Effect of simulated shipping conditions on colour and SO₂ evolution in soave wines

Abstract

AIM: The shelf life of food is defined as the period in which the product will remain safe, is certain to retain desired sensory, chemical, physical, and microbiological characteristics, and complies with any label declaration of nutritional data.1 Wine exhibits a “random” shelf life, as the chemical changes are as dependent on the initial condition of the product, including packaging, as on the storage and freight conditions of the product. However, storage and transport conditions of wine may lead to a reduction in wine quality because of unintended physical and chemical changes. These modifications are generally referred to as oxidative spoilage, and they result in browning and loss of fresh, fruity, and varietal aroma characters.2 Certain protective agents such as SO2 are also typically lost with the onset of oxidative spoilage. Recent studies have shown that the outcomes of oxidation in terms of degree of oxidative spoilage are strongly wine specific,3 so that certain wines appear to be more resistant against oxidative spoilage. In this study, chemical and electrochemical changes under the effects of shipping conditions were measured in thirteen Soave wines, to evaluate the potential of Cyclic Voltammetry in conjunction with other parameters to provide relevant information on the oxidative behaviour of individual white wines.

METHODS: The wines underwent an ageing protocol simulating a freight of 46 days, during which the wine was subjected to specific temperature cycles. In the storage of wines at the departure port, the temperature fluctuated between 16 and 25 °C, reflecting the diurnal cycle; while, during the journey of 28 days, the temperature reached 30 °C. Finally, storage at the arrival port produced an oscillation between 25 and 35 °C. Electrochemical methods, in particular the cyclic voltammetry using either glassy carbon or carbon paste electrodes, have been applied to the analysis of wine phenolics.4 Voltammograms of each wine were collected and their features were analysed in conjunction with concentration of free and total SO2, chromatic and spectrophotometric parameters.

RESULTS: The ageing protocol adopted led each wine to a different free and total SO2 consumption, also reflected in an electrochemical diversity and a general increase of chromatic parameters. Cyclic voltammograms have shown a diversity of electrochemical properties, concentration and type of oxidizable compounds present.

CONCLUSIONS

The objective of this study was to explore the electrochemical and chemical repercussions of adverse temperature conditions on Soave wines to better understand the changes due to freight and storage. Significant and seemingly correlated information derived from the electrochemical profile and SO2 consumption of each wine. This study could also constitute the beginning of research aimed at obtaining predictive parameters of the wine shelf life.