KFL: Sugar and Sorbitol Analysis

Sugar and Sorbitol Analysis

Most of the soluble solids in apple juice consist of the natural sugars fructose, glucose and sucrose. The concentrations of these sugars can be determined by HPLC or enzyme assay. For many fruit juices, the distribution of these sugars is a distinguishing characteristic of the pure juice. Figure 4 is a histogram of the sucrose content of commercial apple juices. The sucrose content of apple juice, expressed as a percentage of total sugars, averages approximately 15%; the large majority of results are in the range of 10-20% of total sugars. Additions of cane or beet sucrose to apple juice will lead to values near the high end of or exceeding this range.

The ratio of fructose to glucose in the samples averaged 2.08, as shown in Figure 5. The HPLC procedure used to generate these data does not differentiate glucose and sorbitol, so the glucose values include sorbitol. The vast majority of fructose/glucose ratio results were greater than 1.7. Since invert sugar and corn syrup sugars have fructose/glucose ratios less than or equal to 1.0, substantial additions of these sugars will lead to reduced fructose/glucose ratios.

Amino Acids

Anthocyanin Pigments

Carbon SIRA

Minerals

Oligosaccharides

Organic Acids

Phenolics

Figure 4

Figure 5