Evaluation of tomato (Solanum lycopersicum) quality at three different ripening stages using viscometry

The quality of tomato (Solanum lycopersicum) was investigated at green (GR), yellowish–orange (YOR) and red ripening (RR) stages using viscometry, to identify the best ripening stage to maximally derive its nutritional values. Selected tomatoes were obtained from a local market in Osogbo, Nigeria at three ripening stages They were cleaned, grated, extracted with muslin cloth and centrifuged. The viscosity of the supernatant - fresh tomato juices (FTJ) was measured with an Ubbelohde viscometer and recorded on an hourly basis for 48 h. The data were analyzed with SPSS. The study established that the viscosity of FTJ ranged from 1.39 to 2.25 cP (GR > YOR > RR), but reduced at the first twelve hours of study and ranged from 1.12 cP (RR) to 1.65 cP (GR). At the last twelve hours of study, the viscosity of the three juices remained fairly constant and ranged from 1.12 to 1.24 cP (RR < YOR < GR). However, the levels of overall reduction observed in viscosities of the FTJ monitored for 48 h were 44.89% (GR), 19.46% (YOR) and 19.42% (RR), indicating poor quality retention in GR tomato. Thus, it is more nutritionally suitable to consume yellowish-orange and red ripen tomatoes.