Flavonol Profiles Research Articles

From Ethnobotany to Biotechnology: Wound Healing and Anti-Inflammatory Properties of Sedum telephium L. In Vitro Cultures.

Sedum telephium is a succulent plant used in traditional medicine, particularly in Italy, for its efficacy in treating localized inflammation such as burns, warts, and wounds. Fresh leaves or freshly obtained derivatives are directly applied to the injuries for these purposes. However, challenges such as the lack of microbiologically controlled materials and product standardization prompted the exploration of more controlled biotechnological alternatives, utilizing in vitro plant cell cultures of S. telephium. In the present study, we used HPLC-DAD analysis to reveal a characteristic flavonol profile in juices from in vivo leaves and in vitro materials mainly characterized by several kaempferol and quercetin derivatives. The leaf juice exhibited the highest content in total flavonol and kaempferol derivatives, whereas juice from callus grown in medium with hormones and callus suspensions showed elevated levels of quercetin derivatives. The in vitro anti-inflammatory and wound-healing assays evidenced the great potential of callus and suspension cultures in dampening inflammation and fostering wound closure, suggesting quercetin may have a pivotal role in biological activities.

Flavonol profiles of mature leaves allow discriminating Toona sinensis Roem from different north-south geographical origins across China with varied antioxidant activities

Toona sinensis (A. Juss.) Roem, a multipurpose economic tree, is widely cultivated across Asia, but its high-yielding mature leaves are largely overlooked. This study systematically analysed the flavonols in the mature leaves of T. sinensis from 44 different geographic locations across China, using HPLC-DAD and HPLC-ESI-MS2 techniques. In total, 18 flavonols were detected, among which 6 (f1, f3, f7, f14, f15, and f17) were firstly identified in this plant. Significant variations in quality among different T. sinensis varieties were observed (p < 0.01). Through OPLS-DA analysis, all samples could be clearly categorised into two distinct geographical groups. The northern varieties (N1–N20) exhibited concise flavonol fingerprints with higher total flavonol content (TFC) (727.55 ± 22.79 mg/100 g fresh weight, FW), predominantly non-acylated flavonols (705.95 ± 21.65 mg/100 g FW), particularly quercetin glycosides (614.60 ± 22.76 mg/100 g FW). In contrast, the southern varieties (S1–S24) presented more intricate flavonol profiles with lower TFC (622.81 ± 21.82 mg/100 g FW) and balanced amounts of quercetin (344.75 ± 16.41 mg/100 g FW) and kaempferol glycosides (278.06 ± 12.29 mg/100 g FW). Notably, the southern samples possessed higher content of acylated flavonols (184.50 ± 12.87 mg/100 g FW), especially galloylated ones, which contributed to their heightened antioxidant activities. Quercetin 3-O-rhamnoside (f11′) and kaempferol 3-O-galloyglucoside (f11) were determined to be the crucial biomarkers for quality discrimination. Considering quality control of mature T. sinensis leaves as potential resources for natural flavonol extraction, this study suggested that their northern/southern geographic origins should be distinguished first. Additionally, the flavonol profiles allow for discriminating the origin and assessing the quality of T. sinensis.

Revalorization of Colombian purple corn Zea mays L. by-products using two-step column chromatography

Colombian purple corn Zea mays L. by-products have been chemically characterized. To achieve this, after Amberlite XAD-7 purification and Sephadex LH-20 fractionation, the accurate anthocyanin and flavonol profile using UHPL-DAD-ESI-MS, total monomeric anthocyanin (TMA), polyphenols using Folin-Ciocalteau reduction capacity (FCRC), and antioxidant activity (DPPH and TEAC) of each fraction were performed. Cob and leaves illustrated a more complete flavonoid profile and a higher content of anthocyanins and flavonols, strongly related to the highest reducing power and radical scavenging activity compared to grains. Furthermore, the most antioxidant fractions corresponded to the higher molecular weight compounds. The cob and leaves were enriched in cyanidin-3-O-glucoside, cyanidin-3-O-malonyl-hexoside, and peonidin-3-O-glucoside, peonidin-3-O-(6′'-malonyl-glucoside). The purification and fractionation allowed us to establish the chemical and antioxidant characterization, and the resulting revalorization, of purple corn by-products for the first time, and to have available pure fractions of Zea mays L. for a wide diversity of industries.

Comprehensive anthocyanin and flavonol profiling and fruit surface color of 20 blueberry genotypes during postharvest storage

Blueberry surface color is determined in large part by anthocyanin pigments and is one of the most important quality traits influencing consumer preference. Postharvest changes in fruit surface color and phenolic compounds, including anthocyanins, have been reported in blueberries; however, the relationships between these changes had not yet been investigated. A total of 25 anthocyanins and 14 flavonols were quantified across 20 blueberry genotypes at harvest and during four weeks of postharvest storage in 2019 and 2020. Total anthocyanin concentration ranged from 585.4 to 2556.4 mg kg‐1 across genotypes and was higher than total flavonol concentration that ranged from 129.3 to 331.0 mg kg‐1. Malvidin glycosides were the major anthocyanins in all genotypes; however, distinct anthocyanin profiles were observed among genotypes based on differences in the type of glycosylation. Quercetin 3-O-galactoside was the most abundant flavonol in all genotypes. Changes in total anthocyanin and total flavonol concentrations showed various trends during storage, depending on the genotype and the season. In contrast, anthocyanin and flavonol profiles for each genotype remained constant during storage and between seasons. Surface color parameters (lightness, chroma, and hue angle) showed weak correlations (r < 0.4) with anthocyanin concentrations measured at harvest and during postharvest storage. However, the color changes (Δ color) over four weeks of storage showed a strong correlation (r > 0.7) with changes in anthocyanin concentrations. This study provides novel understanding of the relationship between changes in anthocyanins and fruit surface color during postharvest storage in blueberries.

Non-Anthocyanin Compounds in Minority Red Grapevine Varieties Traditionally Cultivated in Galicia (Northwest Iberian Peninsula), Analysis of Flavanols, Flavonols, and Phenolic Acids

Non-anthocyanin compounds (NAN) such as flavonol, flavanol, and phenolic acids should be considered in the characterization of minority red grapevine varieties because these compounds are involved in copigmentation reactions and are potent antioxidants. Sixteen NAN were extracted, identified, and quantified by High Performance Liquid Chromatography (HPLC) from grapes of 28 red genotypes of Vitis vinifera L. grown in Galicia (Northwest of Spain) in 2018 and 2019 vintages. The percentage of total NAN with respect to the total polyphenol content (TPC) values was calculated for each sample and established into three categories: high percentage NAN varieties (NANV), those varieties showing low percentages of NAN (ANV), and finally those varieties showing medium percentages of NAN (NANAV). 'Xafardán' and 'Zamarrica', classified as NANAV, had high values of TPC and showed good percentages of flavonol and flavanol compounds. Principal component analyses (PCA) were performed with flavonol, flavanol, and phenolic acid profiles. The flavonol and flavanol profiles allowed a good discrimination of samples by variety and year, respectively. The flavonol profile should therefore be considered as a potential varietal marker. The results could help in the selection of varieties to be disseminated and in the identification of the most appropriate agronomic and oenological techniques that should be performed on them.

Statistical discrimination using different machine learning models reveals dissimilar key compounds of soybean leaves in targeted polyphenol-metric metabolomics in terms of traits and cultivation

Soybean (SB) leaves (SLs) contain diverse flavonoids with health-promoting properties. To investigate the chemical constituents of SB and their correlations across phenotypes, growing periods, and environmental factors, a validated separation method for mass detection was used with targeted metabolomics. Thirty-six polyphenols (1 coumestrol, 5 flavones, 18 flavonols, and 12 isoflavones) were identified in SLs, 31 of which were quantified. Machine learning (ML) modelling was used to differentiate between the variety, bean color, growing period, and cultivation area and identify the key compounds responsible for these differences. The isoflavone and flavonol profiles were influenced by the growing period and cultivation area based on bootstrap forest modelling. The neural model showed the best predictive capacity for SL differences among the various ML models. Discriminant polyphenols can differ depending on the ML method applied; therefore, a cautious approach should be ensured when using statistical ML outputs, including orthogonal partial least squares discriminant analysis.

First accurate profiling of antioxidant anthocyanins and flavonols of Tibouchina urvilleana and Tibouchina mollis edible flowers aided by fractionation with Amberlite XAD‐7

SummaryA purification and fractionation process of the edible flowers of Tibouchina mollis and Tibouchina urvilleana followed by the first attempt to the anthocyanin and flavonol characterisation and identification by UHPLC‐DAD‐ESI‐MS were developed. T. urvilleana exhibited a higher monomeric anthocyanin content, mainly due to the presence of the 3‐O‐(6′‐p‐coumaroyl)‐glucoside derivatives of malvidin and petunidin. Quercetin‐3‐O‐hexoside was the major flavonol identified in T. urvilleana, and the lack of myricetin derivatives was also exhibited. The anthocyanin and flavonol profile of T. mollis was more miscellaneous, characterised by the occurrence of cyanidin‐3‐O‐glucoside followed by the 3‐O‐(6′‐p‐coumaroyl)‐glucoside and 3‐O‐glucoside derivatives of malvidin and petunidin as anthocyanins, and myricetin, quercetin, and 3‐O‐hexosides of kaemperol and quercetin as flavonol compounds. Therefore, the anthocyanin and flavonol profile, through a process based on purification and fractionation, could be a useful tool to ensure the authenticity of the Tibouchina. Furthermore, the purification process made the antioxidant activity increase, which is greatly correlated to the reduction capacity.

Unraveling the Glucosylation of Astringency Compounds of Horse Chestnut via Integrative Sensory Evaluation, Flavonoid Metabolism, Differential Transcriptome, and Phylogenetic Analysis.

The seeds of Chinese horse chestnut are used as a source of starch and escin, whereas the potential use of whole plant has been ignored. The astringency and bitterness of tea produced from the leaves and flowers were found to be significantly better than those of green tea, suggesting that the enriched flavonoids maybe sensory determinates. During 47 flavonoids identified in leaves and flowers, seven flavonol glycosides in the top 10 including astragalin and isoquercitrin were significantly higher content in flowers than in leaves. The crude proteins of flowers could catalyze flavonol glucosides' formation, in which three glycosyltransferases contributed to the flavonol glucosylation were screened out by multi-dimensional integration of transcriptome, evolutionary analyses, recombinant enzymatic analysis and molecular docking. The deep exploration for flavonol profile and glycosylation provides theoretical and experimental basis for utilization of flowers and leaves of Aesculus chinensis as additives and dietary supplements.

Colour of floral styles in the Banksia spinulosa Sm complex (Proteaceae) relates to the anthocyanin and flavonol profile, not soil pH

The cylindrical conflorescences of the Banksia spinulosa Sm complex have several different colour types, i.e., black, red, maroon, lemon, and yellow. It is unknown if colour variation is due to extrinsic factors, importantly soil pH. Recent morphological observations have indicated that style colour are not contiguous, so follow-up chemical and soil analysis was conducted to further characterize the colour difference with respect to putative taxa and abiotic factors. Conflorescences of all known colours were sampled from across the eastern Australian distribution of B. spinulosa, and the respective soils were sampled and analysed for pH and total nitrogen. Regression analyses of this data demonstrated that pH and nitrogen gave nil and limited predictability for style colour respectively, i.e., only the taxa with black styles demonstrated a correlation, which was to a soil with slightly higher nitrogen content (p < 0.05). Furthermore, differences of pH were more often between taxa with conflorescences of the same colour. For chemical characterisation, the coloured styles were removed from conflorescences, extracted, and analysed by liquid chromatography-mass spectrometry (HPLC-MS/MS-DAD). Ten anthocyanin and twelve flavonol monoglycosides were identified by mass spectral fragmentation patterns (MS1 and MS2) and retention times. The data demonstrates that style colour differences are caused by the concentration of anthocyanins and their specific chemistry. It remains to be determined if the differences of anthocyanin expression are caused by other abiotic factors, or if it is intrinsic to the respective taxon.

Vitis vinifera Turkish novel table grape 'Karaerik'. Part II: Non-anthocyanin phenolic composition and antioxidant capacity.

'Karaerik' is a novel table grape (Vitis vinifera L.) native to Turkey and widely cultivated in areas bordering the city of Erzincan. Because of the demonstrated beneficial effects on human health of the grape phenolic composition, the aim of this work was to conduct a detailed profiling of non-anthocyanin phenolic fractions from different grape tissues of the 'Karaerik' table grape. Both qualitative and quantitative characterization of phenolic compounds were achieved using high-performance liquid chromatography-diode array detection-electrospray ionization-tandem mass spectrometry. Total phenolic content and oxygen radical absorbance capacity were also determined to evaluate the antioxidant properties of this table grape. A high number of non-anthocyanin phenolic compounds was identified in 'Karaerik' table grape skins and seeds, including 11 flavonols, six hydroxycinnamic acid derivatives, two stilbenes, several monomeric and dimeric flavan-3-ols and proanthocyanidins. Quercetin-type derivatives dominated the flavonol profile of grape skins, followed by myricetin type. Tartaric acid esters of three acids (caffeic, coumaric and ferulic acids) were the main hydroxycinnamic acid derivatives in this cultivar. Qualitative and quantitative differences were observed in flavan-3-ol composition among the grape tissues. Proanthocyanidins were the most abundant class of phenolic compounds in 'Karaerik' grapes, being mainly located in seeds. Higher antioxidant capacity values were determined in grape seeds, in correlation with the total phenolic content. These results provide useful information for a better understanding of phenolic antioxidants from the 'Karaerik' table grape and will contribute to promoting the varietal identity and health-related properties of this fruit. © 2021 Society of Chemical Industry.

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.

Age- and season-dependent pattern of flavonol glycosides in Cabernet Sauvignon grapevine leaves

Flavonols play key roles in many plant defense mechanisms, consequently they are frequently investigated as stress sensitive factors in relation to several oxidative processes. It is well known that grapevine (Vitis vinifera L.) can synthesize various flavonol glycosides in the leaves, however, very little information is available regarding their distribution along the cane at different leaf levels. In this work, taking into consideration of leaf position, the main flavonol glycosides of a red grapevine cultivar (Cabernet Sauvignon) were profiled and quantified by HPLC–DAD analysis. It was found that amount of four flavonol glycosides, namely, quercetin-3-O-galactoside, quercetin-3-O-glucoside, kaempferol-3-O-glucoside and kaempferol-3-O-glucuronide decreased towards the shoot tip. Since leaf age also decreases towards the shoot tip, the obtained results suggest that these compounds continuously formed by leaf aging, resulting in their accumulation in the older leaves. In contrast, quercetin-3-O-glucuronide (predominant form) and quercetin-3-O-rutinoside were not accumulated significantly by aging. We also pointed out that grapevine boosted the flavonol biosynthesis in September, and flavonol profile differed significantly in the two seasons. Our results contribute to the better understanding of the role of flavonols in the antioxidant defense system of grapevine.

Polyphenolic diversity in Vitis sp. leaves

We identified and quantified the main constitutive polyphenolic compounds of the leaves of seven Vitis species and of one interspecific cross, analysing leaf blades and veins separately, to spread light on the strategic localization of polyphenols in leaf tissues. To the best to our knowledge, the main leaf constitutive polyphenols of V. candicans, V. coignetiae, V. vinifera sylvestris and Börner were never described. V. riparia and V. rupestris (belonging to the same botanical series of Ripariae) displayed similar flavan-3-ol and dimeric proanthocyanidin concentration and similar percentage incidence of caftaric acid over total phenolic acids. V. riparia distinguished respect to the other genotypes for its high flavonol content, the highest percentage incidence of myricetin derivatives and an important diversification in the type of accumulated flavonol. V. berlandieri (series Cinereae) and Börner (hybrid of V. riparia x V. cinerea) accumulated low amounts of flavonol-glucosides comparing to the other species, but they showed a wide profile diversification, as well. However, it was V. v. sylvestris, the wild ancestor of Vitis vinifera subsp. sativa that displayed the widest flavonol profile diversification. The differences in the flavonol profile could be related to the genus Vitis evolution: in fact, with domestication, the flavonoid biosynthetic pathway underwent a progressive simplification; for this, the highest flavonol diversity found in Vitis v. sylvestris is probably a demonstration of its reduced or nil level of domestication. V. amurensis, known for its cold tolerance and resistance to downy mildew, anthracnose and white rot, markedly differentiated respect to the other genotypes, for its high concentration of polyphenols, particularly of vein flavonols and flavanonols. Moreover, V. amurensis leaves generally presented a constantly high concentration of constitutive polyphenols throughout the season that probably contributes to protect against adverse environmental condition. The abundance of polyphenols in V. amurensis leaves emphasizes that this species is a source of natural bioactive compounds that could find application for nutraceutical and pharmacological uses. V. berlandieri and Börner markedly distinguished respect to the other studied species for their exclusive capability to accumulate flavones (mainly orientin, isoorientin, vitexin and isovitexin) in blades and in veins, in considerable amounts.Knowledge about these subjects could contribute to shed light on the identification of species-related molecules involved in the plant-defense mechanisms, to the chemotaxonomy of the genus Vitis, to the possibility of identifying specific natural bioactive compounds to use in plant-based preparation for nutraceutical, cosmetic, feed/food-additive purposes.

Flavonol Profile Is a Reliable Indicator to Assess Canopy Architecture and the Exposure of Red Wine Grapes to Solar Radiation.

Exposure to solar radiation is a determining factor of grape composition. Flavonol synthesis is upregulated by solar radiation leaving a fingerprint on flavonol profile. This study aimed to test the factors affecting flavonol accumulation and profile and their potential as an indicator to assess the overall exposure of red wine grape berry to solar radiation. We performed three experiments to study the response of flavonol accumulation and profile to (1) three different solar radiation exclusion treatments during berry development; (2) canopy porosity and leaf area index (LAI); and (3) spatial variability of water status, vigor and ripening and cultural practices in commercial vineyards. Results showed a strong relationship between global radiation, inverse dormant pruning weights or canopy porosity (inversely proportional to LAI) and % kaempferol or % quercetin. Furthermore, the increase in concentration of the above two flavonols was associated with a reduction of % myricetin. Total flavonol content, % kaempferol, % quercetin, and % myricetin had significant correlations with inverse dormant pruning weights, but these were less sensitive to over-ripening or water deficits. Flavonol profile was associated to site hydrology (wetness index) through changes in vigor, and to LAI; and responded to shoot thinning or fruit-zone leaf removal. These results support the reliability of the flavonol profile as an assessment parameter for studies aiming to discuss canopy architecture or the effect of solar radiation on grapevine berries.

Nanostructured TiO2-induced photocatalytic stress enhances the antioxidant capacity and phenolic content in the leaves of Vitis vinifera on a genotype-dependent manner

Over the past decades, nanotechnology has received great attention and brought revolutionary solutions for a number of challenges in scientific fields. Industrial, agricultural and medical applications of engineered nanomaterials have increased intensively. The ability of titanium dioxide nanoparticles (TiO2 NPs) to produce reactive oxygen species (ROS), when excited by ultra-violet (UV) light, makes them useful for effectively inactivate various pathogens. It is known that ROS also have signalling role in living organisms, therefore, TiO2 NPs-induced ROS can influence both enzymatic and non-enzymatic defence systems, and could play a role in the resistance of plants to pathogens. Herein, we studied the photocatalytic stress responses of grapevine (Vitis vinifera L.) as model plant, when exposed to a well-known photocatalyst, Degussa P25 TiO2 NPs. The photocatalytically produced ROS such as superoxide anion, hydroxyl radical and singlet oxygen were confirmed by electron paramagnetic resonance spectroscopy. Foliar exposure of five red cultivars (Cabernet sauvignon, Cabernet franc, Merlot, Kékfrankos and Kadarka) was carried out in blooming phenophase under field condition where plants are exposed to natural sunlight with relatively high UV radiation (with a maximum of ~ 45 W m−2). After two weeks of exposure, the effects of photogenerated ROS on the total phenolic content, antioxidant capacity, flavonol profile and the main macro-, microelements of the leaves were studied in detail. We found that foliar application of TiO2 NPs boosted the total phenolic content and biosynthesis of the leaf flavonols depending on the grapevine variety. Photocatalytically active TiO2 NPs also increased K, Mg, Ca, B and Mn levels in the leaves as shown by ICP-AES measurements.

Foliar exposure of grapevine (Vitis vinifera L.) to TiO&lt;sub&gt;2&lt;/sub&gt; nanoparticles under field conditions: Photosynthetic response and flavonol profile

In the past decade, utilization of nanostructured materials has increased intensively in a wide range of applications. Titanium dioxide nanoparticles (TiO2 NPs), for instance, can be applied for the inactivation of various pathogens through photo-induced generation of reactive oxygen species. Although TiO2 NPs with high antimicrobial activity are of great importance, in practice, their phytotoxic effects have not yet been fully clarified. In this study, we investigated the potential phytotoxicity of TiO2 NPs on grapevine (Vitis vinifera L.) under field conditions. After foliar exposure, two particularly stress-sensitive parameters, photosynthetic function and the flavonol profile, were examined. Micro- and macroelement composition of the leaves was also studied by ICP-AES measurements. We found that TiO2 NPs significantly decreased the net CO2 assimilation and increased stomatal conductance, indicating metabolic (nonstomatal) inhibition of the photosynthesis. The lower electron transport rate and lower nonphotochemical quenching in treated leaves are indicative of diminished photoprotective processes.

Characterization of Various Color Parameters (Anthocyanins and Flavonols) of Leaves and Flowers in Different Autochthonous Genotypes of Cyclamen purpurascens

Common cyclamen (Cyclamen pururascens Mill.) is a very interesting species not only for various breeding programs but also as an ornamental plant. The plants possess interesting floral and foliage characteristics, nice fragrances, and a very useful flavonol profile. The last is very important from the point of view of protecting against diseases and physiological disorders. Twenty-two different genotypes originating from different regions in Slovenia were analyzed in detail, based on their floral and foliage characteristics. Anthocyanin and flavonol contents were determined using high-performance liquid chromatography (HPLC)-photodiode array-mass spectrometry (MS). Color characteristics were colorimetrically evaluated separately for petals and leaves. In terms of color measurements, significant differences among the sites of origin were shown with parameters a* and L* when petals were analyzed, and with parameter a* when leaves were analyzed. The pH of petal sap stayed within the acid range, ranging from 3.96 to 4.82. Five different anthocyanins (malvidin-3,5-diglucoside, cyanidin-3-neohesperidoside, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, and delphinidine-3-rutinoside) were analyzed in flowers, and this is the first report of delphinidin metabolites naturally present in common cyclamen genotypes. In relation to plant leaves, malvidin-3,5-diglucoside, malvidin-3-rutinoside, malvidin-3-glucoside, cyanidin-3-neohesperidoside, and peonidin-3-neohesperidoside were measured. Fifteen different flavonols were determined in common cyclamen flowers and 10 different flavonols in common cyclamen leaves. Various glycosides of quercetin, myricetin, and kaempferol were analyzed, as well as isorhamnetin-3-rutinoside, laricitin-3-rutinoside, and neohesperidin. The floral and foliage characteristics of the genotypes (physical and chemical) were mainly affected by the environmental conditions of the locality of origin of the genotypes (annual disposition of temperature and precipitation, structure of the soil, etc.).

Green Ultrasound-Assisted Extraction of Antioxidant Phenolic Compounds Determined by High Performance Liquid Chromatography from Bilberry (Vaccinium Myrtillus L.) Juice By-products

In this paper, the effect of ultrasound assisted extraction (UAE) combined with stirring and conventional technique of maceration of wild bilberry juice by-products has been studied. Juice by-products were subjected to conventional maceration by stirring, and ultrasound probe using four different ultrasonic intensities (4.4, 9.4, 13.4 and 16.7 W cm− 2). The anthocyanins and flavonol profile of the obtained extracts were studied by HPLC-DAD. UAE resulted in a decrease of monomeric anthocyanins. However, the total phenolic compounds was higher when ultrasound was used and the extracts obtained with this “green” technology were more antioxidants than the extracts obtained by conventional maceration. Lab parameters and absorbances at 420 and 520 nm showed greater recovery of yellow and red compounds when the ultrasonic intensity was higher.

Partial Solar Radiation Exclusion with Color Shade Nets Reduces the Degradation of Organic Acids and Flavonoids of Grape Berry (Vitis vinifera L.).

The incidence of solar radiation on red-skinned grapes can promote the synthesis of flavonoids desirable for wine production, but elevated temperature may impair their accumulation. We performed a shade cloth trial covering the fruit zone (from pepper-corn size to maturity) with four polyethylene 1 m curtains with different optical properties (20% shading factor Pearl colored and 40% shading factor Aluminet, Blue, and Black colored) and a Control with no cover. Cluster temperature was 3.7 °C lower on the Southwest side in Black-40% clusters during the warmest part of the day compared to Control. Results indicated a lower berry weight under the Aluminet-40%. Berries under the nets often had significantly lower pH and higher TA than Control, but only the Black-40% were significant at harvest. Black-40% had higher values of anthocyanins than Control toward the last weeks of development. Berry skin flavonol and anthocyanin composition and concentration were measured by C18 reversed-phased HPLC; and proanthocyanidin isolates were characterized by acid catalysis in the presence of excess phloroglucinol followed by reversed-phase HPLC. Proanthocyanidins and flavonol contents were lower in Black-40% before veraison and the first part of ripening, respectively. However, their contents in Control decreased toward the end of ripening to a point where any net was different from Control. Anthocyanin and flavonol profiles were richer in 3', 4', 5' hydroxylated forms. Proanthocyanidin chain length was not affected while small changes were observed in the proportion of terminal catechin/epicatechin and in seed galloylation in response to treatments. Results show that shade cloths may efficiently palliate temperature spikes, especially the last weeks before harvest, while transmitting enough radiation into the fruit zone to achieve a better grape composition compared to uncovered grapes.

Chokeberry pomace valorization into food ingredients by enzyme-assisted extraction: Process optimization and product characterization

Currently berry juice pressing residues are used inefficiently due to a lack of innovative processes of their valorization. This study reports valorization of chokeberry pomace via combined high pressure fractionation and enzyme-assisted extraction (EAE), utilizing commercially available cellulolytic and xylanolytic enzyme preparations, namely Viscozyme L and CeluStar XL. The results obtained indicate that optimized enzyme treatment (E/S 6% v/w, 40°C, pH 3.5, 7h), especially using Viscozyme L, facilitates pomace cell-wall breakdown and: (1) increases the yield of water-soluble fraction by 44–113%, monosaccharide content by 12–140%, total phenolic content by 29–41%, radical scavenging capacity by 20–39%; (2) promotes some alterations in phenolic acid and flavonol profiles of EAE-derived supernatants. For the first time antioxidant potential of solid residues from enzyme-treated berry pomaces was evaluated too, indicating that all fractions could be utilized as a low-cost source of high added value functional ingredients with various scientific and commercial applications.