Carbohydrates, Sugars, Organic Acids
The water-soluble dry matter content of different fruits de- pends on variety, ripeness, soil, and climatic conditions.
Sweet cherry’s water-soluble dry matter content is between 10–20% and 12–22% for tart cherries. St´eger-M´at´e et al.
(2010) monitored the change of composition for tart cherry varieties at different stages of ripeness. At 75% ripeness, water-soluble dry matter content was between 11% and 14%
and at 95% ripeness it increased to 14.5–17%.
A significant proportion of the water-soluble dry matter comes from soluble carbohydrates, mono- and disaccharides (glucose, fructose, and sucrose), which are main contributors to the energy content. Glucose–fructose ratio is an informa- tive parameter in case of certain fruits. According to Ameri- can and German nutritional data banks, glucose is dominant in fruits, the level of fructose is lower and sucrose hardly occurs (Tables 26.4 and 26.5).
However, based on Eastern European testing, two-third of total carbohydrates in sweet cherry is fructose (4.2 g/100 g), this is significantly higher than glucose (2.2 g/100 g) (Rodler 2005). Both sweet cherry and tart cherry contain sugar al- cohol, sorbitol (sweet cherry: 0.76 g/100 g; tart cherry:
1.17 g/100 g), which has a laxative effect (Rodler 2005).
Table 26.4. Nutritional Values of Sweet Cherry (Nutrients/100 g)
Proximates
USDA 2010
Souci et al.
2008 Minerals
USDA 2010
Souci et al.
2008 Vitamins
USDA 2010
Souci et al.
2008
Water (g) 82.25 82.8 Calcium (mg) 13 17 Vitamin C (mg) 7 15
Energy (kcal/kJ) 63/263 62/265 Iron (mg) 0.36 0.35 Thiamin (g) 27 39
Protein (g) 1.06 0.90 Magnesium (mg) 11 13 Riboflavin (g) 33 42
Total lipid (fat) (g) 0.20 0.31 Phosphorus (mg) 21 24 Niacin (mg) 0.154 –
Ash (g) 0.48 0.49 Potassium (mg) 222 235 Pantothenic acid (mg) 0.199 0.190
Carbohydrate (g) 16.01 13.3 Sodium (mg) – 2.7 Vitamin B6(mg) 0.049 0.045
Fiber, total dietary (g) 2.1 1.31 Zinc (mg) 0.07 0.085 Folic acid (g) – 52
Sugars, total (g) 12.82 – Copper (mg) 0.06 0.100 Carotene, beta (g) 38 35
Sucrose (g) 0.15 0.193 Manganese (mg) 0.07 0.086 Vitamin A (IU) 64 –
Glucose (g) 6.59 7.134 Fluoride (g) 2 18 Vitamin E (mg) 0.07 0.13
Fructose (g) 5.37 6.32 Selenium (g) 0 1.2 Vitamin K (g) 2.1 1.5
Fruits contain significant amount of organic acids, which are responsible for fruit’s sour tastes and refreshing effects.
Each fruit has a specific organic acid profile. The acid con- tent of sweet cherry is lower (0.2–0.7%) than tart cherry (1.0–1.9%). Malic acid and citric acid are the predominant acids in fruits; oxalic acid, shikimic acid, and fumaric acid also occur in smaller quantities (Usenik et al. 2008).
Some species of fruits are characterized by their acid–sugar ratio; in case of sweet cherry, it is 0.07 and for tart cherry, it is 0.20. The refreshing sweet–tart property of tart cherry is due to a lower Brix/acid ratio. Regarding complex carbo- hydrates, starch can be found in fruits, especially when un- ripe. However, it degrades to sugars during ripening. Pectin generally occurs in fruits (0.2–0.3 g/100 g), but its quantity is not significant (Souci et al. 2008). Dietary fibers are of great importance in a preventive diet. Fibers hinder the de- velopment of colon cancer, stomach, and intestinal disorders.
Furthermore, they can positively influence fat and cholesterol absorption and ensure the peristaltic motion of the intestines.
The water-soluble dietary fiber content of sweet cherry is 0.5 g/100 g and the water-insoluble fiber level is 0.81 g/100 g.
In case of tart cherry, these values are 0.57 g/100 g and 0.47 g/100 g (Souci et al. 2008).
Vitamins
Vitamins are essential substances for living organisms. Even if they are needed in smaller quantities, they are indispens- able for metabolism. Vitamins increase the nutritional value of fruits as well (Tables 26.4 and 26.5). Tart cherry and sweet cherry contain all vitamins in low concentrations, except vi- tamin B12and vitamin D. Their thiamin (vitamin B1) content is 26–50g/100 g; the quantity of riboflavin (vitamin B2) is 33–60g/100 g. They also contain pantothenic acid, folic acid, vitamin B6, ò-carotene, vitamin E, and vitamin C. The latter two vitamins play a significant role in the antioxidant protection system of the human body. They hinder the for- mation of peroxides, the release of harmful free radicals;
Table 26.5. Nutritional Values of Tart Cherry (Nutrients/100 g)
Proximates
USDA 2010
Souci et al.
2008 Minerals
USDA 2010
Souci et al.
2008 Vitamins
USDA 2010
Souci et al.
2008
Water (g) 86.13 84.8 Calcium (mg) 16 8 Vitamin C (mg) 10 12
Energy (kcal/kJ) 50/209 53/225 Iron (mg) 0.32 0.60 Thiamin (g) 30 50
Protein (g) 1.00 0.90 Magnesium (mg) 9 8 Riboflavin (g) 40 60
Total lipid (fat) (g) 0.30 0.50 Phosphorus (mg) 15 19 Niacin (mg) 0.400
Ash (g) 0.40 0.50 Potassium (mg) 173 114 Pantothenic acid (mg) 0.143
Carbohydrate (g) 12.18 9.88 Sodium (mg) 3 2 Vitamin B6(mg) 0.044
Fiber, total dietery (g) 1.6 1.04 Zinc (mg) 0.10 Folic acid (g) 75
Sugars, total (g) 8.49 – Copper (mg) 0.104 Carotene, beta (g) 770 240
Sucrose (g) 0.80 0.418 Manganese (mg) 0.112 Vitamin A (IU) 1283
Glucose (g) 4.18 5.18 Vitamin E (mg) 0.07 0.13
Fructose (g) 3.51 4.283 Vitamin K (g) 2.1
therefore, they contribute to the prevention of arteriosclero- sis and cancer.
Minerals
Potassium is one of the most important mineral (Tables 26.4 and 26.5), and these fruits are rich in this compound (sweet cherry: 222–235 g/100 g; tart cherry: 114–173 g/100 g). They are low in sodium, thus improving the adverse Na/K ratio of the human body. Some trace elements can also be found in these fruits with zinc, copper, and iron being prevalent. The level of copper (0.057 mg/100 g) is one of the highest out of all fruits. Ficzek et al. (2009) monitored macro- and microele- ments during the ripening of four tart cherry varieties ( ´Erdi jubileum, ´Erdi b˝oterm˝o, Maliga eml´eke, and K´antorj´anosi 3).
The mineral content of ´Erdi jubileum is (P: 25–35 mg/100 g;
K: 210–230 mg/100 g; Fe: 0.5–0.7 mg/100 g) and the min- eral content of K´antorj´anosi 3 is (Ca: 50–55 mg/100 g; Mg:
18–20 mg/100 g; K: 190 mg/100 g; Mn: 0.17–0.18 mg/100 g) at optimal ripeness.
Flavonoids, Anthocyanins, Antioxidant Capacity
Plants are rich in aromatic compounds. The most significant group within these aromatic substances is the flavonoids, which belong to the group of polyphenols.
Physiological Effect of Flavonoids
Flavonoids are produced by plants and their primary role is protection against harmful UV rays. Flavonoids are mainly responsible for the yellow, blue, pink, and red color of crops and flowers. However, these substances are not only impor- tant for plants but also for human health as well.
The positive physiological effect of flavonoid molecules on the human body has been proven by numerous clinical trials and studies (Wang et al. 1997). They influence the binding of reactive oxygen (Tsuda et al. 1996), the inhibition of lipoprotein’s oxidation (Marshall et al. 1987, Vaca and Harms-Ringdahl 1989, Narayan et al. 1999, Wang et al. 1999, Ghiselli et al. 1998), and are able to hinder the development of cardiovascular diseases (Bertuglia et al. 1995). They have a synergistic effect with vitamins (enhance the nutritional value of vitamins C and E), which catalyzes their formation.
Furthermore, their immunostimulating and anticarcinogenic effects have also been proven.
Within the flavonoid group, anthocyanins have antioxidant effects. Anthocyanins in food have been linked with health- promoting benefits such as antioxidant and anticancer activ- ities (Koide et al. 1997, Rechkemmer 2000). Seymour et al.
(2008) reported that eating of sour cherries reduced the lipid concentration of liver in animal experiment. Anthocyanins are reported to have antiinflammatory (Wang et al. 1999), antibacterial (Changwei et al. 2008), antistress, and immune
system strengthening effects. Additionally, they are effective supplements of chemotherapeutic and other similarly serious treatments, for example, in case of patients suffering from HIV or cancer (Kamei et al. 1998, Koide et al. 1996, 1997).
Flavonoids
Flavonoids are the derivatives of the 2-phenyl-benzopyrene ring system, where the C15carbon structure forms C6-C3-C6 units.
The following compounds belong to the group of flavonoids: flavones, flavonols (3-hydroxyflavone backbone), flavanols, flavanones (2,3-dihydro-flavones), flavanonols (3- hydroxy 2,3-dihydro-flavones), anthocyanidins, proantho- cyanidins (leuko-anthocyanidins), and isoflavonols (Har- borne and Williams 1998).
The diversity of flavonoids is due to the different number and position of OH- and CH3groups. On the other hand, gly- coside bounds also contribute to this variability, since they occur in plants and lead to higher stability and better water solubility. The glycoside form develops from the condensa- tion of the flavonoid compound and a sugar.
Glycoside⇔Aglycone+Sugar
The occurrence of colorless flavonoid compounds shows a high degree of variability depending on the fruit variety.
Bonerz et al. (2006) studied the level of phenolic com- pounds in five tart cherry varieties (Schattenmorelle, Gerema, Ungarische Traubige, Cig´any 7, and Stevnsbear Birgitte) (Table 26.6).
Out of the flavonoids, he detected the presence of flavanols, particularly catechin (1–14 mg/L) and epicatechin (24–336 mg/L). The dominant flavonols are quercetin-3-rutinoside (18–59 mg/L) and quercetin-3-glucosylrutinoside (11–31 mg/L). Certain tart cherry varieties also contain quercetin-3- glucoside and kaempferol-3-rutinoside. Other phenolic com- pounds, which do not belong to the flavonoid group, have also been detected such as chlorogenic acid, neochloro- genic acid, and 3-coumarolquinic acid. When studying the flavonoid compounds of Balaton and Montmorency vari- eties, Kirakosyan et al. (2009) measured significant amount of isorhamnetin-3-rutinoside. Usenik et al. (2008) tested the same parameters of 13 sweet cherry varieties. The presence of epicatechin (4.3–45.1 mg/L) has also been detected, but its level was lower than measured from tart cherries. The concentration of rutin (20.6–57.8 mg/L), chlorogenic acid, neochlorogenic acid, and coumaroylquinic acid proved to be substantial.
Anthocyanins
Development of the color is the result of many factors. The structure of the aglycone is crucial, but it is influenced by other flavonoid molecules, which are mainly anthocyanins with different structure, occurring in different ratio.
Table 26.6. Phenolic Compounds in Cherry Varieties (mg/L)
Schattenmorelle Gerema
Ungarische
Traubige Cig´any 7
Stevnsbear Birgitte
Catechin 2 14 10 1 4
Epicatechin 206 49 24 146 336
Neochlorogenic acid 398 998 831 212 394
Quercetin-3-(2G-glucosylrutinoside) 29 31 11 19 31
Quercetin-3-rutinoside 59 31 27 23 18
Quercetin–glucoside 8 6 4 3 5
Kaempferol-3-rutinoside 13 9 6 4 8
Anthocyanin (sum) 682 756 569 698 858
Cyanidin-3-sophoroside 73 185 39 37 73
Cyanidin-3-(2G-glucosylrutinoside) 410 395 361 439 515
Cyanidin-3-(2G-xylosylrutinoside) 29 38 23 27 43
Cyanidin-3-rutinoside 164 125 140 180 213
Peonidin-3-rutinoside 5 13 7 15 14
Source:Bonerz et al. (2006).
The main subgroups of anthocyanidins, which differ in the number of hydroxyl groups found on the rings, are pelargoni- din, cyanidin, delphinidin, peonidin, petunidin, and malvini- din (Fleschhut et al. 2006).
The increase in the number of hydroxyl groups makes the blue color more dominant with subgroups pelargoni- din, cyanidin, and delphinidin prevailing, meanwhile an in- crease in the number of methoxy groups strengthens the red tone with subgroups peonidin, petunidin, and malvidin (Mazza and Miniati 1993, Kong et al. 2003). In tart cherry, cyanidin-3-glucosylrutinoside is considered to be the main compound, because its concentration reaches 60–67% of the total anthocyanin content, the remaining 25–33% is cyanidin- 3-rutinoside. The presence of cyanidin-3-sophoroside and cyanidin-3-glucoside has been also reported (Blando et al.
2004). In the German Gerema, in the Hungarian Cig´any 7, and in the Danish Stevnsbear Brigitte varieties, peonidin-3- rutinoside also occurs besides cyanidins (Bonerz et al. 2006).
In sweet cherry, 79–96% of total anthocyanins are cyanidin- 3-rutinoside. Other compounds that also contribute to the color are cyanidin-3-glucoside, pelargonidin-3-rutinoside, and peonidin-3-rutinoside (Usenik et al. 2008).
In 2000, the American Amway Corporation invested two million dollars to study the composition of Hungarian tart cherry varieties; technology testing, clinical trials, and ex- traction of the active ingredients have also been performed.
According to their results, Hungarian tart cherry contains four–five times more anthocyanin than the American Mont- gomercy variety; thus, its nutritional and financial value is significantly higher compared with other European and American varieties (Wang et al. 1997).
At Michigan State University, studies were conducted on the effects of tart cherry on human health for a period more than 10 years. American Montmorency was tested alongside varieties originated from the Carpathian Basin with high dry
matter content. ´Erdi b˝oterm˝o is grown as Danube, meanwhile Ujfeh´ert´oi f¨urt¨os is known as Balaton. The US 17 different an-´ tioxidant compounds have been found in these varieties that were mainly anthocyanin-based coloring agents, melatonin, many phenolic compounds, and vitamin E. These substances have antiinflammatory effect and play important role in the prevention of cancer and arthritis (Burkhardt et al. 2001).
Fresh tart cherry contains high concentration of melatonin, which is also produced by the pineal gland of the human body.
Melatonin is an important antioxidant, because it can fight against free radicals in both aqueous and fatty conditions within the human body. Kirakosyan et al. (2009) studied the level of melatonin in products made from Balaton and Mont- morency tart cherry varieties. They came to the conclusion that freezing and freeze-drying are the best processing tech- nologies to preserve melatonin.
Tests performed on fruit samples justified that certain pa- rameters (e.g., dry matter content, sugar, total acids, and vita- min C) show significant differences depending on the degree of ripeness (Sang et al. 2003, St´eger-M´at´e et al. 2003). In case of raw materials that are rich in ingredients with high biological value, monitoring the concentration during ripen- ing is very important for the industry. The amount of certain parameters determine the characteristics of the product (e.g., carbohydrate- and acid content) and production costs (e.g., water-soluble dry matter content in case of concentrate pro- duction or preparation of the finished product) as well. On the other hand, the concentration of certain parameters is a significant factor regarding the quality of the finished product (e.g., vitamins, minerals).
Hungarian researchers monitored the development of an- tioxidant compounds in four tart cherry varieties ( ´Erdi ju- bileum, ´Erdi b˝oterm˝o, Maliga eml´eke, and K´antorj´anosi 3) during ripening (70%, 80%, 90%, and 100% ripeness, re- spectively). ´Erdi jubileum variety contains high amount of
polyphenols (170–260 mg/L), anthocyanins (90–178 mg/L), vitamin C (28–30 mg/100 g), and rutin (0.055–0.075 mg/mL) at 80–90% ripeness, which is optimal for mechanical harvest.
Furthermore, the color of the fruit skin (depends on the antho- cyanidin content) is the most important indicator of maturity and the quality of fresh cherries (K´allay 2008, St´eger-M´at´e et al. 2010). However, it is important to mention that compo- sition, especially the quantity of compounds with antioxidant effect depends on the ripening stage to a great extent (Ficzek et al. 2009).