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Waste resulting from edible plants is considered one of the best sources of valuable phytochemicals. A promising approach for using these appreciated wastes is extracting precious medically important constituents, for example, free quercetin. Two new cost-effective and green extraction methods are introduced in the present study: ultrasound-assisted glycerol extraction (UAGE) and microwave-assisted extraction (MAE). These extraction protocols are optimized using factorial design to define the highest yield of extraction, and HPLC-UV at 370 nm was used as a method of yield analysis. Quercetin remained stable during the whole process in both extraction protocols. A standard addition technique was performed to quantify quercetin in different extracts and eliminate the matrix effect. In UAGE and MAE, extraction yields were 16.55 ± 0.81 and 27.20 ± 1.55 mg/1g from red onion scales on a dry base, respectively. The amount of quercetin extracted using MAE was superior to UAGE in terms of time and yield. A greenness assessment of the offered studies compared to previously published relevant extraction methods was performed using the analytical eco-scale assessment method (ESA) and national environmental methods index (NEMI). MAE showed to be a greener method with a higher ESA score and a greener NEMI pictogram.

Differential gene expression in the outer and inner scales of onion bulbs in response to heat stress accounts for the fact that only outer scales can form a protective dry brown skin. Abstract The formation of brown protective skin in onion bulbs can be induced by rapid post-harvest heat treatment. Onions that are peeled to different depths and are exposed to heat stress show that only the outer scales form the dry brown skin, whereas the inner scales maintain high water content and do not change color. Our study demonstrates that browning of the outer scale during heat treatment is due to an enzymatic process that is associated with high levels of oxidation components, such as peroxidase and quercetin glucoside. De novo transcriptome analysis revealed differential molecular responses of the outer and inner scales to heat stress. Genes involved in lipid metabolism, oxidation pathways, and cell-wall modification were highly expressed in the outer scale during heating. Defense response-related genes such as those encoding heat-shock proteins, antioxidative stress defense, or production of osmoprotectant metabolites were mostly induced in the inner scale in response to heat exposure. These transcriptomic data led to a conceptual model that suggests sequential processes for the development of browning and desiccation of the outer scale versus processes associated with defense response and heat tolerance in the inner scales.

Onion scales were irradiated and the effects of irradiation on their bioactive properties were studied. The antioxidant and antibacterial activities of extract prepared from irradiated onion scales (upto 6 kGy) were comparable to the extract prepared from non-irradiated onion scales. OSE (0–6%) were encapsulated in 2% alginate beads. The beads containing 6% OSE had the highest a * and the lowest L * values as compared to neat beads that were prepared without OSE. The size of the beads reduced significantly from 2.42 mm (0% OSE) to 2.05 mm (6% OSE). The moisture content of neat (0% OSE) beads was 95.94% as compared to 93.86% in beads incorporated with 6% OSE. Alginate beads containing 6% OSE had the maximum swelling capacity. On basis of DPPH radical scavenging antioxidant assay it was observed that alginate beads containing 6% OSE showed the maximum antioxidant activity. In simulated gastric and intestinal fluid, the antioxidant activity of the beads containing OSE was retained. Irradiated minced chicken muscles containing 6% OSE alginate beads had lower TBARS value (2.0 mg MDA kg −1 meat) as compared to 3.3 mg MDA kg −1 meat for irradiated meat with 0% OSE. There was significant difference (almost 2 log cycle reduction) in the growth of Staphylococcus aureus, Pseudomonas fluorescens in chicken muscle during chilled storage when OSE encapsulated beads were incorporated. Hence, irradiation of onion scales and its encapsulation in alginate beads has a great potential as a functional ingredient in various food products.

In the course of pre- and postharvest epidemiological studies on bulbs contamination by Aspergillus niger, two Sudanese onion cultivars were tested: `Saggai Red' and `El-Hilo White'. A. niger spores, whether seedborne, soilborne or airborne, were avirulent to the healthy growing onion plants. The fungus heavily contaminated the dead onion tissues, mainly the dead leaves followed by the dry scales, the dead roots and, to a lesser extent, the bulb necks, preferring the red-skinned cultivar to the white one. The initial spores carried from naturally contaminated field soil on the dead tissues could germinate and produce massive numbers of new spores on bulbs stored at average climatic conditions of Sudan (23-39 degree C, 29-93% relative humidity). Under laboratory-controlled conditions, optimal growth occurred at 75-85% r.h. on bulbs with dry scales and maximum losses occurred at 100% r.h. and ambient temperature. Under in vitro conditions, the optimal growth and sporulation temperature for A. niger was in the range of 30-35 degree degree C. Early harvesting and removal of the dead onion tissues improved bulb storability in aseptic stores under low temperature and relative humidity conditions.

Skin formation of onion ( L.) bulb involves scale desiccation accompanied by scale senescence, resulting in cell death and tissue browning. Understanding the mechanism of skin formation is essential to improving onion skin and bulb qualities. Although onion skin plays a crucial role in postharvest onion storage and shelf life, its formation is poorly understood. We investigated the mode of cell death in the outermost scales that are destined to form the onion skin. Surprisingly, fluorescein diacetate staining and scanning electron microscopy indicated that the outer scale desiccates from the inside out. This striking observation suggests that cell death in the outer scales, during skin formation, is an internal and organized process that does not derive only from air desiccation. DNA fragmentation, a known hallmark of programmed cell death (PCD), was revealed in the outer scales and gradually decreased toward the inner scales of the bulb. Transmission electron microscopy further revealed PCD-related structural alterations in the outer scales which were absent from the inner scales. transcriptome assembly for three different scales: 1st (outer), 5th (intermediate) and 8th (inner) fleshy scales identified 2,542 differentially expressed genes among them. GO enrichment for cluster analysis revealed increasing metabolic processes in the outer senescent scale related to defense response, PCD processes, carbohydrate metabolism and flavonoid biosynthesis, whereas increased metabolism and developmental growth processes were identified in the inner scales. High expression levels of PCD-related genes were identified in the outer scale compared to the inner ones, highlighting the involvement of PCD in outer-skin development. These findings suggest that a program to form the dry protective skin exists and functions only in the outer scales of onion.

A comprehensive quantitative analysis of flavonoids, sugars, phenylalanine, and tryptophan have been carried out in different onion scales during storage at ambient temperature (20–23 °C) and relative humidity (60–80 %). Depending on the length of storage, dry matter content and composition shows variation inside the onion bulbs. Inner sprouts were observed on longitudinally cut bulbs after 2 months and visible sprouts appeared after 5 months of storage. The bulbs lost 20 to 30 % of their weight at the end of the storage. Higher dry matter content was observed in the inner scales. Significantly high content of quercetin in inner scales and high level of quercetin-3,4′- O -diglucoside and quercetin-4′- O -monoglucoside in outer scales was observed during a 7 months storage. During storage period, high content of fructose and glucose was observed in the middle scales while sucrose was high in the inner scales. There was no particular trend observed within analyzed amino acids. However, the content of phenylalanine was higher than tryptophan.

Onion and garlic are economically important vegetable crops cultivated worldwide. Numerous pests and diseases affect the quality and yield of these crops. In addition to diseases and pests, several physiological disorders affect onion and garlic. The physiological disorders are abnormalities caused by intercultural operations, nutrient management, environmental factors, genetic regulation, etc. These physiological disorders significantly affect the yield and quality of onion and garlic, leading to monetary losses to the farmers. The following physiological disorders are commonly reported in onion: premature bolting, sprouting in storage, watery scale, doubling/twins, basal plate split, and thick neck. Premature sprouting and rubberization are the main physiological anomalies observed in garlic. The present review described the symptoms of these physiological abnormalities, the factors responsible, and ways to avoid or minimise the occurrence of these abnormalities to subsequently reduce the losses of the growers. Further, we also performed bibliometric analysis using the SCOPUS database. This is the first review that describes the progress of research on physiological disorders in onion and garlic in detail, which will positively increase awareness about such important aspects of onion and garlic. Further, it will provide insight to researchers for developing innovative strategies, cultural practices, and varieties to control these physiological abnormalities of onion and garlic.

The distribution of viruses in eastern Australian field garlic was evaluated. Detection assays were developed that involved generic RT-PCR for viruses in the Allexivirus, Carlavirus and Potyvirus genera followed by virus-specific colorimetric dot-blot hybridization. Assays targeted the potyviruses (onion yellow dwarf virus (OYDV), shallot yellow stripe virus (SYSV), and leek yellow stripe virus (LYSV)), the carlaviruses (garlic common latent virus (GCLV) and shallot latent virus (SLV)), and the allexiviruses (garlic viruses A, B, C, X (GarVA, -B, -C, -X) and shallot virus X (ShVX)). Virus incidence in crops was consistently high, with most plants infected with at least one virus from each genus. OYDV, LYSV, SLV, and GCLV were commonly detected. Three of the four allexiviruses were in all districts surveyed but varied in incidence, whereas ShVX and SYSV were not detected. There was no association between virus species complement and bulb size, indicating size is not a good predictor of the virus status of planting material. The variation of virus incidence across different Australian growing districts and in different cultivars implies multiple introductions of viruses rather than spread within the country. The genetic diversity observed within coat protein sequences of some virus species also supports multiple separate introductions.

Remote sensing techniques using visible and near-infrared wavelengths are useful for monitoring terrestrial vegetation. The normalized difference vegetation index (NDVI) is a widely used proxy of vegetation conditions, and it has been measured at various footprint sizes using satellite, unmanned aerial vehicle (UAV), and ground-installed sensors. The goal of this study was to analyze the spatial characteristics of NDVI data by comparing the values obtained at different footprint sizes. In particular, the NDVI was evaluated in garlic and onion fields that featured ridges and furrows. The evaluation was performed using data from a leaf spectrometer, field spectrometers, ground-installed spectral reflectance sensors, a multispectral camera onboard a UAV, and Sentinel-2 satellites. The correlation coefficients between NDVIs evaluated from the various sensors (excluding the satellite-mounted sensors) ranged from 0.628 to 0.944. The UAV-based NDVI (NDVIUAV) exhibited the lowest root mean square error (RMSE = 0.088) when compared with field spectrometer data. On the other hand, the satellite-based NDVI data (NDVISentinel-2) were poorly correlated with those obtained from the other sensors as a result of the footprint mismatch. However, by upscaling the NDVIUAV data to the pixel size of Sentinel-2, the comparison was improved, and the following statistics were obtained: correlation coefficient: 0.504–0.785; absolute bias: 0.048–0.078; RMSE: 0.063–0.094. According to the aforementioned results, ground-based NDVI data can be used to validate NDVIUAV data without further processing and NDVIUAV data can be used to validate NDVISentinel-2 data after upscaling to the Sentinel-2 pixel size. Overall, the results presented in this study may be helpful to understand and integrate NDVI data at different spatial scales.

Since the SARS-CoV-2 virus caused a global pandemic, the amount of misinformation in various media outlets has been on the rise. This has caused confusion among both healthcare workers and the general population about what the proper precautions against COVID-19 are. This study investigated attitudes towards misinformation related to protective measures that can be taken against COVID-19. The study was conducted in Saudi Arabia using an online survey questionnaire during the first three months of lockdown responding to the pandemic. The sample size of the study was N = 1294, of which 275 were healthcare workers and 974 were non-healthcare workers. The findings indicate that the Saudi Arabian population has a “Neutral” attitude towards COVID-19-related misinformation, meaning that, overall, they neither agree nor disagree with the most common COVID-19-related misinformation. Both healthcare workers and non-healthcare workers displayed a “Neutral” attitude towards herbal remedies for COVID-19. The level of agreement regarding the SARS-CoV-2 virus remaining in the throat for two days and the BCG vaccine protecting against COVID-19 was low. The findings of this research imply that knowledge dissemination is severely lacking in Saudi Arabia and that the Ministry of Health in Saudi Arabia should sincerely consider educating healthcare workers better about verified and true information regarding COVID-19. Conclusion: Future research should include larger sample sizes for each of the healthcare specialties surveyed in this study and analyse their attitudes towards COVID-19 misinformation.