Bitterness reduction of naringin and limonin by .BETA.-cyclodextrin.

Abstract

Taste interactions of /?-cyclodextrin with naringin or limonin, which are bitter tasting constituents of citrus fruits and their products, were evaluated by psychophysical methods. The mechanism of interaction of /?-cyclodextrin with naringin or limonin was explained by both the solubilities of the bitter tasting compoundsand the changes brought about by proton shifts within the jS-cyclodextrin. In the presence of 0.5% j5-cyclodextrin, the bitterness of naringin or limonin was reduced to approximately half of what it was without jS-cyclodextrin. This reduction in bitterness by /?cyclodextrin was also observed in the citrus juice itself. The solubilities of naringin or limonin increased with the addition of /?-cyclodextrin. In a series of XHNMRspectra of j5-cyclodextrin in D2O, the low-field triplet signals assigned to the H-3 and H-5 protons, which are located within the cavity of /?-cyclodextrin, showed a gradual shift to the higher-field values with increases in the molar ratio of naringin to jS-cyclodextrin. It was concluded that this bitterness reduction was due to the formation of an inclusion complex between the /?cyclodextrin and the naringin or limonin. The bitterness of citrus fruits and their products is caused primarily by either of two constituents-naringin and limonin. Naringin is said to be the bitter tasting constituent of grapefruit, natsudaidai, buntan oranges and so forth.1} On the other hand, limonin is the bitter tasting component of navel oranges, Valencia oranges and iyo oranges, among others.2'3) These bitter compounds are often necessary components for the acceptable flavors of citrus juices. However, when the intensity of the

Physical Approaches to Masking Bitter Taste: Lessons from Food and Pharmaceuticals

“…For example, adding about 0.5% of cyclodextrin halved the bitterness of naringin and limonin (46). Szejtli and Szente (43) provide an extensive tabulation of studies of bitterness reduction in drugs and foods by cyclodextrins so we will confine our discussion to a few more recent examples.…”

Cyclodextrins as Food Additives and in Food Processing

“…In the first trials, CDs were added to aqueous solutions of naringin or limonin. A relationship was found between bitterness reduction and the formation with these glucosides of a CD inclusion complex [79]. In another study β-CD was polymerized with epichlorohydrin [80] to yield an insoluble polymer that was used to debitter grapefruit and orange juices by batch or column filtration.…”

Effects of Postharvest Time, Heat Treatment, pH and Filtration on the Limonin Content in Newhall Navel Orange (Citrus sinensis Osbeck cv. Newhall) Juice

“…The most commonly used method to reduce the bitterness in processed citrus juices was the use of polymeric adsorbents to selectively remove limonoids. However, in addition to the bitter compounds, some beneficial compounds such as vitamin C, carotenoids, or phenolic compounds might be reduced as well by this debittering method [ 24 , 25 , 26 ]. Although they reduce the bitterness to some extent, the conventional debittering methods, such as the addition of bitterness-suppressing agents, or by adsorption on certain adsorbents, all cause more or less negative effects on the quality of the juices [ 1 , 17 , 21 , 22 ], precluding their practical application in the juice industry.…”