Ozonation of Brazil nuts: Decomposition kinetics, control of Aspergillus flavus and the effect on color and on raw oil quality

Evaluation of the safety and quality of Brazil nuts (Bertholletia excelsa) using the tools of dna sequencing technology and aflatoxin profile

Introduction

Brazil nuts (BNs) result from sustainable extraction and are widely exploited in the Amazon region. Due to the production characteristics in the forest and the nutritional characteristics of these nuts, the occurrence of fungal contamination and the presence of aflatoxins are extensively discussed in the literature as a great aspect of interest and concern. This study aims to evaluate the microbial profile through DNA sequencing and amplification of 16S and ITS genes for bacterial and fungal analysis, respectively, and the presence of mycotoxins using high-performance liquid chromatography with fluorescence detection (HPLC-FD) from different fractions of the nuts processed.

Methods

The BN samples, harvest A (HA) and harvest B (HB), from two different harvests were collected in an extractive cooperative in the Amazon region for microbiological analysis (from DNA extraction and amplification of 16S genes, bacteria analysis, and ITS for fungi) and mycotoxins (aflatoxins AFB1, AFB2, AFG1, and AFG2) using HPLC-FD/KobraCell®.

Results and discussion

The samples showed a very different microbiome and aflatoxin profile. Genera such as Rothia (HA) and Cronobacter (HB) were abundant during the analysis of bacteria; as for fungi, the genera Aspergillus, Fusarium, Penicillium, and Alternaria were also considered prevalent in these samples. Soil microorganisms, including those pathogenic and related to inadequate hygienic-sanitary production practices, as well as aflatoxins, were found in the samples. However, they were within the established limits permitted by Brazilian legislation. Nuts have a diverse microbiota and are not restricted to fungi of the genus Aspergillus. The microbiological and toxicological profile can vary significantly within the same nut in the same extraction region and can be exacerbated by global climate changes. Therefore, it is necessary to advance sanitary educational actions by applying good production practices and inspection programs to ensure the sustainability and quality of the BN production chain.

The potential use of ozone as antifungal and antiaflatoxigenic agent in nuts and its effect on nutritional quality

Abstract Ozone gas is considered as a safe antimicrobial agent in food industries. Here, we evaluated the antifungal and antiaflatoxigenic activities of ozone against fungal contamination in nuts. The most predominant fungal genera in nuts were Aspergillus, Penicillium, Fusarium, and Rhizopus. Ozone (4 ppm) significantly reduced the fungal sporulation of A. flavus and their aflatoxin production. Interestingly, ozone treatment of nuts reduced the total fungal count and increased aflatoxins degradation by approximately 95% and 85%, respectively. Ozone displayed high efficiency to increase the permeability of cell membrane and injury of cell wall of fungi. Increasing the exposure time of ozone in nuts up to 180 minutes showed to reduce the total lipid, carbohydrates, and protein by around 41.2%, 42.7% and 38.4% respectively, in pistachio, almond and peanuts. In conclusion, ozonation is a suitable decontaminating approach for reducing the microbial load in nuts, when used with suitable exposure time.

Pesticide Residues and Berry Microbiome after Ozonated Water Washing in Table Grape Storage

Nowadays, different systems for reducing pesticides in table grapes are being tested at different production stages either in the field or in postharvest. The present study tested ozonated water treatments at the beginning of the cold storage of the Princess® seedless table grape variety to reduce the residue contents of some pesticides and to evaluate their effect on gray mold and the berry microbiome. An ozone generator capable of producing an ozone concentration ranging from 18 to 65 Nm3 was utilized for obtaining three ozone concentration levels in water: 3, 5 and 10 mg/L. Ozonated water was placed in a 70 L plastic box where 500 g grape samples closed in perforated plastic clamshell containers were immersed utilizing two washing times (5 and 10 min). Overall, six ozonated water treatments were tested. After the ozonated water treatments, all samples were stored for 30 days at 2 °C and 95% relative humidity to simulate commercial practices. The pesticide residue contents were determined before the ozonated water treatments (T0) and 30 days after the cold storage (T1). The treatments with ozonated water washing reduced the pesticide residues up to 100%, while the SO2 control treatment reduced the pesticide residues ranging from 20.7 to 60.7%. Using 3 mg/L ozonated water to wash grapes for 5 min represented the optimal degradation conditions for all of the analyzed pesticides, except for fludioxonil, which degraded better with a washing time of 10 min. The ozone treatments did not significantly reduce the gray mold and the fungal and bacterial microbiome, while a relevant reduction was observed in the yeast population.

A critical mini-review on challenge of gaseous O3 toward removal of viral bioaerosols from indoor air based on collision theory

COVID-19, a pandemic of acute respiratory syndrome diseases, led to significant social, economic, psychological, and public health impacts. It was not only uncontrolled but caused serious problems at the outbreak time. Physical contact and airborne transmission are the main routes of transmission for bioaerosols such as SARS-CoV-2. According to the Centers for Disease Control (CDC) and World Health Organization (WHO), surfaces should be disinfected with chlorine dioxide, sodium hypochlorite, and quaternary compounds, while wearing masks, maintaining social distance, and ventilating are strongly recommended to protect against viral aerosols. Ozone generators have gained much attention for purifying public places and workplaces' atmosphere, from airborne bioaerosols, with specific reference to the COVID-19 pandemic outbreak. Despite the scientific concern, some bioaerosols, such as SARS-CoV-2, are not inactivated by ozone under its standard tolerable concentrations for human. Previous reports did not consider the ratio of surface area to volume, relative humidity, temperature, product of time in concentration, and half-life time simultaneously. Furthermore, the use of high doses of exposure can seriously threaten human health and safety since ozone is shown to have a high half-life at ambient conditions (several hours at 55% of relative humidity). Herein, making use of the reports on ozone physicochemical behavior in multiphase environments alongside the collision theory principles, we demonstrate that ozone is ineffective against a typical bioaerosol, SARS-CoV-2, at nonharmful concentrations for human beings in air. Ozone half-life and its durability in indoor air, as major concerns, are also highlighted in particular.

The influence of non-thermal technologies on color pigments of food materials: An updated review

The color of any food is influenced by several factors, such as food attributes (presence of pigments, maturity, and variety), processing methods, packaging, and storage conditions. Thus, measuring the color profile of food can be used to control the quality of food and examine the changes in chemical composition. With the advent of non-thermal processing techniques and their growing significance in the industry, there is a demand to understand the effects of these technologies on various quality attributes, including color. This paper reviews the effects of novel, non-thermal processing technologies on the color attributes of processed food and the implications on consumer acceptability. The recent developments in this context and a discussion on color systems and various color measurement techniques are also included. The novel non-thermal techniques, including high-pressure processing, pulsed electric field, ultrasonication, and irradiation which employ low processing temperatures for a short period, have been found effective. Since food products are processed at ambient temperature by subjecting them to non-thermal treatment for a very short time, there is no possibility of damage to heat-sensitive nutrient components in the food, any deterioration in the texture of the food, and any toxic compounds in the food due to heat. These techniques not only yield higher nutritional quality but are also observed to maintain better color attributes. However, suppose foods are exposed to prolonged exposure or processed at a higher intensity. In that case, these non-thermal technologies can cause undesirable changes in food, such as oxidation of lipids and loss of color and flavor. Developing equipment for batch food processing using non-thermal technology, understanding the appropriate mechanisms, developing processing standards using non-thermal processes, and clarifying consumer myths and misconceptions about these technologies will help promote non-thermal technologies in the food industry.

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.

Influence of ozonation and roasting on functional, microstructural, textural characteristics, and aflatoxin content of groundnut kernels

The present study was conducted to evaluate the influence of ozonation, roasting and their combination on the moisture content, color, functional, structural, textural components, and aflatoxins in groundnut kernels. Samples were subjected to three treatments namely, dry roasting (R): 166°C for 7 min; gaseous ozone treatment (O): 6 mg/L for 30 min; combined ozonation-roasting (OR): gaseous ozonation at 6 mg/L for 30 min followed by dry roasting at 166°C for 7 min. The ozonated-roasted samples had the lowest moisture content (3.45%), the highest total phenolic content (4.18 mg gallic acid equivalents/100 g), and antioxidants capacity (69.59%). The treatments did not induce significant changes in color of kernels (p < .05). Scanning electron microscopy indicated cracking of granules in roasted and swelling in ozonated kernels whereas more uniform orientation of granules was observed in ozonated-roasted kernels. Roasted and ozonated kernels indicated a significant reduction of fracturability force to 54.60 and 14.11%, respectively, whereas ozonated-roasted samples demonstrated a nonsignificant increase (4.37%). An increase in wave number of ozonated samples to 3,289.37 cm^-1 in Fourier transform infrared (FTIR) spectrum (FTIR) indicated stretching in OH groups. FTIR spectrum of ozonated-roasted kernels suggested the formation of a new compound with CC and CC groups. The major aflatoxin B1 was reduced to maximum, that is, 100% in ozonated-roasted kernels followed by ozonated (80.95%) and roasted (57.14%) samples. The findings indicate that the ozonation-roasting treatment had a prominent role in the enhancement of functional compounds, structural and textural attributes along with the considerable reduction in aflatoxin content.

Recent developments for controlling microbial contamination of nuts

In recent years, the consumption of nuts has shown an increasing trend worldwide. Nuts are an essential part of several countries' economies as an excellent source of nutrients and bioactive compounds. They are contaminated by environmental factors, improper harvesting practices, inadequate packaging procedures, improper storage, and transportation. The longer storage time also leads to the greater chances of contamination from pathogenic fungi. Nuts are infected with Aspergillus species, Penicillium species, Escherichia coli, Salmonella, and Listeria monocytogenes. Therefore, nuts are associated with a high risk of pathogens and mycotoxins, which demand the urgency of using techniques for enhancing microbial safety and shelf-life stability. Many techniques such as ozone, cold plasma, irradiation, radiofrequency have been explored for the decontamination of nuts. These techniques have different efficiencies for reducing the contamination depending on processing parameters, type of pathogen, and conditions of food material. This review provides insight into decontamination technologies for reducing microbial contamination from nuts.

Effect of ozone application on the removal of pesticides from grapes and green bell peppers and changes in their nutraceutical quality

The present study evaluates the efficacy of ozonated water for the removal of pesticide residues in grapes and green bell peppers. Fruit fortified with pesticides (azoxystrobin, chlorothalonil, chlorpyrifos, cypermethrin, hexaconazole and methyl parathion) were subjected to 15 and 30 min aqueous ozone treatment. GC analysis of ozonated fruits showed a 48.67% to 96.95% decrease in pesticide residues of different pesticides. Methyl paraoxon, a toxic degradation product of methyl parathion, was detected in the ozonated water sample. To assess the effect of ozonation on the nutraceutical quality of fruits, the concentrations of eleven polyphenols and ascorbic acid were analyzed. The individual polyphenols showed different trend in 15 and 30 min treatment. Overall, there was an increase in the levels of all the polyphenols in grapes after 30 min ozonation treatment. In peppers, there was a net increase in quercetin, quercetin-3-O-glucoside, rutin and kaempferol in 30 min while other polyphenols were decreased. The ascorbic acid content of both the fruits was decreased by more than 70% upon ozonation. Thus, ozonation treatment was effective in pesticide removal. However, it changed the nutraceutical quality of grapes and green bell peppers.

Effect of Ozone Treatment on the Quality of Sea Buckthorn (Hippophae rhamnoides L.)

The aim of this research was to show the effect of the ozonation process on the quality of sea buckthorn (Hippophae rhamnoides L.). The quality of the ozonated berries of sea buckthorn was assessed. Prior to and after the ozone treatment, a number of parameters, including the mechanical properties, moisture content, microbial load, content of bioactive compounds, and composition of volatile compounds, were determined. The influence of the ozonation process on the composition of volatile compounds and mechanical properties was demonstrated. The ozonation had negligible impact on the weight and moisture of the samples immediately following the treatment. Significant differences in water content were recorded after 7 days of storage. It was shown that the highest dose of ozone (concentration and process time) amounting to 100 ppm for 30 min significantly reduced the water loss. The microbiological analyses showed the effect of ozone on the total count of aerobic bacteria, yeast, and mold. The applied process conditions resulted in the reduction of the number of aerobic bacteria colonies by 3 log cfu g-1 compared to the control (non-ozonated) sample, whereas the number of yeast and mold colonies decreased by 1 log cfu g-1 after the application of 100 ppm ozone gas for 30 min. As a consequence, ozone treatment enhanced the plant quality and extended plant's storage life.

Application of ozone for degradation of mycotoxins in food: A review

Mycotoxins such as aflatoxins (AFs), ochratoxin A (OTA) fumonisins (FMN), deoxynivalenol (DON), zearalenone (ZEN), and patulin are stable at regular food process practices. Ozone (O₃ ) is a strong oxidizer and generally considered as a safe antimicrobial agent in food industries. Ozone disrupts fungal cells through oxidizing sulfhydryl and amino acid groups of enzymes or attacks the polyunsaturated fatty acids of the cell wall. Fusarium is the most sensitive mycotoxigenic fungi to ozonation followed by Aspergillus and Penicillium. Studies have shown complete inactivation of Fusarium and Aspergillus by O₃ gas. Spore germination and toxin production have also been reduced after ozone fumigation. Both naturally and artificially, mycotoxin-contaminated samples have shown significant mycotoxin reduction after ozonation. Although the mechanism of detoxification is not very clear for some mycotoxins, it is believed that ozone reacts with the functional groups in the mycotoxin molecules, changes their molecular structures, and forms products with lower molecular weight, less double bonds, and less toxicity. Although some minor physicochemical changes were observed in some ozone-treated foods, these changes may or may not affect the use of the ozonated product depending on the further application of it. The effectiveness of the ozonation process depends on the exposure time, ozone concentration, temperature, moisture content of the product, and relative humidity. Due to its strong oxidizing property and corrosiveness, there are strict limits for O₃ gas exposure. O₃ gas has limited penetration and decomposes quickly. However, ozone treatment can be used as a safe and green technology for food preservation and control of contaminants.