Grapefruit flavanone content

Extraction and finisher pressures can greatly influence the flavonoid content of citrus juices. Generally, as the fruit is squeezed harder more juice is recovered. However, excessive extractor pressures produce juice of a lower quality (35). As shown in Figure 8, grapefruit flavanone glycoside concentrations increase with increasing extractor pressures. In the early portion of the season almost twice as much naringin was obtained under hard squeeze conditions than was obtained with the soft squeeze. The effect of finisher pressure is not as clear, and is dependent on the composition of the raw juice which, in turn, is dependent on the type of extractor used. 

Albach RF, Wutscher HK (1988) Flavanone content of whole grapefruit and juice as influenced by fruit development. J Rio Grande Val Hortic Soc 41 89-95 Albach RF, Juarez AT, Lime BJ (1969) Time of naringin production in grapefuit. J Am Soc Hortic Sci 94 605-609... 

For orange and grapefruit, which are rich in flavanones, Proteggente and associates [13] have found that the total phenolic content (126 mg and 150 mg/ 100 g FW, respectively) was similar and much lower than drat measured for berry fruits. Other data on the phenolic content of these fruits were not available in the literature. 

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