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Individual sugars were analyzed by high performance liquid chromatography (HPLC) in samples of apple juices obtained from the fruits of ‘Jonathan’, ‘Starkrimson’ and ‘Golden Delicious’ cultivars. Samples were harvested from the inside and the periphery of the crown, at different periods during fruits growth, from 7 to 144 days after full bloom (DAFB). Values from 0.42 to 14.33%, 0.29 to 4.06% and 0 to 4.28% were determined for fructose, glucose and sucrose, respectively. The values of fructose and glucose have increased significantly (p-1 being the most specific to sugars signals. FT-MIR coupled to partial least squares (PLS) calibration models for predicting individual sugars of apple juices were developed. The optimal regions and pre-treatments of the spectra were 900-1500 cm-1 and Savitzky Golay first derivative (d1) for fructose, 900-1200 cm-1 and d2 for glucose and 900-1200 cm-1 and standard normal variate for sucrose. In cross-validation, the PLS calibration models showed very good performance for fructose (Rcval2=0.95; standard error of cross-validation (SECV) =0.907) and acceptable for glucose (Rcval2=0.85; SECV=0.424), while for sucrose showed only satisfactory performance (Rcval2=0.75; SECV=0.561). For practical relevance, the FT-MIR predicted values were compared against the HPLC determined reference values in external validations tests. The best results were achieved for fructose (Rp2=0.94; RPD=4.9), while glucose (Rp2=0.84; RPD=2.61) and sucrose (Rp2=0.7; RPD=2.08) models reached satisfactory values.

The study was aimed to characterize the chemical composition and the antimicrobial activity of Romanian propolis ethanolic extracts (EEP) against antibiotic-sensitive and antibiotic-resistant E. coli strains isolated from bovine mastitis. The preliminary antimicrobial screening was performed by a disk diffusion method, followed by determination of minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) based on broth microdilution assay; further, the synergistic action of propolis with antimicrobial drugs was assessed by a disk diffusion method on agar containing subinhibitory concentrations of propolis. For the chemical characterisation of EEP, the flavonoids (flavones/flavonols, flavanones/dihydroflavonols) and total phenolics were evaluated by spectrophotometric methods. The phenolic compounds of these extracts were also determined using HPLC. The results indicated for Romanian propolis ethanolic extracts the typical poplar composition profile with flavonoids and phenolic acids as main biological active compounds, with chromatographic analysis data confirmed also spectrophotometrically. In addition, positively correlated with the chemical composition, a strong antimicrobial efficacy was exhibited towards E. coli strains, along with interesting synergistic interaction with antibiotics that can be further investigated to obtain propolis-based formulation with antibacterial properties. Subsequent in vitro and in vivo studies evaluating the safety and efficacy are intended to consider propolis in veterinary therapeutic protocols.