RT Journal Article SR Electronic T1 Ammonia Content of California Grapes JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 213 OP 220 DO 10.5344/ajev.1969.20.4.213 VO 20 IS 4 A1 C. S. Ough YR 1969 UL http://www.ajevonline.org/content/20/4/213.abstract AB The ammonia content of grapes was discussed along with possible paths of assimilation. Variations due to years were found associated with climate changes. Varieties, rootstocks, and areas caused distinct variations in ammonia content. The changes were less pronounced it ratio of ammonia to total nitrogen was considered. The effect of maturity was especially pronounced in fruit from the warmest areas.Grape juice ammonia values in 310 determinations ranged from 24 to 309 mg/l (average 123 mg/l). The ratio of ammonia to total nitrogen can be fairly constant between varieties and regions.