Effect of ripeness and postharvest storage on the evolution of colour and anthocyanins in cherries (Prunus avium L.)

The relationship between colour parameters and anthocyanins of four sweet cherry cultivars, Burlat, Saco, Summit and Van was studied. The colour (L^∗, a^∗, b^∗, chroma and hue angle parameters) and anthocyanins were analysed during two different years at two different ripening stages (partially ripe, and ripe, respectively). The cherries were analysed at harvest and after storage at 1.5 ± 0.5 °C and 15 ± 5 °C for 30 and 6 days, respectively. The colour was measured by tristimulus colourimetry (CIELAB system) directly on the fruits, while anthocyanins were quantified by HPLC-DAD analysis on methanolic extracts of freeze-dried samples of the fresh cherries and on the differently stored cherries. L^∗, chroma, and hue angle values were always lower for the ripe than for the partially ripe cherries. All of the cultivars were found to contain cyanidin-3-rutinoside and cyanidin-3-glucoside as the major anthocyanins. The total anthocyanin content in fruits of the different cultivars varied in the order Burlat > Saco > Van > Summit. The concentration of anthocyanins increased at both temperatures of storage in both ripe and partially ripe cherries, but the extent of increase varied among cultivars. Cherries stored at 15 ± 5 °C showed higher reduction of L^∗, chroma and hue angle than fruits stored at 1.5 ± 0.5 °C. L^∗, a^∗, b^∗, chroma and hue angle correlated negatively (P < 0.001) with the total anthocyanins levels, but not with the total phenols. These results show that chromatic functions of chroma and hue correlate closely with the evolution of colour and anthocyanins levels during storage of sweet cherries and indicate that colour measurements can be used to monitor pigment evolution and anthocyanin contents of cherries (and vice versa).     

Influence of the elimination and addition of seeds on the colour,phenolic composition and astringency of red wine

Several winemaking techniques have been developed to eliminate seeds to prevent the release of high amounts of very astringent proanthocyanidins, especially when the grapes are unripe. However, there is no scientific information on the effects of this practice. The aim of this paper is to study how the elimination and addition of seeds influence the colour, phenolic composition and astringency of red wine. The elimination of around 80% of the seeds led to a significant decrease of colour intensity and anthocyanin concentration. The addition of seeds originated wines with a greater concentration of total anthocyanin, but did not significantly affect the wine colour. These wines also presented significantly higher levels of proanthocyanidins, a greater proportion of epicatechin-3-gallate, a lower mean degree of polymerization, and, in particular, a drastic increase in astringency. Wines obtained with the elimination of seeds, on the other hand, had exactly the opposite characteristics.     

Increase of trans-resveratrol in typical Sicilian wine using β-Glucosidase from various sources

β-Glucosidase (EC 3.2.1.21) (β-G) from different sources were tested to increase the trans-resveratrol in some Sicilian wines by hydrolysing resveratrol glucoside. β-G from Aspergillus niger mould was tested as a crude and purified enzyme, and compared with the same enzyme from Saccharomyces cerevisiae yeast. Specific purification served to eliminate collateral enzyme activities so that β-G could be used simply and economically. Aspergillus niger β-G produced trans-resveratrol increases of up to 75%, with no change in physico-chemical properties and bouquet, and an increase in health and nutritional properties. S. cerevisiae β-G raised free-terpenol levels, but impaired wine colour due to anthocyanase activity.     

Evolution of polyphenolic compounds in red wine from Cabernet Sauvignon grapes processed by pulsed electric fields during aging in bottle

The evolution of the Folin–Ciocalteu index, colour intensity and the principal individual polyphenols throughout 12 months of aging in bottles of red wine from Cabernet Sauvignon grapes treated and untreated by pulsed electric fields (PEF) have been compared. PEF technology allowed bottling of wines with higher Folin–Ciocalteu index, colour intensity and individual polyphenols concentrations using a shorter maceration time. For both wines, aging did not affect the colour intensity, whereas the Folin–Ciocalteu index decreased. The evolution of the principal individual polyphenols during the 12 months of storage followed a similar pattern in both wines. At the end of aging, there were no significant differences observed in the content of monomeric anthocyanins between both wines, however, the content of flavan-3-ols, flavonols and hydroxycinnamic acids and derivatives was higher in PEF treated wine. These results indicate that PEF could be a suitable technology for obtaining wines with higher phenolic content or reducing the maceration time during vinification.     

Effect of thermal treatment on glucosinolates and antioxidant-related parameters in red cabbage (Brassica oleracea L. ssp. capitata f. rubra)

The effects of various thermal processing treatments (blanching, boiling and steaming) of red cabbage, Brassica oleracea L. ssp. capitata f. rubra cv. ‘Autoro’, were assessed for the levels of glucosinolates (GLS), total phenols (TP), total monomeric anthocyanins (TMA), l-ascorbic acid (L-AA) and soluble sugars, as well as for the antioxidant potential by the ferric reducing ability power (FRAP) and oxygen radical absorbance capacity (ORAC) assays. Individual native GLS were determined by ion-pair HPLC-MS/DAD. There were significant (p < 0.05) losses in blanched red cabbage: TP, 43%, TMA 59%, FRAP 42%, ORAC 51%, L-AA 48% and soluble sugars 45%. Boiling gave less extensive reductions: TP 16%, TMA 41%, FRAP 17%, ORAC 19%, L-AA 24% and soluble sugars 19%. Steaming caused no losses for TP, ORAC, FRAP or soluble sugars. However, significant reductions were found for TMA and L-AA, with 29% and 11%, respectively. In general losses were accounted for in the processing waters; however, TMA was not fully recovered, indicating degradation. Total GLS were severely affected by processing, with reductions of 64%, 38% and 19% in blanched, boiled and steamed red cabbage, respectively. Total aliphatic and indole GLS were similarly affected. Lost GLS were partially recovered in the processing water.     

Phenolic compounds in strawberry (Fragaria x ananassa Duch.) fruits: Composition in 27 cultivars and changes during ripening

Phenolic compounds in fruits of 27 cultivars of strawberry (Fragaria x ananassa Duch.) grown in Norway were characterised and quantified by HPLC-DAD-MSⁿ. Total phenolic content, calculated as the sum of the individual compounds, varied 2.3-fold among cultivars, i.e., from 57 to 133 mg/100 g of fw. There were significant differences among cultivars in concentration of all phenolic compounds. The highest variation between cultivars was found for cinnamoyl glucose (0.6-24.9 mg/100 g of fw). Concentration of anthocyanins, the most abundant class of phenolic compounds in the majority of the cultivars, varied from 8.5 to 65.9 mg/100 g of fw. Flavan-3-ols (11-45 mg/100 g of fw) and ellagitannins (7.7-18.2 mg/100 g of fw) contributed on average 28% and 14% to total phenolic contents in the strawberry cultivars, respectively. In three cultivars harvested at three stages of ripeness, anthocyanins and cinnamic acid conjugates were the compounds most affected by ripening. The anthocyanin profile for the individual cultivars was only slightly affected by ripening and growing conditions.     

Quali-quantitative analysis of flavonoids of Cornus mas L. (Cornaceae) fruits

The methanol extract obtained from the ripe fruits of Cornus mas L. (Cornaceae) have been phytochemically studied. On the basis of HPLC–PDA–MS/MSⁿ analysis eight compounds have been identified as quercetin, kaempferol, and aromadendrin glycosilated derivatives. Three major compounds have been also isolated by Sephadex LH-20 column chromatography followed by HPLC and characterised by NMR spectroscopy. Moreover, LC–PDA–MS analysis of the red pigment revealed the presence of three anthocyanins. The quantitative analysis of all compounds was reported.     

Quantitative analysis and recovery optimisation of flavonoids and anthocyanins in sugar-making process of sugarcane industry

Considering the possible comprehensive utilisation of bioactive constituents in the sugarcane industry, the flavonoids and anthocyanins in raw juice and various intermediate products within the sugar-making process were first analysed by HPLC-UV/DAD. The analysis was intended to reveal their distribution across the whole production chain. As their contents decreased during sugar production, a new strategy was developed and optimised to recover flavonoids and anthocyanins from raw juice, using A D141-type macroporous adsorptive resin for enrichment. The optimum process parameters were feeding with a pH value of 5.21, weight ratio of resin to crude sample of 20 (w/w), followed by adding 30% ethanol 3.57 times the column volume for anthocyanins with a flow rate of 1.69 bed volumes/h, then 100% ethanol 4.00 times the column volume for flavonoids with a flow rate of 2.36 bed volumes/h. Upon employing this method, an increase in efficiency was realised.     

Degradation kinetics and colour of anthocyanins in aqueous extracts of purple- and red-flesh potatoes (Solanum tuberosum L.)

The effect of pH and temperature on the stability and visual colour of aqueous anthocyanin (ACY) extracts from purple- and red-flesh potatoes was evaluated and compared to commercial ACY extracts from grape and purple carrot. Extracts from purple carrot and red-flesh potatoes showed higher stability than grape and purple-flesh potato extracts. Stability to pH (?3) and thermal degradation of extracts (pH 3) followed first-order kinetics. Changes in lightness and hue followed zero-order kinetics, while changes in chroma followed first-order kinetics. Degradation parameters such as t_1/2, k-, D-, z- and Q₁₀-values were determined. Extracts from red- and purple-flesh potatoes at pH 3 showed similar hues to FD&C Red #40 and red cabbage extracts, respectively. The visual colour of both potato ACY extracts was also affected by tinctorial strength. The use of purple- and red-flesh potatoes as a source of natural colorants shows potential use in the pH region around 3.