Temperature control is essential for fermentation that produces desirable characteristics in wine and maximises the utilisation of nutrients, without causing localised exhaustion. The temperature of the vat may be measured manually or with installed sensors, but the final measurement given may be affected by fermentation rate, ambient temperature, type and degree of insulation, cooling systems in place and the type of measurement. This single measurement is often used to make key winemaking decisions, including the application of chilling or heating, or the addition of more nutrients, but is usually used in conjunction with the winemaker’s experience and common sense. Increasingly large tank farms and automation can place severe demand upon human experience, as well as fatigue having severe effects upon decision making. We plan to develop a prototype wireless platform in collaboration with leading researchers from Intel Research Seattle to enable the wireless monitoring of vats to quantify all of the components (the movement of temperature, cooling flow measurements, external temperature factors and historical data) that lead to temperature changes in a tank farm and finally the quality of the wine produced. This will provide a context for the single temperature figure to give the winemaker an indication of how much trust he or she can place in a single temperature figure.
Predictable winemaking depends upon the control of all the factors that affect fermentation, including the grapes, yeast selection, enzyme addition, the size and type of the vats, the temperature control regime, nutrient selection, and pumping regimes. The relationship between yeast behaviour and temperature control is well understood, forming the fundamental basis of winemaking. While manual measurement in small vats is feasible in smaller wineries, large vats in increasingly large commercial tank farms require automated measurement readings within central temperature management systems to provide warnings, guidance and the control of coolant flow.
Temperature control in fermentation is crucial to the development of desirable flavours, alcohol levels and colour in all wine making grape varieties. Schmid et al (“Formation of temperature gradients in large- and small-scale red wine fermentations during cap management”, AJGWR, 15 (3) 249-255, 2009) identify the problems in measuring temperature across a single vat, where thorough mixing was required to reduce the temperature differential across the must to less than 5oC. Sensor lag, broken sensors and poor mixing can easily lead to incorrect results across a single vat. Multiply this by the number of tanks in a farm and we have the potential for an illusion of accurate measurement that may be completely incorrect, at potentially high cost.
The commercial cost of poor temperature control is very high. High temperature fermentation can lead to low-grade wines that either lose retail potential or, at worst, have to be sent for distillation. Wines fermented at too low a temperature may stick or fail to achieve the desirable characteristics again, and have to be downgraded. We cannot have the most experienced winemakers everywhere at the same time; therefore, we must depend upon automated measurement and temperature control systems in a number of cases. It is essential that the measurements that are reported are reported in a framework where a junior or extremely fatigued winemaker can receive as much information as possible to make the correct decision.