Optimal Control Applied to Oenological Management of Red Wine Fermentative Maceration

Abstract

The management of wineries for industrial red winemaking is limited by the capacityand availability of fermentation tanks over the harvest season. The winemakers aim to optimizethe wine quality, the fermentative maceration length, and the fermentation tank’s productive cyclesimultaneously. Maceration in varietal wine production is carried out until a specific sugar content(digging-out point) is attained, finishing before alcoholic fermentation. Winemakers have foundthat by trial and error handling of the digging-out point, they can improve the winery capacity andproduction cost. In this work, we develop an optimal control problem for managing the digging-outpoint considering two objectives associated with process efficiency and costs. A good compromisebetween these objectives was found by applying multi-criteria decision-making (MCDM) techniquesand the knee point. Two control strategies were compared: free nutrition and traditional nutrition.TOPSIS and LINMAP algorithms were used to choose the most suitable strategy that coincided withthe knee point. The preferred option was nitrogen addition only at the beginning of fermentation(6.6–10.6 g/hL of DAP) and a high fermentation temperature (30 °C), yielding the desireng digging-out point with a small error (6-9 g/L)