Application of abscisic acid (S-ABA) at different stages of ripening on color development of ‘Rubi’ table grape

The color of the berries is an important aspect of the quality of table grapes and crucial for marketing. The ‘Rubi’ table grapes grown in the subtropical climate generally lack color intensity due to the inhibition of anthocyanins by high temperatures during ripening. The exogenous application of abscisic acid (S-ABA) can be used to overcome this problem as the accumulation of anthocyanins in the berry skin is regulated by this plant growth regulator. The objective of this study was to assess the effect of the exogenous application of S-ABA at different stages of ripening on color development in ‘Rubi’ table grapes using the soluble solids (SS) content as a marker of ripening. The study was conducted during two seasons in commercial vineyards. The first trial was conducted in Marialva, Parana, Brazil, during the 2019 summer season crop (harvest in December). S-ABA (400 mg L-1) was exogenously applied at different stages of ripening of ‘Rubi’ table grapes (determined by the SS content of the berries): control (without application); SS = 8-9 ºBrix; SS = 10-11 ºBrix; SS = 8-9 ºBrix (two applications; the second one applied 10 days after the first); and SS = 10-11 ºBrix (two applications; the second one applied 10 days after the first). The second trial was conducted in Cambira, Parana, Brazil, during the 2020 off-season crop (harvest in May). S-ABA (400 mg L-1) was exogenously applied at different stages of ripening of ‘Rubi’ grapes: control (without application); SS = 6-7 ºBrix; SS = 7-8 ºBrix; SS = 9-10 ºBrix; SS = 6-7 ºBrix (two applications; the second one applied 14 days after the first); SS = 7-8 ºBrix (two applications; the second one applied 14 days after the first); and SS = 9-10 ºBrix (two applications; the second one applied 14 days after the first). A randomized block design was used as the statistical model with four replications, and each plot consisted of one vine. The variables analyzed were total anthocyanin contents, color index (CIRG), and color attributes (L*, C*, h°, and ΔE) of berry skin. The total anthocyanin accumulation and color attributes of the berries were evaluated every 10 and 7 days after the first application of S-ABA until harvest in the first and second trials, respectively, and the other variables were evaluated at harvest. In the summer-season crop, when the SS content was 8-11 ºBrix, the application of S-ABA increased the concentration of the total anthocyanins 4 times compared to that in the control, improving berry color development. Furthermore, in the off-season crop, when the SS content was 6-10 ºBrix, the application of S-ABA increased the concentration of total anthocyanins 2-3 times compared to that in the control, improving the color attributes of berries. In both crops, a single application of the plant growth regulator was sufficient to intensify the color of the berries.

Physicochemical and sensorial characterization of yacon mixed juice with bioactive properties

ABSTRACT: This study developed a palatable, acceptable, and functional mixed juice of pineapple (Ananas comosus var. Comosus), passion fruit (Passiflora edulis flavicarpa degener), and yacon (Smallanthus sonchifolius), with enhanced bioactive and prebiotic compounds. The ideal proportion of fruit and yacon was derived after planning a mixture with six formulations and by evaluating their bioactive compounds and organic acid profile. The best formulation sensory evaluation was performed by the Just-About-Right test (JAR) and global acceptance. The chosen mixed juice (M6 - 30% pineapple, 45% passion fruit, and 30% yacon) presented results that showed elevated levels of antioxidant activity (82.5% DPPH* inhibition), carotenoids (0.97 mg.100g-1), and total polyphenols (70.28 mg.100g-1). Total flavonols (23.95 mg.100g-1), total anthocyanins (1.37 mg.100g-1), gallic acid (3.13 μg.mL-1), quercetin (2.25 μg.mL-1), syringic acid (1.01 μg.mL-1), citric acid (949.30 mg.100g-1), malic acid (140.35 mg.100g-1), and 0.58% of dietary fiber were also reported. Sensorially, consumers perceived high acidity, strong flavor, and a fibrous texture, which might have affected the global acceptance of the juice (6.0). Results indicated the feasibility of obtaining a functional and palatable mixed juice using yacon.

Bioaccessibility of Antioxidants in Blackcurrant Juice After Treatment Using Supercritical Carbon Dioxide

Blackcurrant juice (Ribes nigrum L.) was subjected to supercritical carbon dioxide (SCCD) at 10, 30 and 60 MPa for 10 min at 45°C as well as thermally treated at 45°C and 85°C for 10 min to determine the stability, antioxidant capacity (AC) and bioaccessibility (BAc) of vitamin C, total anthocyanins and their individual monomers. An in vitro gastrointestinal digestion model completed with dialysis was used to assess BAc. The use of SCCD at each of the pressures applied improved the stability of vitamin C, total anthocyanins, and AC before in vitro digestion. As a result of digestion, L-ascorbic acid was oxidized to L-dehydroascorbic acid, and finally, the total content of vitamin C, anthocyanins, and AC decreased. SCCD did not significantly improve the BAc of vitamin C and total anthocyanins. The highest BAc of vitamin C was noted in fresh juice (FJ) (40%) and after mild heat treatment at 45°C (T45) (46%). The highest BAc of total anthocyanins was also noted in the FJ (4.4%). The positive effect of the application of SCCD on the BAc of the delphinidin-3-O-glycosides was observed compared to T45 and thermal pasteurization at 85°C (T85). Moreover, cyanidins were generally more bioaccessible than delphinidins in all samples. AC after digestion was higher in SCCD samples compared to thermally treated measured using ABTS+• and DPPH• assays, whereas in dialysate similar trends were observed only for AC measured using the ABTS+• assay. This phenomenon was justified by the formation of individual metabolites detected by UPLC-PDA-MS / MS in the model experiment with delphinidin-3-O-rutinoside. The protocatechuic acid which is well known as a strong antioxidant was detected in the model experiment after digestion. Further research is needed to better understand the metabolic pathway of anthocyanins and the possible uses of SCCD to improve the health properties of fruit products.

Cryoconcentration by Centrifugation–Filtration: A Simultaneous, Efficient and Innovative Method to Increase Thermosensitive Bioactive Compounds of Aqueous Maqui (Aristotelia chilensis (Mol.) Stuntz) Extract

Maqui (Aristotelia chilensis (Mol.) Stuntz) is a Chilean berry rich in antioxidants, which are mostly found in the pulp and skin of the fruit. The objective was to evaluate the cryoconcentration process by centrifugation–filtration as a simultaneous, efficient, and innovative method to increase the content of thermosensitive bioactive compounds of aqueous maqui extract. Cryoconcentration separated the concentrated solute from the aqueous maqui extract with an efficiency of more than 95%; it increased the content of total polyphenols and total anthocyanins and antioxidant capacity by 280%, 573%, and 226%, respectively. Although the concentrates obtained by evaporation at 50, 70, and 80 °C increased the content of bioactive compounds, they did so in a lower percentage than the cryoconcentrate. Furthermore, cyanidin 3,5-diglucoside was degraded at 70 and 80 °C. In conclusion, cryoconcentration by centrifugation–filtration as a simultaneous process efficiently separates the solutes from the frozen matrix of aqueous maqui extract, and it maintains and increases the contents of polyphenols and anthocyanins and antioxidant capacity. This method is recommended for concentrating natural berry extracts with thermosensitive compounds.

Phenolic Compound Content and the Antioxidant and Antimicrobial Activity of Wild Blueberries (Vaccinium stenophyllum Steud.) Fruits Extracts during Ripening

The genus Vaccinium contains about 400 species distributed worldwide, but only a few species and varieties have had their phenolic composition and biological activity documented. In this study, phenols, flavonoids, anthocyanins, antioxidant and antimicrobial activity of methanolic extracts of Vaccinium stenophyllum Steud. fruits: 1-totally immature, 2-immature, 3-immature/close to maturity and 4-mature, were determined using UV-Visible spectrometry and HPTLC. The totally immature fruit extract showed the highest content of total phenols (19.153 ± 0.175 mg GAE/g DW), chlorogenic acid (20.867 ± 0.240 mg CAE/g DW), and the highest antioxidant activity by ABTS●+ (196.761 ± 0.641 µM TE/g DW) and DPPH● (146.580 ± 6.466 µM TE/g DW). Immature, immature/close to maturity and mature fruits extracts, exhibited the lowest MIC (9.37 mg/mL) and MBC (18.75 mg/mL) against Escherichia coli, Salmonella choleraesuis, and Shigella flexneri. The mature fruits extract exhibited the highest content of total anthocyanins (0.141 ± 0.004 mg CE/g DW) and cyanidin-3-glucoside (19.230 ± 0.309 mg CGE/g DW). The content of phenols, flavonoids and anthocyanins was higher than that reported for other Vaccinium species. These results showed the relevance of Vaccinium stenophyllum Steud. for breeding purposes to enhance the bioactivity of cultivars, or as a source of natural additives for the food industry, among others.

Ripening and fruit quality of ‘Fortune’ plums treated by pre-harvest application of ripening stimulants

The use of plant growth regulators that increase ethylene production is a common strategy to anticipate fruit ripening, increase peel color, and reduce the number of collections to complete the harvest of the fruits. Besides, this strategy may come true as a helping technique for the farmers to reduce costs with manpower, increasing overall profitability. This work aimed to evaluate the application of several concentrations of ethephon, associated with boric acid, on the anticipation of ripening of ‘Fortune’ plums, cultivated in Serra Gaúcha region, South Brazil. The study was carried out in a commercial orchard during the 2018-2019 and 2019-2020 harvests. It was used a completely randomized design with six treatments and four replicates; each replicate was composed of four plants. The following parameters were evaluated: the amount of fruits collected in each harvest, average fruit mass, diameter, length, firmness, soluble solids content, titratable acidity, SS/TA ratio, total phenolic compounds, and total anthocyanins. According to the results, the application of ethephon was capable of hastening and homogenizing partially plum ripening, but it also caused a reduction of anthocyanin and phenolic compounds contents and fruit firmness. On the other hand, the application of boric acid increased fruit firmness. From an economic standpoint, the pre-harvest application of ethephon may be interesting to reduce manpower requirements during harvest by an earlier harvest and by reducing the number of harvest cycles.

Structural identification and in vitro antioxidant activities of anthocyanins in black chokeberry (Aronia melanocarpa Elliot)

Anthocyanins is a natural edible pigment with many health benefits. The aim of this work was the identification of anthocyanins present in <i>Aronia melanocarpa</i> using mass spectrometric features. The anthocyanins of the <i>A. melanocarpa</i> were analyzed by UV-Vis, HPLC-DAD and LC-EIS/MS methods. The four important anthocyanins were identified as follows: cyanidin-3-galactoside (68.68%), cyanidin-3-arabinoside (25.62%), cyanidin-3-glucoside (5.28%) and cyanidin-3-xyloside (0.42%). Among the four anthocyanin monomers, three anthocyanins with the highest content of <i>A. melanocarpa</i> were selected, and the antioxidant activity was studied with the total anthocyanins. The antioxidant capacity was cyanidin-3-galactoside > total anthocyanin > cyanidin-3-arabinoside > cyanidin-3-glucoside. The activity of the four anthocyanin samples was greater than ascorbic acid. The methodology described in this study will provide an effective tool for anthocyanins identification. Our results suggested that anthocyanins from <i>A. melanocarpa</i> exhibited effective antioxidant activity. These findings may be crucial in future research concerning chokeberry based functional food products.

Effects of Storage Conditions on the Total Content of Anthocyanins and Degradation of Phenolic Compounds During Long Storage of Pomegranate Fruit (Punica Granatum L.)

Effects of storage temperature, elevated CO2 and reduced O2 in the package headspace, packaging material, and their interactions on the total content of anthocyanins and degradation of phenolic compounds in ‘Malase Torsh Saveh’ pomegranate were studied during long storage. The results showed that only storage temperature and its duration had significant effects on the degradation of phenolic compounds. The content of anthocyanins was affected by the single effect of storage time and its 3-way interaction effect with the storage temperature and the surrounding gas composition. Higher amounts of both total anthocyanins and browning pigments were recorded at 2 °C. The Browning index (BI) of the pomegranate extracts changed quadratically with the variations in the total anthocyanins content and linearly with the variations in the content of browning compounds. Thermal dipping treatment and its interaction with the storage time significantly affected the BI values of modified atmosphere packaged pomegranates stored at 6 °C.

Phenolic Profile and Antioxidant Capacity of Selected Medicinal and Aromatic Plants: Diversity upon Plant Species and Extraction Technique

Phenolic content and antioxidant capacity (AC) was evaluated in extracts of bay, sage and thyme leaves, myrtle leaves and berries, and sea buckthorn berries obtained by conventional (CE) and advanced extraction techniques [ultrasound-assisted (UAE) and accelerated solvent extraction (ASE)] using 80% acetone (v/v) as extraction solvent. Extracts were analyzed for phenolic content using UPLC/ESI MS2 and AC by ORAC method. Results indicated the variations in the phenolic composition and concentrations among analyzed plant species and applied extraction methods. Flavonoids showed to be the predominant phenolic group represented by flavonols kaemferol-3-O-hexoside (182.58–321.45 mg 100−1 g dm) and quercetin-3-glucoside (253.05–315.67 mg/100 g dm) in bay leaves, by flavonol isorhamnetine-3-O-hexoside (27.76–45.16 mg/100 g dm) in sea buckthorn berries and by flavone luteolin-7-O-glucoside (470.27–781.78 mg/100 g dm) in sage leaves. Among the phenolic acids, hydroxybenzoic acids and their derivates were the predominant phenolic group in thyme leaves and myrtle. Statistical analysis showed that ASE contributed to the highest content of total flavonols, flavones, hydroxycinnamic and hydroxybenzoic acids as well as AC. CE was more efficient method for the extraction of total flavan-3-ols, while UAE showed the highest efficiency in extraction of total anthocyanins. Analyzed plant extracts proved to be a rich source of various phenolics and results indicated suitable extraction methods for target phenolic compounds characteristic for certain plant species.