Description and management of Aspergillus section Nigri causing post-harvest bulbs rot of onion

When onions are improperly stored, a post-harvest disease known as black mold of onion bulbs can result in considerable economic losses. Aspergillus section Nigri, one of many species, has been implicated in the development of black mold. In the present study, rot onion bulbs were collected from markets in Qena, Egypt. Thirteen Aspergillus section Nigri isolates were obtained and identified by morphological and molecular characterization. The ochratoxins potential of isolated A. section Nigri was tested, and three isolates were producers at the range of 1.5-15 ppm. For the presence of pks gene, no amplification product was detected. Using the fungal growth inhibition test, the isolates of A. niger were inhibited by eco-friendly materials Cement and Zeolite. Cement exhibited maximum percentage growth inhibition against the tested isolates at 74.7-86.7%. The pathogenicity activity of the A. niger isolates was tested by inoculation of healthy onion bulbs, other onion bulbs covered with Cement and Zeolite before inoculation by A. niger was used. The two treatments significantly reduced bulbs rot disease of onion than untreated bulbs. Seven and nine isolates showed 0% rot on covered bulbs by Cement and Zeolite, respectively as compared with inoculated onions, which exhibited rot ranging from 55 to 80%. Using eco-friendly materials with efficiency against post-harvest bulbs rot of onion was evaluated in this study.

Synergistic bactericidal effect and mechanism of ultrasound combined with Lauroyl Arginate Ethyl against Salmonella Typhimurium and its application in the preservation of onions

In the present study, the synergistic bactericidal effect and mechanism of ultrasound (US) combined with Lauroyl Arginate Ethyl (LAE) against Salmonella Typhimurium were investigated. On this basis, the effect of US+LAE treatment on the washing of S. Typhimurium on the surface of onions and on the physical and chemical properties of onion during fresh-cutting and storage were studied. The results showed that treatment with US+LAE could significantly (P < 0.05) reduce the number of S. Typhimurium compared to US and LAE treatments alone, especially the treatment of US+LAE (230 W/cm2, 8 min, 71 μM) reduced S. Typhimurium by 8.82 log CFU/mL. Confocal laser scanning microscopy (CLSM), flow cytometry (FCM), protein and nucleic acid release and N-phenyl-l-naphthylamine (NPN) assays demonstrated that US+LAE disrupted the integrity and permeability of S. Typhimurium cell membranes. Reactive oxygen species (ROS) and malondialdehyde (MDA) assays indicated that US+LAE exacerbated oxidative stress and lipid peroxidation in cell membranes. Field emission scanning electron microscopy (FESEM) demonstrated that US+LAE treatment caused loss of cellular contents and led to cell crumpling and even lost the original cell morphology. US+LAE treatment caused a significant (P < 0.05) decrease in the number of S. Typhimurium on onions, but there was no significant (P > 0.05) effect on the color, hardness, weight and ascorbic acid content of onions. This study elucidated the synergistic antibacterial mechanism of US+LAE and verified the feasibility of bactericidal effect on the surface of onions, providing a theoretical basis for improving the safety of fresh produce in the food industry and to propose a new way to achieve the desired results.

Small-scale genetic structure of populations of the bulb mite Rhizoglyphus robini

Bulb mites are an economically significant pest of subterranean parts of plants and a versatile laboratory animal. However, the genetic structure of their populations remains unknown. To fill this gap in our knowledge of their biology, we set up a field experiment in which we allowed mites to colonize onion bulbs, and then determined the genetic structure of colonisers based on a panel of microsatellite loci. We found moderate but significant population structure among sites separated by ca. 20 m (FST range 0.03-0.21), with 7% of genetic variance distributed among sites. Allelic richness within some bulbs was nearly as high as that in the total population, suggesting that colonisation of bulbs was not associated with strong population bottlenecks. The significant genetic structure we observed over small spatial scales seems to reflect limited dispersal of mites in soil.

Chemical constituents and medicinal properties of Allium species

Allium species, belonging to Alliaceae family, are among the oldest cultivated vegetables used as food. Garlic, onions, leeks and chives, which belong to this family, have been reported to have medicinal properties. The Allium species constituents have been shown to have antibacterial and antioxidant activities, and, in addition, other biological properties. These activities are related to their rich organosulfur compounds. These organosulfur compounds are believed to prevent the development of cancer, cardiovascular, neurological, diabetes, liver diseases as well as allergy and arthritis. There have also been reports on toxicities of these compounds. The major active compounds of Allium species includes, diallyl disulfide, diallyl trisulfide, diallyl sulfide, dipropyl disulfide, dipropyl trisulfide, 1-propenylpropyl disulfide, allyl methyl disulfide and dimethyl disulfide. The aim of this review is to focus on a variety of experimental and clinical reports on the effectiveness, toxicities and possible mechanisms of actions of the active compounds of garlic, onions, leek and chives.

Antimicrobial assessment of polyphenolic extracts from onion (Allium cepa L.) skin of fifteen cultivars by sonication-assisted extraction method

Onion skin possesses various health benefits due to its phenolic and antimicrobial components. In this study, sonication-assisted extracts of onion skin of differentially coloured cultivars (dark-red, red, pink and white) were investigated for their antimicrobial activity against six pathogenic bacteria. Antimicrobial efficacy of fifteen different coloured extracts was analysed by agar well-diffusion assay with principal component analysis (PCA) for comprehensive investigation. Result showed skin extracts of pink cultivars (cv.) significantly (P ≤ 0.05) effective against pathogenic bacteria followed by red and dark red skin. White skin showed least effect on the growth of bacteria. Skin of cv. 'Phursungi Local' (pink) and cv. 'Hissar-3' (pink) showed best range of inhibition against Staphylococcus aureus, Klebsiella pnuemoniae, Bacillus cereus and Solmonella typhimurium compared to other. Only white skin extracts of cv. 'Bhima Shubhra' and 'Udaipur Local' inhibited the growth of Pseudomonas aeruginosa up to 4.0 ± 0.0 mm. Minimum inhibitory concentration (MIC) of the effective extracts was also elucidated in the range between 0.09 - 9.0 mg/mL. Skin extracts of cv. 'Hissar-2' (red) and 'Bhima Shubhra' (white) showed better inhibition at the concentration of 0.45 and 0.72 mg/mL against Streptococcus agalactiae and Pseudomonas aeruginosa, respectively. As per correlation analysis, positive correlation was obtained between total flavonoids and inhibition rate of all the bacteria while a weak correlation (R2 = 0.3967) was observed against Pseudomonas aeruginosa. The waste skin of the analysed cultivars can be utilised in food and health sector as natural preservative and antimicrobial agent.

Effect of storage, food processing and novel extraction technologies on onions flavonoid content: A review

Onions play an important part in the daily diet for most populations around the world owing to their nutritional composition and their unique capacity to naturally flavor dishes. Onions contain quercetin and its derivatives - the predominant flavonoid in onions that exert a great contribution to the effective bioactive properties of onion, including its derived products. The present paper comprehensively reviewed flavonoids (with a specific focus on quercetin in onions): their chemical composition, distribution, bioactivities in onion, and impacting factors with a focus on how they can be affected by various post-harvest conditions (storage and food processing). In addition, research on the extraction of flavonoid compounds from onions using a number of novel technologies was also reviewed.

Predicting the Growth of Listeria monocytogenes and Salmonella Typhimurium in Diced Celery, Onions, and Tomatoes during Simulated Commercial Transport, Retail Storage, and Display

Temperature is arguably the most important factor affecting microbial proliferation in fresh-cut produce. In this study, growth of Listeria monocytogenes in diced onions and celery and Salmonella Typhimurium in diced tomatoes was determined in modified atmosphere packages and snap-fit containers using three fluctuating temperature scenarios for transport, retail storage, and display. As expected, L. monocytogenes growth in diced onions and celery varied depending on the extent of temperature abuse, with exposure to high and intermediate temperature-abuse scenarios generally being growth supportive. A Baranyi primary model with a square-root secondary model for maximum growth rate, and a linear model for maximum population density, were used to estimate Listeria growth under fluctuating temperature. Accuracy and acceptability of the model prediction were evaluated in terms of root mean square error (RMSE) and acceptable prediction zone (APZ), respectively. Overall, growth predictions for L. monocytogenes were more accurate for celery (RMSE, 0.28 to 0.47) than onions (RMSE, 0.42 to 1.53) under the fluctuating temperature scenarios tested. However, both predictions yielded APZ values that ranged from 82 to 100% for celery and 36 to 78% for onions. In contrast, Salmonella Typhimurium populations increased more than 1 log CFU/g in diced tomatoes under the three fluctuating temperature scenarios studied. Overall, these diced products packaged under a high-oxygen atmosphere showed decreased pathogen growth compared with product stored in a passive modified atmosphere. Findings from this study will be particularly useful in assessing the risk associated with consumption of diced celery, tomatoes, and onions and in designing effective packaging strategies to minimize pathogen growth in fresh-cut produce.

Field Evidence Supporting Conventional Onion Curing Practices as a Strategy To Mitigate Escherichia coli Contamination from Irrigation Water

The Produce Safety Rule of the U.S. Food Safety Modernization Act includes restrictions on the use of agricultural water of poor microbiological quality. Mitigation options for poor water quality include the application of an irrigation-to-harvest interval of <4 days; however, dry bulb onion production includes an extended irrigation-to-harvest interval (<30 days). This study evaluated conventional curing practices for mitigating Escherichia coli contamination in a field setting. Well water inoculated with rifampin-resistant E. coli (1, 2, or 3 log CFU/mL) was applied to onion fields (randomized block design; n = 5) via drip tape on the final day of irrigation. Onions remained undisturbed for 7 days and were then lifted to the surface to cure for an additional 21 days before harvest. Water, onions, and soil were tested for presence of rifampin-resistant E. coli. One day after irrigation, 13.3% of onions (20 of 150) receiving the poorest quality water (3 log CFU/mL) tested positive for E. coli; this prevalence was reduced to 4% (6 of 150 onions) after 7 days. Regardless of inoculum level, E. coli was not detected on any onions beyond 15 days postirrigation. These results support conventional dry bulb onion curing practices as an effective strategy to mitigate microbiological concerns associated with poor quality irrigation water.

Home cooking and ingredient synergism improve lycopene isomer production in Sofrito

There has been increasing interest in tomato products rich in lycopene Z-isomers since these carotenoids present greater bioavailability and antioxidant capacity than the all-E lycopene form. Intrinsic food properties as well as processing and the interaction between dietary components can all influence the content, type and bioavailability of carotenoids. The aim of this study was to evaluate whether carotenoid content and isomerization in tomato-based Mediterranean sofrito is affected by the process of home cooking and the presence of other ingredients such as extra virgin olive oil, onion and garlic. We used a full factorial design to clarify the contribution of each ingredient to the carotenoid composition of sofrito and to determine whether this can be improved by the cooking time and ingredient synergism. Cooking time and onion content were associated with a higher production of 5-Z-lycopene, 9-Z-lycopene and 13-Z-lycopene in sofrito. Onion proved to be the most interesting ingredient in the sofrito formulation due to their enhancing effect on lycopene isomerization. The use of onion combined with an adequate processing time may improve the bioavailability of lycopene in tomato products.

Associations between Dietary Allium Vegetables and Risk of Breast Cancer: A Hospital-Based Matched Case-Control Study

Purpose

The protective effect of Allium vegetables against carcinogenesis has been reported in experimental studies particularly focusing on the gut. Therefore, we conducted a hospital-based matched case-control study to explore the association between dietary Allium consumption and risk of breast cancer among Iranian women in northwest Iran.

Methods

A validated, quantitative, food frequency questionnaire was completed in 285 women (aged 25–65 years old) newly diagnosed with histopathologically confirmed breast cancer (grade II, III or clinical stage II, III) in Tabriz, northwest Iran, and the completed questionnaires were included in an age- and regional-matched hospital based-control study. The odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using conditional logistic regression models.

Results

Multivariate analysis showed that there was a negative association between the consumption of raw onion and risk of breast cancer after adjustment for covariates (OR, 0.63; 95% CI, 0.40–1.00); however, this association was insignificant. On the other hand, there was a positive association between consumption of cooked onion and risk of breast cancer, after adjustment for covariates (OR, 1.54; 95% CI, 1.02–2.32). However, reduced risk of breast cancer was associated with higher consumption of garlic and leek with adjusted ORs of 0.41 (95% CI, 0.20–0.83) and 0.28 (95% CI, 0.15–0.51), respectively.

Conclusion

Our findings suggest that high consumption of certain Allium vegetables, in particular garlic and leek, may reduce the risk of breast cancer, while high consumption of cooked onion may be associated with an increased risk of breast cancer.

Occupational exposure to mould and microbial metabolites during onion sorting--insights into an overlooked workplace

Manual sorting of onions is known to be associated with a bioaerosol exposure. The study aimed to gain an initial indication as to what extent manual sorting of onions is also associated with mycotoxin exposure. Twelve representative samples of outer onion skins from different onion origins were sampled and analyzed with a multimycotoxin method comprising 40 mycotoxins using a single extraction step followed by liquid chromatography with electrospray ionization and triple quadrupole mass spectrometry. Six of the 12 samples were positive for mycotoxins. In those samples, deoxynivalenol, fumonisin B1, and B2 were observed in quantitatively detectable amounts of 3940 ng/g for fumonisin B1 and in the range of 126-587 ng/g for deoxynivalenol and 55-554 ng/g for fumonisin B2. Although the results point to a lower risk due to mycotoxins, the risk should not be completely neglected and has to be considered in the risk assessment.

Small is beautiful: Surprising nanoparticles

In the preparation of nanoparticles for drug delivery, it is well known that their size as well as their surface decorations can play a major role in interaction with living media. It is less known that their shape and internal structure can interplay with cellular and in vivo fate. The scientific literature is full of a large variety of surprising terms referring to their shape and structure. The aim of this review is to present some examples of the most often encountered surprising nanoparticles prepared and usable in the pharmaceutical technology domain. They are presented in two main groups related to their physical aspects: 1) smooth surface particles, such as Janus particles, "snowmen", "dumbbells", "rattles", and "onions" and 2) branched particles, such as "flowers", "stars" and "urchins". The mode of preparation and potential applications are briefly presented. The topic has a serious, wider importance, namely in opportunity these structures have to allow exploration of the role of shape and structure on the utility (and perhaps toxicity) of these nanostructures.

Human exposure modelling of quercetin in onions (Allium cepa L.) following thermal processing

Post-harvest treatment can influence levels of secondary metabolites in fruits and vegetables. Onions contain high levels of quercetin but are commonly heat-treated before consumption. Hence, the objective of this study was to examine the effect of cooking treatments on the flavonoid (3,4'-Qdg and 4'-Qmg) concentrations in onion and to determine, by simulation modelling, probable human exposure. Onion samples (n=3) were cooked using three processes (fry, bake and steam) for three time intervals (5, 10 and 15 min). Frying (<10 min) was the ideal cooking method which retained concentrations of 3,4'-Qdg and 4'-Qmg at >50%. Thermal processing (>10 min) was shown to decrease quercetin content in all samples. The simulation model predicted human absorption and exposure. Steaming (15 min) resulted in the lowest quercetin exposure, with mean values of 4000 and 400 μg/day for 3,4'-Qdg and 4'-Qmg, respectively. Untreated onions had mean exposures of 14,000 and 3000 μg/day for 3,4'-Qdg and 4'-Qmg, respectively.

Effects of onion juice on the normal flora of eyelids and conjunctiva in an animal model

Background:

Traditional medicine/complementary alternative medicine may suggest new ideas to modern medicine in order to face new challenges however these concepts should be acknowledged based on experimental studies.

Objectives:

We aimed to study the effects of onion (Allium cepa) juice on the normal flora of conjunctiva and eye lids, and to follow the histopathology changes of conjunctiva in an animal study.

Materials and Methods:

Twenty-four rabbits were randomly classified into three equal groups. Groups 1, 2 and 3 received fresh red onion juice, as an eye drop, into the right eye twice daily for; one week, one month, and two months, respectively. Microbiological sampling by sterile swabs was performed before and after the intervention. Cultural characteristics, including the growth rate and the kind of organisms, are reported. At the end of the study, pathological samples were collected from the inferior fornix.

Results:

After the intervention, the number of positive cultures in the samples, collected from both the conjunctiva and eyelid, had decreased. Group 3 demonstrated the lowest amount of growth after the administration of the onion juice and the bacterial isolation rates from each organism had decreased. All pathological samples revealed some degree of inflammation. There was no evidence of metaplasia or dysplasia. There was no significant difference between the growth rates of organisms in the experimental groups using statistical analysis.

Conclusions:

According to our experiment, onion has an inhibitory effect on the growth of normal eye flora; although the duration of onion juice instillation did not show any significant effect on the group results. Hence, this finding is an initiating point for further investigations into the antimicrobial properties of this herb to treat common eye infections, including conjunctivitis and blepharitis.

Effect of Aqueous Allium cepa and Ixora brachiata Root Extract on Leishmania major Promastigotes

BACKGROUND

Leishmaniasis is a major worldwide public health problem with about two to three million humans threatened by this disease annually. Allium cepa (onion) is an important dietary vegetable and was used as a herbal medicine for centuries. The root of Ixora brachiata is medicinally important.

OBJECTIVES

The aim of this study was to investigate the anti-Leishmania effect of the ethanolic and methanolic extracts of Ixora brachiata root and aqueous onion extracts on Leishmania major promastigotes.

PATIENTS AND METHODS

The parasites isolated from cutaneous leishmaniasis were exposed with different concentrations of selected plant extracts and their inhibitory effects on the promastigotes were evaluated after 24 and 48 hours.

RESULTS

Among tested plant extracts, Ixora brachiata root extracts revealed the best activity against Leishmania major promastigotes with IC100 value of 2.5 mg/mL and IC50 value of 0.078 mg/mL.

CONCLUSIONS

This study showed that aqueous Allium cepa and Ixora brachiata root extracts as natural products could be used as alternative drugs in treatment of leishmaniasis.