CHANGES OF SURFACE COLOR OF THE FRUIT AND OF THE ANTHOCYANIN CONTENT OF SOUR CHERRIES DURING FROZEN STORAGE

Three sour cherry cultivars were studied in two successive growing seasons. Changes in colour and in colouring matter content were tested during a one year storage and one of about 200 days. The changes during storage time were analyzed and the relations between colour indices and anthocyanin content were studied. During frozen storage, the hue changes from red towards yellow. The red character mostly gets weaker and the yellow hue strengthens as a function of time. Both of them are of slight intensity and the latter is non-significant in case of either of the samples tested. Colour of the samples become lighter in a slight degree. This change is significant up to the 200th day of the storage. The chroma shows a slowly decreasing tendency. The changes in anthocyanin content show different tendencies in the two successive seasons studied. In the first year, this content increases significantly with the length of storage time, in the second, a significant decrease can be observed. This difference could be ascribed to the fact, that in the second year, the starting of the experiment has been put to a date 24 days later, and there had to be in consequence a difference in the maturity of the fruits. In the less ripe fruits/1st year/, the biosynthesis of anthocyanins continues, according to the results found by several researchers. In case of more ripe fruits, this goes much slower or does not occur at all. The correlations between the anthocyanin content and the various colour stimulus characters am not unambiguous. This can be attributed to the fact, that the colour stimulus depends not only on the anthocyanin content but also on physical and chemical interactions between pigments and other compounds, not even speaking from the optical effects of the physical state of the fruits. These effects are represented distinctively in the change of various colour stimulus characters.