Material Other Than Grape

Striker mechanisms inevitably entrain leaves, leaf fragments and other vine parts (MOG— material other than grapes) with the grape clusters. 

For making wines from fruits other than the vinifera grape, it is convenient to have a fairly large food chopper or mill in addition to the above equipment. The object in all cases is to reduce the fruit to a mash or puree in which the sugar and other soluble materials are available to the yeast. 

Chirality is a necessary, but not sufficient, condition for optical activity to be measured. If a solution contains equal numbers of right-handed and left-handed molecules, they rotate the plane-polarized light to an equal and opposite extent, so that no net rotation is observed. This mixture is called a racemate, or racemic mixture (Latin, racemus, a bunch of grapes, because Pasteur first isolated racemic tartaric acid from wine), and is sometimes designated ( ) to indicate that there are equal amounts of (+) and (-) material. Between an equal mixture and a pure enantiomer, every other mixture is also possible. We therefore define the term optical purity or enantiomer excess (ee, 7.2). If we have a mixture of 75 % of the (+)-enantiomer and 25 % of the (-)-enantiomer, we say that the optical purity is 50 %. Although the physical properties, other than optical rotation, of the two enantiomers are identical, it is not invariably the case that a racemate has exactly the same physical properties as a pure enantiomer. For example, either pure enantiomer of lactic acid melts at 53 °C but a racemic mixture melts at 16.4 °C. 

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