Juice flavonoid content

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. 

Gil-Izquierdo, A. et al.. Effect of the rootstock and interstock grafted in lemon tree (Citrus limon (L.) Burm.) on the flavonoid content of lemon juice, J. Agric. Food Chem., 52, 324, 2004. 

Recently, ingestion of purple juice for 14 days has been shown to improve endothelial function, as measured by flow-induced vasodilation, in patients with coronary artery disease [78]. The authors attributed this effect to the flavonoidic content of the purple juice. These benefits were observed despite use of antioxidant vitamins, lipid lowering medications and small increases in total cholesterol and triglycerides levels. 

R Grandi, A Trifiro, S Gherardi, M Calza, G Saccani. Characterization of lemon juice on the basis of flavonoid content. Fruit Processing 4 355-359, 1994. 

Extraction and finisher pressures can greatly influence the flavonoid content of citrus juices. Generally, as the fruit is squeezed harder more juice is recovered. However, excessive extractor pressures produce juice of a lower quality (35). As shown in Figure 8, grapefruit flavanone glycoside concentrations increase with increasing extractor pressures. In the early portion of the season almost twice as much naringin was obtained under hard squeeze conditions than was obtained with the soft squeeze. The effect of finisher pressure is not as clear, and is dependent on the composition of the raw juice which, in turn, is dependent on the type of extractor used. 

Composition. Scientific data concerning liquids washed with water from orange juice finisher pulp was first published by Olsen et al. (30). They studied Brix/acid ratios, sucrose, reducing sugars, pH, pectic constituents, turbidity, pulp content, ascorbic acid, viscosity, and flavonoid content of experimental and commercial samples. Characterization of pulp-wash continued with publication of quality data (31), examination of pectic substances (32), microbiology (33), and comparison of pulp-wash with orange concentrate (34). 

Kawaii S, Tomono Y, Katase E, Ogawa K, Yano M. HL-60 differentiating activity and flavonoid content of the readily extractable fraction prepared from citrus juices. J Agric Food Chem 1999 47 128-135. 

What is of particular interest in the case cited is that the interaction apparently oeeurred with whole grapefiuit, which is not usually considered to be a problem, although it is known that the fiuit content of possible active eomponents (e.g. flavonoids) do vary considerably. The juice (as opposed to the whole fruit) more commonly interacts, as the juicing process can increase the flavonoid content. The evidence with pomegranate juice is currently too sparse to predict its effects in practice. 

The flavonoids occurred mainly as glycosides and there were at least three different glycosides of myricetin and five different glycosides of quercetin in the berry extracts. Much of the flavonoid content of the berries was concentrated in the peel (125 mg/100 g) and solids rather than the juice, which contained only 13.39 mg flavonols/100 g. The peels also contained a higher content of quercetin glycosides and two kaenpferol glycosides which did not appear in the juice. 

HERTOG M G L, HOLLMAN p c H and VAN DE PUTTE B (1993h) Content of potentially anticarcinogenic flavonoids of tea infusions, wines, and fruit juices , J Agric Food... 

Torronen, R. et al., Flavonoids and phenolic acids in selected berries. Cancer Lett., 114, 191, 1997. Arts, I.C.W., van de Putte, B., and Hollman, P.C.H., Catechin contents of foods commonly consumed in The Netherlands. 2. Tea, wine, fruit juices, and chocolate milk, J. Agric. Food Chem., 48, 1752, 2000. 

It was postulated that the inhibition of LDL oxidation by red wine may help to explain the French paradox. Since Frankel and co-workers [73] showed that red wine inhibit the oxidation of LDL, several in vitro studies have confirmed this finding [26,74,75]. There is controversy over whether or not the consumption of red wine by humans reduces the oxidation of LDL ex vivo. While several studies found resistance of LDL oxidation after 2 weeks of red wine consumption in healthy subjects [75,76], others found no effect on the oxidation of LDL ex vivo [26,77]. Recently, Stein and coworkers [78] showed that short-term ingestion of purple grape juice (7.7 1.2 mL/Kg/day for 14 days) reduced the susceptibility to oxidation in coronary artery disease patients and that this is a potential mechanism by which flavonoids in purple grape products may prevent cardiovascular events, independent of alcohol content. 

Main actives Sesquiterpene lactones, which are bitter flavoured, triterpenes, steroids, flavonoids, mucilages and an inulin content that varies from 2 to 40% in the autumn. Benefits The bitter components were used to promote the flow of digestive juices in the upper intestinal tract. 

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