 IVES 9 IVES Conference Series 9 Adsorption capacity of phenolics compounds by polyaniline materials in model solution

Adsorption capacity of phenolics compounds by polyaniline materials in model solution

Abstract

AIM: The aim of this work was to study the trapping capacity of four polyaniline polymers towards phenolic compounds in wine-like model solutions.

METHODS: The model wine solution was composed of 12% (v/v) and 4 g/L of tartaric acid adjusted to pH = 3.6. A series of centrifuge tubes (15 mL) were filled with 10 mL of model solution enriched with 50 mg/L of five phenolic compounds (i.e., Gallic acid, caffeic acid, (+)-catechin, (-)-epicatechin, and rutin), and treated with different doses of PANI polymer (i.e., 0, 2, 4 and 8 g/L). After the addition of the polymer, the samples were stirred using a platform shaker at room temperature (20 ºC) for 2, 8, 16 and 24 h. All treatments included three replications. The synthesis and characterization of polyaniline emeraldine base (PANI-EB) and different PANI 50, 100, 150 (polyaniline-PVPP composites where 50, 100, 150 are amount of PVPP) was prepared according to what was reported by Marican et al. (2014). Once the selected contact times were over, the samples were filtered and were by HPLC-DAD, following the methodology described by Gómez-Alonso et al. (2007). In brief, the separation was performed using a reverse-phased LiChrosorb® RP-18 (5 μm) column (250 mm × 4 mm ID) operating at 20 ºC. The injection volume was 25 μL, and for detection and quantification of compounds, the chromatograms were recorded at 280, 320 and 360 nm.

RESULTS: Regardless of the polymer used, the compounds having more affinity for PANI were gallic and caffeic acid, whereas rutin and (+)-catechin were the least removed. For instance, the adsorption percentage of gallic and caffeic acid, with a 4 g/L PANI concentration and 8 h of contact time, reached more than 90% whereas the removal of rutin was lower than 40%. Instead, the phenolic concertation of the samples where no polymer was added (0 g/L of PANI) remain stable over time, very close to 50 mg /L for each of the phenols evaluated. As expected, the concentration of the five phenols decreased as the contact time increased. As an example, a 2 g/L addition of PANI 50 produced a reduction of (-)-epicatechin concentration of 17 mg/L after 8 h of contact time and 25 mg/L after 24 h. Like so, the decrease in the concentration of all phenols was greater when more polymer was added.

CONCLUSIONS: The results obtained suggest that PANI Polymers could be an interesting alternative for analytical or experimental applications in which polyphenolcs need to be removed.

DOI:

Publication date: September 28, 2021

Issue: Macrowine 2021

Type: Article

Authors

María Navarro, JOHN AMALRAJ, V. FELIPE LAURIE

Talca University

Contact the author

Keywords

pani polymers, phenols, model wine solutions

Citation

What are the optimal ranges and thresholds for berry solar radiation for flavonoid biosynthesis?

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Extreme canopy management for vineyard adaptation to climate change: is it a good idea?

Climate change constitutes an enormous challenge for humankind and for all human activities, viticulture not being an exception. Long-term strategic changes are probably needed the most, but growers also need to deal with short-term changes: summers that are getting progressively warmer, earlier harvest dates and higher pH in musts and wines. In the last 10-15 years, a relevant corpus of research is being developed worldwide in order to evaluate to which extent extreme canopy management operations, aimed at reducing leaf area and, thus, limiting the source to sink ratio, could be useful to delay ripening. Although extreme canopy management can result in relevant delays in harvest dates, longer term studies, as well as detailed analysis of their implications on carbohydrate reserves, bud fertility and future yield are desirable before these practices can be recommended.

Effect of partial net shading on the temperature and radiation in the grapevine canopy, consequences on the grape quality of cv. Gros Manseng in PDO Pacherenc-du-vic-Bilh

As elsewhere, southwestern France vineyards face more recurrent summer heat waves these last years. Among the possibilities of adaptation to this climate changing parameter, the use of net shading is a technique that allow for limiting canopy exposure to radiations. In this trial, we tested net shading installed on one face of the canopy, on a north-south row-oriented plot of cv. Gros Manseng trained on VSP system in the PDO Pacherenc-du-Vic-Bilh. The purpose was to characterize the effects on the ambient canopy temperatures and radiations during the season and to observe the consequences on the composition of grapes and wines. Two sorts of net were used with two levels of obstruction (50% and 75%) of the photosynthesis active radiation (PAR). They have been installed on the west side of the canopy and compared to a netless control. Temperature and PAR sensors registered hourly data during the season. On specific summer day (hot and sunny) manual measurements took also place on bunches (temperature) and in different spots of the canopy (PAR). The results showed that, on clear days, the radiation is lowered by the shade nets respecting the supplier criteria. The effects on the ambient canopy temperature were inconstant on this plot when we observed the data from the global period of shading between fruit set and harvest. However, during hot days (>30°C), the temperature in the canopy was reduced during afternoon and the temperature of the bunch surface was reduced as well comparing to the control. A decrease of the maturity parameters of the berries, sugar and acidity, was also observed. Concerning the wine aromatic potential, no differences clearly appeared.

Short-term relationships between climate and grapevine trunk diseases in southern French vineyards

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Influence of agronomic practices in soil water content in mid-mountain vineyards

In the context of LIFE project MIDMACC (LIFE18 CCA/ES/001099), several pilots have been installed in vineyards in mid mountain areas of Catalonia (NE Spain) to test well stablished agronomic practices to increase the adaptation of Mediterranean mid mountain to climate change. Soil water content (SWC) at three different depths (15, 30 and 45cm) was measured in continuum from August 2020. One pilot (WC) included a well-established green cover (GC), a new GC (NC) and a conventional soil management (CM, tilling+herbicides). NC presented an intermediate state between WC and CM, responding similarly to CM in autumn but quickly reaching similar SWC to WC, then following the same evolution till next spring, with CM presenting lower values along autumn and winter. Then vegetation activation decreased SWC in all plots, (much slower in CM, lacking GC). Sensibility to spring rains is again intermediate for NC, which joins SWC evolution of CM by the end of spring till next autumn. It is expected that NC will resemble WC more and more as its GC develops. In the pilot combining vine training (VSP vs Gobelet) and hillside management (slope vs terrace), no clear pattern could be related with these conditions. However, both terraces seem to be more sensitive to spring rains. A third pilot included new vineyards (7 and 1 year old). In the new vineyard (N), higher canopy development, a spontaneous green cover and row straw resulted in a slower SWC dynamic, not so sensitive to rains but conserving more soil water in spring and most of summer, even with presumably a higher water extraction by vines. In the newest vineyard (VN) the deepest sensor is still sensitive to rain events all over the year and SWC is always highest at this depth, revealing small water capture by vines.