Colour and carotenoid content of quick-frozen tomato cubes during frozen storage
1989
Urbanyi, G. | Horti, K. (University of Horticulture and Food Industry, Budapest (Hungary). Dept. of Food and Refrigerating Technology Inst. of Food Technology)
One of the most important quality characteristics of tomato is its colour. Thus, it was found important to investigate the behaviour during frozen storage of the colour and pigment content in quick-frozen tomato cubes, manufactured in increasing amounts in recent years. In a part of the experiments the test material was gained from the same tomato variety at different stage of maturity, while in the other part the fully ripe fruits of three different varieties were used. The colour of tomatoes, frozen at -30 C and stored at -20 C, was studied by the tristimulus method, and the amount of carotenoids by photometry after separation by column chromatography. The colour of the tomato products was found to change continuously during frozen storage. The process appeared in the decrease of the red and the increase of the yellow character, and the simultaneous lightening of the colour. There was no characteristic change in saturation. The extent of change was maturity-dependent. A linear correlation was observed between the colour and the time of storage. In the case of values b, L and TCI the correlation was found to be close and significant. The quantity of carotenoids diminished during frozen storage. The reduction of the quantity of pigments present in the tomato in the largest amount, as well as that of all the carotenoids is in close linear correlation with the storage period. The quantity of the same pigment is in close linear correlation with the b, L colour characters and the Tomato Colour Index /TCI/. Thus, the relatively more rapidly determinable colour characters permit to draw conclusions not only as to the change of colour but to the quantitative change of pigments too.
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