Postharvest calcium chloride dips for increasing peach firmness

Postharvest bruising of peaches might be reduced by increasing fruit firmness. This study evaluated changes in firmness resulting from dipping peaches in a calcium solution soon after harvest. Cartons of 'Harvester' and 'Juneprince' peaches were obtained from a commercial packinghouse from three harvests each. Half were dipped for 30 minutes at room temperature in a 1% calcium chloride solution and held at 0, 4, and 10 degrees C and 95% relative humidity. Non-destructive tests (firmness, mass, and color) were made five or more times during 21 days of storage on 180 fruits from both varieties (30 fruits x 3 temperature x 2 calcium levels). Firmness was from parallel plate deformations at 10 Newtons. Mass was measured to a resolution of 0.001 grams. Destructive tests were made on 15 fruits from each treatment: total soluble solids (% Brix), acidity (pH), firmness (Magness-Taylor), and taste. Firmness (non-destructive and destructive) during storage was higher for fruit treated with calcium than for untreated fruit. However, temperature affected firmness more than the calcium treatment. Calcium treatments increased mass loss only on 'Harvester' fruit stored at 10 degrees C. The main differences in TSS were due to days of storage with little influence caused by the calcium treatments. An undesirable taste was noted in the fruit that was treated with calcium. A study is needed to determine if a lower concentration of calcium chloride could provide beneficial increases in firmness without changing the taste of the fruit. The effect of temperature on calcium absorption should also be studied.