Effect of storage period and temperature on the chemical composition and organoleptic quality of frozen tomato cubes

Micra RS tomatoes, frozen in the form of cubes, were stored during 12 months at -20 and -30 degrees C, analyses being conducted after freezing and after 3-, 6-, 9- and 12-months' storage. The storage did not affect the level of dry matter, soluble solids, sugars, dietary fibre, total nitrogen, nitrates, nitrites, pH, ash or its alkalinity. However, differences in the contents of protopectins, pectins, total acidity, vitamin C, carotenoids, beta-carotene and lycopene and also in the activity of peroxidase, catalase and lipase were statistically significant. In frozen products at a temperature of -30 degrees C in comparison with those at -20 degrees C the contents of the following were: protopectins 33%, pectins 68%, vitamin C 90%, carotenoids 30%, beta-carotene 39% and lycopene 43%, while the activities of catalase and of lipase were 52% and 45% lower, respectively. Organoleptic ecaluation showed good conservation quality in tomato cubes stored at -20 degrees C during 9 months and, in the case of -30 degrees C, throughout the entire investigated period. (C) 2000 Elsevier Science Ltd. All rights reserved.