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

Effects of different preparation and cooking processes on the bioactive molecules of Allium vegetables

Allium species are among the most widely cultivated vegetables for centuries for their positive effects on human health and their variety of uses in food preparation and cooking. Preparation and cooking processes create chemical changes that can affect the concentration and bioavailability of bioactive molecules. Understanding the changes in bioactive compounds and bioactive activities in Allium vegetables resulting from preparation and cooking processes is essential for better retention of these compounds and better utilization of their health benefits. This study aimed to investigate the effects of different preparation and cooking processes on the bioactive molecules of Allium vegetables. This review concludes that bioactive compounds in Allium vegetables are affected by each preparation and cooking process depending on variables including method, time, temperature. Owing to differences in the matrix and structure of the plant, preparation and cooking processes show different results on bioactive compounds and bioactive activities for different vegetables. Continued research is needed to help fill gaps in current knowledge, such as the optimal preparation and cooking processes for each Allium vegetable.

Towards a natural treatment for mania: red onion husk extract modulates neuronal resilience, redox signalling, and glial activation

BACKGROUND

Red onion husk, a readily available agricultural waste material, contains diverse bioactive compounds with potential health benefits. This study aimed to assess the safety and therapeutic potential of red onion husk extract in managing manic-like symptoms and associated neurochemical dysfunctions.

METHODS

Acute and repeated oral dose studies were conducted in mice and rats to evaluate the safety profile of the extract. FT-IR analysis identified functional groups in the extract, while GC-MS analysis identified specific bioactive compounds in the flavonoid-rich fraction. A ketamine-induced manic behaviour model in Wistar rats was employed to assess the extract's efficacy in attenuating manic-like symptoms. Behavioural and neurochemical analyses were performed to further investigate the extract's effects.

RESULTS

The extract demonstrated a favourable safety profile in both acute and repeated dose studies. FT-IR analysis revealed a complex mixture of organic compounds, including hydroxyl groups, alkynes/nitriles, aromatic and non-aromatic C = C bonds, amines, and polysaccharides. GC-MS analysis identified 17 bioactive compounds, including five-methyl-2-phenylindolizine, methadone N-oxide, and 3-phenylthiane, S-oxide. Ketamine administration significantly increased oxidative stress markers, TBARS, and suppressed antioxidant enzyme activities (SOD, GPx, CAT) in both the cerebral cortex and hippocampus, alongside elevated acetylcholinesterase (AchE) activity, indicating enhanced neuronal excitability. Pre-treatment with FRF (25 mg/kg) effectively mitigated ketamine-induced oxidative stress, as evidenced by reduced TBARS levels and partially restored SOD and GPx activities. Interestingly, FRF significantly increased CAT activity (p < 0.001), potentially suggesting an additional compensatory mechanism. Notably, FRF pre-treatment also counteracted ketamine-upregulated AchE activity, offering neuroprotection against heightened neuronal excitability.

CONCLUSION

Red onion husk extract exhibits a favourable safety profile and exerts potent antioxidant and neuroprotective effects, possibly through modulating Nrf2 signalling pathways. Its ability to counteract ketamine-induced oxidative stress and neuronal hyperactivity highlights its potential as a complementary therapeutic strategy for managing manic episodes in bipolar disorder. Further research is warranted to elucidate the precise molecular mechanisms underlying FRF's action and explore its clinical efficacy in human studies.

Valorization of onion peel waste: From trash to treasure

Globally, fruits and vegetables are consumed as raw, processed, or as an additive, accounting for approximately 50% of total food wastage. Among the fruits and vegetables, onion is well known for its potential bioactive components; however, peels of onion are a major concern for the environmental health and food industries. Effective utilization methods for valorizing the onion peel should be needed to develop value-added products, which are more eco-friendly, cost-effective, and sustainable. Therefore, this review attempts to emphasize the conventional and emerging valorization techniques for onion peel waste to generate value-added products. Several vital applications including anticancerous, antiobesity, antimicrobial, and anti-inflammatory activities are thoroughly discussed. The findings showed that the use of advanced technologies like ultrasound-assisted extraction, microwave-assisted extraction, and enzymatic extraction, demonstrated improved extraction efficiency and higher yield of bioactive compounds, which showed the anticancerous, antiobesity, antimicrobial, and anti-inflammatory properties. However, in-depth studies are recommended to elucidate the mechanisms of action and potential synergistic effects of the bioactive compounds derived from onion peel waste, and to promote the sustainable utilization of onion peel waste in the long-term.

Effect of Frozen Treatment on the Sensory and Functional Quality of Extruded Fresh Noodles Made from Whole Tartary Buckwheat

Extruded noodles made from whole Tartary buckwheat are widely known as healthy staple foods, while the treatment of fresh noodles after extrusion is crucial. The difference in sensory and functional quality between frozen noodles (FTBN) and hot air-dried noodles (DTBN) was investigated in this study. The results showed a shorter optimum cooking time (FTBN of 7 min vs. DTBN of 17 min), higher hardness (8656.99 g vs. 5502.98 g), and less cooking loss (5.85% vs. 21.88%) of noodles treated by freezing rather than hot air drying, which corresponded to better sensory quality (an overall acceptance of 7.90 points vs. 5.20 points). These effects on FTBN were attributed to its higher ratio of bound water than DTBN based on the Low-Field Nuclear Magnetic Resonance results and more pores of internal structure in noodles based on the Scanning Electron Microscopy results. The uniform water distribution in FTBN promoted a higher recrystallization (relative crystallinity of FTBN 26.47% vs. DTBN 16.48%) and retrogradation (degree of retrogradation of FTBN 34.67% vs. DTBN 26.98%) of starch than DTBN, strengthening the stability of starch gel after noodle extrusion. FTBN also avoided the loss of flavonoids and retained better antioxidant capacity than DTBN. Therefore, frozen treatment is feasible to maintain the same quality as freshly extruded noodles made from whole Tartary buckwheat. It displays significant commercial potential for gluten-free noodle production to maximize the health benefit of the whole grain, as well as economic benefits since it also meets the sensory quality requirements of consumers.

Characterization of the Volatile Compounds of Onion with Different Fresh-Cut Styles and Storage Temperatures

The flavor of fresh onion and its processed products is an important index with which to evaluate its quality. In this study, the highly volatile compounds of onion with different fresh-cut styles (bulb, ring, and square) and different storage temperatures (4 °C, 20 °C, and 25 °C) were characterized at the molecular level, focusing in particular on the volatile sulfur compounds. Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) were employed. A total of 14 highly volatile compounds were identified in onion samples by HS-GC-IMS, and the square sample contained more volatile components. (E,E)-2,4-heptadianal, ethyl acetate, 2-methyl-1-pentanol, 2-pentylfuran, propyl acetate, and 2,6-dimethylpyrazine were produced in the ring and square samples when stored at higher temperatures, while pentanal, 2-heptenal, hexanal were decreased after cutting. Simultaneously, 16 sulfur compounds were identified in onions by HS-SPME-GC-MS. The sulfur compounds profile of the bulbs was significantly different from that of the rings and squares at any temperature. When stored at a low temperature (4 °C), cutting onions into a ring or square shape produced more sulfur. However, at higher temperatures (20 °C and 25 °C), fresh-cutting decreased the sulfur concentration. The total content of sulfur compounds was higher in the same cut style stored at higher temperatures (20 °C or 25 °C). 2-Mercapto-3,4-dimethyl-2,3-dihydrothiophene and 2,4-dimethylthiophene were formed during storage; however, (E)-1-(prop-1-en-1-yl)-3-propyltrisulfane, 1-(1-(methylthio)propyl)-2-propyldisulfane, (Z)-1-(1-propenyldithio)propyl disulfide, dipropyl trisulfide, and methyl 1-(1-propenylthio)propyl disulfide were lost from all samples after storage.

Novel zero waste tactics for commercial vegetables – recent advances

Commercial vegetables include tomatoes, potatoes, onions, and eggplant due to their surplus production, availability, and affordability. The valorisation of the massive wastage of commercial vegetables and providing a long-term solution has been challenging. The review addresses the implications of biowastes on the environment and fosters the recent investigations into valorising commercial vegetable waste to develop multiple value-added products. It discussed the outcomes of the multiple technologies, majorly on green chemistry extraction, while outlining other methods such as fermentation, enzymatic treatments, 3D printing foods, high-pressure homogenisation, microencapsulation, bio-absorption method, and pyrolysis for their respective vegetable wastes. Agri-residues can be a valuable source for formulating functional ingredients, natural additives, biodiesel, dyes, and animal feed. This comprehensive review proposes a strategy to upcycle low-cost biowaste to boost the economic and ecological benefits. The current review captures the interests and great collaborations between researchers, industrialists, policymakers, waste management bodies, and eco-activists.

A review of plant antipathogenic constituents: Source, activity and mechanism

Green prevention and control of plant pathogens is a development direction of sustainable and low-carbon agriculture given the limitation of traditional chemicals. Plant-derived antipathogenic constituents (PAPCs) exhibit the advantages of being environmental benign and a broad spectrum of target pathogens over traditional chemicals. Here, we review the research advances on plant sources, chemical compositions, activities of antipathogenic constituents in the past 20 years. Reported PAPCs are classified into categories of phenols, flavonoids, terpenoids, alkaloids and antimicrobial peptides. Angiosperms, gymnosperms and some lower plants are the main plant source of detected PAPCs. The PAPCs act on pathogens through multiple pathways including destroying cell structures, blocking key composition synthesis and inhibiting cell metabolism. The development trends of PAPCs are finally prospected. This review serves as a comprehensive review on the study of plant antipathogenic constituents and a key reference for forecasting the source, characteristic and activity of PAPC.

Red onion skin active ingredients, extraction and biological properties for functional food applications

Onion is an important vegetable in the world and the second most important vegetable crop after tomato.Hence, the onion waste, such as onion skin, is produced in abundance causing environmental problems. Due to its bioactive compounds, especially phenolics and flavonoids, red onion skin can be used through appropriate methods for producing value-added products. These phytochemicals are proven to prevent oxidative stress and broad spectrum of microorganisms beside having diverse beneficial biological properties. Extraction step is the most critical processing in making phytonutrient available. Various approaches including conventional and non-conventional technologies applied for extracting different compounds from red onion wastes was summarized in this study. To evaluate the industrial application potential, the use of natural bioactives derived from red onion skin for elaboration of various food systems has been also investigated.

Onion anthocyanins: Extraction, stability, bioavailability, dietary effect, and health implications

Anthocyanins are high-value compounds, and their use as functional foods and their natural colorant have potential health benefits. Anthocyanins seem to possess antioxidant properties, which help prevent neuronal diseases and thereby exhibit anti-inflammatory, chemotherapeutic, cardioprotective, hepatoprotective, and neuroprotective activities. They also show different therapeutic effects against various chronic diseases. Anthocyanins are present in high concentrations in onion. In recent years, although both conventional and improved methods have been used for extraction of anthocyanins, nowadays, improved methods are of great importance because of their higher yield and stability of anthocyanins. In this review, we compile anthocyanins and their derivatives found in onion and the factors affecting their stability. We also analyze different extraction techniques of anthocyanins. From this point of view, it is very important to be precisely aware of the impact that each parameter has on the stability and subsequently potentiate its bioavailability or beneficial health effects. We present up-to-date information on bioavailability, dietary effects, and health implications of anthocyanins such as antioxidant, antidiabetic, anticancerous, antiobesity, cardioprotective, and hepatoprotective activities.

Valorization of Food Processing Waste to Produce Valuable Polyphenolics

Traditional incineration and landfill of food processing waste (FPW) have polluted the environment and underutilized valuable bioactive compounds, including polyphenols in food waste. As one of the most widely occurring compounds in the FPW, polyphenols possess high utilization value in many fields such as human health, energy, and environmental protection. Extracting polyphenols directly from FPW can maximize the value of polyphenols and avoid waste of resources. However, traditional polyphenol extraction methods mostly use the Soxhlet extraction, infiltration, and impregnation method, consuming a large amount of organic solvent and suffering from long extraction time and low extraction efficiency. Emerging green extraction methods such as supercritical fluid extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and other methods can shorten the extraction time and improve the solvent extraction efficacy, resulting in the green and safe recovery of polyphenols from FPW. In this paper, the traditional treatment methods of FPW waste and the application of polyphenols in FPW are briefly reviewed, and the traditional extraction methods and emerging green extraction methods of polyphenols in FPW are compared to obtain insight into the start-of-the-art extraction approaches.

Effects of five extraction methods on total content, composition, and stability of flavonoids in jujube

•

Five methods of extracting flavonoids from jujube were compared in different aspects.

•

The extraction methods can significantly influence the flavonoid compositions.

•

DES-UAE method had outstanding ability to maintain the stability of flavonoids.

•

DES-UAE is an efficient and green method for extracting flavonoids from jujube.

The present study investigated the effects of different extraction methods including water-water bath (W-WB), ethanol-water bath (E-WB), deep eutectic solvent (DES) combined with ultrasound-assisted extraction (DES-UAE), microwave-assisted extraction (DES-MAE), and enzyme-assisted extraction (DES-EAE) on flavonoids (total flavonoid content, flavonoid composition, and stability) in jujube. The highest total flavonoid content of 8.03 mg/g was obtained by the DES-MAE extraction. Fifteen types of flavonoids were identified from jujube. The amount of rutin produced by the E-WB and DES-UAE methods was 66.88 ± 1.58 μg/g and 45.23 ± 3.22 μg/g, respectively. The retention of flavonoids in DES-UAE extracts were 98.15 ± 0.51%, 64.25 ± 2.21% after 2 h of high temperature treatment at 90 °C and 21 days of dark storage, respectively. The flavonoids extracted by different methods were suitable for dark storage under different light contrasts, where the retention of flavonoids extracted by DES-UAE method was 86.44 ± 2.45%. In conclusion, DES-UAE would be an efficient method for flavonoid extraction from jujube.

Therapeutic Efficacy of Flavonoids in Allergies: A Systematic Review of Randomized Controlled Trials

Objective. To assess the clinical efficacy of flavonoid supplements on allergic diseases. Design. Systematic review. Data Sources. MEDLINE/PubMed, Scopus, Web of Science, and Embase databases were searched from inception to September 2021. Eligibility Criteria for Selecting Studies. Eligible study designs were randomized controlled trials that investigated the effect of flavonoids applied to allergic diseases. Results. This review included 15 randomized controlled trials, including allergic rhinitis/cedar pollinosis ( $n=10$ ), asthma ( $n=3$ ), and atopic dermatitis ( $n=2$ ). A total of 990 participants aged 6 to 69 years were included in these studies. Globally, 12 studies (80%) revealed some benefits of flavonoids (isolate or combined with other compounds) in allergic patients, while three studies (20%) reported no statistically significant impact on symptom scores and/or lung function. No severe adverse events related to treatment were reported. According to the GRADE system, the outcomes evaluated were of low to moderate quality of evidence. Conclusions. Overall, this review suggests that the administration of flavonoids may provide a viable strategy for mitigating allergic symptoms. Future trials with high methodological quality are needed to establish definitive conclusions. This trial is registered with PROSPERO registration no. CRD42021237403.

Valorization of Onion Waste by Obtaining Extracts Rich in Phenolic Compounds and Feasibility of Its Therapeutic Use on Colon Cancer

In this study, the total phenolic content, the antioxidant and antiproliferative activities of onion waste extracts were characterized. Some phenolic compounds present in the extracts were also identified and quantified by HPLC-DAD. Additionally, an in-silico analysis was performed to identify the phenolic compounds with the highest intestinal absorption and Caco-2 permeability. The onion extract possessed a high amount of phenolic compounds (177 ± 9 mg/g extract) and had an effective antioxidant capacity measured by ABTS, FRAP and DPPH assays. Regarding the antiproliferative activity, the onion extracts produced cell cycle arrest in the S phase with p53 activation, intrinsic apoptosis (mitochondrial membrane potential modification) and caspase 3 activation. Likewise, onion waste increased intracellular ROS with possible NF-kB activation causing a proteasome down regulation. In addition, the extracts protected the intestine against oxidative stress induced by H₂O₂. According to the in-silico analysis, these results could be related to the higher Caco-2 permeability to protocatechuic acid. Therefore, this study provides new insights regarding the potential use of these types of extract as functional ingredients with antioxidant and antiproliferative properties and as medicinal agents in diseases related to oxidative stress, such as cancer. In addition, its valorization would contribute to the circular economy.

Flavonoids in Treatment of Chronic Kidney Disease

Chronic kidney disease (CKD) is a progressive systemic disease, which changes the function and structure of the kidneys irreversibly over months or years. The final common pathological manifestation of chronic kidney disease is renal fibrosis and is characterized by glomerulosclerosis, tubular atrophy, and interstitial fibrosis. In recent years, numerous studies have reported the therapeutic benefits of natural products against modern diseases. Substantial attention has been focused on the biological role of polyphenols, in particular flavonoids, presenting broadly in plants and diets, referring to thousands of plant compounds with a common basic structure. Evidence-based pharmacological data have shown that flavonoids play an important role in preventing and managing CKD and renal fibrosis. These compounds can prevent renal dysfunction and improve renal function by blocking or suppressing deleterious pathways such as oxidative stress and inflammation. In this review, we summarize the function and beneficial properties of common flavonoids for the treatment of CKD and the relative risk factors of CKD.

Restoring trilinearity with the purpose of advanced modeling: towards a more effective analysis of Pericarpium Citri Reticulatae during storage periods

To accurately quantify Pericarpium Citri Reticulatae samples, trilinear structure was restored in the stacked fingerprints for more robust modeling. Initially, liquid chromatography - diode array detector - mass spectrometry (LC-DAD-MS) and head space-solid phase micro extraction coupled to gas chromatography - mass spectrometry (HS-SPME/GC-MS) were utilized to analyze Pericarpium Citri Reticulatae. Faced with the time-shifts in two-dimensional (2D) matrices across different samples, three algorithms were developed to synchronize them. Furthermore, bilinear and trilinear models were used to realize the quantifications with different principles. Through real cases based on LC-DAD, the advantages and disadvantages of trilinear decomposition over multivariate curve resolution-alternating least-squares can be clarified in the quantification of raw or synchronized fingerprints. Also in the data processing, a modification version of multi-scale peak alignment (^mMSPA) was proved to be more suitable for trilinearity restoring than the other two algorithms. Recognizing these facts, restoring trilinearity were developed for more robust modeling in the application of the Pericarpium Citri Reticulatae fingerprints from different storage periods. After effective analysis, the upward/downward trend of 13 flavonoids were drawn accurately; and several flavour components having the highest contribution rate during storage were outlined reasonably. In conclusion, more robust modeling can be realized in trilinear data synchronized by appropriate algorithms, leading to an accurate quantification in herbal quality researches.

By-Products Revalorization with Non-Thermal Treatments to Enhance Phytochemical Compounds of Fruit and Vegetables Derived Products: A Review

The aim of this review is to provide comprehensive information about non-thermal technologies applied in fruit and vegetables (F&V) by-products to enhance their phytochemicals and to obtain pectin. Moreover, the potential use of such compounds for food supplementation will also be of particular interest as a relevant and sustainable strategy to increase functional properties. The thermal instability of bioactive compounds, which induces a reduction of the content, has led to research and development during recent decades of non-thermal innovative technologies to preserve such nutraceuticals. Therefore, ultrasounds, light stresses, enzyme assisted treatment, fermentation, electro-technologies and high pressure, among others, have been developed and improved. Scientific evidence of F&V by-products application in food, pharmacologic and cosmetic products, and packaging materials were also found. Among food applications, it could be mentioned as enriched minimally processed fruits, beverages and purees fortification, healthier and "clean label" bakery and confectionary products, intelligent food packaging, and edible coatings. Future investigations should be focused on the optimization of 'green' non-thermal and sustainable-technologies on the F&V by-products' key compounds for the full-utilization of raw material in the food industry.

Chiral Flavonoids as Antitumor Agents

Flavonoids are a group of natural products with a great structural diversity, widely distributed in plant kingdom. They play an important role in plant growth, development and defense against aggressors. Flavonoids show a huge variety of biological activities such as antioxidant, anti-inflammatory, anti-mutagenic, antimicrobial and antitumor, being able to modulate a large diversity of cellular enzymatic activities. Among natural flavonoids, some classes comprise chiral molecules including flavanones, flavan-3-ols, isoflavanones, and rotenoids, which have one or more stereogenic centers. Interestingly, in some cases, individual compounds of enantiomeric pairs have shown different antitumor activity. In nature, these compounds are mainly biosynthesized as pure enantiomers. Nevertheless, they are often isolated as racemates, being necessary to carry out their chiral separation to perform enantioselectivity studies. Synthetic chiral flavonoids with promising antitumor activity have also been obtained using diverse synthetic approaches. In fact, several new chiral bioactive flavonoids have been synthesized by enantioselective synthesis. Particularly, flavopiridol was the first cyclin-dependent kinase (CDK) inhibitor which entered clinical trials. The chiral pool approaches using amino acid as chiral building blocks have also been reported to achieve small libraries of chrysin derivatives with more potent in vitro growth inhibitory effect than chrysin, reinforcing the importance of the introduction of chiral moieties to improve antitumor activity. In this work, a literature review of natural and synthetic chiral flavonoids with antitumor activity is reported for the first time.

Bioactive's Characterization, Biological Activities, and In Silico Studies of Red Onion (Allium cepa L.) Skin Extracts

This study aimed to investigate the thermal stability and biological activities of the phytochemicals from the red onion skins extract, which are a rich source of anthocyanins. Eight anthocyanins were identified in the extract by high-performance liquid chromatography, the most abundant ones being cyanidin 3-O-laminaribioside and cyanidin 3-O-(6″-malonoyl-laminaribioside). The study also involved the assessment of the thermal degradation kinetics of anthocyanins and antioxidant activity in the 75-155 °C temperature range. The thermal degradation kinetics was described using the first-order kinetics model. In terms of thermal stability, increasing the temperature resulted in lower half-life values (t_1/2) and higher degradation rate constant values (k) for both anthocyanins and antioxidant activity. The thermodynamic parameters revealed that the phytochemicals' degradation is a non-spontaneous and endothermic reaction. Furthermore, the inhibitory effect of the extract was investigated against the enzymes affiliated with metabolic syndrome, oxidative stress, and inflammatory process diseases. Thus, we also demonstrated that the red onion skins extract exerted inhibitory activity on α-glucosidase, α-amylase, lipase, and lipoxygenase. Considering the high content of bioactives and various biological properties, the red onion skins extract is suitable for multiple applications.

Underutilized Northern plant sources and technological aspects for recovering their polyphenols

Consumers worldwide are increasingly interested in the authenticity and naturalness of products. At the same time, the food, agricultural and forest industries generate large quantities of sidestreams that are not effectively utilized. However, these raw materials are rich and inexpensive sources of bioactive compounds such as polyphenols. The exploitation of these raw materials increases income for producers and processors, while reducing transportation and waste management costs. Many Northern sidestreams and other underutilized raw materials are good sources of polyphenols. These include berry, apple, vegetable, softwood, and rapeseed sidestreams, as well as underutilized algae species. Berry sidestreams are especially good sources of various phenolic compounds. This chapter presents the properties of these raw materials, providing an overview of the techniques for refining these materials into functional polyphenol-rich ingredients. The focus is on economically and environmentally sound technologies suitable for the pre-treatment of the raw materials, the modification and recovery of the polyphenols, as well as the formulation and stabilization of the ingredients. For example, sprouting, fermentation, and enzyme technologies, as well as various traditional and novel extraction methods are discussed. Regarding the extraction technologies, this chapter focuses on safe and green technologies that do not use organic solvents. In addition, formulation and stabilization that aim to protect isolated polyphenols during storage and extend shelflife are reviewed. The formulated polyphenol-rich ingredients produced from underutilized renewable resources could be used as sustainable, active ingredients--for example, in food and nutraceutical industries.

Multifunctional Ingredient from Aqueous Flavonoidic Extract of Yellow Onion Skins with Cytocompatibility and Cell Proliferation Properties

Significant quantities of onion are cultivated annually, such that industrial processing leads to an appreciable amount of by-products, estimated at around 500,000 tons. Onion skins are considered an important source of naturally occurring antioxidant compounds, particularly flavonoid compounds. Our study follows the development of a sustainable solution in order to manage the by-products of yellow onion skins by designing ingredients with multifunctional activities. A green solvent aqueous extraction of flavonoids was applied to obtain a safe, flavonoid-enriched extract, yielding a total flavonoid content of 50.21 ± 0.09 mg quercetin equivalent (QE)/g dry weight (DW), and an antioxidant activity of 250.81 ± 6.76 mM Trolox/g DW. Complex biopolymeric matrices consisting of whey protein isolates, whey protein hydrolysates, maltodextrin, and pectin were further dissolved in the flavonoid-enriched aqueous extract, followed by freeze-drying. Two powders were obtained, both showing satisfactory phytochemical content and good stability during storage. The application of confocal microscopy revealed that the microscopic structure of the powders have a distribution of the bioactive compounds within the biopolymeric matrices. The in vitro digestion suggested remarkable stability in the gastric tract and a flavonoid-controlled release in the intestinal phase. A significant compatibility range of up to 1 mg/mL for both powders was found, whereas concentrations between 10 and 250 µg/mL stimulated cell proliferation after 24 h of cultivation. The powders showed satisfactory thermal and pH stability, which favors their addition to different food matrices.

Improving the quality of sous-vide beef from Holstein-Friesian bulls by different marinades

The aim of the study was to determine effects of four commercial marinades on the colour, tenderness, cooking loss and sensory characteristics of semimembranosus beef muscles before and after sous-vide (SV) treatment. Muscles (n = 24) were marinated using Odessa (O; red pepper, garlic, onion), Mexico (M; red pepper, tomato), Old Polish (OP; pepper, garlic), and Bordeaux (B; pepper, red pepper, garlic) marinades for 24 h at 4 °C. Marinades uptake ranged from 3.3% (M) to 4.4% (B). Marinating and SV significantly affected all colour parameters. In SV beef, the highest values of L* were noted in OP and O samples, whereas the highest a* and b* values in M samples. Overall, marinating reduced (P < 0.05) cooking loss (34.6%) and shear force (19.5%). The use of marinating prior to SV treatment beneficially affected taste, tenderness and juiciness of beef. OP marinade allowed to obtain beef steaks with the best sensory quality and the lowest shear force.

Antioxidant effect of ethanolic onion (Allium cepa) husk extract in ageing rats

The role of natural antioxidants in preventing of age-relating diseases is evident. The vegetable industry generates a large amount of waste, which is a good source of antioxidants.

The aim of the study was the investigation of the antioxidant effect of long-term consumption of ethanolic yellow onion husk extract in ageing laboratory rodents.

Twenty male Wistar albino rats were divided randomly into two groups (n = 10): a control group and an experimental group that received ethanolic yellow onion husk extract (2 mL/rat diluted with distilled water; activity of 4.44 µmol-equiv. quercetin) for 188 days. Oxygen radical absorbance capacity and ferric reducing antioxidant power assays were used to determine the total antioxidant capacity of the extract, which amounted to 941.4 ± 32.7 µmol equiv. Trolox/g raw material and 167.4 ± 16.4 µmol-equiv. quercetin/g raw material, respectively. Oral intake of the onion husk extract affected the indicators of the antioxidant system of the liver and the brain but not of the blood and plasma, mainly due to elevations in the activity of catalase and superoxide dismutase in the liver by 44.4% and 79.1%, respectively, and in the brain by three-fold and 79.1%, respectively.

The availability, cheapness and high antioxidant potential of onion waste qualifies it a good source of functional ingredients and bioactive substances applicable in the food and pharmaceutical industries.

Microwave-Assisted Enzymatic Extraction of Flavonoids from Armeniaca mume Sieb. Blossom and Their Immunomodulating Effect in Mice with DSS-Induced Colitis

Armeniaca mume Sieb. blossom is among the traditional Chinese edible flowers, and it is widely used in the food and pharmaceutical industries. Flavonoids are among the most abundant bioactive compounds in A. mume Sieb. blossom. However, the research on the extraction of flavonoids from A. mume Sieb. blossom and their immunomodulating function is insufficient. In this study, we developed a microwave-assisted enzymatic extraction of flavonoids from A. mume Sieb. blossom (FAMB) and explored their immunomodulating effect on mice with dextran sulfate sodium salt-induced colitis. The results showed that the optimum parameters for microwave-assisted enzymatic extraction of FAMB were as follows: cellulase: 2.0%; microwave power: 200 W; microwave action time: 5 min; and enzymatic hydrolysis time: 50 min. FAMB significantly promoted the lymphocyte proliferation and natural killer (NK) cell killing activity in colitis mice, and increased the concentrations of TNF-α, IFN-γ, and IL-2 in serum. FAMB also significantly reduced the apoptosis of spleen lymphocytes in these mice. These results demonstrated that the microwave-assisted enzymatic method could significantly improve the yield and efficacy extraction of FAMB. FAMB showed a good immunomodulation effect on colitis mice.

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.

Onion Peel Powder as an Antioxidant-Rich Material for Sausages Prepared from Mechanically Separated Fish Meat

Mechanically separated fish meat (MSFM) can be used for the manufacturing of ready-to-eat products, such as sausages; however, it is highly perishable. Several plant by-products, including onion peel, which is rich in polyphenol antioxidants, can be added to food to extend shelf life. This study investigated the effects of the addition of onion peel powder (OPP) to sausage made from MSFM. Sausages were divided into four groups with different amounts of added OPP: 0% (control), 1%, 2%, and 3%. Cooked sausages were stored for 28 days at 5 °C. Samples were analyzed for thiobarbituric acid reactive substances, antioxidant activity, total polyphenol content, pH, and organoleptic properties. The addition of OPP significantly increased antioxidant activity and total polyphenol content and decreased pH, indicating acidic nature of OPP. Polyphenols from OPP effectively suppressed lipid oxidation. A 1–2% addition of OPP enhanced sensory properties. After the 28-day storage, the control samples received the lowest sensory score, due to the presence of a strong fishy odor, which was not present in samples with OPP. HPLC–MS/MS analysis revealed that quercetin is the most dominant compound in OPP. Overall, the results indicate that the addition of OPP in amounts of 1–2% can extend shelf life, without the deterioration of sensory properties.

Extraction of Flavonoids From Natural Sources Using Modern Techniques

Flavonoids are one of the main groups of polyphenols found in natural products. Traditional flavonoid extraction techniques are being replaced by advanced techniques to reduce energy and solvent consumption, increase efficiency and selectivity, to meet increased market demand and environmental regulations. Advanced technologies, such as microwaves, ultrasound, pressurized liquids, supercritical fluids, and electric fields, are alternatives currently being used. These modern techniques are generally faster, more environmentally friendly, and with higher automation levels compared to conventional extraction techniques. This review will discuss the different methods available for flavonoid extraction from natural sources and the main parameters involved (temperature, solvent, sample quantity, extraction time, among others). Recent trends and their industrial importance are also discussed in detail, providing insight into their potential. Thus, this paper seeks to review the innovations of compound extraction techniques, presenting in each of them their advantages and disadvantages, trying to offer a broader scope in the understanding of flavonoid extraction from different plant matrices.