A combination of Fourier-transform infrared spectroscopy (FTIR) and multivariate statistics was applied as screening tool for the quantitative determination of carbohydrates, such as glucose, fructose and sucrose, in 28 processed commercial fruit juices and 5 genuine juices obtained from squeezed fruits. A number of 13 mixtures of glucose, fructose and sucrose standard solutions were prepared at different concentrations, scanned by attenuated total reflectance (ATR) FTIR spectroscopy and analyzed in the 900 and 1400 cm−1spectral range. Principal component analysis (PCA) of the standard carbohydrate solutions enabled a better understanding of the main sources of variability affecting the FTIR spectra. Also, PCA enabled the grouping of apple, orange and peach juices. Calibration models for each carbohydrate, using partial least squares (PLS) regression were developed and used for prediction purposes. Cross-validation procedures indicated correlations of 0.88, 0.92 and 0.98 for glucose, fructose and sucrose, respectively, between HPLC measured values and FTIR first derivative spectra estimates. Carbohydrates in the expected concentration ranges were found for most of the pure fruit labelled juices. The samples with 4–50% pure fruit juice content showed discrepancies from average concentration values of authentic juices, mainly a high sucrose concentration can flag sucrose addition to maintain the juice sweetness intensity. The present results confirmed the efficiency of FTIR spectroscopy, in combination with multivariate statistics, as a rapid, reliable and cost-effective tool for routine monitoring of multiple constituents in fruit juices, as quality indicators.

Our study aimed to compare the phenolic and flavonoid composition of two medicinal plants from the wild flora of Romania, traditionally known to be efficient in preventing cardiotoxicity: Cornus mas and Crataegus monogyna. As most previous studies have focused on fruits, our investigations aimed to fingerprint and quantify the two classes of compounds in aqueous leaf extracts, based on HPLC-DAD-ESI(+)MS analysis. The specific HPLC-DAD fingerprint was coupled with UV spectra at 280 and 340 nm to discriminate between three subclasses of compounds: two hydroxycinnamic acids and a flavonoid glycoside. While the C. monogyna extract contained more than 98% vitexin isomers (2'-and 4'-O-rhamnoside), the C. mas extract was very complex, containing a mixture of phenolic derivatives and flavonoid glycosides. The spectral patterns of C. mas, combined with the molecular mass and specific fragmentations allowed the identification of epi-catechin, coumaric and caffeic acids and quercetin derivatives. Based on LC-MS peak area and parallel calibrations with gallic acid and rutin, the mean concentration for flavonoids in C. mas was 13 mg/100 ml, while aprox. 65 mg/100 ml in C. monogyna extracts. Using the Folin method, the total phenol content was 105 mg/100 ml in C. mas and around three times less in the C. monogyna extract, while the antioxidant activity was increased only 1.5-1.7 times in C. mas extract compared to C. monogyna. These findings suggest a higher stability and potential of flavonoids to act as antioxidants in hydrophilic environment.

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Berry fruits are known to be a rich source of natural compounds which provide them many health benefits. The most common compounds that occur in berries are vitamins, flavonoids, anthocyanins and phenolic acids. The objective of this work was to identify and compare the phenolic acids, flavonol glycosides content and antioxidant potential in blueberry, blackberry, raspberries and cranberries. Berries methanolic extracts were analyzed by HPLC/PDA-ESI/MS. Antioxidant activity was determinate using FRAP assay. Antioxidant activity of analyzed berries varied considerably. Blueberry extract demonstrated the highest ferric reducing antioxidant potential (48.3 μM Fe 2 /g) while lower values were obtained for cranberries extract (19.6 μM Fe 2 /g). Berries extracts were characterized by the presence of 16 compounds in different ratios. Blueberry extract was characterized by the presence of a large amount of phenolic acids such as chlorogenic and caffeic acid while raspberries extract was found to have high amount of ellagic acid. All analyzed berries contain higher levels of bioactive compounds which are responsible for their antioxidant potential. Based on quantitative analysis of phenolics these fruits can be highly recommended for daily consumption.

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