Thermal degradation of onion quercetin glucosides under roasting conditions

Quercetin derivatives in roasted Coffea arabica and its popular beverages

This study is focused on quantification of six quercetin derivatives in roasted Coffea arabica L. from different geographical origins and post-harvest processing methods for the first time. Popular beverages (espresso and moka) were also studied. By developing and validating new extraction techniques from roasted coffee and coffee beverages, it was found that Ethiopian roasted coffee exhibited the highest total contents of quercetin derivatives (108.85 ± 10.03 ng/g), with quercetin-3-glucuronide being the most abundant (60.28 ± 5.95 ng/g). Guatemalan and Colombian coffees had high levels of quercetin-3-glucuronide (56.06 ± 5.95 ng/g and 51.14 ± 0.19 ng/g) as well. The study also showed that natural and honey post-harvest processing preserved more quercetin derivatives compared to washed method. Furthermore, espresso extraction yielded higher flavonoids content than moka. This research suggests that the selection of specific combination of coffee origins and post-harvest methods could enhance the intake of flavonoids and potentially promote the health status.

A combined drying process involving hot air and roasting for improving summer congou black tea quality

The present study aim to investigate the effects of three drying processes on the flavor-related compounds and sensory quality of summer black tea. A total of 234 flavonoids and 1200 volatile compounds were identified in tea samples by using UPLC-MS/MS and HS-SPME-GC-MS, respectively. It was found that the combining hot-air and roasting drying process increased the level of epigallocatechin, epicatechin, gallic acid, theaflavins, and umami and sweet amino acids in tea samples. Conversely, the contents of epigallocatechin gallate, caffeine, kaempferol and acylated kaempferol glycosides, and quercetin and acylated quercetin glycosides were found to decrease. Analysis of the volatile compounds revealed that combined drying process enhanced the contents of volatile substances with sweet, nutty, and floral properties while reducing those with green attributes. Sensory evaluation results showed that the combined drying process improved the mellow taste and pure aroma, decreased the bitterness and astringency, and weakened the unpleasant flavor of summer black tea. Overall result indicated that the combined drying process could improve the flavor quality of summer black tea. This study may provide data support and feasible strategies for improving summer congou black tea quality.

Phenolic compounds profile in extracts of Smilax spp., antioxidant activity, and inhibition of advanced glycation end products

Smilax genus possesses bioactive properties attributed to phenolic compounds, which may exhibit antioxidant effects and inhibit the advanced glycation end products (AGEs). However, identifying these phenolic compounds and AGEs has become increasingly relevant to understanding such activities. This study aimed to identify phenolic compounds in extracts of Smilax spp. and evaluate their antioxidant and AGEs inhibitory activities. To achieve this, the Smilax genus was identified via PCR, and phenolic compounds including chlorogenic acid, naringenin-6-C-glucoside, quercetin, quercetin-3-O-glucoside, and myricetin were identified using HPLC-MS/MS. Antioxidant activity was assessed by ferric reducing antioxidant power (FRAP), and radicals such as 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2'-azino-bis-[3-ethyl-benzothiazoline]-6-sulfonic acid (ABTS), while AGEs inhibition was evaluated using a model system formed by bovine serum albumin-glucose. The highest antioxidant activity was 3612.18 mM TE/g, and the inhibition of AGEs was 52.44 %. These results demonstrate that Smilax spp. can inhibit AGEs, neutralize free radicals, and reduce compounds associated with antioxidant capacity.

Improvement of Selected Quality and Safety Traits in Turmeric-Enriched Kale Pesto Using Blue Light and Sous-Vide

The potential of blue light (BL) and sous-vide (S-V) as a novel approach for food preservation was investigated via measurements of the total phenolic content (TPC), antioxidative activity, color, and their antibacterial effect on Listeria monocytogenes in two versions of laboratory-prepared kale pesto, with and without the addition of turmeric. The TPC ranged from 85 to 208 mg/100 g GAE d.m. and 57 to 171 mg/100 g GAE d.m., respectively. In both versions, the highest TPC was in the blue light-sous-vide samples, while the lowest was after the sous-vide, with a loss of polyphenols of almost 40% during storage when turmeric was absent. Antioxidative capabilities of the pesto were initially estimated at 54.07 and 7.46 µmol TE/g d.m., respectively, indicating significant bioactivity enhancement by turmeric. In turmeric-enriched pesto, sous-vide decreased the antioxidative activity levels by 12% in fresh pesto and by 45% during storage. Meanwhile, blue light compensated for the losses caused by the sous-vide treatment. Although the hue angle (h°) of sous-vide pesto was lower than that of blue light pesto in most samples, sequential BL and S-V ultimately yielded the lowest h°. The sequential BL and S-V treatment resulted in a 1.7 log reduction in the L. monocytogenes population, whereas adding turmeric increased the treatment efficacy by another 2.0 logs. Thus, as a source of photosensitizing molecules, turmeric was highly antibacterial after photothermal activation with blue light and sous-vide. This study suggests that blue light could be an effective (pre)treatment used on pesto sauces to preserve bioactivity and to improve safety when enriched with a natural additive like turmeric.

Chemical, sensory and biological variations of black tea under different drying temperatures

As the final processing step, drying temperature between 90 and 140 ℃ is usually applied to terminate enzymatic activities and improve sensory characteristics of black tea. Liquid chromatography tandem mass spectrometry (LC-MS) based non-targeted and targeted metabolomics analyses combined in vitro biological assays were adopted to investigate the chemical and biological variations after drying. Fifty-nine differentially expressed metabolites including several hydroxycinnamic acid derivatives and pyroglutamic acid-glucose Amadori rearrangement products (ARPs) were identified, the latter of which was correspondingly accumulated with increasing temperature. The levels of theaflavins (TFs), thearubigins (TRs), monosaccharides and free amino acids gradually decreased with increasing temperature. Furthermore, the bioassays of black tea showed that drying under 110 ℃ provided the highest antioxidant capacities, but the inhibitory effects on α-glucosidase and α-amylase were decreasing along with increasing drying temperature. These results are valuable for optimizing drying process to obtain superior sensory properties and preserve bioactivities of black tea.

Identification, Bioaccessibility, and Antioxidant Properties of Phenolic Compounds in Carob Syrup

Carob syrup is a brown, thick syrup produced from carob pulp that can be directly consumed or used as a sweetener, which also finds applications in folk medicinal practices. In this work, the quali-quantitative phenolic profile of five different carob syrups was elucidated before and after in vitro gastro-intestinal digestion. Moreover, the anti-oxidant properties of undigested and digested carob syrups were investigated. A total of 75 phenolic compounds were identified in undigested carob syrups. The most important phenolic compound in all the samples was gallic acid, the concentration of which ranged between 54.28 and 117.73 mg/100 g. Additional compounds belonging to the classes of hydroxybenzoic acids (in particular glycosylated gallic acid derivatives), hydroxycinnamic acids, and flavonoids (especially flavonols) were also identified. During in vitro gastric digestion, gallic acid mono- and di-hexosides were diglycosylated, releasing gallic acid, which was further degraded in ellagic acid through oxidative polymerization in the intestinal phase of the digestion. Ellagic acid was the major compound detected after in vitro gastro-intestinal digestion of carob syrups. With few exceptions, the anti-oxidant properties of carob syrup were preserved even after digestion. Carob syrup can be considered an important source of phenolic compounds with demonstrated positive effects on human health.

A critical examination of human data for the biological activity of quercetin and its phase-2 conjugates

This critical review examines evidence for beneficial effects of quercetin phase-2 conjugates from clinical intervention studies, volunteer feeding trials, and in vitro work. Plasma concentrations of quercetin-3-O-glucuronide (Q3G) and 3'-methylquercetin-3-O-glucuronide (3'MQ3G) after supplementation may produce beneficial effects in macrophages and endothelial cells, respectively, especially if endogenous deglucuronidation occurs, and lower blood uric acid concentration via quercetin-3'-O-sulfate (Q3'S). Unsupplemented diets produce much lower concentrations (<50 nmol/l) rarely investigated in vitro. At 10 nmol/l, Q3'S and Q3G stimulate or suppress, respectively, angiogenesis in endothelial cells. Statistically significant effects have been reported at 100 nmol/l in breast cancer cells (Q3G), primary neuron cultures (Q3G), lymphocytes (Q3G and3'MQ3G) and HUVECs (QG/QS mixture), but it is unclear whether these translate to a health benefit in vivo. More sensitive and more precise methods to measure clinically significant endpoints are required before a conclusion can be drawn regarding effects at normal dietary concentrations. Future requirements include better understanding of inter-individual and temporal variation in plasma quercetin phase-2 conjugates, their mechanisms of action including deglucuronidation and desulfation both in vitro and in vivo, tissue accumulation and washout, as well as potential for synergy or antagonism with other quercetin metabolites and metabolites of other dietary phytochemicals.

Phenolic changes in a combined herbal extract of Lithospermum erythrorhizon, Houttuynia cordata, and Spirodela polyrhiza and alleviation of DNCB-induced atopic dermatitis in BALB/c mice

Atopic dermatitis (AD) is an inflammatory skin disease showing skin barrier dysfunction, eczematous lesions, severe itching, and abnormal immune responses. The aim of this study was to determine whether an herb combination of Lithospermum erythrorhizon (LE), Houttuynia cordata (HC), and Spirodela polyrhiza (SP) has a superior anti-AD effect. Forty-two compounds were identified in LE, HC, SP, and a combined herb extract of LE, HC, and SP (LHS) using ultra-high-pressure liquid chromatography (UHPLC)-Orbitrap mass spectrometer (MS). The concentration of flavonoid glycosides including orientin (luteolin-8-C-glucoside), quercetin-3-O-rhamnoside, and luteolin-7-O-glucoside in the LHS was increased than in individual extracts. Furthermore, the treatment of LHS most effectively inhibited the increase of epidermal thickness, the number of mast cells, and the release of immunoglobulin E compared with that with each extract. These results suggest that the potential anti-AD effects of the LHS are due to the changes of bioactive compounds by the combination of herbs.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01329-7.

Antioxidant activities of thermally treated Sesamum indicum L. leaf extracts and their inhibitory effects against growth and metastatic properties of human colon cancer cells

The study aimed to investigate antioxidant activities of two different thermally treated sesame (Sesamum indicum L.) leaf ethanol extract, steamed sesame leaf extract (SSLE) and roasted sesame leaf extract (RSLE), and their inhibitory effects on uncontrolled growth and increased metastatic properties in human colon cancer cell lines. Both SSLE and RSLE contained pedaliin as the major polyphenol and its aglycon, pedalitin, as a minor component and exhibited radical scavenging activities and ferric reducing antioxidant power. SSLE and RSLE decreased growth of HT29 and HCT116 colon cancer cells, which was attributed to the induction of apoptosis and cell cycle arrest at either G2/M (by SSLE in HCT116) or S phase (by RSLE in HCT116). Furthermore, SSLE and RSLE inhibited migration and adhesion in both cell lines. These results indicate that thermally treated sesame leaves retained pedaliin content and exhibited antioxidant activities and inhibitory activities against the growth and metastatic properties of colon cancer cells.

The stability of phenolic compounds and the colour of lingonberry juice with the addition of different sweeteners during thermal treatment and storage

Lingonberries (Vaccinium vitis-idaea L.) are rich in phenolic compounds associated with several health benefits. The berries are also astringent, sour, and bitter and the addition of a sweetener is necessary to increase the palatability of lingonberry products. The addition of a sweetener may, however, affect the stability of phenolic compounds in the product. The aim of this study was thus to determine the effects of the addition of sweeteners (sucrose, acesulfame K or sucralose) and temperature on the stability of anthocyanins, flavonols, flavan-3-ols, hydroxycinnamic acids and the colour of lingonberry juice during thermal treatment and storage. The addition of sweeteners did not affect the stability of phenolic compounds or the colour of lingonberry juice during thermal treatment or storage. The stability of the phenolic compounds was significantly affected by temperature. Anthocyanins were the least stable of the phenolic compounds. The half-lives of total anthocyanins were 3.8, 2.0 and 0.8 h at 75, 85 and 95 °C, respectively. The half-lives during storage were 12.8 and 2.7 weeks at 6 and 22 °C, respectively. Cyanidin-3-galactoside, the major anthocyanin in lingonberries, was extensively degraded during storage, probably due to galactoside side-activities of the enzyme preparation used in juice production. After thermal treatment, the juices were darker and bluer, with lower chromaticity, while after storage, the juices were lighter, more yellow, and had higher chromaticity.

Composition and Biological Properties of Blanched Skin and Blanch Water Belonging to Three Sicilian Almond Cultivars

The almond industry produces, by bleaching and stripping, two by-products: blanched skin (BS) and blanch water (BW). The aim of this study was to investigate the nutritional and polyphenolic profile, as well as the antioxidant, antimicrobial, antiviral, and potential prebiotic effects of BS and BW from three different Sicilian cultivars. The total phenols and flavonoids contents were ≥1.72 and ≥0.56 g gallic acid equivalents and ≥0.52 and ≥0.18 g rutin equivalents/100 g dry extract (DE) in BS and BW, respectively. The antioxidant activity, evaluated by 2,2-diphenyl-1-picrylhydrazyl scavenging ability, trolox equivalent antioxidant capacity, ferric-reducing antioxidant power, and oxygen radical absorbance capacity, was ≥3.07 and ≥0.83 g trolox equivalent/100 g DE in BS and BW, respectively. Isorhamnetin-3-O-glucoside was the most abundant flavonoid detected in both by-products. No antimicrobial effect was recorded, whereas BS samples exerted antiviral activity against herpes simplex virus 1 (EC₅₀ 160.96 μg/mL). BS also showed high fibre (≥52.67%) and protein (≥10.99) contents and low fat (≤15.35%) and sugars (≤5.55%), making it nutritionally interesting. The present study proved that the cultivar is not a discriminating factor in determining the chemical and biological properties of BS and BW.

Hydrothermal treatment improves xanthine oxidase inhibitory activity and affects the polyphenol profile of Flos Sophorae Immaturus

BACKGROUND

Flos Sophorae Immaturus (FSI) is rich in polyphenols and a potential uric acid-lowering food. However, the processing of FSI is greatly restricted due to the heat sensitivity and low solubility of polyphenols. In this study, hydrothermal treatment - an effective strategy - was applied to FSI processing. The variation of xanthine oxidase (XO) inhibitory effect and polyphenol composition of FSI during hydrothermal treatment were recorded.

RESULTS

The XO inhibition rate of FSI increased from 32.42% to 89.00% after hydrothermal treatment at 220 °C for 30 min, as well as total polyphenols (from 0.66 to 1.11 mg mL^-1 ) and flavonoids (from 1.21 to 1.58 mg mL^-1 ). However, high thermal temperature (>160 °C) and extended thermal time (>90 min) caused the degradation of polyphenols. Rutin, kaempferol-3-O-rutinoside and narcissoside rapidly degraded and converted to quercetin, kaempferol and isorhamnetin when the temperature exceeded 160 °C. The maximum yields of quercetin, kaempferol and isorhamnetin were at 220 °C for 30 min, 90 min and 90 min, respectively. Meanwhile, the conversion kinetics conformed to the first-order model. Interestingly, these newly formed polyphenols possessed better XO inhibitory effects than their derivatives with 3-O-rutinoside.

CONCLUSION

Polyphenol conversion during hydrothermal treatment was the main reason for enhancing XO inhibitory activity. Therefore, hydrothermal treatment is an appropriate method for improving the XO inhibitory effect of FSI. © 2022 Society of Chemical Industry.

Bioprospecting of Targeted Phenolic Compounds of Dictyota dichotoma, Gongolaria barbata, Ericaria amentacea, Sargassum hornschuchii and Ellisolandia elongata from the Adriatic Sea Extracted by Two Green Methods

The content of bioactive compounds in four brown and one red algae from the Adriatic Sea (Dictyota dichotoma, Gongolaria barbata, Ericaria amentacea, Sargassum hornschuchii and Ellisolandia elongata) is explored. The efficiency of two different extraction methods viz. ultrasound-assisted extraction (UAE) and matrix solid-phase dispersion (MSPD) to obtain the extracts rich in phenolic compounds was compared. The effect of the extraction solvent to modulate the phenolic profile was assessed. In general, the mixture ethanol/water in an isovolumetric proportion showed the best results. The total phenolic content (TPC) and antioxidant activity (AA), as well as the individual polyphenolic profile, were evaluated for five target algae. TPC values ranged between 0.2 mg GAE/g (for E. elongata) and 38 mg GAE/g (for S. hornschuchii). Regarding the quantification of individual polyphenols by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, the presence of a high number of hydroxybenzoic acid derivatives (mainly of 3- and 4-hydroxybenzoic acids) in all species was noted. In G. barbata their concentrations reached up to 500 mg/kg. IC50 values (ABTS assay) ranged between 44 mg/L (for S. hornschuchii) and 11,040 mg/L (for E. elongata). This work contributes to the in-depth characterization of these little-explored algae, showing their potential as a natural source of phenolic compounds.

Stability of polyphenols in food processing

In recent years, polyphenols have attracted considerable attention due to their diverse potential health-beneficial effects on humans. Polyphenols are widely distributed in natural plants, and therefore play an important role in human food. Thermal processing, irradiation, fermentation, high pressure, microwave, and drying are several popular food processing methods. However, polyphenols are instable in food processing, which easily degrade and react with other components because of their polyhydroxy characteristic. Traditional and advanced technologies have been used to characterize the stability of polyphenols. The main influence factors of stability of polyphenols such as pH, temperature, light, oxygen, enzymes, metal ions, as well as macromolecules, are summarized. Besides, thermal processing greatly promoted the degradation of polyphenols. Thermal degradation mechanisms and products of some polyphenols, such as quercetin and rutin, have been intensively demonstrated. Nevertheless, the structural changes of polyphenols caused by food processing, may lead to different bioactivities from the obtained results based on unprocessed polyphenols. Therefore, to maximize the beneficial effects of polyphenols ingested by human from processed food, the stability of polyphenols in food processing must be thoroughly investigated to assess their real bioactivities. In addition, some available technologies for improving the stability of polyphenols in food processing have been proposed.

Onion and garlic polysaccharides: A review on extraction, characterization, bioactivity, and modifications

Allium cepa (onion) and Allium sativum (garlic) are important members of the Amaryllidaceae (Alliaceae) family and are being used both as food and medicine for centuries in different parts of the world. Polysaccharides have been extracted from different parts of onion and garlic such as bulb, straw and cell wall. The current literature portrays several studies on the extraction of polysaccharides from onion and garlic, their modification and determination of their structural (molecular weight, monosaccharide unit and their arrangement, type and position of glycosidic bond or linkage, degree of polymerization, chain conformation) and functional properties (emulsifying property, moisture retention, hygroscopicity, thermal stability, foaming ability, fat-binding capacity). In this line, this review, summarizes the various extraction techniques used for polysaccharides from onion and garlic, involving methods like solvent extraction method. Furthermore, the antioxidant, antitumor, anticancer, immunomodulatory, antimicrobial, anti-inflammatory, and antidiabetic properties of onion and garlic polysaccharides as reported in in vivo and in vitro studies is also critically assessed in this review. Different studies have proved onion and garlic polysaccharides as potential antioxidant and immunomodulatory agent. Studies have implemented to improve the functionality of onion and garlic polysaccharides through various modification approaches. Further studies are warranted for utilizing onion and garlic polysaccharides in the food, nutraceutical, pharmaceutical and cosmetic industries.

Antioxidant and Antiglycation Effects of Cistus × incanus Water Infusion, Its Phenolic Components, and Respective Metabolites

Reactive oxygen and carbonyl species promote oxidative and carbonyl stress, and the development of diabetes, metabolic syndrome, cardiovascular diseases, and others. The traditional herb Cistus × incanus is known for its antioxidant properties; therefore, the current study aimed to assess how the chemical composition of a C. incanus water infusion corresponds with its antioxidative and antiglycative effects in vitro. The composition of infusions prepared from commercial products was analyzed with UHPLC-ESI-qTOF-MS. Total phenolics, flavonoids, and non-flavonoid polyphenols were determined. Antioxidant activity of infusions and selected polyphenols was investigated using DPPH, ABTS, and FRAP. Fluorometric measurements and methylglyoxal capture were performed to investigate the antiglycation activity. PCA and PLS-DA models were applied to explore the correlation between chemical and antioxidant results. The principal flavonoids in C. incanus were flavonols. In vitro tests revealed that a stronger antioxidant effect was demonstrated by plant material from Turkey rich in flavonoids, followed by Albania and Greece. Flavonols and ellagic acid displayed stronger antiradical and reducing power than EA-derived urolithins. Hyperoside was the most potent inhibitor of glycation. The results indicate that flavonoids are primarily responsible for rock rose antioxidant and antiglycation properties. PLS-DA modeling can be used to identify the origin of plant material with sensitivity and specificity exceeding 86%.

Thermal Stability of Anisoyl Kaempferol Glycosides in Jack Bean (Canavalia ensiformis (L.) DC) and Their Effect on α-Glucosidase Inhibition

Kaempferol glycosides are functional components of jack bean. The chemical stability of kaempferol glycosides under simulated food processing conditions was evaluated in this study by subjecting the methanol extract and each compound to heat treatment. During the heat treatment, rearrangement of the anisoyl group on the rhamnose moiety of the kaempferol glycoside was observed, followed by hydrolysis upon long-term heat treatment. One of the two regioisomers produced under heating conditions showed higher α-glucosidase inhibitory activity than the dominant anisoyl kaempferol glycoside. This rearrangement reaction was also observed upon the heat treatment of methyl-3-O-anisoyl-rhamnose, with the rearrangement from the 3-position to the 2-position occurring preferentially. The approach adopted in this study can be used to design appropriate food processing conditions, which, in turn, will increase the functional value of foods.

The Effect of Sodium Total Substitution on the Quality Characteristics of Green Pickled Tomatoes (Solanum lycopersicum L.)

Green pickled tomatoes are a traditional fermented product in Romania. This study was focused on the effect of total substitution of NaCl with KCl and MgCl₂ on physicochemical and microbiological quality; bioactive compounds; and microstructural, textural, and sensorial properties of fresh and pickled green tomatoes during 28 days of fermentation. By the means of physicochemical composition, the NaCl addition induced the most stable characteristics for the pickles compared to the other two types of salts. The content of total flavonoids in green pickled tomatoes with NaCl (34.72 ± 0.43 mg CE/g DW) was significantly lower compared with the control sample (63.80 ± 0.55 mg CE/g DW). The total number of lactic acid bacteria (LAB) at the final stage of fermentation varied between 4.11 and 4.63 log CFU for all variants. The textural analysis revealed that the NaCl has the lowest influence on the textural parameters. Finally, the overall acceptance of green pickled tomatoes containing KCl and MgCl₂ was found to be proper to be consumed as a substitute for pickles with NaCl.

Effects of roasting conditions on Korean rice wine (Makgeolli) with licorice (Glycyrrhiza uralensis Fischer)

The present study investigated the effect of roasting process (temperature: 150, 180, and 210 °C; time: 10, 20, and 30 min) of licorice on the browning index (BI), total flavonoid content (TFC), and antioxidant activity for ingredient of Makgeolli. The antioxidant activity was measured by assaying DPPH radical scavenging activity (DPPH·IC₅₀) and Trolox equivalent antioxidant capacity (TEAC). In addition, the quality characteristics of Makgeolli with different amount (0%, 6%, 12%, and 18%) of roasted licorice extract (RLE) were measured comparison to un-roasted licorice extract (ULE). When superimposing the contour plots of the responses in which the limits of each response were determined, the optimum conditions for roasting licorice were 178 °C for 24 min. Moreover, results revealed that Makgeolli with 12% RLE under optimum roasting condition was superior with respect to antioxidant activity and more acceptable based on sensory properties than ULE.

Protective Effect of Nigella sativa and Onion Extract against 5-Fluorouracil-Induced Hepatic Toxicity

Aim: The present study intended to compare the antioxidant, anti-lipid peroxidation, and anti-inflammatory potentials of Nigella Sativa (NS) and onion extract on 5-FU-induced liver damage in rats. Material and methods: 48 rats were divided into control, control group of the onion extract, control group of the NS extract, 5-FU-treated, concomitant NS-treated, and concomitant onion extract-treated. Liver sections were processed for histological analysis (light and electron microscopic examination). Liver enzymes (ALT, AST, and ALP), inflammatory markers (TNF-α and IL-1), antioxidant markers (SOD, GSH, and GSH/GSSG ratio), 4-HNE, NF-κB, and Nrf2 were evaluated. Results: The 5-FU-treated group exhibited inflammation, congested hepatic sinusoid, and steatosis. Improvement with few pathological residues was seen in the concomitant extract-treated groups. The 5-FU-treated group showed higher liver enzymes. The enzymes decreased in the concomitantly treated groups. 5-FU induced liver damage through oxidative stress, inflammation, and lipid peroxidation. Concomitantly using NS and onion extracts resulted in a reduction in oxidative stress, lipid peroxidation, and inflammation. Conclusion: NS and onion extracts attenuated 5-FU-induced liver damage via antioxidative, anti-lipid peroxidative, and anti-inflammatory mechanisms. NS's role was exceptional when compared with onion extract.

Cooking African Pumpkin Leaves (Momordicabalsamina L.) by Stir-Frying Improved Bioactivity and Bioaccessibility of Metabolites-Metabolomic and Chemometric Approaches

The leaves of African pumpkins (Momordica balsamina L.) are a commonly consumed traditional vegetable. They are a good source of polyphenolic antioxidants and carotenoids, which are, however, affected by cooking or digestion. We investigated the effect of household cooking methods (stir-frying or boiling) on the changes in bioactive metabolites, antioxidant capacity, release and accessibility of β-carotene and also inhibition of inhibitory activity against α-amylase and α-glucosidase enzymes during in vitro digestion of African pumpkin leaves compared to the raw leaves. Compared to boiled or raw leaves, stir-frying improved the availability of bioactive metabolites at the gastrointestinal phase. Quercetin 3-galactoside and rhamnetin 3-O-glucoside (marker compounds) discriminated the stir-fried leaves from raw leaves and boiled leaves after digestion. Stir-frying improved the release and accessibility of β-carotene and enhanced the antioxidant activities compared to boiling. Dialysable fractions of stir-fried leaves exhibited the greatest inhibitory activity against α-amylase and α-glucosidase enzymes compared to the raw and boiled leaves, as well as acarbose. Stir-frying, therefore, is recommended for use in household cooking to benefit consumers by increasing the intake of phenolics and β-carotene.

Migration of Avocado Virgin Oil Functional Compounds during Domestic Cooking of Eggplant

Avocado virgin oil (AVO) was used during eggplant deep-frying, boil, and boil in a water-oil mixture (W/O). There were measured the contents of moisture, dry matter, fat, total (TPC) and ten individual phenols, antioxidant activity (ABTS and DPPH), and total sterols; as well as the profiles of eight fatty acids and fourteen sterols/stanols. The values of raw and processed foods were compared and studied with multivariate analysis. The antioxidant capacity of AVO lowered after deep frying but augmented in eggplant and water after all treatments. The TPC was steady in AVO and raised in fried eggplant. Thermal treatments added to the initial profiles of the AVO, eggplant and water, nine, eight, and four phenols, respectively. Percentages of the main fatty acids (oleic, palmitic and linoleic), and sterols (β-sitosterol, campesterol, and Δ5-avenasterol), remained unchanged between the raw and treated AVO; and the lipidic fractions from processed eggplant. Cooking leads to the movement of hydrophilic and lipophilic functional compounds between AVO, eggplant and water. Migration of sterols and unsaturated fatty acids from AVO to eggplant during deep frying and W/O boiling improved the functional properties of eggplant by adding the high biological value lipophilic fraction to the naturally occurring polyphenols.

Post-harvest Industrial Processes of Almond (Prunus dulcis L. Mill) in Sicily Influence the Nutraceutical Properties of By-Products at Harvest and During Storage

Almond cultivation in Sicily is experiencing a phase of great interest which is mainly concentrated in the development of specialized orchards, with irrigation and by adopting cultivars with high qualitative and quantitative performances. These are mostly Mediterranean genotypes with high fat content and hard or semi-hard shell, extremely different from the varieties of Californian diffusion. The development of the sector comprises the primary production of almonds but also a series of secondary products which often represent a burden for the company. From these considerations several researches have been developed with the aim of giving a value to these by-products through circular economy paths. One of the by-products widely produced, besides the shell, is the skin which covers the seed and is produced during the peeling phase. It is well-known that tegument is an important component of almond because it contains important bioactive substances (phenols and aromas) which are usually dispersed during peeling. This paper examined three different Italian cultivars widely spread in Sicily, two of Apulian origin, (Genco and Tuono), and one locally cultivated variety (Vinci a tutti). These three cultivars occupy an increasingly large area and are very popular with consumers and industry. The production of secondary products, therefore, evidences significant quantities and the possibility to give them an added value becomes a need for the sector. Therefore, the content of phenols and proanthocyanins in the skin at harvest and during storage was analyzed, adopting two different separation methods, with and without water. During the analysis it was possible to observe the different behavior of the three cultivars due to genetic and industrial factors. Skin separated without using hot water showed a higher total phenolic presence with average increases of about 20%, and with even higher increases, between 28 and 32%, for proanthocyanins. Vinci a tutti evidenced the highest total phenolic content after 8 months of storing while roasting has revealed to be a more effective skin separation approach.

Influence of Cooking Methods on Onion Phenolic Compounds Bioaccessibility

The impact of domestic cooking (baking, boiling, frying and grilling) and in vitro digestion on the stability and release of phenolic compounds from yellow-skinned (YSO) and red-skinned onions (RSO) have been evaluated. The mass spectrometry identification pointed out flavonols as the most representative phenolic class, led by quercetin-derivatives. RSO contained almost the double amount of phenolic compounds respect to YSO (50.12 and 27.42 mg/100 g, respectively). Baking, grilling and primarily frying resulted in an increased amount of total phenolic compounds, especially quercetin-derivatives, in both the onion varieties. Some treatments promoted the degradation of quercetin-3-O-hexoside-4′-O-hexoside, the main compound present in both the onion varieties, leading to the occurrence of quercetin-4′-O-hexoside and protocatechuic acid-4-O-hexoside. After in vitro digestion, the bioaccessibility index for total phenolic compounds ranged between 42.6% and 65.5% in grilled and baked YSO, respectively, and between 39.8% and 80.2% in boiled and baked RSO, respectively. Baking contributed to the highest amount of bioaccessible phenolic compounds for both the onion varieties after in vitro digestion. An in-depth design of the cooking process may be of paramount importance in modulating the gastro-intestinal release of onion phenolic compounds.

Impact of Household Cooking Techniques on African Nightshade and Chinese Cabbage on Phenolic Compounds, Antinutrients, in vitro Antioxidant, and β-Glucosidase Activity

Different household cooking techniques (boiling, steaming, stir frying, and microwave) were tested on the changes of targeted phenolic compounds, antioxidant property (ferric reducing-antioxidant power (FRAP) activity), α-glucosidase activity, antinutritive compounds, and sensory properties in commonly consumed traditional leafy vegetables in Southern Africa, the non-heading Chinese cabbage (Brassica rapa L. subsp. chinensis) and African nightshade (Solanum retroflexum Dun). Stir frying increased kaempferol-3-O-hydroxyferuloyl-trihexoside, kaempferol-dihexoside, sinapoyl malate, rutin, and isorhamnetin-O-dihexoside in Chinese cabbage leaves, followed by steaming. Similarly, stir frying increased kaempferol-3-O-rutinoside, chlorogenic acid, caffeoylmalic acid, and quercetin-3-O-xylosyl-rutinoside in nightshade, followed by steaming. Biomarkers, sinapoyl malate (Chinese cabbage) and caffeoylmalic acid (nightshade), separated the stir frying from the other cooking techniques. Steaming and stir-frying techniques significantly increased the FRAP activity; whereas boiling and microwaving reduced the tannin, oxalate, and phytate contents in both leafy vegetables and steroidal saponins in nightshade. Stir-fried nightshade leaf extract showed the most effective inhibition against α-glucosidase activity, with an IC₅₀ of 26.4 μg ml^-1, which was higher than acarbose, a synthetic compound (positive control; IC₅₀ 69.83 μg ml^-1). Sensory panelists preferred the stir-fried Chinese cabbage and nightshade leaves, followed by steamed, microwaved, and boiled vegetables.

Effects of Different Processing Treatments on Almond (Prunus dulcis) Bioactive Compounds, Antioxidant Activities, Fatty Acids, and Sensorial Characteristics

Almond is one of the most commonly consumed nuts worldwide, with health benefits associated with availability of bioactive compounds and fatty acids. Almond is often eaten raw or after some processing steps. However, the latter can positively or negatively influence chemical and sensorial attributes of almonds. This work was carried out to assess the effects of two processing treatments, namely; roasting and blanching on (i) contents of bioactive compounds, (ii) contents of fatty acids (3) antioxidant activities (4), sensorial characteristics of four neglected Portuguese almond cultivars (Casanova, Molar, Pegarinhos and Refêgo) and two foreign cultivars (Ferragnès and Glorieta). Results showed that in general, levels of bioactive compounds and antioxidant activities increased with roasting and decreased with blanching. Fatty acid profiles of raw kernels of all cultivars were generally identical although Refêgo exhibited a high content of α-linolenic acid. Following roasting and blanching, content of polyunsaturated fatty acids increased while saturated fatty acids, monounsaturated fatty acids and several health lipid indices decreased. Roasting positively affected perception of skin color and sweetness of Ferragnès and Glorieta as well as skin roughness of Molar and Pegarinhos. Blanching on the other hand led to positive changes in textural properties of Refêgo and Pegarinhos. This study reveals the nutritive benefits of consuming neglected almond cultivars in Portugal, and the novel data reported here could be of interest to growers, processing companies and consumers.

Chemometric contribution for deeper understanding of thermally-induced changes of polyphenolics and the formation of hydroxymethyl-L-furfural in chokeberry powders

During fruit juice powdering process numerous alterations may occur as a result of interactions of native bioactives and carriers. The objective was to investigate the effect of carrier addition on the changes in polyphenols' profile in chokeberry powders obtained by spray- (180 °C), vacuum- (50, 70, 90 °C) and freeze-drying and to evaluate the interactions between bioactives toward formation of process contaminants. Phenolic acids, anthocyanins, flavonols, flavan-3-ols and procyanidins were identified in powders (18.1 - 35.4 g kg^-1 dry matter). Vacuum drying at 90 °C resulted in a significant increase in (+)-catechin and HMF contents. The addition of inulin enhanced the generation of HMF compared to maltodextrin. Overall, addition of maltodextrin allowed for better anthocyanins' retention. Depending on the drying method used, maltodextrin allowed for better retention of polyphenolics during freeze- and vacuum drying, while inulin during spray drying. The elaboration of the results was supported by chemometric analysis.

Domestic cooking methods affect the stability and bioaccessibility of dark purple eggplant (Solanum melongena) phenolic compounds

Eggplant is an important component of the Mediterranean Diet, which becomes edible after cooking. This study determined the fate of dark purple eggplant phenolic compounds after baking, boiling, frying, grilling and digestion. Thirty-seven phenolic compounds were identified and quantified in raw eggplant. Frying determined a 74% increase in total hydroxycinnamic acids whereas a decrease was observed after boiling (27%), grilling (51%), and baking (60%). After digestion, 45%, 33% and 22% of total phenolic compounds resulted bioaccessible in baked, grilled and fried dark purple eggplant. Fried eggplant displayed the highest amount of phenolic compounds (751.46 mg/100 g) after digestion. The cooking methods differently affected the release of individual phenolic compounds. Baking and grilling resulted in higher amount of bioaccessible caffeoylquinic acids whereas frying in di-caffeoylquinic acids and hydroxycinnamic acid-amides. A careful design of the cooking method may be pivotal to modulate the release of specific phenolic compounds.

Allium Flavonols: Health Benefits, Molecular Targets, and Bioavailability

Allium species are revered worldwide as vegetables, condiments, and spices as well as the therapeutic agents in traditional medicine. The bioactive compounds in alliums mainly include organosulfur compounds, polyphenols, dietary fibers, and saponins. Flavonoids, particularly flavonols from alliums, have been demonstrated to have the antioxidant, anticancer, hypolipidemic, anti-diabetic, cardioprotective, neuroprotective, and antimicrobial activities. However, flavonols are mostly characterized from onions and have not been comprehensively reviewed across different species. This article therefore focuses on flavonol profiles from different Allium species, their health effects, underlying molecular mechanisms, and bioavailability. Intriguingly, the functional health effects of flavonols were mainly ascribed to their antioxidant and anti-inflammatory activities involving a cascade of multiple signaling pathways. Although the Allium-derived flavonols offer tremendous potential in preventing chronic disease risks, in-depth studies are needed to translate their clinical application.

Effects of treatment temperatures on redox potential and sensory evaluation of different spices and herbs applied to cooked pork sausages

BACKGROUND

This study aimed to investigate the effects of treatment temperatures (22, 78, 100 °C) on the antioxidant activity of 13 types of dried ground spices and herbs (black mustard, black pepper, blackberries, onion, cumin, galangal, lemon balm, lovage, marjoram, oregano, parsley, rosemary and watercress) through measurements of redox potential. Four different combinations of spices and herbs were created and applied to cooked pork sausages, then sensory evaluation was carried out.

RESULTS

The redox potential was temperature dependent. A temperature of 78 °C was chosen to produce the cooked pork sausages with the addition of the spice and herb combinations. The combinations were black mustard, onion, and cumin (at a 1:1:1 ratio); onion, marjoram, and parsley (at a 1:1:1 ratio); black pepper, lemon balm, and parsley (at a 1:2.35:1.65 ratio) and black pepper, cumin, and lovage (at a 1:2:2 ratio). In pork sausages cooked at 78 °C, the variants at 12 g kg^-1 had a more intense aroma and taste than those at 6 g kg^-1 spice and herb combinations, and received a superior sensory evaluation in total.

CONCLUSIONS

The most desirable treatment temperature possibly applied in food products was 78 °C as it gave the highest number of negative results in redox potential of water extracts. The addition of the tested spice and herb combinations contributed to the increase of antioxidant possibility of 78 °C-cooked pork sausages. Further investigation of the redox potential in other meat products (raw meat products at 22 °C, sausages from cooked meat at 100 °C) with the addition of the current spice and herb combinations will be undertaken in subsequent research. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The Antioxidant Content of Coffee and Its In Vitro Activity as an Effect of Its Production Method and Roasting and Brewing Time

Coffee is one of the most popular beverages in the world. The high production and health properties of coffee make it one of the best among daily drinks. Coffee is wrongly identified as only a stimulant because of its caffeine content. On the other hand, coffee is one of the best sources of other bioactive compounds, such as flavonoids and phenolic acids. Organic coffee is produced without artificial fertilizers and pesticides. Not only the high quality of beans but also roasting and brewing times guarantee the best taste and quality of coffee beverages. The aim of the present experiment was to determine the best level of roasting and brewing time for organic and conventional coffee. The experiment was carried out with Peru coffee beans from organic and conventional farms. The contents of caffeine and bioactive compounds were measured in different roasted and brewed coffee drinks. The obtained results showed that the conventional coffee contained significantly more caffeine, total flavonoids, and quercetin derivatives than the organic coffee. On the other hand, the organic coffee was characterized by a higher level of almost all bioactive compounds. The best level of roasting was determined to be medium, and the optimal brewing time was 3 minutes.

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

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

Narrow-Banded UVB Affects the Stability of Secondary Plant Metabolites in Kale (Brassica oleracea var. sabellica) and Pea (Pisum sativum) Leaves Being Added to Lentil Flour Fortified Bread: A Novel Approach for Producing Functional Foods

Young kale and pea leaves are rich in secondary plant metabolites (SPMs) whose profile can be affected by ultraviolet B (UVB) radiation. Carotenoids and flavonoids in kale and pea exposed to narrow-banded UVB, produced by innovative light-emitting diodes (LEDs), and subsequently used for breadmaking were investigated for the first time, thus combining two important strategies to increase the SPMs intake. Breads were also fortified with protein-rich lentil flour. Antioxidant activity in the ‘vegetable breads’ indicated health-promoting effects. Lentil flour increased the antioxidant activity in all of the ‘vegetable breads’. While carotenoids and chlorophylls showed a minor response to UVB treatment, kaempferol glycosides decreased in favor of increasing quercetin glycosides, especially in kale. Additionally, breadmaking caused major decreases in carotenoids and a conversion of chlorophyll to bioactive degradation products. In ‘kale breads’ and ‘pea breads’, 20% and 84% of flavonoid glycosides were recovered. Thus, kale and pea leaves seem to be suitable natural ingredients for producing innovative Functional Foods.

Different effects of heating and freezing treatments on the antioxidant properties of broccoli, cauliflower, garlic and onion. An experimental in vitro study

BACKGROUND

Vegetables have some beneficial effects on human health due to their antioxidant compounds, like polyphenols. Cooking leads to many physical and chemical changes to plant structure that can alter the phytochemical compounds of vegetables.

OBJECTIVES

To investigate the effects of heat treatment and freezing on the antioxidant properties of garlic, onion, broccoli and cauliflower.

DESIGN AND SETTING

Experimental in vitro study in a university laboratory.

METHODS

Fresh broccoli (Brassica oleracea var. italica), cauliflower (Brassica oleracea var. botrytis), garlic (Allium sativum) and onion (Allium cepa) were obtained from a local store. These vegetables were divided into three treatment groups: raw, heated and frozen. The heat treatment consisted of heating them in a drying oven at 150 °C for 20 minutes. The freezing treatment consisted of keeping them frozen at -20 °C until analysis. The total phenolic content, antioxidant activity and malondialdehyde levels of the vegetables were measured using the Folin-Ciocalteu phenol reagent, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and thiobarbituric acid reactive substances, respectively.

RESULTS

Heat treatment had deleterious effects on the antioxidant properties of onion and garlic; and it decreased the antioxidant activity of broccoli. Freezing improved the antioxidant activity of broccoli and garlic, but had detrimental effects for cauliflower and onion.

CONCLUSIONS

Heat treatment and freezing exhibit different effects on the antioxidant properties of broccoli, cauliflower, garlic and onion. Convenient cooking and storage patterns should be identified for each vegetable, to obtain the best nutritional benefit from the antioxidant compounds of vegetables.

Effects of heat treatment of mandarin peel on flavonoid profiles and lipid accumulation in 3T3-L1 adipocytes

Citrus peel, a primary byproduct of citrus fruits, contains a variety of flavonoids. Heat treatment is a favorable food processing for solid peel to release bioactive compounds from tissues and intensify nutritional effects. In this study, we explored alterations of flavonoids by thermal treatment of mandarin peel and their effects on lipid accumulation and intracellular levels during differentiation of 3T3-L1 cells to adipocytes. The heat-treated sample showed stronger inhibition on the formation of lipid droplets than the non-treated sample, along with enhanced intracellular levels of flavonoids. Overall flavonoids, especially flavonoid aglycones showing better efficacy, were found to increase in the peel after heat-treatment. Our findings indicate thermal processing could help release flavonoids from citrus peel and convert them into aglycone forms, leading to efficient cellular uptake and suppression of lipid accumulation in 3T3-L1 cells. This study provides useful information of heat-treated citrus peel as potential dietary supplements with antiobesity-related effects.

Apple Pomace Extract as a Sustainable Food Ingredient

Apple pomace is a by-product of apple processing industries with low value and thus frequent disposal, although with valuable compounds. Acidified hot water extraction has been suggested as a clean, feasible, and easy approach for the recovery of polyphenols. This type of extraction allowed us to obtain 296 g of extract per kg of dry apple pomace, including 3.3 g of polyphenols and 281 g of carbohydrates. Ultrafiltration and solid-phase extraction using C18 cartridges of the hot water extract suggested that, in addition to the apple native polyphenols detected by ultra-high-pressure liquid chromatography coupled to a diode-array detector and mass spectrometry UHPLC-DAD-ESI-MSⁿ, polyphenols could also be present as complexes with carbohydrates. For the water-soluble polyphenols, antioxidant and anti-inflammatory effects were observed by inhibiting chemically generated hydroxyl radicals (OH•) and nitrogen monoxide radicals (NO•) produced in lipopolysaccharide-stimulated macrophages. The water-soluble polyphenols, when incorporated into yogurt formulations, were not affected by fermentation and improved the antioxidant properties of the final product. This in vitro research paves the way for agro-food industries to achieve more diversified and sustainable solutions towards their main by-products.

Brassica-enriched wheat bread: Unraveling the impact of ontogeny and breadmaking on bioactive secondary plant metabolites of pak choi and kale

Consumption of Brassica vegetables is linked to health benefits, as they contain high concentrations of the following secondary plant metabolites (SPMs): glucosinolate breakdown products, carotenoids, chlorophylls, and phenolic compounds. Especially Brassica vegetables are consumed as microgreens (developed cotyledons). It was investigated how different ontogenetic stages (microgreens or leaves) of pak choi (Brassica rapa subsp. chinensis) and kale (Brassica oleracea var. sabellica) differ in their SPM concentration. The impact of breadmaking on SPMs in microgreens (7 days) and leaves (14 days) in pak choi and kale as a supplement in mixed wheat bread was assessed. In leaves, carotenoids, chlorophylls, and phenolic compounds were higher compared to those of microgreens. Breadmaking caused a decrease of SPMs. Chlorophyll degradation was observed, leading to pheophytin and pyropheophytin formation. In kale, sinapoylgentiobiose, a hydroxycinnamic acid derivative, concentration increased. Thus, leaves of Brassica species are suitable as natural ingredients for enhancing bioactive SPM concentrations in bread.

Flavonoid loaded nanoparticles as an effective measure to combat oxidative stress in Ribonuclease A

Flavonoids like quercetin and myricetin serve as naturally occurring antioxidants but their bioactivity is limited due to low aqueous solubility and oxidation under physiological conditions. In this current study, the antioxidant activity of quercetin and myricetin loaded chitosan nanoparticles during the induced oxidation of Ribonuclease A (RNase A) has been compared with the corresponding free flavonoids. Oxidation of RNase A leads to intermolecular dityrosine (DT) bond formation which shows a characteristic fluorescence emission around 405 nm. Although both quercetin and myricetin loaded nanoparticles initially exhibit lower antioxidant property compared to the free flavonoids, however, with increase in oxidant concentration over time the DT fluorescence showed greater increase for free flavonoids in comparison to the nanoparticles. The polyphenol loaded nanoparticles are also found to be effective in preventing bacterial cell damage in oxidizing medium. The slow release of flavonoids from the nanoparticles is responsible for their prolonged antioxidant effect in the oxidizing medium unlike the free flavonoids which are exhausted almost completely in the initial phase.

Revisiting the chemistry of apple pomace polyphenols

Hot water is an easily implementable process for polyphenols extraction. To evaluate the effect of this process on apple pomace, the overall polyphenolic composition was assessed before and after hot water extraction, followed by extractions with aqueous/organic solutions. As determined by UHPLC-DAD, flavan-3-ols were the main apple native polyphenols. Their amount decreased 50% after hot water extraction, while the other classes remained unchanged. Dihydrochalcones and hydroxycinnamic acid oxidation products, were also observed, alongside with non-extractable oxidised procyanidins that represented more than 4-fold the amount of native apple polyphenols in the pomace. Microwave superheated-water extraction of the insoluble cell wall material in water/acetone solutions and the high amounts of polyphenols that were insoluble in water/ethanol solutions suggested that oxidised procyanidins could be covalently linked to polysaccharides. These complexes represented up to 40% of the available polyphenols from apple pomace, potentially relevant for agro-food waste valuation.