Orange juice, adulteration

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. 

Sawyer (53J included the concentrations of ascorbic and nicotinic acids along with other analytical parameters to detect orange juice adulteration by dilution or addition of peel extracts. He observed that the relation between the total invert sugar to total soluble solids ratio and nicotinic acid became significantly correlated by the dilution of juices with sucrose or partially inverted sucrose. 

Figure 10 14 Overlay of chromatograms of an authentic orange juice and an orange Juice adulterated with 10% of a partly inverted sucrose. Chromatographic conditions see...

Fig. 9-140. Overlay of chromatograms of an authentic orange juice and an orange juice adulterated with 10% of a partly inverted sucrose. — Chromatographic conditions see Fig. 9-139 sample preparation according to Low peaks (1) to (6) are increased by the addition of inverted sugar (taken from [209]).

Johnson MR, Kauffman FL (1985) Orange juice adulteration detection and action of the FDA. J Food Qual 8 81 85... 

For lemon juice, the flavonoid composition was characterized by HPLC with photodiode detection at 287 nm (108), the HPLC condition based on a procedure proposed by Kirksey et al. (103) for the detection of fruit juice adulteration. Hesperidin and eriocitrin were the characteristic flavonoids of lemon juice. Flavonoid content by HPLC was used to study the effects of processing and pulp removal on flavonoid composition in lemon juice. Eriocitrin is also used in distinguishing lemon juice from grapefruit and orange juices, which do not contain this flavonoid. 

Naturally occurring coloring material obtained by this means could be added to orange juice without any adulteration being considered a color addition (69 ). None of the color concentrates are presently being used in orange juice. 

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. 

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. 

Adjustment of the formol values in commercial orange juice with inexpensive amino acids such as glycine has been detected by Benk and Cutka (67) by means of thin-layer and paper chromatography. Aranda et aT. (68) studied the TLC amino acid patterns as a means of detecting adulteration by amino acids and concluded that amino acids added in sufficient quantities to balance the formol index value could be detected. 

Several workers reported finding commercial samples of orange juice in which the formol value had been adjusted with ammonium salts (67,71,72). These workers suggested the determination of ammonia as a means of detecting this type of adulteration. 

It was suggested by Gherardi trt al. (92) that adulteration of orange juices with pulp and peel extracts could be detected by... 

The same investigators qualitatively examined the organic acids in orange juice by GLC (100). They reported the following acids lactic, oxalic, malonic, phosphoric, succinic, benzoic, adipic, malic, tartaric, iso-citric, aconitic and citric. They (100,101) also examined commercial sucrose and citric acid in an attempt to detect acidic impurities in these adulterants. Differences in the acid patterns were observed, but they concluded that the levels in sugar and citric acid were too low to be useful in detecting adulterations. 

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). 

McHard et aK (152) using plasma spectroscopy investigated 32 elements in Florida and Brazilian frozen concentrated orange juice samples. Using probability statistics they suggested the relative occurrence of the minor elements Ba, B, Ga, Mn and Rb as ratios to zinc could act as "fingerprint" indicators of the geographic source of a sample. No relationship to adulteration was implied. 

Fischer (167) proposed groups of constituent ratios as a means of evaluating orange juice. Nine groups of 29 ratios between total sugars, N-compounds, non-volatile acids, ash and ash constituents were used to detect dilutions and various adulterants. 

Sawyer (8) conducted an investigation of the chemical composition of pulp extracts, and fresh and concentrated orange juices. He concluded from results of chemical analyses that a general composition of a juice may be determined, including type of adulteration. 

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