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Conditioning refers to postharvest treatments that extend the shelf life of fresh commodities. Conditions during fruit development, season, and fruit maturity influence the physiological state of the fruit, which may affect the treatment necessary for conditioning. In order to understand the basis of conditioning, we measured changes in biochemical parameters in green and yellow lemon flavedo associated with a 3-day treatment at 15 degreesC, shown to produce conditioning. Sugars, starch, and abscisic acid (ABA) were measured and proteins were visualized after denaturing electrophoresis. Raffinose increased in yellow flavedo from coastal lemons from 0.10 to 0.29 mg g(-1) fresh weight during this treatment, while sucrose content went from 2.68 to 3.86 mg g(-1) fresh weight. Glucose and fructose increased as well. Similar changes were seen for green flavedo. Starch levels in these fruits were low, around 1% to 3% of the soluble sugars. For desert lemons, initial ABA content was 10.74 and 16.03 mug g(-1) dry weight in green and yellow flavedo, respectively. After a 3-day treatment at 15 degreesC, green and yellow flavedo had ABA contents of 16.22 and 20.61 mug g-l dry weight. Proteins were characteristic of fruit maturity level but did not respond to conditioning within the limits of resolution of the gels.