Chemical determination of orange juice in refreshments, concentrated and other derivative products

Abstract

A chemical determination of orange juice in refreshments, concentrated and liophilized juices and jams is described. The method involves the precipitation of the quaternary ammonium bases by Reineck salt, separation of the diferents bases by paper chromatography and colorimetric determination of betaine, natural compound present in the orange juice, as betaine reineckate. Results obtained with a great variety of orange species, showed that the determination is pratical, reproducible, simple and that it can be done in any modest laboratory. The method seems to be specific for citric fruits; in mixtures orange and apple, pineapple, or tomato juices, for instance, the orange juice was easily determined. The betaine content of different Brazillian orange was determined; the mean value found was 85 mg of betaine per 100 ml of juice. The betaine content of 37 elaborated products was determined. From these, 23 were prepared in our laboratory. It was found that the storage time does not alter the betaine content of the elaborated product. The sensitivity of the method permits the determination of orange juice content of refreshments to the dilution of 1%.