Naringin in grapefruit

Caccamese, S., Manna, L., and Scivoli, G., Chiral HPLC separation and CD spectra of the C-2 diastereomers of naringin in grapefruit during maturation. Chirality, 15, 661, 2003. 

Control of Juice Bitterness. A number of advances have been reported in this field since it was last reviewed (3). A commercial application of the cellulose acetate adsorption technique for the removal of limonin from citrus juices was undertaken (49). New sorbent gel forms of cellulose esters for adsorption of limonin were developed (50). Knowledge was gained that limonoids are biosynthesized in citrus leaves and translocated to the fruit (12) and that specific bioregulators can inhibit accumulation of XIV in citrus leaves (15). Additional studies were carried out on the use of neodiosmin to suppress limonin and other types of bitterness (30,51). The influence of extractor and finisher pressures on the level of limonin and naringin in grapefruit juice was reported (34). Also, further studies were conducted on the microbial sources and properties of limonoate dehydrogenase (52), the enzyme that converts XIV to XV and can be used to prevent limonin from forming in freshly expressed citrus juices (53). 

One of the earliest methods to measure the bitter naringin and other flavanones in grapefruit juice was developed by W. B. Davis in 1947 (12). This test is based on the reaction of dilute alkali with flavanones to form the corresponding yellow chalcones. The flavanone concentration is then determined by measuring the absorbance of the chalcones at 427 nm. Davis pointed out that the procedure was not specific for any flavanone but could be used to determine the principle flavanones in citrus juice, i.e., naringin in grapefruit juice and hesperidin in orange juice. 

He suggested that the method might also be suitable for the determination of flavones and flavonols. This method is still widely used to measure naringin in grapefruit juice albeit it is not specific for naringin, it is a simple, rapid and inexpensive method of analysis. However, since grapefruit contains both bitter and nonbitter flavanone glycosides, Davis values are only a crude approximation of bitterness. 

Direct ultraviolet spectrophotometric methods have been developed to measure naringin in grapefruit (19J and hesperidin in orange juice (20, 21j. While these methods are rapid, they are also nonspeciTTc for flavonoid bitterness. 

Rygg, G.L. Harvey, E.M. 1938. Behavior of pectic substances and naringin in grapefruit in the field and in storage. Plant Physiol. 13 571-586. 

Early (not quite mature) citrus juices, lemon, Hamlin and Navel juices can develop the so-called limonin-bittemess. Additionally, there can also be a flavonoid-induced bitterness, like naringin in grapefruit juice. Adsorber resin treatment can successfully eliminate this bitterness below the detectable limit. See also [20]. 

In all the citras fruits, the essential oil is contained in numerous oval, balloon-shaped oil sacs or glands situated irregularly just below the surface of the colored portion of the peel (the flavedo). The white inner mesocarp (the albedo) does not contain any oil sacs but does carry the bitter glycosides such as hesperidin in lemon, orange, and tangerine, or naringin in grapefruit. 

McIntosh C, Mansell R (1990) Biosynthesis of naringin in Citrus paradisi UDP-glucosyltransferase activity in grapefruit seedlings. Phytochemistry 29 1533-1538... 

Fuhr, U. and Kummert, A.L., The fate of naringin in humans a key to grapefruit juice-drug interactions, Clin. Pharm. Ther., 58, 365, 1995. 

Another important interaction is that of limonin with the bitter flavanone glycoside naringin. Both of these bitter substances are present in grapefruit juice and Guadagni et al. (25) found that they interact at subthreshold levels in an additive way. Less than threshold amounts of limonin or naringin contribute to the bitterness of a mixture of the two compounds. The bitterness of the mixture can be predicted by adding the taste-unit contribution of each component (taste unit = concentration/ threshold). 

It is difficult to quantitatively define grapefruit qualityTn terms of bitterness because individual taste thresholds and bitterness preferences vary markedly. Guadagni et al. (37) found that 7% of a 27 member taste panel could detect as Tittle as 1.5 ppm naringin in water. Yet, another 7% of that same panel could not distinguish a 50 ppm naringin solution from water alone. 

Hagen et a/L (42) determined the relative amounts of all the flavanone glycosides in Texas grapefruit. Their results are shown in Table III. Naringin is the dominant flavonoid in grapefruit and is primarily responsible for the immediate bitter taste in grapefruit. The equally bitter poncirin and the much less bitter neohesperidin are present in relatively small amounts and do not contribute significantly to overall bitterness. 

Table V. Effect of Enzyme Treatment on Naringin Content and Bit-terness Perception in Grapefruit Juice.(79) ...

Introduction. Naringin is a bitter flavanone glycoside found in grapefruit. It is not the only bitter compound in... 

Several TLC methods have been widely used to quantitatively estimate the flavonoids for quality control purposes rather than to detect adulteration. The potential exists, however, for testing authenticity. Naringin is an important compound in grapefruit juice, since it is largely responsible for the bitter character of the juice. Fisher et al. (121) developed a TLC procedure for naringin estimation. This was later modified by Tatum and Berry (122). Swift (123) developed a TLC-spectrophotometric assay for the neutral methoxylated flavones in orange peel. The method was subsequently expanded to the determination of these compounds in orange juice (124). 

Ribeiro, I.A. Ribeiro, M.H.L. 2008. Naringin and naringenin determination and control in grapefruit juice by a validated HPLC method. Food Control 19 432-438. Rice-Evans, C.A. Miller, N.J. Paganga, G. 1996. Structure-antioxidant activity relationships of flavonoids and phenolic acids. Free Radic. Biol. Med. 20 933-956. Rietjens, I.M.C.M. Boersma, M.G. Haan, L.D. Spenkelink, B. Awad, H.M. Cnubhen, N.H.P. van Zanden, J.J. Woude, H.V.D. Alink, G.M. Koeman, J.H. 

SOARES NEE and HOTCHKISS JH, Naringinase immobilisation in packaging films for reducing naringin concentrations in grapefruit juice. Journal of Food Science, 1998, 63, 61-65. 

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