Effects of debittering on red grapefruit juice concentrate

Clarified, debittered grapefruit juice concentrate (64.2 °Bx) was produced by membrane filtration, debittering, and an evaporation process. Debittering by an XAD-16 adsorption column removed more than 78% of bitterness in grapefruit juice, based on naringin content. Also, some of the non-bitter flavonoids, such as narirutin and hesperidin, were nearly completely removed. Other values, such as vitamin C, and total phenolics, based on absorbance at 325 nm, were also reduced (P<0.05) after debittering. The vitamin C loss can probably be attributed to juice handling during processing. Absorption spectra in the 200–450 nm region showed characteristic absorption maxima around 280 and 322 nm in the control but no spectral fine structure in debittered concentrate. Besides differences in flavonoid profile, there was a slight difference in colour. Debittered concentrate had less chroma (CIE C*) and more lightness (CIE L*) than the control. Thus, the colour of debittered concentrate could be described as slightly paler than that of the control.