VARIABILITY IN SUGARS, ACIDS, FIRMNESS, AND COLOR CHARACTERISTICS OF 12 PEACH GENOTYPES

A wide range of color, sugar, and acid composition was found among 12 peach [Prunus persica (L.) Batsch] genotypes. Among the high-acid genotypes, a trend of increasing Hunter 'a' values, fructose, soluble solids concentration (SSC) : titratable acidity (TA) ratio, and decreasing TA and citric acid levels was noted with decreasing mesocarp firmness. Mesocarp firmness was correlated with both skin and flesh 'a' values within all genotypes. Among genotypes, the Hunter 'a'/firmness relationship varied. 'Elberta', a cultivar known to retain a greenish ground color, had a lower Hunter 'a' value when soft than did more recent releases such as 'Dixiland', 'Redhaven', and 'Suwanee'. 'Sam Houston', a low-acid cultivar, had lower TA and malic, citric, and quinic acid levels than the other cultivars. The dominant acid for all genotypes was malic (50% to 60% of total) with about equal amounts of citric and quinic. Soluble sugars included sucrose (54% of total), fructose (31%), and glucose (15%). 'Sam Houston' had lower SSC, a higher percentage of sucrose, lower levels of glucose and fructose, but the same relative sweetness values as the high-acid cultivars.