CURRANTS AS A PRODUCT OF HIGH NUTRITION VALUE

VAIOS Th KARATHANOS
PROFESSOR OF THE DEPARTMENT OF FOOD SCIENCE AND DIET
HAROKOPIO UNIVERSITY
Introduction
The raisin and even currants (black corinthian raisins) are a dried fruit used for centuries as an ingredient of Greek diet with references from ancient times. There is mention of Homer for drying grapes offered to Odysseus on the island of Corfu. The currants were, along with dried figs, the main sweetener for centuries.

The trade of native Greek variety, black corinthian raisins (currants), flourished with many exports to the West during the period of Elizabethan era (16th century). In the second half of the 19th century and the period of recovery of the newly established Greek state, currants’ exports accounted for 80% of total Greek exports. Even today currants are exported almost entirely to the markets of Western Europe (about 25,000 tonnes per year) and either consumed in biscuits and other bakery or snack. Especially in Northern Europe and in the U.S.A., currants are consumed as “brunch” by students and other consumers in large quantities instead of fresh fruit with very good acceptance among young students.
Significant investments, strict quality control under the supervision of the Ministry of Rural Development and Food and the expertise make today the Greek corinthian raisins a product with high purity, of the safest food products and valuable exportable product.
Currants, along with olive oil, are considered in the western markets as one of the most characteristic ambassadors of Greek food.
The following text  is a summary of research carried out at Harokopio University or other research centers regarding currants. Already one doctoral dissertation has been prepared related to currants and ongoing research projects about the effects of currants to nutrition and consumer health. Full list and detailed presentation of positive health effects is available to any interested party.

 

The Nutritional Value of currants
The latest dietary recommendations suggest eating variety of nutritious foods, which, within the recommended caloric intake, provide a variety of , nutritious and beneficial to human health, components. As “nutritional” are characterized foods that provide adequate amounts of micronutrients (vitamins, minerals, polyphenols, etc.) in proportion to the calories they give back. They include foods from all food groups, focusing mainly on fruits, vegetables and wholegrain cereals, low-fat foods and foods with no added sugar [1].
Currants belong to the “Nutritional” fruit. They can be eaten as a nutritious snack, rich in dietary fiber, carbohydrates with a low glycemic index, minerals, vitamins and other micronutrients [2,3].  Their content in fat and cholesterol is low. The overall nutritional value of currants makes them a great choice of snack for both weight control and for maintaining good human health. Their proper use of the daily diet helps the control of glucose and cholesterol, the good functioning of the digestive system and the regulation of blood pressure [2,4,5].
Regarding the containing of currants in carbohydrates, a large percentage consist of one very large percentage of fructose, which provides energy and also classifies the currants in low glycemic index foodstuffs [6]. Postprandial glycemic response is influenced by both the glycemic index of the carbohydrate and the amount of carbohydrate in the food. Currants, although they are a food rich in carbohydrates, contain a high percentage of fructose, which has a glycemic index of 19, significantly lower than that of glucose (100). Fructose has the property of being sweeter than the common sugar and the glucose that is present in most foods that are based on flour thus imparts much greater sweetness impression compared to contribute calories. Obviously the fructose of currants is natural, coming from the grape and it is not a product of starch’s hydrolysis. The fructose content, combined with the relatively high content of currants in fiber, low in fat, and no cholesterol, making currants a healthy snack for all groups of people.
Additionally currants contain very high percentage of fiber and fruit-oligosaccharides, which gives them prebiotic properties. These components act as substrate for beneficial bacteria in the colon, thus helping in proper functioning of the digestive system while preventing the biosynthesis of cholesterol [2,4,5]. Research in healthy volunteers [5] showed that eating 1 currants equivalent per day (2 tablespoons, about 40 g) can reduce the transit time in the colon and levels of bile acids, thereby playing an important role in the function of the colon bowel and decreasing the risk of cancer of the colon.
Additionally, this dried fruit is a source of vitamins and minerals such as iron, potassium and calcium. Compared with the banana, which is considered very good source of potassium, an equivalent currants (2 tablespoons) provides similar amount of potassium (352 mg vs. 358 mg / equivalent food, USDA), thus playing an important role in regulating blood pressure [7].
Currants have additionally polyphenolic components [8] (flavonoids, anthocyanins, proanthocyanidins, procyanidins, resveratrol). Polyphenols are compounds that exhibit antioxidant, anti-inflammatory, anti-aging and anti-cancer activity [4,11]. Studies have shown that regular consumption of antioxidant compounds may help prevent diseases such as cardiovascular diseases and cancer. In the Laboratory of Chemistry-Biochemistry-Physical Chemistry of Food Harokopio University, have been detected and quantified a range of antioxidant polyphenolics in currants [9], including benzoic acids, cinnamic acids and flavonoids such as quercetin and resveratrol. Further laboratory studies have shown that currants polyphenols can prevent the oxidation of atherogenic low-density lipoprotein (LDL, known as “bad cholesterol”), the peripheral blood mononuclear cells of healthy volunteers and to protect other endogenous antioxidants in the human body [11,12]. In a recent survey indicated further that currants’ polyphenols exhibit in vitro antitumor activity in gastric epithelial cells [13].
It should also be noted that drying of currants, even subsequent heating during cooking eg. bakery with currants, does not create inferior product. This has been demonstrated by investigations [14] and it is understood if we consider that the positive effect of the components of currants is not based on the presence of heat-sensitive vitamins, but on the strong presence of antioxidants, encapsulated in the natural membrane and the large amount of dietary fiber.

 

Conclusion
All these above make the currants a nutritionally excellent product, whose good consumption in daily diet may be beneficial for human health.
Contains functional components (fiber, polyphenols), ie components that beyond the nutritional value, provide a beneficial effect on human health and reduce the risk for chronic diseases such as colon cancer and cardiovascular disease. The standards of the Mediterranean diet suggest eating 4-5 fruits a day. By eating a currants’ equivalent (2 tablespoons, 40 g approx) is covered one- third of the daily requirement of fruits.
Currants may well be compared with any fresh fruit from most of which excels in the antioxidant content, trace elements and the percentage of dietary fiber. Due to its ease of maintenance can be easily available and does not require special storage conditions as other fresh fruit. Prerequisite, of course, is the existence of appropriate packaging (eg individual polyethylene packaging) and its production to be made in factories certified and all the required quality standards to be fulfilled  (ISO 22000). Also, it is essential the existence of  appropriate quality certificates from accredited laboratories (ISO 17025) and under the supervision of the Ministry of Rural Development and Food.
The Greek currants (black corinthian raisins) are, therefore, a food rich in nutrients, which classify them as a “functional” food, namely those foods that contain ingredients that beyond the nutritional value provide a beneficial effect on human health.

 

Bibliography
1. Rampersaud GC. A Comparison of Nutrient Density Scores for 100% Fruit Juices. J. Food Sci. 2007; 72 (4): S261-S266.
2. Camire M., Dougherty MP. Raisin Dietary Fiber Composition and in Vitro Bile Acid Binding. J. Agric. Food Chem. 2003; 51 (3): 834-837.
4. Puglisi MJ, Vaishnav U, Shrestha S, Torres-Gonzalez M, Wood RJ, Volek JS, Fernandez ML. Raisins and additional walking have distinct effects on plasma lipids and inflammatory cytokines. Lipids Health Dis. 2008 Apr 16: 7-14.
5. Spiller GA, Story JA, Lodics TA, Pollack M, Monyan S, Butterfield G, Spiller M. Effect of sun-dried raisins on bile acid excretion, intestinal transit time, and fecal weight: a dose-response study. J. Medicinal Foods 2003; 6(2): 87-91.
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7. Lazarou C, Kouta C. Nutritional approaches in tackling hypertension. Brit. J. Comm. Nurs. 2008; 13(9): 423-428.
8. Karadeniz F, Durst R.W, Wrolstad R.E: Polyphenolic composition of raisins. J. Agric. Food Chem. 2000; 48: 5343-5350.
9. Chiou A, Karathanos VT, Mylona A, Salta FN, Preventi F, Andrikopoulos, NK. Currants (Vitis vinifera L.) content of simple phenolics and antioxidant activity. Food Chem. 2007; 102: 516-522.
10. Boskou G, Salta NF, Chrysostomou S, Mylona A, Chiou A., Andrikopoulos KN. Antioxidant capacity and phenolic profile of table olives from the Greek market. Food Chem. 2006, 94: 558-564.
11. Kris-Etherton PM, Hecker KD, Bonanome A, Coval SM, Binkoski AE, Hilpert KF, Griel AE, Etherton TD. Bioactive compounds in foods: their role in the prevention of cardiovascular disease and cancer. Am. J. Med. 2002 Dec 30; 113 Suppl. 9B: 71S-88S.
12. Kaliora AC, Kountouri AM, Karathanos VT. Antioxidant properties of raisins (Vitis Vinifera L.). J. Medicinal Foods 2009; 12(6): 1302-1309.
13. Kaliora AC, Kountouri AM, Karathanos VT, Koumbi L, Papadopoulos NG, Andrikopoulos NK. Effect of Greek Raisins (Vitis Vinifera L.) from different origins on gastric cancer cell growth. Nutrition and Cancer 2008; 60(6): 1-9.
14. Mourtzinos I, Konteles S, Kalogeropoulos N, Karathanos VT. Thermal Oxidation of Vanillin Affects its Antioxidant and Antimicrobial Properties. Food Chem.; 114(3): 791-797.

 

Source: skos.gr
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