with the improvement of people's living standards. In this context, future research should seek more efficient, safe, economical, and environmentally friendly methods of grain storage and continuously improve the level of scientific grain storage.

A comprehensive review on advances in storage pest management: Current scenario and future prospects

Modernization of the agricultural production system led to a significant increase in annual food production intended to meet the ever-growing consumer demand. In many countries, most of the food grains produced is stored for contingency and regular supply. These stored grains, in general, are directly or indirectly infested by insects, resulting in severe grain damages and storage losses, thus, causing a threat to food safety and security. Although a variety of insect management options, such as physical, mechanical, biological, and chemical methods, are available, fumigation has been practiced for decades in storage. However, opportunities for fumigation are narrowing after the phase-out of methyl bromide. Besides, safe food and health concerns paved the path for green chemistry and non-chemical management practices. This review includes the list of stored-grain insects and their detection methods. The different management strategies such as the modern storage structures (hermetic and low-pressure storages), modified or controlled storage atmosphere, application of ozone as fumigant, irradiation, and physical options are presented. Further, the details on sustainable biological options, such as semiochemicals, natural enemies, biopesticides, and entomopathogenic nematodes, are supplemented. The use of inert dusts as grain protectant and in combination with the biological entity is included. Studies on alternative fumigants', novel management options, such as molecular biology tools (RNAi and CRISPR) and nanotechnology in stored grain protection, are also highlighted. This review helps the reader to understand the overall factors affecting grain storage and the different options to manage the insects causing storage losses.

Mechanisms underlying the inhibitory effects of linalool on Aspergillus flavus spore germination

Biogenic volatile organic compounds hold remarkable potential for controlling fungal decay in agro- and food products. Recently, we reported that linalool, the major volatile component of the Zanthoxylum schinifolium pericarp, showed great potential as a biofumigant to control Aspergillus flavus growth in postharvest grains. In this study, the inhibitory effects of linalool on A. flavus growth in stored grains and its underlying mechanism were investigated through transcriptomic and biochemical analyses. Linalool vapor at 800 μL/L can effectively prevent A. flavus growth in 22% moisture wheat grains. Linalool at 2 μL/mL completely inhibited the germination of A. flavus spores, and 10 μL/mL caused spore death. Scanning electron microscopy revealed that linalool treatment caused wrinkling and spore breakage. Transcriptomics showed that 3806 genes were significantly differentially expressed in A. flavus spores exposed to 2 μL/mL linalool, predominantly showing enrichment regarding the ribosome, DNA replication, glutathione metabolism, peroxisome, and MAPK signaling pathways. Flow cytometry showed that linalool treatment caused hyperpolarization of mitochondrial membrane potential. 4,6-Diamidino-2-phenylindole staining indicated that linalool caused DNA fragmentation in A. flavus spores, and monodansylcadaverine staining confirmed that linalool induced autophagy in A. flavus spores. We thus propose that linalool can damage the plasma membrane, cause mitochondrial dysfunction and DNA damage, and induce autophagy in A. flavus spores. These findings considerably improve our understanding of the mechanisms underlying the inhibitory effects of linalool on A. flavus, which is crucial regarding the development of applications to prevent postharvest grain spoilage due to A. flavus infestations. KEY POINTS: • The inhibitory potency of linalool on A. flavus spore germination was determined. • Transcriptomic analyses were performed to identify differentially expressed genes of A. flavus exposed to linalool. • A functional mechanism underlying the inhibitory effects of linalool on A. flavus spore germination is proposed.

Current progress on innovative pest detection techniques for stored cereal grains and thereof powders

For stored grains and their powders, pest infestation has always been a knotty problem and thus comprises a serious threat to global food security. Obviously, timely, rapid and accurate pest detection methods are of extreme importance to protect grains from pest mouth. In facing the defects of traditional methods, such as visual inspection, grain flotation and pest trap, diverse innovative approaches progressed fast alternatively, either targeting pest itself or diagnosing pest-induced changes. The former includes machine vision, metabolite analysis, pest-specific protein techniques, molecular techniques, bioacoustics analysis, conductive roller mill, low-field nuclear magnetic resonance spectroscopy and imaging, while the latter consists of thermal imaging, near-infrared spectroscopy and hyperspectral imaging, impact acoustics analysis, soft X-ray imaging and tomography. The principle, operation procedure, pros and cons and application scenarios were discussed for each method. The results herein hope to promote the technical revolution of pest inspection in stored cereal grains and their powders.

Effect of radiation processing on phenolic antioxidants in cereal and legume seeds: A review

Phenolic compounds in cereal and legume seeds show numerous benefits to human health mainly because of their good antioxidant capacity. However, long-term storage and some improper preservation may reduce their antioxidant potential. It is necessary to retain or modify the phenolic antioxidants with improved technology before consumption. Radiation processing is usually applied as a physical method to extend the shelf life and retain the quality of plant produce. However, the effect of radiation processing on phenolic antioxidants in cereal and legume seeds is still not well understood. This review summarizes recent research on the effect of radiation, including ionizing and nonionizing radiation on the content and profile of phenolic compounds, and antioxidant activities in cereal and legume seeds, the influencing factors and possible mechanisms are also discussed. The article will improve the understanding of radiation effect on phenolic antioxidants, and promote the radiation modification of natural phenolic compounds in cereal and legume seeds and other sources.

Computational cold plasma dynamics and its potential application in food processing

Cold plasma is a novel nonthermal technology that has been used for preserving and maintaining the quality of food materials. Researchers developed numerous cold plasma equipment to study the effect of plasma on food materials; however, the degree of processing such as flow of plasma species from the source of plasma to the food material and their interaction/diffusion into the food, differs with respect to the equipment. The computational study can simulate the flow dynamics of plasma which in turn can improve the efficiency of processing and design aspects. Computational fluid dynamics (CFD) is the most reliable, cost-effective, and robust numerical tool used for simulating various high-end food processing technologies. In cold plasma processing, computational study aids in revealing the distribution of reactive species and their flow dynamics on the target surface. As CFD studies on plasma interaction with food materials are not available, this review is focused on covering the basics of using CFD in cold plasma simulation. It also explores the significant use of CFD in cold plasma simulation in various sectors along with its possible and futuristic applications in food processing.

Technologies for disinfection of food grains: Advances and way forward

Growing demand from the consumers for minimally processed and high-quality food products has raised the scientific quest for foods with improved natural flavours in conjunction with a restricted supplement of additives. In this context, achieving quality and safe food grains and the identification of suitable processing and disinfection technologies have also become the key issues. Microbial contamination is one of the major reasons responsible for the spoilage of food grains. Various sources of contamination such as air and water (both contaminated with dust and dirt), animals (insects, birds, rodents), environmental conditions (rainfall, drought, temperature), unhygienic handling, harvesting, processing equipment and improper storage conditions are responsible for the microbial spoilage of food grains. In order to maintain the food grains safe and un-contaminated, several food processing technologies have been explored and implemented, with the ultimate purpose of maintaining the safety, freshness and nutritional attributes of the food products. Among these technologies, microwave, radiofrequency, infrared, ohmic heating, novel drying methods along with non-thermal methods such as cold plasma, irradiation, ozonation and nanotechnology have attracted much attention because of considerable reduction in the overall processing time with minimum energy consumption. This review aims to discuss the advances involving the said technologies for controlling the microbial contamination of food grains in accordance with their inactivation. Current research status of the thermal and non-thermal emerging technologies for the preservation of food grains as well as perspectives for further research in this area are also elaborated in detail.