304 INTERNATIONAL CONGRESS OF VITICULTURE 



the vine tendrils, with "vhich it bears a certain morphologic analogy, would 

 appear to make it a desirable material for the purpose stated. A summary 

 average analysis of grape stems shows their composition to be as follows: 



GREEN STEMS (1). Per Cent 



Fiber .' (about) 20 



Tannic acid from 1 to 2 



Resinous matters (about) 1.5 



Potassium bitartrate from 0.6 to 1.2 



Free acids from 0.3 to 0.9 



Mineral matter from 2 to 2.5 



Moisture from 74.9 to 73.4 



DRY STEMS (2). % 



Fiber of cellulose 41.61 



Tannic acid 10.23 



Pectous matter 4.94 



Sugars :. 4.00 



Cream of tartar , .. 3.37 



Free tartaric acid.. 0.23 



Mineral matter 4.59 



Moisture .. 27.03 



Total 100.00 



Grape stems are not utilized at present for any particular purpose, and 

 end usually in the manure heap, save when they are not separated from the 

 pomace in wine making, in which case the pomace after having been pressed, 

 goes to the distillery for distillation and subsequent treatment for extract- 

 ing the raw cream of tartar, of which grape stems contain, if green, accord- 

 ing to Ottavi Marescalchi, from 0.6 to 1.2 per cent; if dry, according to 

 Girard & Lindet, about 3.37 per cent. 



In rational wine making the separation of the stems, the presence of 

 which in the fermenting mass is undesirable, chiefly because of their impart- 

 ing greenness and unpleasant acidity (racemic and tannic acids) to the re- 

 sulting wine, is a recognized necessity and an established fact, the stems 

 being separated by means of a stemmer, usually attached to the grape 

 crusher. As a rule the stemming, crushing, and, if necessary, the cutting 

 of the grapes, is accomplished in one operation by one single machine, the 

 separated stems being conveyed, through a chute, outside of the crushing 

 room, where they gather in a heap, which is removed from time to time. 



Stems represent, as a rule, from 3.5 to 4.5 per cent of the grapes vin- 

 taged, while skins, seeds and other solid matter of the grapes, before they 

 are fermented, represent from 12 to 18 per cent of the mass; the total solid 

 matter of the grapes averaging thus from 15.5 to 22.5 of the whole mass. 



The dry pomace of unstemmed grapes contains on an average 28 per 

 cent of stems, 40 per cent of skin and 24 per cent of seeds; while the dry 

 pomace of stemmed grapes is made up of 33 per cent of seeds and 67 per 

 cent of skins. 



(1) Ottavi Marescalchi, I residui della vinificazione, Casale 1901, p. 6. 



(2) Girard & Lindet (Ace. od Sciences, 1898). 



