459 



DEFECTS A.ND DISEASES OF WINE. 



Wine, like milk, is susceptible of attack and deterioration from 

 a number of causes. It may be defective or it may be diseased, 

 or, as it often happens, it is both defective and diseased at the same 

 time. The defects are either natural or acquired. 



Natural defects are those inherent to the commoner and 

 inferior kinds of grapes; to the soil itself, -the manures used, to 

 insufficient ripeness, or to the bad manipulation during the process 

 of making. 



Acquired defects or diseases result from carelessness and 

 tainted casks and vessels. These defects only manifest themselves 

 after fermentation. They constitute the diseases of wines as is 

 generally understood, and each individual one is produced by the 

 presence and the work within the wine of numberless microbes, each 

 kind easily identified from the other by its shape and other charac- 

 teristics which accompany its growth. 



I will rapidly review the more common defects and diseases 

 met with in wines. 



Earthy taste. Often inherent to the soil where the grapes 

 were grown. Clayey soils are in this respect more susceptible of 

 imparting an earthy taste to wines than do light loams, which pro- 

 duce wines said to be "clean" to the taste. This defect can be 

 aggravated by long fermentation, especially when the stalks have 

 not been sufficiently separated. Long intervals between rackings 

 also add to it, and for that reason it is advisable to draw the clear 

 wine from over its lees more frequently than would otherwise be 

 done. Occasional light fixings after racking, followed up by 

 another racking, will be found helpful. 



Greenness. This defect is caused by an undue proportion of 

 tartaric acid and malic acid in wet seasons, when the grapes have 

 not matured properly. A strong attack of a fungoid disease, 

 bringing about a loss of the leaves of vines, will favour the same 

 defect. Blending in the vat with a proportion of dead ripe and 

 healthy grapes is the best means of correcting this defect. 



Harshness, caused by excess of tannin. This constituent of 

 wine, which is essential to its good keeping, is generally more 

 perceptible in young wines. Time mellows it down, and it is 

 gradually transformed into gallic acid. Beware of iron coining into 

 contact with such wine, as the chemical reaction which follows 

 would produce ink. If the harshness is excessive, heavy finings by 

 means of gelatine, 3 to 3| ounces per 100 gallons, will precipitate 

 and remove a portion of the tannin. As such a fining would also 

 remove some of the colouring matter, wines already light in colour 

 should be treated in some other way ; for such wine, blending with 

 light, mellow wines, low in tannin, will correct the defect. 



Stalky Taste and Bitterness. This defect is due to another 

 cause altogether to that which produces the disease of " bitterness," 



