Chip electrophoresis as a novel approach to measure the polyphenols reactivity toward human saliva

Abstract

Saliva is a biological fluid with a multifunctional role that makes it interesting in terms of research and diagnostic possibilities. In food research, human saliva represented a useful tool by which we measure the tactile sensation elicited by polyphenol-rich beverages called astringency. A method based on SDS-PAGE analysis of saliva before and after the binding reaction with wine polyphenols has been successfully used in previous studies for measuring wine astringency by means of the saliva precipitation index. In this work, chip electrophoresis was used alternatively to SDS-PAGE and results were compared. Chip electrophoresis provides a very good reproducibility for wine and grape astringency. Moreover, this approach is much faster than the conventional SDS-PAGE method requiring several hours for an analysis. Another advantage over traditional gel is lower sample and reagent volume requirements, as well as the lower and less toxic wastes, contributing benefits to health and environment. The application of this novel method allowed, using the principal component analysis, to distinguish grapes and wines according to the saliva precipitation index and structural characteristics determined by the phoroglucinolysis analysis.

Transfer of tannin characteristics from grape skins or seeds to wine-like solutions and their impact on potential astringency

“…From the obtained Pearson correlation matrix (p < 0.05), the SPI was positively related to the PAs concentration (mg/L) (R ¼ 0.968), to the %G (R ¼ 0.954), to the %exECG (R ¼ 0.940), to the %exC (R ¼ 0.817), and negatively to %P (R ¼ À0.724) and to % tC (R ¼ À0.927). This confirms the observations previously made on salivary protein precipitation and seed tannin characteristics (Rinaldi, Iturmendi, et al, 2014;.…”

“…In Fig. 1A and B are shown the electrophoretic patterns of salivary proteins before (saliva) and after the interaction of human saliva with NSk and MSk tannins of Aglianico, Merlot and Cabernet Sauvignon, obtained by chip electrophoresis (Rinaldi, Iturmendi, et al, 2014).…”

“…The SPI was obtained by the chip electrophoresis of human saliva before and after the binding assay (Rinaldi, Iturmendi, et al, 2014). Quantitative data were obtained by the interpolation of the relative decrease of fluorescence of selected proteic bands versus the concentration of tannin B (Biotan, Laffort, France) expressed in gallic acid equivalent (GAE, g/L).…”

Effect of Different Enological Tannins on Oxygen Consumption, Phenolic Compounds, Color and Astringency Evolution of Aglianico Wine

“…After this period, wine tannins bound to proteins were separated from supernatant by centrifugation (10 min 10,000 g at 4 °C), which was analyzed by chip electrophoresis. The commercial Experion Pro260 analysis kit (Bio-Rad, Milano, Italy) and Experion system were used for the SPI determination, as described by Rinaldi et al, 2014 [ 49 ]. The SPI was calculated by the percentage reduction in the fluorescence signal of salivary proteins with respect to control saliva (before reaction).…”

Evolution of Sangiovese Wines With Varied Tannin and Anthocyanin Ratios During Oxidative Aging

“…The saliva samples (before and after the binding reaction) were treated with the Experion reagents in accordance with the instructions, and then separated on the Experion automated electrophoresis station according to the manual instruction. The SPI was calculated by the percentage reduction of the fluorescence signal of salivary proteins compared to control saliva (before reaction) (Rinaldi et al, 2014 ). Results are expressed as mg/L of gallic acid equivalent (GAE).…”