The red color makes the differenceNumerous studies have demonstrated that flavonoid compounds are particularly high in fruits such as blood oranges . These oranges are native to the volcanic soils around Mount Etna on the island of Sicily, in Italy. Due to the large fluctuations of temperature characteristic of this region, Red Oranges have much higher levels of antioxidant compounds such as Vitamin C, flavonoids and carotenoids than regular oranges. Their distinctive red color, in fact, is due to the presence of one particular flavonoid family known as anthocyanins, which are present in both the peel and the juice portion of the orange. This is the same red pigment found in blueberry and pomegranate juices, but is unique in richnes the cocktail of antiooxidant in red oranges among citrus fruits.
Up until the past decade, most of the studies on the health-promoting benefits of red oranges, similar to other citrus fruit, focused almost exclusively on their high vitamin C content. More recently, however, improvements in chemical analysis methods such as High pressure liquid chromatography (HPLC), and tests of anti-oxidant capacity such as Oxygen Radical Absorbance Capacity (ORAC) and a vitamin E based assay known as Trolox Equivalent Antioxidant Capacity (TEAC), have allowed researchers to determine specific constituents and to quantify the relative effect of these constituents individually, as well as any synergistic effects that can be measured in whole food compounds.
As indicated in Figure 1, Anthocyanins, abundant in Blood Orange varieties are almost not present in the traditional ornage juice sold in the US stores shelves. Vitamin C content in freshly squeezed red oranges is approximately 2 times higher than non-pigmented oranges, while the flavonoids hesperidin and nairirutin are approximately 2-3 times greater. (Proteggente et al. 2003).
A 1999 study argued that the antioxidant activity of red orange juice is mainly related to its total flavonoid content, including the anthocyanins and also hesperidin and nairirutin. Oranges with higher levels of these compounds were demonstrated to be better antioxidants (Rapisarda et al, 1999). More recent studies have given more importance to the Vitamin C components (Arena E. et al. 2001; Proteggente et al. 2003), but what does seem clear is that in addition to the anti-oxidant properties of Vitamin C, which are well known, the abundant flavonoids present in red orange juice are themselves a significant source of dietary antioxidants.
Studies on anthocyanins found in red oranges have shown protective effects on heart muscle and red blood cells from oxygen mediated damage (Amorini et al, 2003), against LDL oxidation (Amorini et al. 2001) and against free radical associated DNA damage (Aquaviva et al. 2003). Cyandin-3-glycoside (C3G), the most common anthocyanin present in red orange juice, has been shown in one study to have antioxidant activity higher than either Vitamin C or resveratrol, an anti-oxidant component of red wine (Amorini et al., 2001).
Hesperidin and nairirutin, the other main flavonoids in red orange juice, are metabolized by the human gut to form the compounds hesperitin and naringenin, which have also been shown to have many health-promoting effects. A hesperitin metabolite, for example, has been shown to protect human skin fibroblast cells from ultra violet A-induced oxidative stress (Proteggente et al., 2003). Hesperitin and naringenin together were shown to lower cholesterol levels by inhibiting cholesterol ester synthesis in human liver cells (Borradaile et al. 1999). Hesperitin and naringenin have also been shown in vitro to have antiplatelet (Jin YR et al., 2007), anti-inflammatory (Hirata et al. 2005), neuroprotective (Heo et al. 2004), anticarcinogenic (Shen et al. 2004), and anti-inflammatory (Rotelli et al. 2003) activity.
Ironically however, these same free radical scavenging qualities that make flavonoids such effective anti-oxidants also make them unstable to high temperatures or UV light for long periods. A recent study by Fiore et al., showed that red orange juices that were both flash pasteurized and refrigerated maintained a high level of both anthocyanins and antioxidant ability for up to four months—values comparable to freshly squeezed juice (Fiore et al. 2005). On the other hand, high temperature processing and long shelf-storage were both shown to degrade anthocyanins to the point where they were almost negligible, according to the authors.
This is a unique benefit of Blood Orasnge juice against companies that are selling products with less amounts of juice or with juice that has been sterilized etc. This, I think, is your products greatest leverage against the ‘multi-nationals’—as Fiore points out on p. 1133 (I’ve attached the article)—there is huge difference between the cold pasteurized and sterilized juices—that might be good to put into a graphic.
Also: Rapisarda’s articles (attached) points out that anthocyanin levels can vary significantly according to variety, environmental conditions, fruit maturity and cold storage (for example, he reports a 500% increase in C3G over 120 days’ storage at 8°C).
In addition to in vitro evidence for the anti-oxidant abilities of red orange juice, several human trials have also demonstrated that the red orange juice flavonoids can increase the antioxidant capacity in plasma or in specific types of blood cells after they are ingested. Citrus flavonoids such as hesperidin and nairirutin are present in red oranges as glycosides—that is bound to sugar molecules. In the human digestive tract, enzymes remove the sugar molecules, creating what are known as aglycones (molecules ‘without sugars’). The anthocyanins such as C3G, interestingly, as also present in red orange juice as glycosides, but appear to be absorbed with their sugar molecules intact (Cao et al. 2001; Prior, 2003). In both forms, flavonoids then enter the bloodstream and become biologically active as free radical scavenging anti-oxidants.
This was demonstrated in a 2005 study with human subjects found a significant increase in plasma vitamin C and the anthocyanin C3G after consuming red orange juice for a period of 21 days (Riso et al. 2005). They also found increased white blood cell DNA resistance to oxidative stress in the group consuming the red orange juice over the control group. Another more recent group found decreased DNA damage in one type of white blood cell for 24 hours following a single serving of red orange juice given to volunteers. Interestingly, this effect was not seen after volunteers were given a drink supplemented with the same amount of vitamin C (Guarnieri et al. 2007).
Extracts taken from blood orange juice have also been shown to have some beneficial therapeutic effects in human studies in physical stress recovery. One group found a marked decrease in levels of serum free radicals and other markers of oxidative stress in diabetic patients given the extract daily for 2 months (Bonina et al. 2002). This free radical-lowering effect was also found in professional handball players also given the extract daily for a 2 month period (Bonina et al. 2005).
Conclusion:
Daily consumption of Blood Orange juice has been an integral part of the Mediterranean diet for generations. As part of this healthy diet, daily intake of red orange juice provides high levels of flavonoids, including anthocyanins, hesperidin and nairirutin, as well as vitamin C, beta-carotene and dietary fiber. Taken together, all of these compounds have important health benefits, but as a whole food, red orange juice has synergistic benefits greater than those of the individual phytonutrients and vitamins, ones that we are only just beginning to truly understand. This is why a daily glass of red orange juice may just prove to be an economical way not only to maintain good health but also to protect against many of the common diseases of aging, including atherosclerosis, stroke, diabetes, and many cancers.
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