Scrimgeour et al.
Elevated storage temperature and wine composition
713
Exploring the effect of elevated storage temperature on wine composition N. SCRIMGEOUR, S. NORDESTGAARD, N.D.R. LLOYD and E.N. WILKES Commercial Services, The Australian Wine Research Institute, Adelaide, SA 5064, Australia Corresponding author: Mr Neil Scrimgeour, email
[email protected] Abstract Temperature can play a significant role in the development of wine at many stages during its lifetime. Elevated temperature, however, poses a significant risk to the sensory attributes of wine and its resultant shelf-life. Wines often experience difficult environmental conditions during transport and storage, and this can directly impact on the colour, aroma and mouthfeel of the wine. Higher and/or fluctuating temperature can essentially accelerate the ageing process. Unfortunately, these changes often go unnoticed until the wine reaches the consumer. Numerous studies have investigated the impact of elevated temperature on wines, with noticeable effect, such as reduction of sulfur dioxide, colour development (especially browning of white wines) and changes in the profile of volatile compounds, being common. Unfortunately, most of these studies tend to have a narrow scope and tend to focus only on a limited number of wine types or on specific compounds. The chemistry changes involved in heat-affected red wines are generally more complex than they are in white wines, but it is arguable that white wines are more sensitive to the effect of heat and therefore require the same or a greater level of research consideration with respect to temperature effects. The focus of this review is to highlight the common effects that different wine types and styles can experience when subjected to elevated storage temperature that are considered to be beyond the limits that most winemakers and consumers would accept. This review will also summarise the fundamental chemical kinetics that play a significant role in wine development at elevated temperature. Keywords: ageing, browning, degradation, elevated temperature, exposure, heat, kinetics, sulfur dioxide
Introduction Wine is a sensitive and complex combination of chemical components. It is a carefully crafted product that reflects the intimate care and attention afforded to it and is the result of a myriad of considered processing operations and decisions. Unfortunately, all of this good work can be undone if a wine is not stored and transported under the conditions required to maintain its optimal state. There are many instances in the life of a wine where temperature can play a significant role in its development and, in some unfortunate cases, chemical degradation. A wine can experience elevated temperature during crushing, fermentation, blending, maturation, bottling, shipping and storage. If temperature is not adequately controlled across these critical control points, there is a significant risk to the physical, chemical and sensory attributes that the wine can portray. Ideally, wines should be stored in cool cellars or airconditioned facilities (15–20°C) but more often than desired, wines may experience less than optimal environmental conditions during transport or other means of storage, where they are exposed to higher and fluctuating temperature (Robinson et al. 2010, Cejudo-Bastante et al. 2013, Pereira et al. 2014). There is no ‘ideal’ storage temperature for wine in general because the development of a wine is a careful balance between allowing complexity and maturity to develop and preventing oxidative and temperature-influenced characteristics from taking hold. Wine held at low temperature (e.g.
