Adulterations of citrus juices

Numerous surveys in the literature report extensive adulteration of citrus juices in commercial channels. For example,... 

Chloramine-T. The chloramine-T determination (128) has been used as a test for dilution or adulteration of citrus juices. 

Chapter 18 reports the investigations of Petrus and relates the room temperature fluorescence, and visible and UV spectral characteristics of citrus juices and related products to the detection of adulteration. 

Minerals. Determinations of inorganic constituents (e.g. total ash, alkalinity of the ash) are classical methods for estimating juice content of citrus juices and beverages. Refinements were made to correct for inorganic sulfites, benzoates and phosphates used as adulterants or preservatives (34). 

Rouseff RL (1988) Differentiating citrus juices using fiavanone glycoside concentration profiles. In Nagy S, Attaway JA, Rhodes ME (eds) Adulteration of fruit juice beverages (Food science and technology, vol 30) Marcel Dekker, New York, pp 49-66 Rouseff RL (ed) (1990) Bitterness in foods and beverages. (Developments in Food Science, vol 18) Elsevier, New York... 

Royo Iranzo and Aranda (1 ) and Royo Iranzo et aK (2) found from one half to one third of the commercial European bottled orange juices tested were adulterated. Mears and Shenton [3) reported the most common form of adulteration in the early 1970 s was the use of fruit by-products such as extracts of peel and pulp (pulp-wash). It appears that the problem has continued into the 1980 s. Three orange juice surveys in the United States (162 samples obtained from retail outlets) conducted by the Florida Department of Citrus during 1979 and 1980 indicated gross adulteration by orange pulpwash (PW) and/or sugars and/or dilution (Petrus et al., unpublished data). 

The Florida Department of Citrus rules (4 ) prohibit the addition of any PW to frozen concentrated orange juice (FCOJ). The U. S. regulations, while not as strict, prohibit addition of PW beyond that obtained from the particular batch of fruit from which the juice was obtained (5j. Since Florida produces most of the FCOJ in the United States, this type of adulteration is a national as well as a state problem. 

Phenolics. The phenolics of citrus represent a varied and widely studied class of compounds. They range from the lipid-soluble methoxylated coumarins and psoralens to the water-soluble glycosides of the flavanones and flavones. They include the intensely bitter naringin and the highly insoluble hesperidin. Different classes within the group have characteristic UV spectra which have been used to detect adulterations in juices and oils. 

Maraulja and Dougherty (131) reported chloramine-T values for Florida Hamlin, Pineapple and Valencia were slightly higher for hard squeeze juices than for soft squeeze juices. Chloramine values were considerably higher for the albedo and flavedo components than for juice and were suggested for detecting adulteration with water extracts of peel and rag (75,132). Chloramine values are often included with other analytical parameters for citrus juice authentication (133,134). 

Lifshitz et aK ( ) investigated the purity of Israeli citrus juice by a multivariate method. They selected 5 analytical parameters and concluded that adulteration or dilution of 15% or more was very likely to be detected at a 1% level of significance. However, adulteration with orange pulpwash was not included in their study. 

Authentication and the detection of adulteration are serious problems within the citrus juice industry. Traditional multicomponent analysis methods are limited by the time required to perform the individual analyses and to construct the database required. Py-MS rapidly provides fingerprints of the original juice, which facilitates the use of multivariate pattern recognition procedures to detect potentially adulterated samples and to confirm authentication, as weU as helping in quality control. More recently, the combination of Py-MS and ANNs has been applied to problems of adulteration within the olive oil industry, shellfish, and milk. ... 

P Mouly, EM Gaydou, J Estienne. Column liquid chromatographic determination of flavanone glycosides in citrus. Application to grapefruit and sour orange juice adulterations. J Chromatog 634 129-134, 1993. 

While our work on the RIA and EIA for limonin was in progress, a research group in Israel (35) reported on an immunoassay for estimating the orange juice content of commercial soft drinks and reconstituted juice. This is of great importance to the citrus industry since adulterated or improperly reconstituted products greatly affect the quality of the product and thus ultimately reflect upon citrus quality control credibility. 

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