Quality of processing tomato (Lycopersicon esculentum) fruit from four bloom dates in relation to optimal harvest timing

Two related processing tomato (Lycoperscion esculentum (L.)) fruit quality issues were investigated: (1) the difficulty of representative sampling to test quality, given the wide range of fruit age at harvest time; and (2) identifying the best time to harvest for maximum quality. In a Hastings, New Zealand, trial we tagged large samples of opening flowers on each of four dates about a week apart, and at harvest we compared quality of fruit homogenate (puree). There was a distinct pattern of higher quality in the latest-set (youngest) fruit in terms of total solids, degrees Brix (soluble solids), titratable acidity, and Bostwick flow (gross viscosity). These data are indirect evidence that fruit would have higher quality if harvested at an earlier stage of maturity than currently practised. Average skin and puree colour were both slightly less red in the fruit from the last bloom date. However, these fruit were much more variable in colour than the earliest-set (oldest) fruit, raising the concern that fruit maturity and/or quality may not be a consistent function of fruit age.