Onion Peel Research Articles

Effects of the Ethanolic Extract of Onion Peel on the Physicochemical Properties of Wheat Starch

AbstractThe objective of this study is to examine the interactions between wheat starch (WS) and ethanol extract of onion peel (EEOP) at varying concentrations (1.0%, 2.5%, 5.0%, and 10.0%) during the process of gelatinization, and to assess the impact of these interactions on the physicochemical and retrogradation characteristics of wheat starch. In contrast to the control group, the incorporation of EEOP results in a reduction in retrogradation, an increase in solubility, and an increase in the swelling degree of wheat starch. Furthermore, the addition of the EEOP effectively hinders the retrogradation process of wheat starch. The incorporation of EEOP has the potential to decrease the enthalpy associated with starch retrogradation. Accordingly, the addition of 10% EEOP results in a decrease of 43.6% in the enthalpy of starch retrogradation in wheat starch after a storage period of 15 days, as compared to the control group. In addition, the incorporation of an enzyme known as EEOP has the potential to reduce the occurrence of crystallization in the process of starch retrogradation. Hence, the incorporation of EEOP may impede the regression of WS.

Probing Anticancer Molecules from Onion Peels Waste; First Synthesis and Biological Studies of a Rare Quercetin Derivative-Pachypodol

Background: The constant increase in global onion production escalates the generation of onion peel waste. For instance, globally, >50 lakh tons of onion waste are generated annually. Methods: Its objectionable odor precludes its use in agriculture or disposal as landfilling presents environmental issues. Previous studies show that two major flavonoids, quercetin and its glycosides (spiraeoside), have been identified in abundance in onion waste. By utilizing the spiraeoside (quercetin-4ʹ-glucoside), a rapid synthesis of pachypodol (quercetin-3,3′,7-trimethyl ether, and a rare flavonol), an essential Ayurvedic product, has been developed and achieved. Pachypodol and analogs were studied for their ability to inhibit matrix metalloproteinase-2 and -9 (MMP-2 & 9) activity. Amongst the compounds tested, pachypodol significantly inhibited MMP-2 activity. Results: In-silico docking studies suggest that, unlike most known MMP inhibitors, pachypodol interacts selectively with MMP-2 through the residues Ile222, Tyr223, and Thr227 in a zincindependent manner. Conclusion: The experimental studies also prove that pachypodol inhibits the MMP-2 enzyme in a zinc-independent way.

Onion Peel as a Potential Source of Antioxidants and Antimicrobial Agents

Dry outer onion leaves resulting from the industrial processing of onions are currently discarded as agricultural waste, although some studies have demonstrated that onion peel has beneficial biological effects. Considering the traditional applications of onion peel, the present study evaluated comparatively the chemical and biological characteristics of four types of onion peel extracts, utilizing methanol, ethanol, acetone, or ethyl acetate as the extracting solvent. The extracts were analyzed for their chemical composition, antioxidant potential, and antimicrobial activity. The chemical analysis by UHPLC-DAD-ESI/MS identified 23 compounds in the extracts, belonging to phenolic acids and flavonoids. Quercetin was the main compound in all extracts, ranging in concentrations from 14.91 mg/g DW in the ethanol extract to 48.53 mg/g DW in the methanol extract. The highest contents of total phenols and flavonoids were found in the acetone extract, and the methanol extract demonstrated the highest antioxidant activity in DPPH and ABTS assays. The antimicrobial potential of the extracts was screened using a microdilution method against a spectrum of gastrointestinal microorganisms. The results revealed that all four extracts have significant antimicrobial potential against the tested microorganisms, of which the ethanol extract demonstrated the highest antimicrobial potency.

Microwave and ultrasound-assisted natural deep eutectic solvents-based extraction of pectin from onion peel wastes

ABSTRACT Pectin was extracted from onion peels using microwave and ultrasound-assisted natural deep eutectic solvents (NADES) and compared with conventional acid-extracted pectin. The primary screening trials indicated that the suitable combination of hydrogen bond acceptor and donor was choline chloride and tartaric acid, respectively. The Box-Behnken design was further used to optimize processing conditions like microwave intensity (26.903 W/g), microwave processing duration (2.99 min), and sonication duration (10.18 min) for maximizing the pectin yield from onion peel powder. The moisture, ash, and equivalent weight of extracted pectin were in the range specified by the International Pectin Producers Association. The higher anhydrouronic acid content of the NADES-extracted pectin indicated the higher purity of pectin compared to the conventional acid-extracted pectin. The NADES-based extraction was found to be a promising system for extracting pectin with a higher degree of esterification from onion peels.

Effect of onions tunic extract on sodium oxalate-induced acute kidney injury

Acute kidney injury (AKI) is one of the global health concerns afflicting the human population and urolithiasis (kidney stone), especially the calcium oxalate stone is the most prominent amongst the stone formers with a huge recurrence rate. This study elucidates the ameliorative potential of the tunic of onions against Wistar kidney rats toxified with sodium oxalate.Ethylacetate extract of the tunic of onions otherwise regarded as Onions peel extract (OPE) in this study was prepared to get the flavonol-rich extracts. Adult male Wistar rats received 70 mg/kg body weight sodium oxalate with or without co-treatment with OPE, quercetin or cystone. Biochemical analyses were carried out on the plasma and urine, followed by a histopathological assessment of the kidney. Intoxication with sodium oxalate brought about electrolyte imbalance, nephrotic syndrome (high concentrations of total protein and albumin in the urine and low concentrations in the plasma) reduced renal function (low renal clearance of creatinine and urea) and damage to the kidney as well as fluid accumulation. Treatment with flavonol extract from onion tunic mitigated these deleterious changes as a result of sodium oxalate intoxication. The finding suggests that onion peel has the potential to prevent damage arising from oxalate toxicity in the kidney.Graphical

Biodegradable film of carboxymethyl cellulose modified with red onion peel powder waste and boron nitride nanoparticles: Investigation of physicochemical properties and release of active substances

The aim of this study was to modify carboxymethyl cellulose (CMC) films with onion peel extract (OPE) (0–2 g), onion peel powder (OPP) (0–2 g) and boron nitride nanoparticles (BN) (0–100 mg). 17 different CMC/OPE/OPP/BN films were provided and the physicochemical properties of films were studied. The release of active compounds of the composite film was investigated over time. The obtained results showed that OPE, OPP and BN increased the physical resistance and flexibility of the films. The percentage of moisture and solubility of the films decreased with the increase of OPE, OPP and BN. By adding BN, OPE and OPP, the structure of the film became stronger and the permeability to water vapor decreased. Addition of OPE and OPP significantly increased the antioxidant property of the film. In general, it can be said that the antioxidant substances of the onion peel are protected inside the film by preparing a CMC/OPE/OPP/BN film, which, in addition to stabilizing the antioxidants, can play an effective role in the controlled release of these antioxidant substances.

Reduction of Cr (VI) Formation in Leather with Herbal Extracts

This study investigates the effects of extracts from natural products such as oak bark, and onion peel, on the formation of Hexavalent Chromium (chromium (VI)) or (Cr (VI)) in leather during the finishing process. To enable chromium (VI) formation, finished leather samples were aged under various conditions, including exposure to UV light. The amount of chromium (VI) in each leather sample was measured using a PC UV-Visible spectrophotometer at 540 nm based on the ISO/FDIS 17075 standard method. The results showed that extracts from Quercus cortex, and Allium cepa significantly reduced chromium (VI) formation in the leather under all aging conditions.

Comparative Analysis of Polyphenol Content and Antioxidant Activity of Different Parts of Five Onion Cultivars Harvested in Korea.

Onions are typically consumed as the bulb, but the peel and root are discarded as by-products during processing. This study investigated the potential functional use of these by-products by analyzing the polyphenols, antioxidant compounds, and antioxidant activity contained in onions. In this study, the bulb, peel, and root of five onion cultivars ('Tank', 'Bomul', 'Gujji' 'Cobra', and 'Hongbanjang') harvested in Korea were investigated. Caffeic acid and quercetin were most abundant in the peel, whereas methyl gallate was the predominant polyphenol in the bulb. Both DPPH and ABTS radical scavenging activity were higher in onion peel and root than in the bulb. These findings suggest that onion peel and roots, which are often discarded, have abundant antioxidant substances and excellent antioxidant activity. This study provides basic data for the future use of onion peel and roots as functional ingredients with high added value.

Green Synthesis of Silver/Silver Chloride Nanoparticles using Shallot Peel Extract as Reducing Agent

Precious metal nanoparticles, especially silver, can be an alternative antibacterial agent that is more promising than antibiotics, which tends to induce resistance over time. Unfortunately, most Silver nanoparticle (AgNP) manufacturing methods involve hazardous substances, extreme conditions, high energy, and complicated separations. Reduction of AgNO3 solution with plant extracts can serve as a ‘green’ synthesis pathway, especially if using food processing waste or other biological materials. Reducing substances that are commonly found in plant extracts, such as flavonoids, are widely contained in shallots (Allium cepa L. var. aggregatum) which are commonly used as food ingredients in Indonesia, but the processing waste is still not widely used. This paper describes the synthesis of silver nanoparticles (AgNP) with the AgNO3 solution reduction method, using onion peel waste extract as a reducing agent. Experiments were carried out with variations in the ratio of AgNO3 solution to onion peel extract. The resulting AgNPs were characterized by TEM and UV-vis.

Phytosynthesis via wasted onion peel extract of samarium oxide/silver core/shell nanoparticles for excellent inhibition of microbes

The aqueous onion peel extract (OPE) was used to synthesize silver nanoparticles (Ag-onion), samarium oxide nanoparticles (Sm2O3-onion), and silver/samarium oxide core/shell nanoparticles (Ag@Sm2O3-onion). The produced nanoparticles were characterized by thermal gravimetric analysis (TGA), infrared spectra (FT-IR), absorption spectra (UV–Vis), energy band gap, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), zeta potential, and transmission electron microscopy (TEM). OPE and NPs were tested for the disinfection of some water microbes. XRD analysis exhibited an amorphous structure of samarium oxide in both Sm2O3-onion and Ag@ Sm2O3-onion. The isolated bacteria from the water sample were Bacillus subtilis (OQ073500) and Escherichia coli (MW534699), while the isolated fungi were Alternaria brassicae (MZ266540), Aspergillus flavus (MT550030), Aspergillus penicillioides (MW957971), Pythium ultimum (MW830915), Verticillium dahlia (MW830379), Fusarium acuminatum (MZ266538), Candida albicans (MW534712), and Candida parapsilosis (MW960416). High levels of antimicrobial activity were seen in both the nanoparticles and the aqueous onion peel extract. Based on experimental results, Ag@Sm2O3 demonstrated the highest activity as an effective disinfectant, indicating the effectiveness of the modification process.

Statistical Optimization of α-Amylase Production from Novel Local Isolated Bacillus spp. NRC1 and Its Textile Applications

By employing Plackett–Burman design (PBD) to investigate the qualitative interactions between eleven parameters [potato shell weight, incubation time, glucose, lactose, baker's yeast, peptone, (NH4)2SO4, CuSO4, FeSO4, CaCl2, KCl], and central composite design (CCD), the production of α-amylase by a local bacterial isolate Bacillus spp. NRC1 using agro-industrial wastes was improved. Using a variety of waste materials, including corn cobs (CC), onion peels (OP), rice straw (RS), potato shells (PS), Molokhia stem (MS), okra suppression (OS), lemon peels (LP), and pea peels (PP), Bacillus spp. NRC1 was tested in the production of amylase. Out of the eight agro-industrial wastes tried, the highest amylase yield (6.99 U/ml) was reached using potato peels. The statistical optimization of enzyme production was carried out using PBD followed by CCD design, causing 2.06-fold and 1.51-fold increase, respectively. The overall increase was 3.11-fold. In PBD design, potato peels, peptone and (NH4)2SO4 were positive factors for amylase production. The crude enzyme was tested for its ability to desize cotton fabric and subsequently studying its effect on fabric dyeability. The produced amylase proved its potentials in textile industry.Graphical

Red Onion Peel Powder as a Functional Ingredient for Manufacturing Ricotta Cheese.

Onion (Allium cepa L.) is a vegetable widely cultivated and consumed due to its rich content in bioactive compounds. Red onion peel (ROP) powder, which is a by-product derived from the onion industry, has been attracting significant interest as a potential functional ingredient for improving the overall quality of foods. The present study explores the potential of ROP powder as a functional ingredient to improve the quality and nutritional value of whey cheese. Despite being frequently viewed as a food processing waste byproduct, ROP is a rich source of bioactive substances, including antioxidants, flavonoids, and dietary fiber, having antioxidant and antibacterial effects. The ROP extract exhibited high amounts of total polyphenols (119.69 ± 2.71 mg GAE/g dw) and antioxidant activity (82.35 ± 1.05%). Different quantities (1 and 3%) of ROP powder were added to cheese formulations, and the subsequent impact on the texture characteristics, sensory attributes, and phytochemical composition of the value-added cheeses was evaluated. The findings show that the addition of ROP powder improved the texture and the color of the cheeses, providing a visually appealing product. Additionally, adding the ROP powder significantly raised the amount of phytochemicals and antioxidant activity (17.08 ± 0.78 µmol TE/g dw for RCROP1, 24.55 ± 0.67 µmol TE/g dw for RCROP2) in the final product's formulation. Moreover, adding powder to cheese is an effective way to increase the value of onion by-products and produce polyphenol-enriched cheese.

Application of some Plant Extracts as Biocolorants for Leather During Finishing Process

In this research, chrome-tanned bovine crust leathers were dyed during the finishing process using plant extracts: walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa). In this study, the standard recipe applied by the factory was used in the leather finishing process. For this recipe, various plant extracts were used instead of pigments, and groups that did not contain pigment and any dyestuff were formed as the control groups. After these processes, color measurement analyzes were performed on Konica Minolta CM 3600d spectrophotometer. In order to investigate the effects of walnut shell (Juglans regia), oak bark (Quercus cortex), and onion peel (Allium cepa) on the other performance properties of leather, dry and wet rub fastness test according to standard method TS EN ISO 11640 (2001) was performed. The results of the study were statistically evaluated using the NCSS method (Number Cruncher Statistical System). As a result of the study, it was noticed that, depending on the extract, different colors were obtained. It was found that the dry and wet fastness of leathers treated with plant extracts improved.

A sustainable synthesis, characterization of modified waste onion peels and its exploration in various applications

The modification of waste to a bio-based material that is economical, environmentally sustainable, and extremely effective is crucial for organic conversions. For bio waste, that doesn’t decompose easily and have bad impact on environment such as onion peels, a suitable method is introduced which focuses on utilizing onion peels, a commonly discarded agricultural waste, as a valuable resource for antibacterial studies and bio sensing of heavy metals. A comparative study to analyse these properties were done using onion peel extract and saponified onion peels. The saponified material was obtained by treating onion peels (Allium cepa) with sodium hydroxide in the presence of calcium carbonate. The popularity of saponification reaction and saponified material is rising because of their special qualities and uses as disinfectants, surfactants, antifungal agents, in drugs for target based delivery etc. The saponified onion peels was analyzed by FTIR (Fourier transform infrared spectroscopy), and XRD (X-ray diffraction), EDX (energy-dispersive X-ray), SEM (scanning electron microscopy). Furthermore, against Bacillus subtilis (Gram positive), antibacterial activity of onion extract and saponified onion peels were studied. In comparative study onion peel extract shows better inhibition zone then saponified onion peels. Bio sensing of heavy metals were done by using these materials, onion peel extract shows visual colour change with Nickel chloride (NiCl2), Cobalt chloride (CoCl2), Potassium bromide (KBr), Manganese sulphate (MnSO4), Mercury chloride (HgCl2) and Copper sulphate (CuSO4) metal salts.

Agro-industrial by-products as ruminant feed: Nutritive value and in vitro rumen fermentation evaluation.

In recent years, agricultural by-products have generated increasing interest as ruminant feed. In a completely randomized design with five experimental treatments, this in vitro study investigated the nutritional value of citrus pulp and onion peel as alternative feed for ruminants and their effects on rumen fermentation, digestibility, and gas production. The first group was the control (50% grass hay/50% concentrate mixture). The other four treatments represented citrus pulp and onion peel at inclusion levels of 10 and 20%, replacing the expensive, high-quality feed ingredients such as the concentrate mixture. The chemical composition showed that citrus pulp is an energy-rich material that could be included up to 20% to replace part of the concentrate in a mixed diet without any adverse impacts on rumen fermentation parameters. The onion peels were rich in fiber and minerals. Their inclusion in the diet of over 10% had detrimental effects on rumen fermentation. The inclusion of either citrus pulp or onion peel in the diet did not have the potential to reduce enteric methane production. In conclusion, citrus pulp showed promising results as a new feed for ruminants. It was effective when included in up to 20% of a ruminant diet, replacing the concentrate mixture.

Relative impact of vermiwash against phytophagous insects and growth properties of yardlong bean (<em>Vigna unguiculata</em>)

Due to severe insect infestation, yardlong (Vigna unguiculata) bean expansion and production have been declining in Sri Lanka. This experiment tested the effectiveness of several vermiwash against phytophagous insects in yardlong bean. Ten distinct types of vermiwash were generated by alternately and separately feeding exotic (Eudriluseuginea) and indigenous types earthworm with the specified botanicals, viz. onion and garlic peel, marigold and neem leaves, and the materials given for mass culturing. Eleven treatments including 10 vermiwash and untreated control and three blocks were laid on Randomized Complete Block Design. Since the third week of planting, vermiwashes have been administered to the corresponding plots at weekly intervals. Before each application of treatment, the total number of insects in each treated and untreated plot were carefully counted. ANOVA assessed treatment effects, and Duncan's Multiple Range Test compared mean separation values at 5% significance using SAS software. Plots treated with vermiwash made from indigenous earthworm varieties with garlic peel (1.33), exotic varieties with onion peel (2.33), and native varieties with onion peel (3.00) had the significantly similar fewest epilachna beetles. Further, vermiwash of an indigenous variety with neem leaves, where the maximum yield of yardlong beans was also discovered, had a considerably lower population of epilachna beetles. Furthermore, with the exception of the vermiwash of exotic species with onion peel, practically all treatments were less harmful to ladybird beetles. As demonstrated by this experiment, vermiwash has a beneficial effect on plant development in terms of both plant height and leaf area. Vermiwash made from combining an indigenous species of earthworm with neem leaves was potentially suggested for yardlong bean production since it was both environmentally and economically efficient.

English

The use of hydrogen energy is considered to be an alternative energy that provides renewable fuel energy solutions. The production of bio-hydrogen with basic materials such as organic waste and industrial waste is easy to implement and seems to be promising as an energy source in the future. One method that can be done to produce hydrogen is a photocatalyst. To increase hydrogen production, photocatalysts were selected using activated carbon made from biomaterials, namely using onion peels. In onion peel, aromatic compounds / aromatic rings with hydroxyl functional groups are the main components of activated carbon to support the photocatalyst process. The method used in this study is using experimental methods involving several research variables including independent variables are the mass of activated carbon 2.7 and 16 grams and variations in light irradiation, namely purple, green, yellow and without light. The control variables include the length of light exposure time of 30 minutes, the volume of the solution is 100 mL and the dimensions of the catalyst are 60-200 mesh. The results stated that the mass variation of 16 grams with purple light irradiation was able to produce the highest hydrogen worth 749.18 μmol g-1. This result is influenced by the electrons contained in the aromatic ring being delocalized and causing electrons to move freely energetically throughout the structure, giving rise to properties such as conductivity. The electron delocalization process that occurs in activated carbon causes electrons to move energetically, thus affecting the O-H covalent bond found in H2SO4 solution and triggering the weakening of hydrogen bonds in acidic solutions. The reaction caused by the delocalization process takes place continuously, triggering the breaking of the hydrogen chain

Development of Antibacterial Cotton Fabric by Application of Fruit and Vegetable Peel Extracts - A Sustainable Approach

The objective of this study is to assess the effect of Solanum incanum fruit (SIFE) and red onion peel (ROPE) extracts treatments on cotton fabric properties. The two factor factorial design was used, the first factor is concentration of the methanolic extract with two levels (3 g/l and 5 g/l) and the second is combination of extracts (25:75 SIFE: ROPE; 50:50 SIFE: ROPE; 75:25 SIFE: ROPE, 100% SIFE, 100% ROPE). Each extract was applied separately and in combination of different proportions on cotton fabric by the pad-dry-cure method using citric acid as a cross-linking agent. After treatment, the physical properties antimicrobial, wash durability and structual properties were determined. Air permeability, water absorbency and tensile strength were decreased for the treated fiber compared with control. Among all treatments, the cotton fabric treated with 50:50 combination was found best in bacterial reduction. This study concluded that, the natural source can sucessfully replace with synthetic chemicals.

Extraction of Bioactive Compounds from Yellow Onion Peels: Taguchi-SAW Hybrid Optimization

The aim of this study was to obtain an extract rich in bioactive components from yellow onion peels, which are generally considered waste material. Accordingly, a three-factor three-level Taguchi (L9) experimental design with three factors, namely ethanol concentration (A; 50%, 75%, 100%), extraction temperature (B; 30, 40, 50 °C), and sonication time (C; 10, 20, 30 min) was used to optimize the ultrasound-assisted extraction process of onion peel powders. Through Taguchi optimization, the optimum extraction conditions were determined as A2B3C2 to obtain the extract with the highest total phenolic matter (TPM) content and antioxidant activity (DPPH (%)). In addition, the extract produced under A2B1C2 conditions was found to be the richest in total monomeric anthocyanin (TMA) content with the highest level of color pigments. In order to determine the overall optimization conditions and to reduce the three-response optimization process to a single response, the simple sum weighting (SAW) method was used as a multi-criteria decision-making method. As a result of the optimization, it was concluded that an extract rich in bioactive components with optimal TPM and TMA contents and DPPH (%) value could be obtained as a result of sonication at 30 °C for 20 min to onion peel powders mixed with a solvent containing 75% ethanol (A2B1C2). The extraction conditions of bioactive components from yellow onion peels were successfully optimized by the Taguchi-SAW hybrid optimization method.

Onion peel extract as milk freshness indicator in biopolymer-based intelligent packaging films

Intelligent food packaging is used to monitor quality / freshness of packaged food product, and to communicate them to consumers. Natural color-based pH indicators can be effective agents in biopolymer-based intelligent packaging systems. In this study, gelatin and sodium alginate-based sustainable intelligent packaging films incorporated with onion peel extract (OPE) as the pH indicator were fabricated for monitoring and indicating milk freshness. Effects of incorporation of OPE on moisture content, solubility, swelling, transparency, antioxidant activity, and total phenolic contents of the fabricated films were also evaluated. The developed films were characterized using Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and their color changes due to pH sensitivity were measured. The fabricated intelligent films / labels were tested against milk at different pH of 6.5, 6, 5.5, 5, 4.5, 4, and 3.5, and the discernible color changes were measured. The developed intelligent films / labels showed significant change in their color with change in pH of the milk samples. Thus, the films can be used as sustainable alternative, as freshness indicator for packaged milk.