Antioxidant potential and α-glucosidase inhibitory activity of onion (Allium cepa L.) peel and bulb extracts

Allium cepa L. is a commonly consumed vegetable that belongs to the Amaryllidaceae family and contains nutrients and antioxidants in ample amounts. In spite of the valuable food applications of onion bulb, its peel and outer fleshy layers are generally regarded as waste and exploration of their nutritional and therapeutic potential is still in progress with a very slow progression rate. The present study was designed with the purpose of doing a comparative analysis of the antioxidant potential of two parts of Allium cepa, i.g., bulb (edible part) and outer fleshy layers and dry peels (inedible part). Moreover, the inhibitory effect of the onion bulb and peel extracts on rat intestinal α-glucosidase and pancreatic α-amylase of porcine was also evaluated. The antioxidant potential of onion peel and bulb extracts were evaluated using 2,2-diphenyl- 1-picryl hydrazyl (DPPH), ferric-reducing antioxidant power assay (FRAP), 2,2’-azino-bis- 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assay, H2O2 radical scavenging activity and Fe2+ chelating activity. Total flavonoids and phenolic content of ethanolic extract of onion peel were significantly greater as compared to that of onion bulb. Ethanolic extract of onion peel also presented better antioxidant and free-radical scavenging activity as compared to the ethanolic extract of bulb, while the aqueous extract of bulb presented weakest antioxidative potential. Onion peel extract’s α-glucosidase inhibition potential was also correlated with their phenolic and flavonoid contents. The current findings presented onion peel as a possible source of antioxidative agents and phenolic compounds that might be beneficial against development of various common chronic diseases that might have an association with oxidative stress. Besides, outer dry layers and fleshy peels of onion exhibited higher phenolic content and antioxidant activities, compared to the inner bulb. The information obtained by the present study can be useful in promoting the use of vegetable parts other than the edible mesocarp for several future food applications, rather than these being wasted.

Effect of integrated weed management practices on the growth, yield, quality and economic of onion (Allium cepa L.)

A field study was conducted at research field of Spices Research Sub-Centre (SRSC), Faridpur, Bangladesh to find out the efficacy of weed management practices on the growth, yield, quality and economics of onion with the variety BARI Piaz-6. Thirteen treatments such as: T1-control as check (no weeding), T2-weed free, T3-one hand weeding (HW) at 45 days after transplanting (DAT), T4-two HW at 25 and 45 DAT, T5-three HW at 25, 45 and 65 DAT, T6-pre-emergence (PE) spray of pendimethalin 33 EC @ 330g a.i/litre + one HW at 45 DAT, T7- PE spray of pendimethalin 33 EC @ 330g a.i/litre + two HW at 45 and 65 DAT, T8- post emergence (POE) spray of pendimethalin 33 EC @ 330g a.i/litre at 25 DAT + one HW at 65 DAT, T9- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + one HW at 45 DAT, T10- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + two HW at 45 & 65 DAT, T11- POE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre at 25 DAT + one HW at 65 DAT, T12- PE spray of pendimethalin 33 EC @ 330g a.i/litre + POE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre at 45 DAT + one HW at 65 DAT and T13- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + POE spray of pendimethalin 33 EC @ 330g a.i/litre at 45 DAT + one HW at 65 DAT were compared by randomized complete block design with three replications. The study revealed that the weed management treatments under the study significantly influenced all parameters except total soluble solid content of onion bulb. Weed density had reverse effect on growth, development and yield of onion. Among the weed’s infestation, Cyperus rotundus (55-60%), Echinochloa crusgalli (10-15%) and Chenopodium album (8-10%) were predominant. The highest weed density (137.25 weeds/m2) were recorded from the T1. The lowest weed density (15.24 weeds/m2) were observed from T13. The T3 had the least weed control efficacy (23.56%). The maximum fresh yield (19.49 t/ha) of onion bulb were obtained from T2 followed by T13 (19.31 t/ha). The highest benefit-cost ratio (2.19) was calculated from the T13 closely followed by T12 (2.18). From this study it was concluded that Pre-emergence application (PE) application of oxyflourfen or pendimethalin + post-emergence (POE) application of oxyflourfen or pendimethalin at 45 DAT (days after transplanting) + once HW (hand weeding) at 65 DAT and also PE of oxyflourfen or pendimethalin + twice HW at 45 & 65 DAT exhibited good performance to control weeds in onion field.

Phytochemistry of Allium cepa L. (Onion): Its Nutritional and Pharmacological Importance

The present study was conducted to review the phytochemical composition, nutritional and pharmacological values of Allium cepa L. (Onion). Attempts have been made to compile the findings of 75 articles into a single manuscript. Onion is cultivated all over the world. The onion bulbs are comprised of polysaccharides including peptides, fructans, flavonoids (mostly quercetin), saccharose and organosulfur compounds having salutary effects on human health. The onion in the diet gives us a positive response in nutritional manner. The nutritional contents of onion bulb are crude oil, vitamin E, sodium, potassium, and zinc. The onion bulb has the potential to reduce the problem of stomach cancer, osteoporosis, and brain cancer in human beings. In addition, onion is antidiabetic, anti-inflammatory, anti-scar, antispasmodic, antiseptic, anti-genotoxic, anti-mutagenic, diuretic,anti-parasitic, antimicrobial, antipyretic, and Analgesic.

Influence of smoking and natural preservatives on shelf – life and microbial quality of Clarias gariepinus during storage

This study investigated the shelf – life and microbial quality of smoked Clarias gariepinus using Onion Bulb (OB), Holy Basil (HB) and Turmeric Rhizome (TR) as preservatives during 56 days storage. Sixteen C. gariepinus (1- 1.5kg) were distributed to four experimental containers: Control, TR2, OB3, and HB4 and the experiment were carried out in triplicates. Clarias gariepinus were smoked in a smoking kiln at 40o C- 60o C and 120-150 C for 6 and 18 hours respectively. Biochemical parameters, organoleptic assessment, and microbial analysis were carried out. Data were analyzed using ANOVA at P= 0.05. The result showed that the crude protein of C. gariepinus washigher in the treated groups compared to the control. Also, the result shows that the biochemical parameters, organoleptic assessment and the microbial loads in smoked C. gariepinus were reduced in the OB, HB, and TR than the control at 1 day, 28 days and 56 days storage respectively. It can be concluded that the natural plants may enhance the shelf life, consumer acceptability, and inhibit the growth of the microbial pathogen in smoked fish. Keywords: Catfish, Onion bulb, Holy basil, Microbial loads, Turmeric, Preservatives

Studies on engineering properties of multiplier onion

The knowledge of physical and mechanical properties of onion bulb is important for successful design of any planter. Multiplier onion is propagated through bulbs and bulbs are planted manually. Manual planting of onion bulb is highly labour intensive (80-100 man-days ha-1) due to the close plant geometry (plant to plant and row to row spacing is 10 × 15 cm) among the vegetable crops. Engineering properties of multiplier onion were determined in order to design and develop a tractor operated raised bed onion bulb planter. In multiplier onion each onion comprises of 4-5 bulbs. These bulbs were cleaned, separated into single bulbs and divided in to 9 categories manually based on their individual weight viz., <2g, 2-3 g, 3-4 g, 4-5 g, 5-6 g, 6-7 g, 7-8 g, 8-9 g, >9 g. The onion bulb had a moisture content of 80.62±0.87 %. It was observed that the properties varied for different sizes of onion grades and the grades had highly significant effect on most of the properties. The linear dimensions of onion bulbs viz., length, width, thickness for nine grades ranged from 21.21±2.60 to 32.31±3.30 mm, 13.54±1.77 to 30.95±2.91 mm and 10.91±1.40 to 22.63±2.15 mm. The geometric mean diameter, sphericity, shape index and projected area all ranged from 28.22±2.04 to 14.54±0.96 mm, 0.87±0.06 to 0.69±0.08, 1.78±0.32 to 1.22±0.14 and 5.50±0.51 to 1.55±0.30 cm2, respectively. The one hundred onion bulb weight, bulk density, true density were in the range of 1185±19.59 to 121.6±6.30 g, 793.20± 9.45 to 480.19±13.13 kg.m-3, 1086± 205.22 to 1013.6±348.85 kg.m-3, respectively. The angle of repose decreased with increase in size of onion bulbs. The interaction between sphericity, shape index and angle of repose indicated that as the size of the onion size increase angle of repose decreased.

Complete genome sequence resources for the onion pathogen, Pantoea ananatis OC5a

Here we report on the genomic sequence and annotation for Pantoea ananatis OC5a, a strain that was isolated from an onion bulb grown in New York and that is pathogenic to onions, causing center rot of onion. OC5a is the first P. ananatis strain pathogenic to onions from New York to be completely assembled and sequenced. Having been assembled using long PacBio reads and high-fidelity Illumina reads, this genome is closed, complete, and of high-quality.

Anticoagulant Activity of Dayak Onion Bulb (Eleutherine bulbosa) Extract on Human Blood Samples

Cardiovascular disease can occur due to disruption of the hemostatic system by forming blood clots in blood vessels, or commonly known as deep vein thrombosis. The curative action that has been carried out in the form of heparin anticoagulant administration had many side effects such as bleeding, hematuria, thrombocytopenia, and hypersensitivity; therefore, alternative anticoagulant ingredients such as onion bulbs have emerged. Dayak onion bulb (Eleutherine bulbosa) is known to contain eleutherinol compound, which has anticoagulant activity. This study aims to determine the potential anticoagulant activity of Dayak onion bulbs extract (Eleutherine bulbosa) on human blood samples. This anticoagulant activity test was carried out by observing the length of time for blood clotting in the extract treatment group with several concentrations (0, 10, 12.5, 16, 25, and 50%) by Clotting Time (Lee-White) method. The results showed a significant delay in blood coagulation time in the group treated with Dayak onion bulbs extract as increasing the concentration. About 50% Dayak onion onion bulb extract was showed a twofold increase in blood coagulation time thanthat of no extract administration. So that, Dayak bulb onion has the opportunity to be an alternative natural anticoagulant. Keywords: anticoagulants; Dayak onion bulbs (Eleutherine bulbosa); clotting time