terclim by ICS banner
IVES 9 IVES Conference Series 9 CHANGES IN CU FRACTIONS AND RIBOFLAVIN IN WHITE WINES DURING SHORT-TERM LIGHT EXPOSURE: IMPACTS OF OXYGEN AND BOTTLE COLOUR

CHANGES IN CU FRACTIONS AND RIBOFLAVIN IN WHITE WINES DURING SHORT-TERM LIGHT EXPOSURE: IMPACTS OF OXYGEN AND BOTTLE COLOUR

Abstract

Copper in white wine can be associated with Cu(II) organic acids (Cu fraction I), Cu(I) thiol species (Cu fraction II), and Cu sulfides (Cu fraction III). The first two fractions are associated with the repression of reductive aromas in white wine, but these fractions gradually decrease in concentration during the normal bottle aging of wine. Although exposure of white wine to fluorescent light is known to induce the accumulation of volatile sulfur compounds, causing light-struck aroma, the influence on the loss of protective Cu fractions is uncertain. Riboflavin is known to be a critical initiator of photochemical reac-tions in wine, but the rate of its decay under short-term light exposure in different coloured bottles and for wine of different oxygen concentrations is not well understood. This study aims to gain insights into the rate of change in Cu fractions and riboflavin concentrations during the exposure of white wine with different oxygen concentrations and/or different bottle colours to light over a period of days to months.

A Chardonnay wine with an addition of 0.5 mg/L riboflavin, 0.3 mg/L Cu and different concentrations of oxygen (10 and 0.5 mg/L) was exposed to fluorescent light at 20°C in Flint coloured bottles. The wine was also investigated using other coloured bottles (Arctic blue, French green, Antique green and Amber) with the minimum oxygen concentration. The Cu fractions were quantified using colorimetry and riboflavin concentrations measured by ultrahigh-performance liquid chromatography. The results showed that for wine in Flint bottles with low oxygen, light exposure accelerated the decrease in Cu fraction I and II, with the change in Cu fraction I being most pronounced (i.e., a 10-fold decrease in 24 hours). In contrast, high oxygen concentrations resulted in no light-induced decrease in Cu fractions I or II. Riboflavin concen-trations became depleted after only 20 hours of irradiation under high oxygen concentrations, while 0.07 mg/L remained in the wine with low oxygen. The darker coloured wine bottles slowed the changes observed for Cu fractions and riboflavin from a minimum period of hours (i.e., for Flint bottles) to a maxi-mum period of months (i.e., for Amber bottles). Although light is known to induce light-struck aroma in wine, this study has demonstrated it can also accelerate the removal of protective fractions of Cu and this has implications for the general reductive development of wine.

DOI:

Publication date: February 9, 2024

Issue: OENO Macrowine 2023

Type: Article

Authors

Isara Vongluanngam1,2,3*, Xinyi Zhang1,2, John W. Blackman1,2, Leigh Schmidtke1,2,3, Kerry L. Wilkinson3,4, Andrew C. Clark1,2,3

1. School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Locked Bag 588, Wagga Wagga, NSW 2678, Australia
2. Gulbali Institute, Charles Sturt University, Wagga Wagga, NSW 2678, Australia
3. The Australian Research Council Training Centre for Innovative Wine Production, University of Adelaide (Waite Campus), South Australia 5064
4. Discipline of Wine Science and Waite Research Institute, The University of Adelaide, PMB 1, Glen Osmond, SA 5064, Aus-tralia

Contact the author*

Keywords

Riboflavin, Cu fractions, Wine bottle colour, Photo-degradation

Tags

IVES Conference Series | oeno macrowine 2023 | oeno-macrowine

Citation

Related articles…

AGEING REVEALS THE TERROIR OF AGED RED BORDEAUX WINES REGARDLESS OF THE VINTAGES! TARGETED APPROACH USING ODOROUS COMPOUNDS LEVELS INCLUDING TERPENES AND C13 NORISOPRENOIDS

The chemistry of wine is notably complex and is modified by ageing of the bottles. The composition of wines is the result of vine production (under the influence of vintage, climate and soils); yeast production (under the influence of juice composition and fermentation management); lactic bacteria production (under the influence of young wine composition and malolactic fermentation management); and of the ageing process either in vats, barrels or bottles or both. The composition is linked to the quality perceived by consumers but also to their origin, sometimes associated to the “terroir” concept.

Read More

INOCULATION OF THE SELECTED METSCHNIKOWIA PULCHERRIMA MP1 AS A BIOPROTECTIVE ALTERNATIVE TO SULFITES TO PREVENT BROWNING OF WHITE GRAPE MUST

Enzymatic browning (BE) of must is caused by polyphenol oxidases (PPOs), tyrosinase and laccase. Both PPOs can oxidize diphenols such as hydroxycinnamic acids (HA) to quinones, which can later polymerize to form melanins [1], which are responsible of BE in white wines and of oxidasic haze in red wines. SO₂ is the main tool used to protect must from BE thanks to its capacity to inhibit PPOs [2]. However, the current trend in winemaking is to reduce and even eliminate this unfriendly additive. Among the different possible alternatives for protecting must against BE, the inoculation with a selected Metschnikowia pulcherrima MP1 is without any doubt one of the most promising ones.

Read More

MODULATION OF YEAST-DERIVED AROMA COMPOUNDS IN CHARDONNAY WINES USING ENCAPSULATED DIAMMONIUM PHOSPHATE TO CONTROL NUTRIENT RELEASE

Yeast-derived aroma compounds are the result of different and complex biochemical pathways that mainly occur during alcoholic fermentation. Many of them are related -but not limited- to the availability of nutrients in the fermentation medium and linked to nitrogen metabolism and biomass produced. Besides, the metabolic phase of yeast also regulates the expression of many enzymes involved in the formation of aroma active compounds. The work investigates the overall effect of continuous supplementation of nutrients during alcoholic fermentation of a grape must on the volatile composition of wines.

Read More

WINE FERMENTATION METABOLITES PRODUCED BY TWO TORULASPORA DELBRUECKII STRAINS ISOLATED FROM OKANAGAN VALLEY, BC, CANADA VINEYARDS

Wine aroma is influenced by various factors, from agricultural practices in the vineyard to the enological choices made by winemakers throughout the vinification process. Spontaneous fermentations have a characteristically deeper complexity of aromas when compared to fermentations that have been inoculated with Saccharomyces (S.) cerevisiae because of the diversity of microflora naturally present on grape skins. Non-Saccharomyces yeast are being extensively studied for their ability to positively contribute to wine aroma and flavour. These yeasts are known to liberate more bound volatile compounds present in grape must than S. cerevisiae through the enzymatic action of β-glucosidases and β-lyases1.

Read More

OENOLOGICAL POTENTIAL OF AUTOCHTHONOUS SACCHAROMYCES CEREVISIAE STRAINS AND THEIR EFFECT ON THE PRODUCTION OF TYPICAL SAVATIANO WINES

Due to the global demand for terroir wines, the winemaking industry has focused attention on exploiting the local yeast microflora of each wine growing region to express the regional character and enhance the sensory profile of wines such as varietal typicity and aroma complexity. The objective of the present study was to isolate and compare the indigenous strains of Saccharomyces cerevisiae present in different vineyards in the Mesogeia – Attiki wine region (Greece), evaluate their impact on chemical composition and sensory profile of Savatiano wines and select the most suitable ones for winemaking process.

Read More