Grape Surface Research Articles

Analysis of discharge parameters of an argon cold atmospheric pressure plasma jet and its impact on surface characteristics of White Grapes

An argon cold atmospheric-pressure plasma (CAP) jet operated using bipolar pulsed power supply has been characterised electro-optically and the discharge parameters are optimized. An analysis has been done on the impact of the argon CAP jet treatment on the surface properties of white grapes for different treatment time period. The developed argon CAP jet is a plasma source based on dielectric barrier discharge (DBD) that has been tuned at various input parameters including applied voltage, frequency, average power consumption, and argon flow rate. Optical Emission Spectroscopy (OES) is used to identify the generated species along with plasma parameters. The collisional–radiative (CR) model is employed to extract the electron density (ne) and electron temperature (Te) from the spectra at the optimised applied voltage of 4 kV, frequency 20 kHz and argon flow rate of 4 slpm. The OES results coupled with the CR model (ne ∼ 1014 cm−3 and Te ∼ 1 eV) and the plasma gas temperature measurement through OH (A-X) transitions (Tg ∼ 310.5 K) show the non-equilibrium nature of the argon CAP jet. A comparative analysis between untreated and treated white grapes reveals that the argon CAP jet treatment influences surface microstructure, increasing hydrophilicity (with a ∼49.3% decrease in water contact angle) along with slight changes in surface temperature (∼5 °C increase), colour (ΔE* < 1.5), and physiochemical properties such as chemical composition (no change) and Total Soluble Solid (TSS) content (∼8.3%). It is inferred that this type of CAP jet treatment of white grapes only affects the physical characteristics of the grape surface and does not alter any chemical compositions.

Effects of Meyerozyma guilliermondii PJ15 on the biocontrol of Penicillium crustosum causing postharvest decay in Orah and its influence on the microbial diversity of Orah

Abstract Objectives Isolate biocontrol microorganisms that inhibit Penicillium crutosum, and explore their effects on the microbial control and microbial diversity change of Penicillium crustosum causing postharvest decay in Orah. Materials and Methods The biocontrol effect was verified by confrontation experiment. The microbial diversity was analyzed using high-throughput sequencing technology. Metabolomics analysis was performed using LC-MS/MS. Results a strain of Meyerozyma guilliermondii PJ15 that strongly inhibited Penicillium crustosum was isolated from grape surface, which could effectively inhibit the mycelium growth and green spore production of Penicillium crustosum. PJ15 could reduce the sourness and nutrient loss of Orah caused by Penicillium crutosum. Compared with the control, PJ15 treatment increased pH by 11.32%, soluble protein by 154.51%, ascorbic acid by 160.99%, and soluble total sugar by 203.53%. Microbial diversity analysis showed that PJ15 has a relatively small impact on the bacterial composition and diversity on the surface of Orah, but has a significant impact on the fungal composition and diversity. It can increase the fungal diversity of Orah invaded by Penicillium crustosum, increase the density of fungal interaction networks, and form a stronger coexisting survival interaction network. The vaccination of PJ15 downregulated differential metabolites 5,6-Epoxytetraene, which showed a positive correlation with Penicillium crustosum and a negative correlation with PJ15. Conclusions Meyerozyma guilliermondii PJ15 has a strong inhibitory effect on the growth of Penicillium crustosum, and has a significant impact on the fungal composition and diversity on the surface of Orah. It has the potential for biocontrol of Penicillium crustosum causing postharvest decay in Orah.

Pesticides and winemaking: A comprehensive review of conventional and emerging approaches.

The use of pesticides in viticulture may play a crucial role in ensuring the health and quality of grapes. This review analyzes the most common pesticides used, illustrating their classification and toxicity, and their variations throughout the winemaking process. Fungicides are generally harmless or mildly toxic, whereas insecticides are classified as either highly or moderately hazardous. Potential alternatives to synthetic pesticides in wine production are also reviewed, thereby including biopesticides and biological agents. Analytical methods for detecting and quantifying pesticide residues in wine are then described, including liquid chromatography and gas chromatography coupled with mass spectrometry. This review also discusses the impact of the winemaking process on pesticide content. Pesticides with strong hydrophobicity were more likely to accumulate in solid byproducts, whereas hydrophilic pesticides were distributed more in the liquid phase. Grape's skin contains lipids, so hydrophobic pesticides adsorb strongly on grape surfaces and the clarification has been shown to be effective in the reduction of hydrophobic compounds. Therefore, the final wine could have more quantities of hydrophilic pesticides. Alcoholic fermentation has been shown to be crucial in pesticide dissipation. However, pesticide residues in wine have been shown an antagonistic effect on yeasts, affecting the safety and quality of wine products. Therefore, proteomic and genomic analyses of yeast growth are reviewed to understand the effects of pesticides on yeast during fermentation. The last section describes new effective methods used in removing pesticides from grapes and wine, thereby improving product quality and reducing harmful effects.

Characterization and analysis of dynamic changes of microbial community associated with grape decay during storage

The rot caused by pathogens during the storage of table grapes is an important factor that affects the development of the grape industry and food safety, and it cannot be ignored. The development of innovative methods for pathogen control should be based on a comprehensive understanding of the overall microbial community changes that occur during grape storage. The study aims to investigate the relationship between the native microbiota (including beneficial, pathogenic and spoilage microorganisms) on grape surfaces and the development of disease during grape storage. In this study, the bacteria and fungi present on grape surfaces were analyzed during storage under room temperature conditions using high-throughput sequencing. During the storage of grapes at room temperature, observable diseases and a noticeable decrease in quality were observed at 8 days. Microbial community analysis showed that 4996 bacterial amplicon sequence variants (ASVs) and 488 fungal ASVs were determined. The bacterial richness exhibited an initial increase followed by a subsequent decrease. However, the diversity exhibited a distinct pattern of gradual decrease. The fungal richness and community diversity both exhibit a gradual decrease during the storage of grapes. Fungal β-diversity analysis showed that despite the absence of rot and the healthy state of grapes on the first and fourth days, the fungal β-diversity exhibited a significant difference. The analysis of changes in genera abundances suggested that Candidatus Profftella and Aspergillus exhibited dominance in the rotting grape at 16 days, which are the main pathogens that caused disease in the present study. The co-occurrence networks among the microbial showed that the Candidatus proftella genera has a positive correlation with Aspergillus niger, indicating that they work together to cause disease and promote growth in grapes. Predicting the function of bacterial communities found that the microorganisms associated with lipid metabolism at 4 days play an important role in the process of postharvest decay of grapes.

Microbial Diversity Associated with the Cabernet Sauvignon Carposphere (Fruit Surface) from Eight Vineyards in Henan Province, China.

The microbial diversity on the carposphere (berry) surface of the grape cultivar Cabernet Sauvignon grown in eight different locations/vineyards of Henan Province was determined by high-throughput sequencing of the bacterial 16S rRNA gene and fungal 18S rRNA gene. The structure of bacterial and fungal communities varied according to the sampling sites, but with some common phyla. Proteobacteria and Ascomycota were dominant/common phyla for bacteria and fungi, respectively. A total of 27 and 20 bacterial and fungal families, respectively, and 39 and 20 bacterial and fungal genera, respectively, with statistically significant differences, were found among different sampling sites. The difference for metabolic pathways of bacteria among the sampling sites existed. In addition, various abundances of enzymes from different sites might indicate that different function patterns exist in microbiota from different sites. The results revealed that locations of grape vineyards might play a significant role in shaping the microbiome, as well as the fact that vineyards can be distinguished based on the abundance of several key bacterial and fungal taxa. Overall, these findings extend our understanding of the similarities and differences in microbial community and their metabolic function on Cabernet Sauvignon grape surfaces from different geographic locations.

Natural pre-treatment in raisins production: Effects on quality during storage

BRS Vitoria raisins were produced with a pre-treatment using a natural surfactant, i.e., extra-virgin olive oil (EVOO), to (i) better elucidate its action on the grape surface using scanning electron microscopy; (ii) evaluate its influence on the oleanolic and ursolic acid content of raisins through HPLC-DAD; (iii) assess raisins characteristics during 180-day storage at different temperatures by using physicochemical and microbiological analyses with multivariate-based chemometric methods (MASLT). Grapes which presented adequate physicochemical characteristics and high concentration of anthocyanins originated raisins similar to those reported in the literature. The pre-treatment accelerated the dehydration process (about 26%) mainly because of the non-uniform redistribution of the surface waxy components accompanied by the formation of microholes and cracks. The small amount of EVOO used did not affect the oleanolic acid content in raisins, yet this compound proved to resist drying, which means that there is no loss of wax during the pre-treatment. For both untreated (RW) and pre-treated raisins (RP), the main changes triggered over time were not related to microbiological characteristics. Most of the changes appeared to occur right during drying and not during storage for RW, whereas for RP the physicochemical characteristics that mostly correlated with the storage changes were total monomeric anthocyanins, total acidity, and total sugars; also, they tended to reach an equilibrium and equaled RW at the end of 180 days, especially at 35 °C. These parameters proved to be the main characteristics related to the changes triggered in raisins. For both raisins, sugar crystals were formed in the flesh, but they were not visible to the naked eye or perceived by consumers. The results show that it is highly desirable to have a high-quality product at the beginning of storage, which was possible thanks to the EVOO pre-treatment used.

Effect of Pretreatment and Drying on the Nutritional and Functional Quality of Raisins Produced with Seedless Purple Grapes.

Raisins, known for their delicious taste and high nutritional value, are among the most widely consumed dried fruits globally. The natural waxy layer on the surface of grapes impedes water migration, making pretreatment necessary before drying. This study evaluated the effects of various pretreatment methods on the nutritional and functional quality of seedless purple raisins. By using non-pretreated dry seedless purple raisins as a control, the impact of physical and chemical pretreatment methods on the nutritional and functional qualities of seedless purple raisins was assessed through the analysis of nutrient content, phenolic compounds, and antioxidant activity. Our results demonstrate that physical pretreatment significantly increases the levels of vitamin C, fructose, glucose, total acid, total phenolics, total flavonoids, total anthocyanins, and antioxidant activity compared to chemical pretreatment and the control group. The correlation analysis revealed that phenolic substances were closely linked to antioxidant capacity. Additionally, phenolic compounds, including resveratrol, ferulic acid, chlorogenic acid, ethyl coumarate, and cinnamic acid, were more abundant following physical pretreatment. The OPLS-DA model effectively differentiated the three groups of processed samples, showing that different pretreatments significantly affect the nutritional and functional quality of seedless purple raisins. These findings suggest that physical pretreatment offers considerable potential for improving the drying quality of seedless purple raisins.

Biocontrol of Alternaria alternata in cold-stored table grapes using psychrotrophic yeasts and bioactive compounds of natural sources

Alternaria alternata is a common fungal pathogen causing postharvest decay in table grapes. This study addressed the potential of autochthonous yeasts and bioactive compounds of natural sources to act as biocontrol agents (BCAs) against A. alternata in cold-stored table grapes. With this purpose, 19 yeast capable of growing at 0–1 °C were isolated from the surface of Red Globe table grapes. These isolates, along with the pre-isolated strain Metschnikowia pulcherrima RCM2, were evaluated as BCAs in wounded berries. From these results, six yeast isolates were pre-selected to be combined with bioactive compounds of natural sources, like phenolic compounds (PCs) of side streams of wine industry, including bunch stem extract (BSE) (5–25 %), and cane extract (CE) (5–25 %), and functional polysaccharides from shrimp waste such as chitosan (CH) (0.5 %). Then, the biocontrol efficacy of combined treatments beyond individual ones was compared. The results revealed that 4 yeast isolates, namely M. pulcherrima RCM2 and ULA146, and Aureobasidium pullulans FUL14 and FUL18, were the most effective. However, when combined with the natural bioactive compounds, their efficacy against A. alternata did not increase significantly. Notably, ULA146 and FUL18 demonstrated a biocontrol efficacy of 36–37 %, comparable to that of the treatment with commercial doses of SO2, which only showed a 27 % reduction in the lesion diameter. These findings highlight the potential of using psychrotrophic yeasts as BCAs against A. alternata in cold-stored table grapes. Combining these yeast strains with BSE, CE and CH did not increase BCAs efficacy against this pathogen at the concentrations tested. The development of effective biocontrol strategies for A. alternata could contribute to reducing reliance on chemically synthesized fungicides, promoting sustainable practices, aiming to improve the quality and safety of cold-stored table grapes.

Facile synthesis of gold nanostars for the duplex detection of pesticide residues in grapes using SERS.

In recent years, concerns have been raised regarding the contamination of grapes with pesticide residues. As consumer demand for safer food products grows, regular monitoring of pesticide residues in food has become essential. This study sought to develop a rapid and sensitive technique for detecting two specific pesticides (phosmet and paraquat) present on the grape surface using the surface-enhanced Raman spectroscopy (SERS) method. Gold nanostars (AuNS) particles were synthesized, featuring spiky tips that act as hot spots for localized surface plasmon resonance, thereby enhancing Raman signals. Additionally, the roughened surface of AuNS increases the surface area, resulting in improved interactions between the substrate and analyte molecules. Prominent Raman peaks of mixed contaminants were acquired and used to characterize and quantify the pesticides. It was observed that the SERS intensity of the Raman peaks changed in proportion to the concentration ratio of phosmet and paraquat. Moreover, AuNS exhibited superior SERS enhancement compared to gold nanoparticles. The results demonstrate that the lowest detectable concentration for both pesticides on grape surfaces is 0.5mg/kg. These findings suggest that SERS coupled with AuNS constitutes a practical and promising approach for detecting and quantifying trace contaminants in food. PRACTICAL APPLICATION: This research established a novel surface-enhanced Raman spectroscopy (SERS) method coupled with a simplified extraction protocol and gold nanostar substrates to detect trace levels of pesticides in fresh produce. The detection limits meet the maximum residue limits set by the EPA. This substrate has great potential for rapid measurements of chemical contaminants in foods.

Process parameters optimization for red globe grapes to enhance shelf-life using non-equilibrium cold plasma jet

In this work, a non-equilibrium cold plasma jet (NECPJ) operated by a bi-polar pulse power source was designed and developed, and its impact on red globe grapes (Vitis vinifera) was analyzed for shelf-life enhancement. A total of 17 separate experiments were conducted using a Box-Behnken design to identify the optimum plasma process parameters, i.e., applied voltage, gas flow rate, and treatment time. Food quality parameters such as pH, total suspended solids (TSS), weight loss, total phenol and flavonoid content, vitamin C, contact angle, and firmness were studied. Field emission scanning electron microscopy (FESEM) images were also taken to see the effect of NECPJ treatment on grape surfaces and E. coli bacteria. The results showed that the linear, quadratic, and interaction effects of all three process parameters were statistically significant (p < 0.001, p < 0.01). Accordingly, the optimized plasma process parameters were identified as applied voltage 3.36 kV, gas flow rate 2.87 SLPM, and treatment time 1 min. A shelf-life study of twenty-eight days was done with and without plasma treatment. It was found that NECPJ-treated grapes had a higher shelf-life. The treated grapes contained higher levels of vitamin C, firmness, red grape color index, and total soluble solids than controls. It is inferred that NECPJ can help reduce red globe grape deterioration and maintain quality during post-harvest storage.

Ultrasound synergistic slightly acidic electrolyzed water treatment of grapes: Impacts on microbial loads, wettability, and postharvest storage quality

Microbial contamination is the principal factor in the deterioration of postharvest storage quality in grapes. To mitigate this issue, we explored a synergistic treatment which combines ultrasound (US) and slightly acidic electrolyzed water (SAEW), and rigorously compared with conventional water cleaning (CW), exclusive US treatment, and standalone SAEW treatment. The US + SAEW treatment proved to be markedly superior in reducing total bacterial, mold & yeast counts on grapes. Specifically, it achieved reductions of 2.23 log CFU/g and 2.76 log CFU/g, respectively, exceeding the efficiencies of SAEW (0.78, 0.75), US (0.58, 0.65), and CW (0.24, 0.46). The efficacy of this synergistic treatment is attributed to the ultrasound removal of the wax layer on grape skins, which transitions the skin from hydrophobic to hydrophilic. This alteration increases the contact area between the grape surface and SAEW, thereby enhancing the antimicrobial efficacy of SAEW. From a physicochemical quality standpoint, the US + SAEW treatment exhibited multiple advantages. It not only minimized weight loss, color deviations, polyphenol oxidase activity and malondialdehyde synthesis in comparison to CW-treated samples but also preserved firmness, sugar-acid ratio and the activities of key enzymes including phenylalanine ammonia-lyase, superoxide dismutase and catalase, and thus maintaining high levels of total phenolics, total ascorbic acid, total anthocyanins, and antioxidants. Consequently, US + SAEW treatment put off the times of decay onset in grapes by 12 days, outperforming both SAEW (8) and US (4) in comparison to CW. These results highlight the potential of US + SAEW as an effective strategy for maintaining grape quality during their postharvest storage period.

Antibiotic resistance gene distribution in Shine Muscat grapes and health risk assessment of streptomycin residues in mice

Antibiotic residues and antibiotic resistance genes (ARGs) in fruits and vegetables pose public health risks via the food chain, attracting increased attention. Antibiotics such as streptomycin, used directly on seedless grapes or introduced into vineyard soil through organic fertilizers. However, extensive data supporting the risk assessment of antibiotic residues and resistance in these produce remains lacking. Utilizing metagenomic sequencing, we characterized Shine Muscat grape antibiotic resistome and mobile genetic elements (MGEs). Abundant MGEs and ARGs were found in grapes, with 174 ARGs on the grape surface and 32 in the fruit. Furthermore, our data indicated that soil is not the primary source of these MGEs and ARGs. Escherichia was identified as an essential carrier and potential transmitter of ARGs. In our previous study, streptomycin residue was identified in grapes. Further short-term exposure experiments in mice revealed no severe physiological or histological damage at several environment-related concentrations. However, with increased exposure, some ARGs levels in mouse gut microbes increased, indicating a potential threat to animal health. Overall, this study provides comprehensive insights into the resistance genome and potential hosts in grapes, supporting the risk assessment of antibiotic resistance in fruits and vegetables.

IoT for Monitoring Fungal Growth and Ochratoxin A Development in Grapes Solar Drying in Tunnel and in Open Air.

Optimisation of solar drying to reduce fungal growth and Ochratoxin A (OTA) contamination is a crucial concern in raisin and currant production. Stochastic and deterministic analysis has been utilized to investigate environmental indicators and drying characteristics. The analysis was performed using two seedless grape varieties (Crimson-red and Thompson-white) that were artificially inoculated with Aspergillus carbonarius during open-air and tunnel drying. Air temperature (T) and relative humidity (RH) were measured and analysed during the drying experiment, along with grape surface temperature (Ts), and water activity (aw). The grape moisture content, fungal colonization, and OTA contamination were estimated, along with the water diffusivity (Deff) and peel resistance (rpeel) to water transfer. Monitoring the surface temperature of grapes is essential in the early detection of fungal growth and OTA contamination. As surface temperature should be carried out continuously, remote sensing protocols, such as infrared sensors, provide the most efficient means to achieve this. Furthermore, data collection and analysis could be conducted through the Internet of Things (IoT), thereby enabling effortless accessibility. The average Ts of the grapes was 6.5% higher in the tunnel than in the open-air drying. The difference between the RH of air and that in the plastic crates was 16.26-17.22%. In terms of CFU/mL, comparison between white and red grapes in the 2020 and 2021 experiments showed that the red grapes exhibited significantly higher values than the white grapes. Specifically, the values for red grapes were 4.3 in 2021 to 3.4 times in 2020 higher compared to the white grapes. On the basis of the conducted analysis, it was concluded that tunnel drying provided some advantages over open-air drying, provided that hygienic and managerial requirements are met.

The Impact of a Commercial Biostimulant on the Grape Mycobiota of Vitis vinifera cv. Barbera.

Reducing the use of fungicides, insecticides, and herbicides in order to limit environmental pollution and health risks for agricultural operators and consumers is one of the goals of European regulations. In fact, the European Commission developed a package of measures (the European Green Deal) to promote the sustainable use of natural resources and strengthen the resilience of European agri-food systems. As a consequence, new plant protection products, such as biostimulants, have been proposed as alternatives to agrochemicals. Their application in agroecosystems could potentially open new scenarios regarding the microbiota. In particular, the vineyard microbiota and the microbiota on the grape surface can be affected by biostimulants and lead to different wine features. The aim of this work was to assess the occurrence of a possible variation in the mycobiota due to the biostimulant application. Therefore, our attention has been focused on the yeast community of grape bunches from vines subjected to the phytostimulant BION®50WG treatment. This work was carried out in the CREA-VE experimental vineyard of Vitis vinifera cv. Barbera in Asti (Piedmont, Italy). The composition of fungal communities on grapes from three experimental conditions such as IPM (integrated pest management), IPM+BION®50WG, and IPM+water foliar nebulization was compared by a metabarcoding approach. Our results revealed the magnitude of alpha and beta diversity, and the microbial biodiversity index and specific fungal signatures were highlighted by comparing the abundance of yeast and filamentous fungi in IPM and BION®50WG treatments. No significant differences in the mycobiota of grapevines subjected to the three treatments were detected.

Microbial diversity on grape epidermis and wine volatile aroma in spontaneous fermentation comprehensively driven by geography, subregion, and variety

On their journey from the wine grape to the resulting wine, microbiota from grape surfaces controlled by multiple factors is transferred to wine spontaneous fermentation process with indisputable consequences for wine quality parameters. The associated microbiota was regionally distinct (defined to microbial terroir) but how these microbial patterns with significantly regional distinctiveness quantitatively drive the wine regional characteristics are not definite within a complete grape ecosystem at different geographical (> 300 km), subregional (< 10 km), and varietal scales. Here, we collected 24 samples (containing two grape varieties) from four subregions of two regions in Xinjiang wine production area to investigate fungal distribution patterns and the association with wine chemical composition at different evaluation scales. Meanwhile, the relationships were established between geographical, subregional, varietal community of fungi, and wine volatile aroma using partial least squares regression (PLSR) and structural equation modeling (SEM). Results show that microbial and volatile samples present the significantly regional difference inside the complete ecosystem. Microbiota showed a stronger heterogeneity at geography scales, which drove the distributions of subregional and varietal microbiota thereby influencing the volatile composition of finished wines. Moreover, geographical microbiota seems to weaken the effects of varietal community on wine aroma compounds. Microbial communities respond to environmental changes within a completely set grape-related ecosystem at different scales, and these responses resulted in the wine regional distinctiveness based on the volatile profiles. Our findings further confirmed the important role of microbial terroir in shaping wine styles and provided the new cerebration for the terroir drivers of microbiota.

MICROBIAL DIVERSITY ON GRAPE SURFACE AND ITS RESEARCH STATUS

The microbial diversity of grape surfaces, also known as "microbial terroir", plays a critical role in winemaking and has applications in crop health and plant protection. Next-generation Sequencing (NGS) has revolutionized our understanding of grape surface microbiota by providing insights into the complex and dynamic microbial communities present on grape berries. NGS studies have confirmed the existence of distinct regional differences in grape surface microbial diversity, highlighting the concept of microbial terroir. This diversity is influenced by various natural and human factors, such as soil type, climate, vineyard management practices, and grapevine genetics, which contribute to the unique microbial terroir of each location. The application of NGS in studying microbial terroir has not only advanced our knowledge of grape and wine science, but also has implications in crop health and plant protection. The identification and characterization of microbial communities using NGS can help to develop sustainable and eco-friendly strategies for managing grapevine diseases and pests. The ongoing research in this area is expected to further expand our understanding of microbial terroir and its applications, contributing to the advancement of grape and wine science, and promoting environmentally responsible grape production practices. Based on bibliometric analysis, the current research focuses on the selection autochthonous S. cerevisiae, non-Saccharomyces and LAB. Plant growth-promoting bacteria considered as a new agroecological manageme. Interest in the role of natural microbial diversity in winemaking remains high.

A dual-state-emission chalcone-based supramolecular probe for ratiometric detection of penconazole in environmental samples

Penconazole (PEN) is a systemic triazole fungicide widely pulverized on fruits and vegetables to control powdery mildew disease. PEN has various hazardous effects on mammalians primarily through PEN-induced excessive generation of reactive oxygen species, which may cause metabolic disorders, cancer, etc. Therefore, development of an effective analytical method for PEN is of great importance for the environmental safety and human health. In the present work, we report a supramolecular fluorescent probe OPyCH@ALB constructed by selecting of a dual-state-emission chalcone as the indicator and albumin as the host, for the first time, successfully realizing the ratiometric detection of PEN. This probe is capable of detecting PEN with rapid response (10 s), high sensitivity (LOD = 0.28 μM, 76 ppb), high selectivity, and a visible fluorescence color change from green to red. Based on this probe, the portable paper-based test strips, which enable the on-site monitoring of PEN without the involvement of any complicated testing apparatus, were fabricated. Furthermore, this probe was used to realize the qualitative and quantitative analysis of PEN in ground water and soil with high accuracy, and successful achieved on-site recognition of PEN on the surface of grapes. We expect that this method will be applied as a convenient and affordable tool for the rapid monitoring of PEN at the point-of-use, such as in residential, agricultural, and food production settings.

Interaction between Six Waxy Components in Summer Black Grapes (Vitis vinifera) and Mancozeb and Its Effect on the Residue of Mancozeb.

Mancozeb, an antifungal typically used for the growth of fruits, has the characteristic of non-internal absorption, and has a risk of binding to the waxy components of fruits. This work investigated the interaction of pesticide molecules with the waxy layer on the grape surface and their effects on pesticide residues in grapes. The study observed significant changes in the compositions of the waxy layer on the grape surface after soaking in a mancozeb standard solution. The six substances-oleanolic acid, ursolic acid, lupeol, octacosanol, hexacosanal, and γ-sitosterol-with discernible content differences were chosen for molecular docking. Docking results were further visualized by an independent gradient model based on Hirshfeld partition (IGMH). Hydrogen bonds and van der Waals forces were found between mancozeb and the six waxy components. Moreover, the negative matrix effects caused by the presence or absence of wax for the determination of mancozeb were different through the QuEChERS-HPLC-MS method. Compared with the residue of mancozeb in grapes (5.97 mg/kg), the deposition of mancozeb in grapes after dewaxing was significantly lower (1.12 mg/kg), which further supports that mancozeb may interact with the wax layer compositions. This work not only provides insights into the study of the interaction between pesticides and small molecules but also provides theoretical guidelines for the investigation of the removal of pesticide residues on the surface of fruits.

Physico-Chemical Characterization of an Exocellular Sugars Tolerant Β-Glucosidase from Grape Metschnikowia pulcherrima Isolates.

A broad variety of microorganisms with useful characteristics in the field of biotechnology live on the surface of grapes; one of these microorganisms is Metschnikowia pulcherrima. This yeast secretes a β-glucosidase that can be used in fermentative processes to liberate aromatic compounds. In this work, the synthesis of an exocellular β-glucosidase has been demonstrated and the optimal conditions to maximize the enzyme's effectiveness were determined. There was a maximum enzymatic activity at 28 °C and pH 4.5. Furthermore, the enzyme presents a great glucose and fructose tolerance, and to a lesser extent, ethanol tolerance. In addition, its activity was stimulated by calcium ions and low concentrations of ethanol and methanol. The impact of terpene content in wine was also determined. Because of these characteristics, β-glucosidase is a good candidate for use in enology.

Novel alternative pretreatment approaches for production of quality raisins from grapes: Opportunities and future prospects

AbstractRaisins are high‐value products obtained by drying grape berries. Natural drying of grapes is difficult because a hydrophobic waxy cuticle is present on the berry surface. Pretreatment is an important operation in raisin production in which the waxy layer is dissolved or removed for enhancing the drying rate of grapes. Chemical pretreatment consisting of dipping grape bunches in a solution of alkali and oil emulsion is commonly followed for raisin production. However, the threat of chemicals to human health, the environment, and longer processing time lead to the development of an alternative to chemical pretreatment. Various alternative methods have been explored including the abrasive pretreatment and some novel thermal and nonthermal techniques. The potential of these alternative pretreatments has been discussed in this review along with a critical analysis of literature on grape drying. The fundamentals of grape drying and unit operations of the chemical and abrasive process of raisin production have also been narrated. An abrasive process as the best alternative to chemicals in raisin production has been described in detail along with future prospects of different physical pretreatments. This review provides comprehensive information on raisin production with a focus on chemical‐free processing of grape for raisin production.Practical applicationsRaisins are dried grapes rich in nutritional and functional ingredients that are beneficial for human health. A predrying treatment to remove or to dissolve the waxy layer from surface of grapes is an important operation in raisin production. The chemical method of pretreatment is prevalent among raisin processors. However, a chemical method has some limitations like longer processing time, intense use of chemicals, food safety issues, and so forth. Many novel pretreatments like superficial abrasion, thermal, and nonthermal techniques have been explored by researchers and it has the potential to produce safe raisins without use of any chemicals. These alternative techniques can be adopted for industrial‐scale processing of raisins. A lot of literature is available on the grape drying process, modeling, and quality aspects of raisins. All this information has been summarized in this comprehensive review with a comparison of unit operations, analysis of findings, and future aspects for the production of safe raisins. This review will be very useful for industrial‐scale processing of raisins adopting novel processes and it will also provide in‐depth knowledge to the academician and research scholars.