We are encouraged to store wines horizontally in a cool cellar with a constant temperature of 10°C, that boasts good humidity and is ‘free from vibration’. How does vibration spoil a wine if the other required storage elements are present? Alan Godfrey, via email Andy Howard MW replies: Correct storage of wine (particularly fine wines) is important, with the dangers of high temperatures, excessive variation in temperature, low humidity and strong light being obvious things to avoid. Vibration is also a danger, but the science behind this is less easy to understand. A 2008 work noted that excessive vibration results in a number of undesirable issues. Vibration can disturb sediment present in the bottle, but it also causes complex chemical reactions which are less visible. Vibration (and the resulting increased kinetic energy in the bottle) leads to a decrease in tartaric and succinic acids, causing a reduction in esters, which dulls flavours. Vibration also increases the amount of propanol in a wine (reducing aromatics), raises isoamyl alcohol (accentuating acetone notes) and results in a higher refractive index, which makes a wine taste sweeter.