Technologies for disinfection of food grains: Advances and way forward

Advances in ozone technology for preservation of grains and end products: Application techniques, control of microbial contaminants, mitigation of mycotoxins, impact on quality, and regulatory approvals

Ozone has emerged as a promising technology for preserving stored grains and end products. Its efficiency as a biocide and the absence of residues make it an attractive alternative to traditional chemical methods of food preservation. This study reviews recent advancements in ozone application techniques, including continuous flow treatments, closed-loop recirculation systems, and low-pressure application systems, as well as their impact on product quality. The study also examines the mechanisms of ozone action, its half-life in grain storage environments, and methods to ensure uniform gas distribution. The results of this study provide a foundation for understanding ozone reactions in various grain types and application systems, offering essential information for effectively sizing treatment systems, estimating ozone concentrations over time, and determining the quantity of products to be treated. A thorough comprehension of ozone behavior in porous environments, such as silos, and its stability under diverse environmental conditions is crucial for enhancing its applicability. While scientific evidence supports ozone's efficacy in controlling pests and microorganisms, further investigation is needed on its impact on the nutritional quality of grains and final products. Additionally, the review highlights the latest regulatory approvals for ozone use in the food industry, emphasizing the importance of compliance and safety. The findings underscore the need for continued technological development and economic analysis to evaluate the long-term viability of ozone applications in agriculture.

Research progress in the application of infrared blanching in fruit and vegetable drying process

Fruits and vegetables offer substantial nutritional and health benefits, but their short shelf life necessitates effective preservation methods. Conventional drying techniques, while efficient, often lead to deterioration in food quality. Recent advancements highlight the potential of infrared blanching (IRB) as a preparatory process to improve drying outcomes. This review systematically evaluated the application of IRB for various fruits and vegetables, including tomatoes, potatoes, carrots, mangoes, apples, peaches, strawberries, grapes, and green beans. IRB demonstrated notable improvements in texture, color retention, and nutrient preservation in dried products. Key operational parameters for effective IRB include product thickness (2-5 cm), treatment duration (30 s to several minutes), and the distance from the infrared (IR) emitter (10-30 cm). These factors collectively ensure efficient heat penetration and energy transfer. Regarding IR generators, far-IR heaters are advantageous due to their uniform heating capabilities, whereas near-IR heaters deliver rapid heating. Catalytic IR generators are also emerging as promising options for industrial-scale applications. This review further explores the principles and mechanisms of IRB, particularly its impact on drying kinetics and the retention of vitamins, antioxidants, and bioactive compounds. Evidence indicates that IRB can reduce drying times by up to 50%, increase drying rates, and lower energy consumption by approximately 17%, achieving energy efficiency levels of 80%-90%. However, limitations such as the shallow penetration depth of IR radiation remain challenging. Potential solutions, such as the development of hybrid blanching methods, are discussed to optimize the drying process further and enhance the quality of dried fruits and vegetables.

Recent developments in applications of physical fields for microbial decontamination and enhancing nutritional properties of germinated edible seeds and sprouts: a review

Germinated edible seeds and sprouts have attracted consumers because of their nutritional values and health benefits. To ensure the microbial safety of the seed and sprout, emerging processing methods involving physical fields (PFs), having the characteristics of high efficiency and environmental safety, are increasingly proposed as effective decontamination processing technologies. This review summarizes recent progress on the application of PFs to germinating edible seeds, including their impact on microbial decontamination and nutritional quality and the associated influencing mechanisms in germination. The effectiveness, application scope, and limitation of the various physical techniques, including ultrasound, microwave, radio frequency, infrared heating, irradiation, pulsed light, plasma, and high-pressure processing, are symmetrically reviewed. Good application potential for improving seed germination and sprout growth is also described for promoting the accumulation of bioactive compounds in sprouts, and subsequently enhancing the antioxidant capacity under favorable PFs processing conditions. Moreover, the challenges and future directions of PFs in the application to germinated edible seeds are finally proposed. This review also attempts to provide an in-depth understanding of the effects of PFs on microbial safety and changes in nutritional properties of germinating edible seeds and a theoretical reference for the future development of PFs in processing safe sprouted seeds.

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.

Comparison of microwave and autoclave treatment for biomedical waste disinfection

As the world is facing a Covid-19 pandemic, this virus teaches a lesson about the importance of on-site disinfection. On-site disinfection/sterilization with real-time monitoring of biomedical waste generated from the medical facilities is mandatory to prevent hospital-acquired infection (HAI). In this study, the life cycle assessment of two technologies, i.e., microwave (radiation-based) and autoclave (steam-based) were performed to summarize the inside-out evaluation of both technologies in terms of efficiency, efficacy, and cost-effectiveness. The results of disinfection efficacy indicated a log 10 reduction (almost 100%) in the vegetative load of microorganisms compared to the control, showing a similar level of disinfection efficacy of both strategies. Additionally, both technologies were compared on several parameters, and it was discovered that the autoclave uses more time and resources than the microwave. The total cost of an autoclave to the government is approximately double that of a microwave, while the operational cost of an autoclave is more than double that of a microwave. The findings from this study indicate that MACS may be used as a dry technique of biomedical disinfection, and its portability, tunability, and compactness make it a suitable alternative for biomedical disinfection and sterilization.

Graphical abstract

Design, construction, and testing of passive type solar tunnel for maize grain disinfestations

In this study, a solar tunnel of passive-type designed, constructed and tested for storage insect pest disinfestation. The designed solar tunnel was 1.9 m wide and 3 m long with the maize grain holding capacity of 150 kg, 300 kg, and 450 kg with 5 cm, 10 cm, and 15 cm layer thickness respectively. To evaluate the performance of the solar tunnel, maize grain infested with storage pests was kept in the solar tunnel with 5 cm, 10 cm, and 15 cm layer thickness for 4 consecutive days. During the study, the temperature and relative humidity profile of the air in the tunnel and the temperature in maize grain was recorded. Germination percentage and number of live insects were evaluated after each day of disinfestations. The highest temperature recorded in the solar tunnel was in the range of 64.6–67.6 °C during the study period. Complete disinfestations of the grain were obtained on the first day for 5 cm layer thickness and the second day for 10 and 15 cm layer thickness. The higher germination percentage was recorded for 15 cm layer thickness in all experimental days. Of all the treatments the combination of the layer thickness of 15 cm and two day disinfestations time were found to be the best combination for using the tunnel for maize grain disinfestations in terms of achieving complete disinfestations; maintaining germination capacity of the grain and time required to disinfect a large amount of grain.