Foaming in Apple Wine

At Kiviks Musteri AB, situated in the southeast part of Scania, a wide variety of products based on fruits and berries, are produced. One of these products is base apple wine, which is used for the production of cider and mulled wine and also is sold to other producers of cider. A foaming problem has occurred at some customers when the cider is bottled, and this problem has been traced to the base wine. The aim of this paper is to investigate what causes the foaming and how the foaming is affected by the clarifying agents used during the production of the wine. An investigation whether silica based antifoaming agents might be a solution of the problem will be performed. During the work fermentations, clarification and foaming tests will be performed in laboratory scale in Kivik. Tests with four different silica based antifoaming compounds are carried out and on these samples the surface tension and viscosity are measured to see how these factors correlate with the foaming when antifoaming agents are added to the wine. What is more, fermentations with a new yeast type and fermentations with less fruit are made to investigate if this could give better foaming properties in the wine. The tests showed that it is probably proteins that are the main cause of the foaming, but an increase of the amount of bentonite, the clarifying agent reducing protein content in the wine, is not possible since this causes too much sediment. Antifoaming agents gave reduced foaming times, which were at an acceptable level, but when the wine was mixed to cider base and filtered the effect was lost. No significant differences were observed between the four antifoaming compounds. The test with the new yeast type gave no positive results when it came to foaming. The test with less fruit showed a decrease in foaming but not sufficient enough.