Screening of Antioxidant Properties of the Apple Juice Using the Front-Face Synchronous Fluorescence and Chemometrics

Abstract

Fluorescence spectroscopy is gaining increasing attention in food analysis due to its higher sensitivity and selectivity as compared to other spectroscopic techniques. Synchronous scanning fluorescence technique is particularly useful in studies of multi-fluorophoric food samples, providing a further improvement of selectivity by reduction in the spectral overlapping and suppressing light-scattering interferences. Presently, we study the feasibility of the prediction of the total phenolics, flavonoids, and antioxidant capacity using front-face synchronous fluorescence spectra of apple juices. Commercial apple juices from different product ranges were studied. Principal component analysis (PCA) applied to the unfolded synchronous fluorescence spectra was used to compare the fluorescence of the entire sample set. The regression analysis was performed using partial least squares (PLS1 and PLS2) methods on the unfolded total synchronous and on the single-offset synchronous fluorescence spectra. The best calibration models for all of the studied parameters were obtained using the PLS1 method for the single-offset synchronous spectra. The models for the prediction of the total flavonoid content had the best performance; the optimal model was obtained for the analysis of the synchronous fluorescence spectra at Δλ = 110 nm (R 2 = 0.870, residual predictive deviation (RPD) = 2.7). The optimal calibration models for the prediction of the total phenolic content (Δλ = 80 nm, R 2 = 0.766, RPD = 2.0) and the total antioxidant capacity (Δλ = 70 nm, R 2 = 0.787, RPD = 2.1) had only an approximate predictive ability. These results demonstrate that synchronous fluorescence could be a useful tool in fast semiquantitative screening for the antioxidant properties of the apple juices.

Effects of Apple Juice Manufacturing Processes on Procyanidin Concentration and Nondestructive Analysis by Fluorescence Fingerprint

“…These peaks can be related to chlorogenic acid and chlorophyll, respectively (Włodarska et al 2017). Another strong peak was observed at Ex/Em of 210/350 nm in both samples, which might be related to L(+)-ascorbic acid.…”

Bioactive Compounds and Physicochemical Properties of Fruit – Orange Juice Mixes with Rosemary Extract

“…Concerning the apple juice, it was reported that the TF content as determined by a spectrophotometric method was in the range of 42.33-298.7 mg CE/L with mean value and standard deviation of 134 69 (Wlodarska, 2017).. As a matter of fact, it may be suggested that the addition of orange juice to all tested fruit juices (1:1) may contribute to the enhanced level of flavonoid in the fruit juices, as the major phenolic compounds detected in different citrus fruits are categorized as flavonoids and phenolic acids (Pellegrini et al, 2003 andPeterson et al, 2006). Figure (3) also represents the anthocyanin content (mg/L) of all fruitorange juices with added RE and their controls.…”