Managing Minerals in Winemaking

Mineral deficiencies or excesses can become sources of frustration for amateur winemakers because minerals, metals and other ionic substances cannot be easily measured and their role in biochemical and chemical reactions can be quite complex. One of the most remarkable and visible effects of these substances are tartrate crystals resulting from wine containing a high potassium content and subjected to cold temperatures. Some less visible or less understood effects are stuck fermentation due to mineral deficiency or unusually premature or advanced phenolic browning — a condition whereby polyphenols are oxidized into their brown-colored forms. So where do these substances come from and how can they be best managed in a home winery? Ionic substances Ionic substances, or ions, are atoms or molecules that have either gained or lost one or more electron and therefore carry a charge. Those that lose electrons become positively charged and are called cations. Those that gain electrons become negatively charged and are called anions. For example, potassium (K) has a high tendency to lose an electron and is therefore found in its ionic form, K+;