Determination Of Sugar Content Research Articles

Determination of sugar and acid content in apple

A description is given of rapid methods for the determination of sugar and acid contents in apple to be used in breeding for fruit quality. Special attention is given to sampling. Besides the stage of maturity of the fruit, its position on the tree has an effect on the chemical composition of the sample. When only part of the fruit is used for analyzing, the difference in content of the exposed and shaded sides should be taken into account.

TESTING THE SUGAR CONTENT OF BEETS FOR GENETICAL PURPOSES

Since sugar beets are raised solely for sugar the one characteristic of prime importance is the sugar content. It has been shown (6) that some of the difficulties involved in the breeding of beets are matters of flower development and fertilization. Pritchard (5) claimed that there is no correlation between morphological characters and sugar content and further that sugar content of the beet is not inherited. Such studies are dependent upon exact control of pollination and a correct determination of sugar content in the beet. The purpose of this paper is to point out a source of error in the methods1 now used in sugar beet testing and to present a method in which this particular error will not be possible. There are various methods in use for sampling individual beets for sugar determinations (1, 2, 3, 4, 7, 8, 9). The simpler of these methods is to grind the beet pulp and extract the juice. Another method involves boring a hole through the beet and catching the pulp and juice as they ooze out. The underlying principle of these methods is to break the cells of the beet tissue. Lead sub-acetate is then added to the normal weight of the pulp and the sugar diffuses throughout the liquid because of the cells having been broken. Ten or more minutes are allowed for cold water digestion. Theoretically, polarization of the filtrate from these preparations should give a relatively accurate reading of the percentage of sugar content in the beet. Actually, however, mechanical devices which it is necessary to use either in grinding or boring the beet cannot be relied upon to break all of the cells. Since hundreds, and often thousands, of beets are tested in this way the test for the group may vary in proportion to the efficiency of the grinding machine or the boring rasp which may be used in securing the pulp. The rasp may be in perfect cutting condition for the first beet but it naturally becomes duller as subsequent borings are made so that a variation in sugar content which is due to the method will make the data valueless.