Fruit juice analysis

Fruit juices, analysis of 957-960 FT-ICR mass spectrometry 322 Fuchsones, tautomerism in 357, 358 Fukui function 90 Fulvic acids 946... 

D. List, I. Ruwisch, and P. Langhans, Application of Flow Injection Analysis in Fruit Juice Analysis [in German]. Fluess. Obst, 53 (1986) 10. 

The introduction of synthetic materials into natural products, often described as adulteration , is a common occurrence in food processing. The types of compounds introduced, however, are often chiral in nature, e.g. the addition of terpenes into fruit juices. The degree to which a synthetic terpene has been added to a natural product may be subsequently determined if chiral quantitation of the target species is enabled, since synthetic terpenes are manufactured as racemates. Two-dimensional GC has a long history as the methodology of choice for this particular aspect of organic analysis (38). 

To detect adulteration of wine. Bums et al. (2002) found that the ratios of acetylated to p-coumaroylated conjugates of nine characteristic anthocyanins served as useful parameters to determine grape cultivars for a type of wine. Our laboratory utilized mid-infrared spectroscopy combined with multivariate analysis to provide spectral signature profiles that allowed the chemically based classification of antho-cyanin-containing fruits juices and produced distinctive and reproducible chemical fingerprints, making it possible to discriminate different juices. " This new application of ATR-FTIR to detect adulteration in anthocyanin-containing juices and foods may be an effective and efficient method for manufacturers to assure product quality and authenticity. 

Wrolstad, R.E. et al., Use of anthocyanin pigment analysis for detecting adulteration in fruit juices, in Methods to Detect Adulteration in Fruit Juice and Beverages, Vol. 

Lee, J., Durst, R., and Wrolstad, R., AOAC official method 2005.02 total monomeric anthocyanin pigment content of fruit juices, beverages, natural colorants, and wines by the pH differential method, in Official Methods of Analysis of AOAC International, Horowitz, H., Ed., AOAC, Washington, D.C, 2005. 

The polysaccharide composition and structure of pectic polysaccharides present in fruit-derived products have been the aim of numerous studies [14-19]. However, the attention of scientists was focused on the analysis of rhamnogalacturonan I or so-called pectic hairy regions. As far as we know, the presence of RG-II in fruit juices has not been reported. 

Although SPME was applied initially for the analysis of relatively volatile environmental pollutants in waters, rapid developments have enabled SPME to be successfully applied for the analysis of pesticides in water, wine and more complex food samples such as honey, fruit juice and pears, vegetables and strawberries. With food samples, most analysts recognize the need for some sample pretreatment in order to minimize matrix effects. The matrix can affect the SPME efficiency, resulting in a reduced recovery of pesticides. The most common method is simply to dilute the sample or sample extract with water. Simpltcio and Boas comminuted pears in water prior to the determination of pesticides. Volante et al. extracted over 100 pesticides... 

Biosensors may provide the basis for in-field analyses and real-time process analysis. However, biosensors are generally limited to the determination of a limited range of analytes in defined matrices. Enzyme-based biosensors, principally acetylcholinesterase (AChE) inhibition, have been successfully used in environmental analysis for residues of dichlorvos and paraoxon, " carbaryl " and carbofuran. " Immunochemically based biosensors may be the basis for the determination of pesticide residues in liquid samples, principally water and environmental samples, but also fruit juices. The sensors can be linked to transducers, for example based on a piezo-... 

In the case of the low abundance of some compounds, there are difficulties with signal overlap. To overcome these difficulties, there have been developments involving NMR hyphenation with techniques such as HPLC and mass spectrometry. In LC/NMR methods of analysis, NMR is used as the detector following LC separation and this technique is capable of detecting low concentrations in the nanogram range. This technique has been reported for the detection and identification of flavanoids in fruit juices and the characterization of sugars in wine [17]. 

Dremel B.A., Schaffar B.P., Schmid R.D., Determination of glucose in wine and fruit juice based on a fiber-optic glucose biosensor and flow-injection analysis, Anal. Chim. Acta 1989 225 293. 

There is increasing interest in the use of specific sensor or biosensor detection systems with the FIA technique (Galensa, 1998). Tsafack et al. (2000) described an electrochemiluminescence-based fibre optic biosensor for choline with flow-injection analysis and Su et al. (1998) reported a flow-injection determination of sulphite in wines and fruit juices using a bulk acoustic wave impedance sensor coupled to a membrane separation technique. Prodromidis et al. (1997) also coupled a biosensor with an FIA system for analysis of citric acid in juices, fruits and sports beverages and Okawa et al. (1998) reported a procedure for the simultaneous determination of ascorbic acid and glucose in soft drinks with an electrochemical filter/biosensor FIA system. 

Figure 3.31 Analytical isotachophoresis. Ascorbic acid (vitamin C) is naturally present in many foods and is often added to others. Occasionally the cheaper isomer, is oascorbic acid, which has no vitamin action, is used and is distinguishable from the natural isomer by many analytical methods, (a) shows the analysis of a sample of commercial fruit juice while (b) shows the same fruit juice to which a known amount (4 nmol) of isoascorbic acid has been added. (Reproduced by permission of LKB, Stockholm, Sweden.)...

Fort he determination of preservatives and sweeteners in soft drinks or fruit juices LC analysis with UV detection is widely used. The sample pretreatment, prior to LC analysis, often consists only of degassing, filtration and dilution of the Uqirid [2]. Sometimes a Uqirid-Uqitid extraction, suitable not only for soft drinks but also for more complex matrices, is appUed [3]. Chemometric methods appUed to overlapped spectra offer the advantage of minimizing or eliminating sample preparation by allowing to simirltaneoirsly determining one or more analytes in relatively complex matrices. 

The AOAC 16 " edition describes a difference spectrophotometric method for the analysis of benzoic acid in various food preparations, such as jam, jellies, soft drinks, catsup, beverages, and fruit juices [14]. Before measuring any absorbance values, the sample is extracted four times with ether, and the ether extract purified by washing with solutions of HCl (1 + 1000) and 0.1 % of NH4OH. The maximum absorbance (at 272 nm) was subtracted by the average of the baseline absorbencies at -267.5 and 276.5 nm. 

Among the numerous applications of SPE are separations of phenolic acids and flavonoids from wines and fruit juices. Sep-Pak Cig cartridges have been used for the fractionation of flavonol glycosides and phenolic compounds from cranberry juice into neutral and acidic parts before HPLC analysis. Antimutagenic flavonoids were identified in aqueous extracts of dry spinach after removal of lipophilic compounds by SPE. ... 

Wang, J. and Sporns, P., Analysis of anthocyanins in red wine and fruit juice using MALDI-MS,... 

Bremner, P.D. et ak. Comparison of the phenolic composition of fruit juices by single step gradient HPLC analysis of multiple components versus multiple chromatographic runs optimised for individual families. Free Radical Res., 32, 549, 2000. 

Later, the chemical characterisation of the volatiles from yellow passion fruit essence and from the juice of the fruit was done by GC-MS and GC-olfactom-etry (GC-O) [27]. Esters were the components found in the largest concentrations in passion fruit juice and essence extracted with methylene chloride. Analysis by GC-O yielded a total of 66 components which appeared to contribute to the aroma of passion fruit juice and its aqueous essence. Forty-eight compounds were identified in the pulp of Brazilian yellow passion fruits (Passiflora edulis f. flavicarpa) [48]. The predominant volatile compounds belonged to the classes of esters (59%), aldehydes (15%), ketones (11%), and alcohols (6%). 

Fruit juices such as grapefruit, orange, and apple may reduce the bioavailability and exposure of fexofenadine. This is based on the results from three clinical studies using histamine-induced skin wheals and flares coupled with population pharmacokinetic analysis. Therefore, to maximize the effects of fexofenadine, it is recommended that ALLEGRA-D 24 HOUR should be taken with water... 

Foods. The determination of antioxidants and food preservatives is a very active part of the gas chromatography field. Adaptations and sample types are almost limitless for example, analysis of fruit juices, wines, beers, syrups, cheeses, beverages, food aromas, oils, dairy products, decomposition products, contaminants, and adulterants. A detailed discussion of this field may be found in Chapter 9. 

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