306 THE MONTHLY BULLETIN. 



WHEN ARE GRAPES RIPE? 



By Frederic T. Bioletti, Department of Viticulture, University of California, Berkeley. 



The fruit standardization law of California provides that "Grapes 

 packed for table use .shall show a sugar content of not less than 17 per 

 cent Balling's scale, except Emperor, which shall show not less than 

 16 per cent Balling's scale." 



Doubt has been expressed by some as to the reasonableness or advis- 

 ability of this detinitiou of ripeness. Some investigations of the Cali- 

 fornia Agricultural Experiment Station may throw light on the question. 



Since 1914 the changes in composition of grapes during ripening have 

 been observed with numerous varieties in different localities. The 

 changes of most interest in this connection are those in sugar content 

 and in acidity. The sugar content is expressed by the "Balling degree" 

 and the acidity enables us to calculate the Balling acid ratio; that is, 

 the figure obtained by dividing the sugar expressed as Balling degrees 

 by the acidity expressed as grams of tartaric acid in 100 c. c. of juice. 



Of particular interest are some results obtained during the shipping 

 season of 1916. 



Nearly 400 samples of grapes being packed for shipping were exam- 

 ined at the packing houses. First, each sample was tasted and judged 

 by from four to six persons, and their opinions noted. The samples 

 were arranged as to edibility according to the following scale: 



1. Too sour to be eaten. 



2. Disagreeably sour. 



3. Edible, but too sour. 



4. Ripe. 



5. Agreeably ripe. 



6. Very sweet. 



The Balling degree and aridity of each sample was then determined 

 and the results tabulated. 



By this means we were able to determine what Bailing degree and 

 what Balling acid ratio corresponded to the various degrees of ripeness 

 in the opinions of the tasters. As the tasters were different in each 

 packing house, the averages represent the consensus of opinion of over 

 300 tasters, which is perhaps as good a measure of the public taste as can 

 easily be obtained. 



The legal standard, of course, is not intended to represent the max- 

 imum degree of edibility or desirableness, but the minimum — the point 

 below which the consumer would fail to be pleased and therefore cease 

 to be a consumer. This degree is represented in the scale by "3, edible, 

 but too sour." In Table I is given the average "Balling" and "Balling 

 acid ratio" of all samples classed by the judges as: "Edible, but too 



