Onion By-products Research Articles

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.

Onion Byproduct Contains Factors with the Ability to Modulate Plasma Lipids and Lipoprotein Levels

Heart diseases due to hyperlipidemia (primary or secondary) can lead to cause chest pain, heart attacks, strokes, cardiac arrhythmias, cardiac failure. Because of these risks, treatment is often recommended for people with hyperlipidemia, because it is well known factor to increase incidence of heart diseases. This may lead to development of atherosclerotic plaques which is major etiological factor for establishing coronary artery disease (CAD). Hypolipidemic drugs used in allopathy include Statins, Fibric acids, Niacin, and Resins but all have their low compliance due to frequent side effects. Medicinal herbs like Onion and Ginger are hypolipidemic agents commonly used as flavoring agents and making foods spicy and tasty. We have compared hypolipidemic potential between these two medicinal herbs. The study was conducted at Ghurki Trust teaching hospital, Lahore from January to June 2023. Eighty secondary hyperlipidemic patients were enrolled after getting written consent which was approved by Ethics committee of the hospital. They were divided in two equal groups comprising 40 patients in each group. Group-I was treated by Ginger 10 grams daily in three divided doses for 2 months. Group-II was advised to take Onion 200 grams daily in divided amount with each meal i.e.; breakfast, lunch, and dinner for two months. After two months therapy it was observed by statistical analysis that 10 grams ginger reduced TC (total cholesterol) of 38 hyperlipidemic patients 12.4 gm/dl and LDL-C (low density lipoprotein cholesterol) 27.3 mg/dl. In group-II, onion reduced TC in 35 patients 17.9 mg/dl and LDL-C 14.8 mg/dl. Changes in tested parameters are significant biostatistically with p-values <0.01 to <0.001. We concluded from this research work that Onion and Ginger reduces risk of CAD by decreasing plasma total

Liquid submerged fermentation by selected microbial strains for onion skins valorization and its effects on polyphenols

Onion skins, actually recycled as organic fertilizers, could be used as a substrate in environmental-friendly bioprocesses to recover high-value bioactive compounds and food ingredients.In this work, a bioprospecting method was carried out including 94 bacterial and 45 yeast strains from several agri-food and environmental niches to verify their ability to grow on onion skins as unique nutrients source.Red and yellow onion skins were assessed by newly selected starter-driven liquid submerged fermentation assays mainly aimed at the release and modification of polyphenols through microbial activities. Fermented onion skins were also investigated as a inexpensive favourable source of microbial enzymes (amylases, proteases, lipases, esterases, cellulases, xylanases).In red onion skins, the treatment with Lactiplantibacillus plantarum TB 11–32 produced a slight increase of bioactive compounds in terms of total phenolics, whereas with the yeast strain Zygosaccharomyces mrakii CL 30 − 29 the quercetin aglycone content increased of about 25% of the initial raw material.In yellow onion skins inoculated, the highest content of phenolic compounds was detected with the yeast strain Saccharomyces cerevisiae En SC, while quercetin aglycone increased of about 60% of the initial raw material in presence of the bacterial strain L. plantarum C 180 − 34.In conclusion, the proposed microbial pre-treatment method can be a potential strategy to re-use onion skins as a fermentation substrate, and as a first step in the development of a biorefinery process to produce value-added products from onion by-products.

Biorefining process of agricultural onions to functional vinegar

Biorefinery of onion vinegar (OV) is attractive as a method for producing functional foods from onions or onion by-products. In this study, a two-stage fermentation of OV using Saccharomyces cerevisiae ATCC9763 and Acetobacter pasteurianus CICC20001 was carried out at 28 °C, the titratable acidity reached 4.01%, and the Y A/E was 69.64% at 72 h. Based on this, semi-continuous fermentation was performed, proceeded to charge-discharge consisting of three cycles, and the yield, productivity, and specific production rate were 76.71%, 17.73 g/(L·d), and 20.51 h−1, respectively, which was higher than fed-batch fermentation. The in vivo antioxidant experiments showed that OV significantly increased GSH-Px, SOD, and CAT enzyme activities of Caenorhabditis elegans at 271.57, 129.26, and 314.68%, respectively. Nutritional analysis revealed that the total flavonoids and polyphenols were 3.01 mg/mL and 976.76 µg/mL, respectively. It was also shown that the acetic acid to total organic acid (A/T) ratio of OV was 79.02%, and the total free amino acid content was 262.30 mg/100 mL, 1.78–7.44 times higher than other fruit vinegar. The OV prepared in this study showed higher quality than the commercial vinegar.

Valorization of agro-industrial byproducts: Extraction and analytical characterization of valuable compounds for potential edible active packaging formulation

Large amounts of byproducts having high environmental impact are produced in the agro-industrial field. However, they are often rich of bioactive molecules and can represent a good source of new products. In a sustainability context, supporting Circular Economy project, this work aimed at extracting active compounds from onion, artichoke and thistle byproducts, and exploited new applications in the field of food packaging. Compound characterization achieved by chromatographic techniques demonstrated the presence of valuable ingredients such as quercetin and chlorogenic acid, and prebiotic carbohydrates. A high content of total phenolic compounds was evaluated mainly in artichoke and onion byproducts, and the addition of the extracts to oil samples showed a significant increase of oxidative stability, measured by Oxitest, even higher than 100% respect to blank oil. An active film based on the use of edible substances has been realized, and preliminary data about its application on food products showed promising developments.

From By-Products to Fertilizer: Chemical Characterization Using UPLC-QToF-MS via Suspect and Non-Target Screening Strategies

The increasing demands of agriculture and the food market have resulted in intensive agricultural practices using synthetic fertilizers to maximize production. However, significant efforts have been made to implement more environmentally friendly procedures, such as composting, to overcome the adverse impact of these invasive practices. In the terms of this research, composting was applied to the production of two biofertilizers, using onion and mushroom by-products as raw materials respectively. The main purposes of this work were to identify the compounds that pass from the raw materials to the final products (onion-based and mushroom-based), as well as the characterization of the chemical profile of these final products following suspect and non-target screening workflows via UPLC-qToF-MS. Overall, 14 common compounds were identified in the onion and its final product, while 12 compounds were found in the mushroom and its corresponding product. These compounds belong to fatty acids, organic acids, and flavonoids, which could be beneficial to plant health. The determination of parameters, such as the pH, conductivity, organic matter, nitrogen content, and elemental analysis, were conducted for the overall characterization of the aforementioned products.

Thermal stability and bioavailability of bioactive compounds after baking of bread enriched with different onion by-products

This study investigated the effects of the addition of onion waste fractions into gluten-free (GF) bread to promote its health benefits. 5% of the control (C) GF flour blend was replaced with three waste fractions in the form of: fried onion (FO), dried onion (DO) and onion peel (OP). Antioxidant activity, content of flavonols and total polyphenols of breads increased in the following order: C < FO < DO < OP. No differences were observed in sensory analysis. We found that quercetin glycosides, dimers and trimer in OP-bread, determined according to their mass spectra, decomposed during baking and released free quercetin, which points to their thermal instability. Cross-over study revealed that consumption of OP-bread significantly increased (p < 0.05) antioxidant activity of consumers’ blood compared to control bread consumption, indicating good bioavailability of flavonols. Results suggest incorporation of OP into GF bread can increase its biological value with satisfactory sensory acceptance.

Natural valuable compound extraction from onion by-products using a pulsed electric field

Natural valuable compound extraction from onion by-products using a pulsed electric field

Physicochemical properties and in vitro antidiabetic potential of fibre concentrates from onion by-products

Onion by-products, Paste and Bagasse, were used to produce fibre concentrates (FCs), which were studied for dietary fibre (DF) content, physicochemical properties, effects on glucose adsorption, in vitro glucose diffusion, alpha-amylase activity and starch digestibility. FC dietary fibre was composed of cellulose and pectic polysaccharides with different degree of branching. FCs had lower bulk densities, and higher oil-holding and cation exchange capacities, as well as higher hydration properties, than cellulose. Onion FCs had the desired physicochemical properties as fibre sources or low-calorie bulk ingredients in food applications. Both onion FCs were found to have higher glucose-adsorption capacity than cellulose. The retardation of glucose diffusion by FCs were higher than cellulose. All FCs reduced the glucose production rate by inhibiting alpha-amylase activity, and decreased starch digestibility. The results verified the hypoglycaemic effect and the in vitro antidiabetic potential of onion by-product FCs.

Evaluation of ensemble Monte Carlo variable selection for identification of metabolite markers on NMR data

The aim of this study was to investigate the potential of the recently developed ensemble Monte Carlo Variable Selection (EMCVS) method to identify the relevant portions of high resolution 1H NMR spectra as a metabolite fingerprinting tool and compare to a widely used method (Variable importance on projection (VIP)) and recently proposed variable selected methods i.e. selectivity ratio (SR) and significance multivariate correlation (sMC). As case studies two quantitative publicly available datasets: wine samples, urine samples of rats, and an experiment on mushroom (Agaricus bisporus) were examined. EMCVS outperformed the three other variable selection methods in most cases, selecting fewer chemical shifts and leading to improved classification of mushrooms and prediction of onion by-products intake and wine components. These fewer chemical shift regions facilitate the interpretation of the NMR spectra, fingerprinting and identification of metabolite markers.

Status and trends of nutraceuticals from onion and onion by-products: A critical review

AbstractThe pivotal roles of vegetables are predominantly important for health due to availability of minerals, vitamins, phytochemicals and antioxidants. These foods and food products those are prepared from such kind of material having natural origin have great importance due to their versatile nature. Onion importance is greatly increasing and now it has become second most medicinal and horticultural crop after tomatoes. It has multiple functional compounds including organosulphur, anthocyanins, flavonoids, quercetin, kaempferol and polyphenols. Antibacterial, anti-inflammatory and antioxidant properties are the various diverse functions of onions, which have sound effects on human health. Fructo-oligosaccharides are present in abundant quantity in it due to which the growth of potentially harmful bacteria in the colon is retarded by the oligomers thus reducing the risk of emerging tumors in the colon and also initiates the growth of healthy bifidobacterium. In the nutshell, the onion and onion by-prod...

양파껍질 열수추출물의 in vitro 및 in vivo 항염증 효과

Onion (Allium cepa) is one of the flavonoids-rich materials in human diet and onion peel, which is the onion byproducts, contains over 20 times more quercetin than the flesh. In this study, to examine the anti-inflammatory effects of onion peel hot water extract (OPHWE), the cell viability, nitric oxide (NO), pro-inflammatory cytokines, such as interluekin-6 (IL- 6), tumor necrosis factor-α (TNF-α), and IL-1β, were measured using the murine macrophage cell line RAW 264.7 cells. The Balb/c mice were used for an in vivo acute toxicity test and ICR mice were used for measurement of inhibition effects of croton oil-induced mouse ear edema. As a result, NO levels decreased in a dose-dependent manner. The production of IL-6, TNF-α, and IL-1β was suppressed by 38%, 41%, and 34% respectively, compared with that of the LPS only group, without any cytotoxicity. The edema formation in the ICR mouse ear was also reduced compared to that in control. Moreover, there were no mortalities occurred in mice administered 5,000 mg/kg body weight of OPHWE. These results suggest that OPHWE has considerable anti-inflammatory activities and can be regarded as a potent candidate material to treat inflammatory diseases.

Simultaneous Extraction of Essential Oils and Flavonoids from Onions Using Turbo Extraction-Distillation

A simultaneous turbo hydrodistillation (THD) extraction of essential oil (EO) and flavonoid contents from onion (Allium cepa L.) was studied. Optimization of EO extraction was performed, and the effectiveness of THD in the extraction of onion total phenol content (TPC), total quercetin (TQ), quercetin aglycon (QA), quercetin-3,4′-diglucoside (QDG), quercetin-4′-monoglucoside (Q4G), quercetin-3-monoglucoside (Q3G), and kaempferol (KMF) was evaluated and compared with conventional solvent extraction of fresh onion. THD offers valuable extraction of onion by-products: 68.90 g/t of EO, 95.86 % of total phenol, and 55.94 % of total quercetin contents. The conventional extraction of fresh onion allowed the presence of QDG (684.78 mg/100 g dry weight (DW)) and Q4G (423.44 mg/100 g DW), whereas QA, Q3G, and KMF were also present in onion by-products obtained by THD. At 180-min THD process, the highest phenol content was obtained in the aqueous phase (47.58 mg quercetin equivalents/g DW). QDG (315.29 mg/100 g DW) and Q4G (335.05 mg/100 g DW) were mainly present in the aqueous phase, whereas QA (271.79 mg/100 g DW) was mainly present in the solid phase. Q3G and KMF were detected in minor quantities in onion extracts.

산업체 적용을 위한 양파껍질 추출물의 항산화활성

This study investigated the antioxidant activity of onion peels extracted from onion byproducts by hot water treatment. Hot water extraction of freeze dried onion peel powder was analyzed for total polyphenol content, 2,2'-diphenyl- 1-picryllhydrazyl (DPPH), and 2,2'-azino-bis(3-ehtylbenzothiazoline-6-sulphonic acid) (ABTS) radical scavenging activities, reducing power, oxygen radical absorbance capacity (ORAC). Total polyphenol content was the highest (233.90 mg/g) in onion peel extract mix with ethanol (OPME-1). The DPPH radical scavenging activity (IC 50 ), reducing power, and ORAC obtainbed from onion peel extract mix with ethanol precipitation (OPMPE-1) were the highest at 1.15 mg/mL, 1.69 A700, and 318,509 µM TE/mL, respectively. The ABTS radical scavenging activity was the highest at 432.78 mg amino acids (AA) eq/g in the OPM. The results of this study suggest that onion peel extracts have marked antioxidant activity, which can have significant health benefits.

Use of Alliaceae residues to control soil-borne pathogens

The presence of large amounts of sulfur compounds in the organs of Allium species has lead to the suggestion that the residues of this plant family could be used in soil biofumigation. In this paper, we report the preliminary results of laboratory bioassays and field experiments that investigated the biofumigant effects of onion and leek residues. The active molecules in these Allium species were determined to be dimethyl disulfide (DMDS) and dipropyl disulfide (DPDS). The results show that onion by-products and DMDS not only had a high level of biofumigant activity, but also stimulated vegetative growth. In the field, when Allium by-products were incorporated into the soil, DPDS was frequently released and was detectable for up to one month afterwards. This treatment increased asparagus and strawberry productivity by 15–20%, a result that is comparable to those obtained using Brassica-based biofumigation. Given the concordance between the results of the bioassays and those of the preliminary field trials, onion by-products may have practical potential as new biofumigants and could be used as an alternative to methyl bromide. In the agronomic context, it is crucial to develop improved application techniques that reduce the quantity of onion by-products that need to be incorporated into soil.

Biopreservation of 'Birgah' Eggplant from Polyphenol Oxidase Activity Assayed In Vitro with Onion (Allium Cepa L.) by-products

Eggplants are vegetables largely consumed in many recipes as fresh and whole product or, more recently, as minimally processed vegetable (MPV). The main issue in diced eggplant consists in the oxidation due to polyphenol oxidase (PPO, EC 1.14.18.1), an enzyme producing pigments responsible for the undesirable dark color which spoiled the product. The aim of this work was to study fresh or heat-treated (100 °C for 15 min) onion by-products (paste, juice and bagasse) in order to evaluate in vitro the PPO enzyme inhibition capacity in minimally processed eggplant cv. 'Birgah’. The heated onion juice was the most suitable anti-browning extract among all by-products tested, followed by pasteurised paste and fresh juice (54.2, 41.2 and 37.3 % reduction in PPO activity, respectively). Data suggested that the thermal treatment enhances the effects of the extracts probably due to a synergic action between some endogenous active compounds present in onion and Maillard reaction products obtained during heating.

The Impact of Pasteurisation and Sterilisation on Bioactive Compounds of Onion By-products

Onion (Allium cepa L.) waste disposal represents a worldwide environmental problem. A solution to this issue could be the use of onion waste as food-grade ingredients, which could be added to processed foods for their enrichment in bioactive compounds. For this purpose, onion waste should be adequately processed and stabilised. Thus, the objective of this work was to study the composition of processed onion waste, assessing the effects of processing and thermal stabilisation on onion waste bioactive compounds. Onion waste was triturated (‘Paste’) and triturated + pressed (‘Bagasse’, solid residue and ‘Juice’, liquid fraction). All by-products were stabilised by pasteurisation and sterilisation. Results indicated that bagasse was an enriched dietary fibre product (361–453 mg/g dry weight (DW)); paste showed high alkyl or alkenyl cystein sulphoxide (ACSO) content (5.6 mg/g DW); and juice showed large fructans concentration (205–221 mg/g DW). In paste and bagasse, pasteurisation and sterilisation improved soluble/insoluble fibre ratio, with no changes in total dietary fibre concentration in pasteurised products and a slight decrease (8 % on average) in the sterilised ones. In juice, thermal treatments produced fructans losses, more pronounced after sterilisation (59 % on average) than after pasteurisation (36 % on average). However, sterilisation provided by-products with better ACSO results than pasteurisation. As a conclusion, industrial processing has an important impact on the bioactive composition, generating products with different functional applications. Moreover, pasteurisation resulted to be the most suitable treatment to obtain safe products enriched in dietary fibre and fructans, while sterilisation could be used to produce products rich in ACSOs.

Onion (Allium cepa L.) by-products as source of dietary fiber: physicochemical properties and effect on serum lipid levels in high-fat fed rats

The effect of industrial processes used to obtain onion by-products was evaluated. Fiber composition and physicochemical properties were assessed in order to choose the best process to obtain high-fiber ingredients. Moreover, the effect of the inclusion of the dietary fiber-rich onion by-products in a high-fat diet on serum lipids of rats was also evaluated. Bagasse was the best by-product since it showed the highest fiber content with a balanced soluble-to-insoluble fiber ratio and the best physicochemical properties. This fact is related to its high fiber content and also due to its composition, rich in uronic acids and polysaccharides, which explains its high cation exchange capacity, water-holding capacity and swelling capacity. In addition, the inclusion of Bagasse in a high-fat diet produced a reduction in the serum lipid and total cholesterol increases induced by high-fat diet. This effect could be related to the high cation exchange and swelling capacities that Bagasse showed, since these properties can create a concerted effect in reducing the number of intact micelles available, the transit time, and consequently the total time available for cholesterol and lipid absorption in the small intestine.

A novel idea in food extraction field: Study of vacuum microwave hydrodiffusion technique for by-products extraction

Vacuum microwave hydrodiffusion and gravity (VMHG), a modified form of solvent free microwave hydrodiffusion and gravity (MHG) technique, was used for extraction of onion by-products. A detailed study concerning about optimisation of different parameters like irradiation power, degree of vacuum and extraction time was performed. Subsequently, the temperature difference in different parts of matrix and also in the reactor was evaluated both in case of MHG and VMHG. Extracts obtained by VMHG, MHG and also conventional solvent extraction method (CSE) were analyzed for quantification of flavonoids by HPLC, along with studying the distribution of flavonoids in different intervals of time at optimised conditions. Two different methods were selected for evaluating the antioxidant capacity of these extracts along with determination of their phenolic content by the Folin–Ciocalteu method: the reduction of the stable DPPH (2,2-diphenyl-1-picrylhydrazyl) radical and the inhibition of the AAPH-induced peroxidation of linoleic acid in SDS micelles. Reduction of pressure up to 0.7 bar at microwave power of 500 W helped to increase the antioxidant activity of onion extracts with 57% increase in total quercetin contents against those obtained at atmospheric pressure. VMHG proved itself an efficient and environment-friendly technique allowing the extraction of flavonols at lower reactor temperature (81 °C ± 1), with improved alterations of tissues observed by microscopic studies, from onion by-products just in 26 ± 1 min, in the absence of any solvent.

Effect of sterilisation on dietary fibre and physicochemical properties of onion by-products

Food industries are forced to develop productions without secondary residues. Therefore, there is a considerable emphasis on the recovery, recycling and upgrading of wastes. The possibility has been suggested for the conversion of onion waste into food ingredients, but with a stabilisation treatment being necessary. The objective of this work was to study the effect of sterilisation on fibre fractions, fibre composition and physicochemical properties of onion by-products to evaluate the use of sterilised onion by-products as a source of fibre.Sterilisation produced insoluble dietary fibre decreases and soluble dietary fibre increases, improving the soluble:insoluble ratio. Uronic acids of insoluble dietary fibre were partly solubilised and losses of cellulose and Klason lignin were observed. Physicochemical properties slightly changed with sterilisation. Sterilised by-products showed less oil holding capacity, cation exchange capacity and swelling capacity than control ones, although their physicochemical properties were generally higher than those of cellulose. Therefore, sterilisation would be considered a good method to stabilise onion by-products to use as a potential dietary fibre ingredient.