Monitoring the Effect of Micro-oxygenation before Malolactic Fermentation on South African Pinotage Red Wine with Different Colour and Phenolic Analyses

Abstract

The use of micro-oxygenation and its effect on the quality of the red wine varietal, Pinotage, is largely unknown. The influence of adding different oxygen dosages before malolactic fermentation on the phenolic composition and colour stabilisation of wine made from Pinotage was studied, and the suitability of certain spectrophotometric and RP-HPLC analyses to determine these changes were assessed in tanks of commercial lengths. Total oxygen dosages of 0 mg/L, 16 mg/L and 32 mg/L were applied, after which the wines underwent malolactic fermentation and maturation in the same tanks for two additional months. Decreases in anthocyanin concentration showed a strong inversely proportional correlation with increasing polymeric pigment concentration. This suggests that the addition of oxygen contributed to the early stabilisation of wine colour in Pinotage red wine. Overall, tannin concentrations were not significantly influenced by the oxygen treatments, although lower levels were observed in wines treated with oxygen. An important finding of the study was that there appeared to be little difference in the colour and phenolic composition of the wines between the 16 mg/L and 32 mg/L oxygen treatments. Good correlations were found between certain spectrophotometric techniques and the RP-HPLC analysis used to study changes induced by micro-oxygenation (total anthocyanins, total phenols). The colour and phenolic composition of Pinotage wine can be influenced before malolactic fermentation by micro-oxygenation. Some spectrophotometric phenolic analyses showed the same tendencies as observed with RP-HPLC (anthocyanins, monomeric flavan-3-ols, tannins), indicating their suitability to follow phenolic and colour changes induced by micro-oxygenation in Pinotage red wine.

he Impact of Different Tannin to Anthocyanin Ratios and of Oxygen on the Phenolic Polymerisation Over Time in a Wine-like Solution

“…When the samples were coloured according to the C/Ox treatment, the samples were distributed along the PC2 axis (21.3%), with Ox samples being characterised by a generally higher phenolic and especially tannin concentrations (Figures 2 and 3). Contrary to the findings of Geldenhuys et al (2012), oxygen was also found to play an important role in tannin concentrations (Figure 2 A3). However, Geldenhuys et al (2012) applied progressive micro-oxygenation, whereas in this study a large amount of oxygen was added at a time.…”

“…Contrary to the findings of Geldenhuys et al (2012), oxygen was also found to play an important role in tannin concentrations (Figure 2 A3). However, Geldenhuys et al (2012) applied progressive micro-oxygenation, whereas in this study a large amount of oxygen was added at a time. A general loss of colour and reduction in phenolic levels was found over time, especially pronounced from 0 M (Table 1) to 3 M, except for the total tannin concentration as determined by the MCP method (Figure 3).…”

Evaluation of grape and wine quality parameters of Agiorgitiko (Vitis vinifera K. cv.) cultivar qrown in Nemea

“…In Table 4.9 are presented the results of the spectrophotometric analyses of wine phenolic compounds. The phenolic content in DMAC index ranged from 231.11 (Vin 9, 2013) to 1104.46 mg/l of catechin equivalents (Vin 8, 2012), with our results being similar to literature (Geldenhuys et al, 2012) for 2013 but twofold increased in 2012.…”

Effect of acetaldehyde addition on the phenolic substances and volatile compounds of red Tempranillo wines

“…() studied the effect of MOX at different SO 2 concentration values and reported a significant decrease in the monomeric anthocyanins and flavan‐3‐ol fractions in wines with a lower SO 2 concentration, together with an increase in the polymeric pigments (Geldenhuys et al. ) and in the concentration of tannins. After a MOX treatment a decrease in the total red pigments occurred, but the proportion of pigments in red form increased (Atanasova et al.…”