Quantification Of Anthocyanins Research Articles

Melatonin triggers tissue-specific changes in anthocyanin and hormonal contents during postharvest decay of Angeleno plums

Plum is a stone fruit that stands out for having a short shelf-life because of its high susceptibility to rapid deterioration. Part of this deterioration is explained by fruit overripening. Recently, the role of melatonin in delaying postharvest decay has been investigated but its regulatory function during overripening is still under extensive debate. In this study, to understand physiological events taking place in plums overripening and elucidate the role of melatonin on the postharvest quality of these fruits and its relationship to other plant hormones, Angeleno plums were sprayed with 10−4 M of melatonin solution immediately after harvest. We carried out tissue-specific (mesocarp and exocarp) analysis of total phenols and anthocyanin quantification, as well as the evaluation of different phytohormones by LC-MS/MS and fruit quality parameters. Results showed that during postharvest, endogenous melatonin contents decreased both in the mesocarp and the exocarp of Angeleno plums. Likewise, plum firmness also decreased and a strong correlation was found for this parameter with jasmonic acid (JA) and cytokinins. Conversely, after exogenous melatonin application, endogenous melatonin content increased both in mesocarp and exocarp but it had a differential effect depending on the plum tissue. Indeed, total phenol and anthocyanin contents arose by 21% and 58%, respectively, in the mesocarp after melatonin treatment but no variations were found in the exocarp of Angeleno plums. Hormonal analysis of Angeleno mesocarp also revealed an increase in the JA and its precursor, 12-oxo-phytodienoic acid (OPDA), on the fourth day after melatonin application as well as a positive correlation between melatonin and gibberellin 1 (GA1). These results suggest that melatonin may be acting as a signal molecule increasing phenolic compounds contents through direct regulation and by signaling with other phytohormones. Therefore, this research provides valuable information for understanding the regulatory role of melatonin and its relationship with plant hormones during overripening to contribute to improve the postharvest quality of plums.

Handheld Multifunctional Fluorescence Imager for Non-invasive Plant Phenotyping.

Fluorescence imaging has shown great potential in non-invasive plant monitoring and analysis. However, current systems have several limitations, such as bulky size, high cost, contact measurement, and lack of multifunctionality, which may hinder its applications in a wide range of settings including indoor vertical farming. Herein, we developed a compact handheld fluorescence imager enabling multipurpose plant phenotyping, such as continuous photosynthetic activity monitoring and non-destructive anthocyanin quantification. The compact imager comprises of pulse-amplitude-modulated multi-color light emitting diodes (LEDs), optimized light illumination and collection, dedicated driver circuit board, miniaturized charge-coupled device camera, and associated image analytics. Experiments conducted in drought stressed lettuce proved that the novel imager could quantitatively evaluate the plant stress by the non-invasive measurement of photosynthetic activity efficiency. Moreover, a non-invasive and fast quantification of anthocyanins in green and red Batavia lettuce leaves had excellent correlation (>84%) with conventional destructive biochemical analysis. Preliminary experimental results emphasize the high throughput monitoring capability and multifunctionality of our novel handheld fluorescence imager, indicating its tremendous potential in modern agriculture.

Colorimetric selective quantification of anthocyanins with catechol/pyrogallol moiety in edible plants upon zinc complexation.

Here is examined the colour development from common anthocyanins (i.e., cyanidin, delphinidin, malvidin, and pelargonidin glycosides) and from anthocyanins-rich extracts (i.e., bilberries, strawberries, and raspberries), using zinc-anthocyanin complexes as molecular probe. We have observed the absorbance increase in the blue region in presence of large excess of zinc ion at acidic pH for cyanidin and delphinidin derivatives, likely due to quinoidal base stabilization from catechol and pyrogallol moiety. The assay condition were studied and applied to natural extracts containing these compounds. The same behaviour was observed for bilberry and, to a minor extent, for raspberry extracts, due to the larger cyanidin/delphinidin contents in the former than in the latter. Anthocyanin standard UV-Vis analysis in buffer has shown a very good linear correlation for cyanidin and delphinidin (R2=0.995 and 0.997, respectively), good precision (CV%=7.4% and 5.3% respectively), high sensitivity (Cyε600nm=8300M-1cm-1, LOD=0.264±0.005mgL-1, LOQ=0.478±0.007mgL-1, and Dpε600nm=15,900M-1cm-1, LOD=0.143±0.002mgL-1, LOQ=0.478±0.007mgL-1). The effectiveness of this colorimetric method for the selective quantification of catechol/pyrogallol-based anthocyanins has been demonstrated in the aforementioned complex real matrices and compared to LC-MS/MS analysis and pH-differential method, offering a valuable tool to characterize plant and food extracts particularly rich in zinc-coordinating anthocyanins.

A stability-indicating HPLC-UV method for the quantification of anthocyanin in Roselle (Hibiscus Sabdariffa L.) spray-dried extract, oral powder, and lozenges

Hibiscus sabdariffa L. (H.S.) plant and its calyces have received much attention from researchers because of their potential medicinal and nutritional values. Calyces are the major source of anthocyanin in this plant. Therefore, a well-developed, efficient, and accurate analytical method is needed to assure proper standardization and control the quality of H.S. plant herbal and nutraceutical products. The objective of this work is to develop a simple, rapid, stability-indicating HPLC-UV method for the quantitative determination of anthocyanin in spray-dried aqueous extract (SDE), oral powder, and compressible lozenges formulations using Delphinidin-3-O-sambubioside (Dp3S) as a marker compound. The chromatographic conditions were optimized using Eclipse plus® C18 column. The mobile phase comprised water acidified with 0.2% formic acid (FA) and acetonitrile (ACN) (90:10, v/v) using a gradient system at a flow rate of 0.8 mL/min. The detection wavelength was 525 nm. The column was maintained at 45 °C, and the injection volume was 15 μL. The developed method was validated according to the international conference of harmonization (ICH) guidelines for linearity, detection and quantitation limits, accuracy, precision, specificity, and robustness. Forced degradation studies under acid, base, oxidation, heat, and U.V light, were performed on the pure compound, extract, and the H.S. developed formulations. Significant degradation of the compound was observed under all tested conditions except U.V. light, where degradation was minimum. There was no interference from impurities, degradation products, or excipients at the retention time of Dp3S 3.2 min indicating the specificity of the method. The developed method was statistically confirmed to be accurate, precise, and reproducible. This simple, rapid, and specific method can be employed efficiently to determine anthocyanin in H.S. plant extract and nutraceutical products.

Accurate Quantification of Anthocyanin in Red Flesh Apples Using Digital Photography and Image Analysis

Red fleshed apples (Malus × domestica Borkh.) differ in colour intensity between cultivars, seasons and sites. The objective of this study was to develop a procedure for predicting anthocyanin content from digital images of flesh discs. Flesh cylinders of uniform colour were excised, scanned and their colours determined in the R, G and B and the L*a*b* colour spaces. Anthocyanin content was also quantified chemically. A calibration line was constructed to predict anthocyanin content of flesh discs of varying colour from a scan or a photograph in the studio or outdoors. Anthocyanin concentration was linearly related to the logarithms of G, B and L*. From these relationships, the anthocyanin content of a flesh disc was predicted, pixel by pixel. Colour corrections were applied using a reference colour chart included in all images. The Finlayson algorithm was most effective for correcting the G parameter obtained by a flatbed scanner. For variable imaging methods (scanning or photography), the Vandermonde algorithm for correcting the L* parameter and the Finlayson algorithm for correcting the G parameter were most effective in predicting anthocyanin content. The procedure allows accurate prediction of anthocyanin content of red fleshed apples from simple colour scans or photographs.

Influence of processing methods on the content of polyphenols and anthocyanins and on the antioxidant activity of Rubus brasiliensis Mart. fruits

Abstract Little is known about the phytochemical composition and the influence of different processing methods on the concentration of bioactive compounds and on the antioxidant activity of the fruits of Rubus brasiliensis Mart., a native plant of Brazil. This work aimed to evaluate the influence of different processing methods on the quantification of phenolic and anthocyanin compounds and on the antioxidant activity of R. brasiliensis fruits. The plants were processed by different ways - the extracts of fruits were obtained by Spray Dryer (SD) or Lyophilization (LYO), and the fruits were dried directly in an oven (OD) and were also evaluated after freshly thawed (FT). The processing methods were independent. After processing, the polyphenol and anthocyanin contents and antioxidant activity were evaluated. The Total Phenolic Content (TPC) was assessed using the Folin-Ciocalteu technique. The pH differential method was used for quantification of anthocyanin and the antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. R. brasiliensis fruits have a high content of polyphenols and anthocyanins, and an expressive antioxidant activity that can bring benefits to the population. The FT fruits showed the lowest content of total polyphenols. However, the OD fruits showed the most interesting results, since the total polyphenols and anthocyanins contents and the antioxidant activity were similar to the other processing methods performed in this work and were more economically viable. Obtain a bioactive content and adequate antioxidant activity after simple processing such as drying is very interesting when using these fruits for longer, or even, obtaining pharmaceutical formulations. It could be determined, for the first time, the content of polyphenols and anthocyanins and the antioxidant activity of the fruits of R. brasiliensis, as well as the best way to process these fruits by drying them in an oven.

In Vitro Propagation Method for Production of Phenolic-Rich Planting Material of Culinary Rhubarb 'Malinowy'.

Culinary rhubarb is a popular vegetable crop, valued for its long, thickened stalks, very rich in different natural bioactive ingredients. Tissue cultures are a useful tool for vegetative propagation of virus-free rhubarb plants and rapid multiplication of valuable selected genotypes. The aim of this study was to develop an effective method for in vitro propagation of selected genotypes of Polish rhubarb ‘Malinowy’ characterized by high yield and straight, thick and intensive red stalks. Identification and quantification of anthocyanins and soluble sugars by the HPLC method in shoot cultures and ex vitro established plantlets were also performed. Shoot cultures were established from axillary buds isolated from dormant, eight-year-old rhizomes. Effective shoot multiplication of rhubarb ‘Malinowy’ was obtained in the presence of 6.6 µM benzylaminopurine or 12.4 µM meta-topolin. Both cytokinins stimulated shoot formation in a manner that depended on sucrose concentration. Increasing the sucrose concentration from 59 to 175 mM decreased the production of shoots and outgrowth of leaves by 3-fold but enhanced shoot length, single shoot mass and callus formation at the base of shoots. This coincided with increased accumulation of soluble sugars (fructose, glucose) and anthocyanins-cyanidin-3-O-rutinoside (max. 208.2 mg·100 g−1 DM) and cyanidin-3-O-glucoside (max. 47.7 mg·100 g−1 DM). The highest rooting frequency (94.9%) and further successful ex vitro establishment (100%) were observed for shoots that were earlier rooted in vitro in the presence of 4.9 µM indole-3-butyric acid. Our results indicated that anthocyanin contents in leaf petioles were influenced by developmental stage. Under in vitro conditions, it is possible to elicit those pigments by sucrose at high concentration and meta-topolin.

Optimization of a Novel Method Based on Ultrasound-Assisted Extraction for the Quantification of Anthocyanins and Total Phenolic Compounds in Blueberry Samples (Vaccinium corymbosum L.).

In recent years, consumers’ preference for fruits such as blueberry has increased noticeably. This fact is probably related to their bioactive components such as anthocyanins, phenolic compounds, vitamins, minerals, and tannins that have been found in blueberries by the latest research studies. Both total anthocyanins (TA) and total phenolic compounds (TPC) are known for their multiple beneficial effects on our health, due to their anti-inflammatory, anti-oxidant, and anti-cancer properties. This is the reason why the development of new methodologies for the quality control analysis of raw materials or derived products from blueberry has a great relevance. Two ultrasound-assisted extraction methods (UAE) have been optimized for the quantification of TA and TPC in blueberry samples. The six variables to be optimized were: solvent composition, temperature, amplitude, cycle, extraction solvent pH, and sample/solvent ratio using response surface methodology. The optimized methods have proven to be suitable for the extraction of the TPC and TA with good precision (repeatability and intermediate precision) (coefficient of variation (CV) < 5%) and potentially for application in commercial samples. This fact, together with the multiple advantages of UAE, makes these methods a good alternative to be used in quality control analysis by both industries and laboratories.

High-Performance liquid chromatography-tandem mass spectrometry with polar C18 for rapid quantification of anthocyanin and flavonoid in black soybean extracts

ABSTRACT Black soybean (Glycine max L.) is one of the most popular crops with various application in the world. Its seed coat contains various natural pigments compounds such as anthocyanin and flavonoid. In this study, we optimize the extraction conditions of eight polyphenols from whole of black soybean and seed coat, evaluate their extraction effect, and separation resolution at different pH-range. The multiple reaction monitoring (MRM) method was analyzed by using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with simultaneous positive and negative electrospray ionization in a single analytical run. Eight polyphenols were separated within 9 minutes of run time with LC-MS/MS operated mode. The calibration graphs were linear over the concentration ranges of 0.01 to 1 mg/L for all polyphenol. Regression coefficients were in the range > 0.99. The limit of detection value, calculated from the blank tests based on 3σ, was 1 µg/L for all polyphenol. The RSD values corresponding to the intra-day and inter-day repeatability were lower than 11% and accuracies between 85-115%. It is shown that the modified solvent system that applied in LC-MS/MS detection could be developed as a useful tool for the study of water-soluble phenolic compounds.

Chemical and Sensory Characterisation of Two Rubus rosifolius (Red Raspberry) Varieties.

Raspberries are economically important fruits, being highly valued for their taste and medicinal properties. Prior to our recent finding, the occurrence of different varieties of Rubus rosifolius growing in Jamaica had not been previously reported. Upon close observation of the plants, differences in various physical features pointed to the existence of two distinct plant morphotypes, which were described as Red “R” and Wine Red “WR.” With an aim to determine which variety may be more favourable for value-added food production, we undertook their physicochemical and sensory analysis. This characterisation led to the rationalisation of the differences in the perceived sensory properties of these biologically active fruits. Total phenolic content was determined using the Folin-Ciocalteu reagent assay, and the identification and quantification of anthocyanins were done via HPLC-MS and HPLC-UV, respectively. Proximate and physicochemical analyses were also carried out. The findings of the analyses were associated with those of a consumer sensory analysis. The WR fruits had a greater quantity of the deep red anthocyanin, cyanidin-3-glucoside (66.2 mg/100 g FW), and a significantly lower lightness value. They also received a significantly higher sweetness score, which is associated with their higher total sugar content (4.8 g/100 g) and maturity index (6.7). The R fruits had a higher quantity of the orange-coloured pelargonidin-3-rutinoside (17.2 mg/100 g FW) and significantly higher titratable acidity (1.3 g citric acid/100 mL), the latter being associated with its significantly more sour taste. The high total phenolic contents suggest a health-functional value of these R. rosifolius berry fruits. Our findings, which revealed that the WR variety was the preferred choice among consumers, may be used to guide future product-development endeavours of these commercially valuable fruits.

Anthocyanin based agricultural wastes as bio-adsorbents for scavenging radioactive iodide from aqueous environment

Abstract To provide an alternative solution for radioactive iodine remediation, mangosteen pericarps, red onion peels, red dragon fruit peels, and passion fruit rinds (anthocyanin-based adsorbents) were successfully employed for iodide (I−) removal from aqueous solution with minimal processing. The adsorption results revealed that 0.5 g/L of mangosteen pericarps and red onion peels removed up to 90 % of 10 mg/L I− within 30 min. For both adsorbents, the experimental and the predicted Langmuir isotherms adsorption capacity (qmax) were over 70 mg/g. Anthocyanin quantification revealed that the quantity of vacuole pigments coincided with I− adsorption capacity across different adsorbents. O+, as part of the flavylium cation in anthocyanin, attracted I− via electrostatic force, and the adsorption was controlled by ion-exchange. The computational radial distance was predicted to be ∼3.28 A. Further characterization by UV–vis spectrometry, FTIR, EDX, XPS, and XAS supported the claim of flavylium cation in anthocyanin as the main I− adsorbing functional group. Thus, the anthocyanin-based materials from agriculture waste can be used sustainably to remove radioactive I− from nuclear power facilities, water treatment plants and for environmental remediation.

Argentine Patagonia barberry chemical composition and evaluation of its antioxidant capacity.

An important portion of vitamins, minerals and polyphenols components in human diet are captured from fruit consumption. Argentinean Patagonia Berberis microphylla was characterized with the phenolic content, the proximate composition and the identification and quantification of anthocyanins, not-anthocyanins and proteins. The antioxidant capacity of berberis ethanolic extracts (EB) was determined by the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. EB was used to reduce production of reactive substances species (ROS) in zebrafish. EB presented a total polyphenols content of 1,035.03mg GAE/100g fresh weight (FW). EB presented an ABTS value of 116.25±17μmol TE/g FW. EB presented a DPPH value of 137.80±1.90μmol TE/g FW. EB was able of reducing the ROS in zebrafish. Berberies Protein Isolate (BPI) presented proteins with bands from 15 to 62kDa. BPI presented an ABTS value of 593.11±8.60 μmol TE/g. The BPI duodenal digest presented a value of 641.07±12.60 μmol TE/g digests. PRACTICAL APPLICATIONS: The practical applications of the present study are to increase scientific knowledge for consumers about the quality and benefits of the consumption of the native fruit (Berberis microphylla) from the Patagonia region of Argentine. This work describes the protein profile of berberies, their digestibility and their antioxidant activity. This study allows to better understand the phytonutrients that make up this fruit. Future studies may identify the peptides present in hydrolyzates. The bio-compounds of this fruit could be used as functional ingredients by the food industry for different purposes.

Kinetic Modelling of Anthocyanin Extraction from Grape (Vitis vinifera) using Response Surface Methodology

Anthocyanins are natural food colorants and functional compound, those substitute synthetic colours. One of the major source of Anthocyanin is Grapes, and by implementing suitable extraction process, it is possible to obtain high yield extract. In our study, we have optimized anthocyanin extraction from grape pomace (Vitis vinifera) by using response surface methodology. Owing to its simple, economical and efficient alternative to other extraction process, this method of extraction was found to be appropriate. Various parameter combinations were performed to determine the anthocyanin concentration such as extraction temperature, extraction time and pH and the process was optimized and validated. Various characterization of grapes and anthocyanin such as moisture, ash, total phenolic content, quantification of anthocyanin, HPLC and FTIR were also performed.

Comparative analysis of metabolites in contrasting chickpea cultivars

Chickpea (Cicer arietinum L.) is a good source of nutrients for animals and human consumption. In the present study, we analyzed the anthocyanin and total phenolic contents in two contrasting (desi and kabuli) chickpea cultivars. The quantification of anthocyanins showed higher amount in desi as compared to kabuli chickpea. The total phenolic contents was estimated in desi and kabuli chickpea using two different solvents (50% Acetone and 70% Methanol extracts) for coverage of all potential phenolic compounds. In continuation, desi chickpea culitvars (himchana and ICC4958) were found to be significantly higher total phenolic contents (in both solvent extracts) as compared to kabuli cultivars (JGK-03 and L-552). Higher phenolic contents was found to be directly correlated to higher anthocyanin contents in desi as compared to kabuli chickpea. The volatile organic compounds were also analyzed using gas chromatography mass spectroscopy technique in both cultivars. The significant compositional differences in volatile organic composition (polar and non-polar) of desi and kabuli cultivars were also found to be noticed using two different solvent extractions (methanol and chloroform). The comparative analysis of volatile organic acids in methanolic and chloroform extracts of desi cultivars (himchana and ICC4958), kabuli cultivars (JGK-03 and L-552) and between desi and kabuli cultivars was also carried out for in-depth understanding of the differential patterns of low molecular weight metabolites. Six metabolites were found to be common in all four selected cultivars in chloroform extracted samples, while four were found to be common in all four selected cultivars in methanolic extracted samples. The remaining detected metabolites are uncommon among different cultivars and represented as cultivar specific signatory metabolites. In conclusion, the present investigation revealed higher anthocyanin and phenolic contents in desi cultivars as compared to kabuli cultivars and differential accumulation of volatile organic compounds in chickpea cultivars. The metabolite alterations among desi and chickpea cultivars could be the potential attribute for diversity, resilience and commercial usuages.

Identification and quantification of anthocyanins in purple-fleshed sweet potato leaves

As phytochemical-enriched edible greens, sweet potato (Ipomoea batatas L.) leaves have become popular. However, the profile and content of phytochemicals in sweet potato leaves are mostly unknown. We previously bred a purple-fleshed sweet potato P40 that demonstrated cancer prevention due to high levels of anthocyanins in the tuberous roots. The objectives of this study were to identify and quantify anthocyanins in P40 leaves when compared with the white-fleshed Bonita and orange-fleshed Beauregard. The mature leaves of P40 at 6-week vine stage were collected and extracted for anthocyanin analysis by HPLC-MS/MS. Fourteen anthocyanins, including a novel anthocyanin (peonidin 3-caffeoyl-p-coumaryl sophoroside-5-glucoside), were identified and quantitated. The contents of anthocyanins in P40 leaves (32.7 ± 2.9 mg/kg DW) were much lower than that in the root (13,100 ± 70 mg/kg DW). Furthermore, anthocyanin contents in P40 leaves were even lesser than those of the orange-fleshed Beauregard (334 ± 60.9 mg/kg DW) and white-fleshed Bonita (563 ± 50.4 mg/kg DW). Total phenolic contents as measured by Folin-Ciocalteu were 36.8 ± 4.8 mg GAE/g DW in the leaves of P40, but 41.2 ± 5.0 mg GAE/g DW in Beauregard and 46.7 ± 2.1 mg GAE/g DW in Bonita. No anthocyanin was detectable in the stem of these three sweet potato varieties. Taken together, this study reports for the first time the profile and content of anthocyanins in the leaves of three sweet potato varieties with a new anthocyanin identified. The unexpected lower levels of anthocyanins in the purple-fleshed sweet potato leaves when compared with either the counterpart tuberous roots or the control white-fleshed and orange-fleshed sweet potato varieties advanced our existing knowledge and also validated a diverse phenotype of anthocyanin biosynthesis between sweet potato leaves and roots.

Identification and quantification of anthocyanins in seeds of Kersting’s groundnut [Macrotyloma geocarpum (Harms) Marechal &amp; Baudet] landraces of varying seed coat pigmentation

The present study identified and quantified the anthocyanin pigments in seed of eight Kersting’s groundnut [Macrotyloma geocarpum (Harms) Marechal & Baudet] landraces of variable seed coat pigmentation. The analysis was carried out using ultra-performance liquid chromatography coupled with a photodiode array detector and mass spectrometry. Although the findings revealed similar anthocyanin profiles in seeds of the eight landraces tested, the relative concentrations of the individual anthocyanin compounds showed marked variations. Delphinidin-3-O-glucoside, cyanidin-3-O-glucoside and peonidin-3-O-glucoside were the most abundant anthocyanins, with concentrations ranging between 21.4–239.0, 23.6–130.6 and 21.4–135.4 µg/g of dry seed, respectively in seeds of the test landraces, while total anthocyanins ranged between 95 and 505 µg/g of dry seed. The preponderance of delphinidin 3-O-glucoside was observed in the black and brown mottled seeds. This study is the first report regarding the profile and concentrations of anthocyanins in Kersting’s groundnut and suggests that the seeds of this underutilized grain legume can potentially be exploited as a natural source of anthocyanins for the development of cosmetic, food and pharmaceutical products.

Effects of In Vitro Gastrointestinal Digestion on the Antioxidant Capacity and Anthocyanin Content of Cornelian Cherry Fruit Extract.

Red fruits are considered a major source of antioxidant compounds in the human diet. They usually contain anthocyanins, phenolic pigments that confer them multiple health-promoting properties. The health benefits of these bioactive phytocompounds are strongly related to their bioavailability, which has been reported to be low. The aim of the present study is to investigate the changes in antioxidant capacity and anthocyanin content of Cornelian cherry fruit extract during gastrointestinal digestion. Thus, the work was designed using a simulated in vitro digestion model. The antioxidant capacity (AA) was tested by the 2,2-azinobis (3-ethylbenzothiazolyne-6-sulphonic acid) radical cation (ABTS) method, while quantification of anthocyanins (TAC) was accomplished by the means of the pH differential method and high performance liquid chromatography (HPLC). The results showed that gastric digestion had no significant effect on the TAC of the extract, while the AA slightly increased. After duodenal digestion, only 28.33% of TAC and 56.74% of AA were maintained. Cornelian cherries’ anthocyanins were stable in stomach, so they can be absorbed in order to manifest their antioxidant capacity at the cellular level. The duodenal digestion dramatically decreased the TAC and AA level in the fruit extract.

Application of digital images and multivariate calibration for the quantification of anthocyanin and antioxidant activity in grape juice

Background and Aims The current methods for measuring the anthocyanin concentration (AC) and antioxidant activity (AA) of grape juice have limitations. The objective of this work was therefore to evaluate the application of digital imaging as a simple, fast and low‐cost method for determining AC and AA in juice. Methods and Results The AC and AA of 75 grape juice samples were measured using reference methods and then correlated against digital images of 200 dpi resolution obtained with a scanner, using partial least squares regression. The samples were separated with the Kennard–Stone algorithm into calibration sets (50 samples) and external validation sets (25 samples). The models used for the quantification of AC and AA presented a root mean square error of calibration of 8.8 mg/L and 9.8 μmol and a root mean square error of prediction of 7.5 mg/L and 8.0 μmol, respectively. The correlation coefficients for the adjustment were 0.8479 and 0.9258 for the models in the determination of AC and AA, respectively. Conclusions Digital imaging and multivariate calibration can be used to measure efficiently selected parameters of grape juice composition. Significance of the Study Analytical methods based on digital imaging offer promising alternatives to conventional methods, since they are fast, simple, non‐destructive and employ little or no chemical reagents, thereby reducing analysis costs and facilitating in situ analysis.

Study on the regulation of anthocyanin biosynthesis by exogenous abscisic acid in grapevine

Anthocyanins are important components not only for the red wine and table grapes, but also for the antioxidant capacity and disease prevention. The aim of this work was the investigation of the regulation mechanism of exogenous hormones on anthocyanins. The experiment took place in 2016, in a vineyard located in Ningxia (China). Chemical analysis, high-performance liquid chromatography (HPLC) and transcriptional studies were carried out to clarify the anthocyanin biosynthesis regulation. Vitis vinfera L.cv. ‘merlot’ in four treatments: 300, 600 and 900 mg L−1 exogenous abscisic acid (ABA) were sprayed to clusters respectively on 50 days after full bloom, equal volume of distilled water were sprayed as control group. Grape samples were collected at five berry development stages from veraison to harvest. Anthocyanin quantification and characterization were detected by spectroscopy and HPLC. Quantitative real-time (qRT-PCR) was carried out to clarify the expression levels of structural and regulatory genes. Compared with the control group, 600 mg L−1 ABA significantly increased the content of Malvidin-3-O-glucoside after veraison. The content was 6.02 mg g−1 at fruit maturity, which was 1.45 times of the control. During ripening, the methoxylated pigments was enhanced by 300 and 600 mg L−1 ABA treatments. The expression of PAL, F3’H, F3’5’H, UFGT and MybA1 genes were positively induced by 600 mg L-1 ABA. The ratio changes between Delphinidin-3-acelylglucoside and Cyanidin-3-acelylglucoside were associated with the proportion of F3’5’H/F3’H gene expression. A positive correlation among anthocyanin contents and different sugars has been identified as well. Thus, ABA, sugars and relevant genes play the important roles on grape coloring and 600 mg L−1 ABA treatment was optimal for accumulating anthocyanins in ‘merlot’ grape.

Antioxidant activities and quantification of anthocyanins in some coloured grape hybrids

Antioxidant activities and quantification of anthocyanins in some coloured grape hybrids