Harvest time and storage conditions of ‘Star Ruby’ grapefruit (Citrus paradisi Macf.) for short distance summer consumption

Abstract

The effects of harvest date (four 3-week-spaced dates from early May to end of June) and storage temperature (6 and 10 °C) on grapefruit weight loss, decay and internal quality were evaluated at two given periods (early July and end of August). Harvest dates were before flowering (BF), at full bloom (FB), after flowering (AF) and 6 weeks after full bloom (6FB). Fruit internal quality was assessed by the percentage of juice (PJU), total soluble solids (TSS), titrable acidity (TA) and TSS:TA ratio. On orchard, between the first and the last harvest dates, PJU and TSS and TA decreased whereas TSS:TA increased sharply. PJU remained quite unchanged until after flowering, where it sharply declined leading to values near the minimum for marketing in 6FB fruit especially for small diameter ones. No clear chilling injuries were noticed even after more than 16 weeks at 6 °C. That temperature induced higher TA, lower TSS:TA ratio values and lower fruit weight loss than at 10 °C. Small diameter fruit weight loss was higher than that of large diameter fruit for both temperatures. For all harvest dates TSS, TA and TSS:TA were similar at the two tested periods for marketing (early July and end of August). By August, PJU of BF fruit was lower and close to the minimum value for marketing. Conversely, harvest date had a clear influence on decay with 30.7% of decay in BF fruit versus 5.5% in 6FB fruit by the end of experiment (end of August) mainly due to a longer storage duration and not to a higher sensitivity to decay of BF fruit. For short distance local summer marketing, we recommend to harvest grapefruit after flowering, but not too late, and to store them at 10 °C.