Organic acids and their changes during peach (I'rum4.s persica L. Batsch) fruit ripening were quantified by HPLC for clingstone cultivars, 'Babygold 5' and 'Babygold 7', and a freestone cultivar, 'Cresthaven'. At full maturity, 'Babygold 5' and 'Babygold 7' had about 60% malic, 20% citric and 19% quinic acid; whereas 'Cresthaven' had similar amounts of all three organic acids (37, 3.5 and 28%, respectively). During fruit ripening, 'Babygold 5' and 'Babygold 7' increased in malic acid and decreased in citric and quinic acids, whereas, 'Cresthaven' showed little change in these organic acids.

Babygold 5 (BG5) and Redhaven (RDH) peaches at maturity 4 were held at 2.3°C for 0, 2 and 4 weeks. After each cold storage treatment half of the fruit sample was evaluated; the other half was ripened for 8 days at 21°C and respiration was measured daily. The evaluations on both samples were for malic, citric and quinic acids, titratable acidity (TA), soluble solids (SS) and flesh firmness. Malic acid in ripened BG5 and RDH Fruits increased relative to their unripened counterpart over the cold storage time; citric acid increased in BG5, decreased in RDH; quinic acid decreased in both cultivars; TA increased; SS decreased in BG5, did not change in RDH; flesh firmness increased in BG5, did not change in RDH. Respiratory rate increased with cold storge time in both cultivars. Overall, BG5 showed more susceptibility to chilling than RDH.