Seasonal Variation of Naringin and Certain Other Flavanone Glycosides in Juice Sacs of Texas Ruby Red Grapefruit

SUMMARY A recently developed chromatographic‐fluorometric method was used for individual quantitative determination of naringin, neohesperidin, poncirin, naringeuin‐7‐β‐rutinoside, hesperidin, and isosakuranetin‐7‐β‐rutinoside in juice sacs of Texas Ruby Red grapefruit harvested in late July and late September, 1964, and monthly thereafter through late April, 1965. The concentrations of the six glycosides in these juice sacs were found to decrease rapidly and approximately porportionally during the period from late July through late November. In December–April, the concentrations of all six glycosides tended to decrease, although the monthly changes were slight. These results are compared with data obtained from the same samples by the Davis method for “naringin” determination and with taste‐panel evaluations of grapefruit juice bitterness.