No abstract

The effects of clarification agents and methods on pomegranate juice quality were studied. Fruits were pressed as whole, and extracted juice was clarified with gelatin, polyvinylypolypyrrolidone (PVPP) and natural sedimentation. In order to determine the effects of these clarifying techniques on product quality, pH, total phenolic substances (TPS), anthocyanin, turbidity, and total colour density tests were applied to each sample. In clarification, the main purpose was to reduce the amount of phenolic substances. Phenolic substances were controlled in each clarification method. The most effective method was the application of 1 g/L gelatine for clarification. Sensory evaluation also applied for clarified juices and gelatin application was selected by panelists to be superior.

Pomegranate juice powder is easier to handle and has more potential applications than the concentrate. In this study, the response surface, 3-level factorial design was used to evaluate the influence of spray-drying conditions on the physicochemical properties of a powdered product obtained by drying pomegranate juice concentrate (PJC). It was spray-dried with a lab-scale spray-dryer using 18 and 7 dextrose equivalent (DE) maltodextrins (MD) as drying-aid agents. Adding MD significantly reduced the hygroscopicity and stickiness of the pomegranate juice powder, and thus yielded higher recovery. The maximum achieved ratio of PJC ⁄ MD was 1 ⁄ 1, and it was obtained with the use of DE7 MD. However, graphical optimisation studies resulted in 125-145°C and 0.6-0.8 PJC ⁄ MD ratio as optimum variables to produce acceptable dried powder. The results indicated that increasing inlet air temperature increases solubility time and loss of anthocyanins and decreases bulk density and moisture content of the powder.

There is an increasing interest to bio-components obtained from fruit & vegetable wastes. Anthocyanin is one of the components regained from fruits especially from red ones. Sour cherry is considered as industrial fruit since most of the grown fruit is processed into juice and hence considerable amount of pomace is removed from process. The influences of process parameters on the extraction of phenolic compounds from sour cherry pomace were investigated. Fifty-one percent ethanol concentration, 75°C temperature and 12 mL/g solvent to solid ratio were selected as optimum process parameters. Time effect on the process efficiency was monitored at three different temperatures (25, 50 and 75°C) and total phenolic and total anthocyanin contents were found to reach equilibrium concentrations between 80 and 100 min time intervals. Ethanol concentrations affected differently extraction yield of anthocyanins and non-anthocyanin phenolics. Various individual phenolic compounds present in sour cherry pomace were identified and quantified by HPLC equipped with UV/ Vis PDA. Of the phenolic compounds, cyanidin-3-glucosylrutinoside, neochlorogenic acid and catechin were the most abundant ones found in the pomace. 14.23 ± 0.38 mg/g total phenolic, 0.41±0.02 mg/g total anthocyanin, 0.19 ± 0.02 mg/g cyanidin-3-glucosylrutinoside, 0.22 ± 0.01 mg/g neochlorogenic acid and 0.22±0.02 mg/g catechin contents (dry weight) were determined in the pomace at optimum extraction conditions.

Fourier transform infrared (FTIR) spectroscopy and chemometric techniques were used to detect the adulteration of pomegranate juice concentrate (PJC) with grape juice concentrate (GJC). The main differences between PJC and GJC infrared spectra occurred in the 1780-1685 cm À1 region, which corresponds to C@O stretching. Principal component analysis of the spectra was used to: (1) differentiate pure PJC and GJC samples and (2) classify adulterated (containing 2-14% vol/vol GJC) and pure PJC samples. Two principal components explained 99% of the variability in each of these applications. Partial least square analysis of the spectra resulted in prediction of the GJC adulterant concentration in PJC with a correlation coefficient, R 2 , of 0.9751. Partial least square analysis of spectra could also predict % titratable acidity and total solids in PJC with correlation coefficients of 0.9114 and 0.9916, respectively. Therefore, FTIR and chemometrics provide a useful approach for authenticating pomegranate juice concentrate.