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http://journals.tubitak.gov.tr/agriculture/

Turkish Journal of Agriculture and Forestry Turk J Agric For(2013) 37: 568-574© TÜBİTAKdoi:10.3906/tar-1210-21

Study of postharvest changes in the chemical compositionof persimmon by HPLC

Hande BALTACIOĞLU1,*, Nevzat ARTIK2

1Department of Food Engineering, Faculty of Engineering, Middle East Technical University, Ankara, Turkey2Department of Food Engineering, Faculty of Engineering, Ankara University, Ankara, Turkey

* Correspondence: bhande@metu.edu.tr

1. IntroductionPersimmon (Diospyros kaki L.), a tree belonging to the family Ebenaceae, was originally cultivated in China and Japan. In Turkey, persimmon fruits are widely cultivated in the Mediterranean and Black Sea regions, and Turkish persimmon production reached 15,000 t year–1 in 1997 (Ünal 2004). Persimmon fruits range in color from light yellow-orange to dark red-orange and can be classified in 2 main groups: astringent and nonastringent. Astringent persimmons might not be consumed before softening due to their high levels of soluble tannins, whereas nonastringent varieties can be eaten fresh (Ito 1971).

Persimmon fruit is a good source of carbohydrates, organic acids, vitamins (mainly A and C), minerals, phenolic compounds, dietary fiber, and carotenoids (Homnava et al. 1990; Senter et al. 1991; Gorinstein et al. 2001; Del Bubba et al. 2009; Veberic et al. 2010). Phenolic compounds have been reported to exhibit antioxidant, anticarcinogenic, antimutagenic, and cardioprotective effects. Together with ascorbic acid they protect body tissues against oxidative stress (Gorinstein et al. 1998; Scalbert and Williamson 2000; Suzuki et al. 2005). Ito (1971) reported that fructose and glucose were the main

sugars in persimmon fruits, comprising more than 90% of the total sugars. Sucrose was detected at minor levels.

As a consequence of their valuable health effects and high economic value, persimmon fruits are the target of increasing scientific interest. In particular, this fruit is generating research focusing on its sugar, phenolic, and ascorbic acid contents, which have direct and/or indirect effects on the pharmaceutical properties of this fruit.

In addition to their beneficial health effects, phenolic compounds also influence sensory qualities of fruits such as color, taste, and flavor, and astringency caused by phenolic compounds affects the consumption quality of fruits. The stage of maturity significantly influences the concentration of phenolic compounds (Baltacıoğlu et al. 2011). Although many articles in the literature investigated the phenolic composition of persimmon, only a few investigated the changes in phenolic compounds throughout the ripening process (Sattar et al. 1992; Karhan et al. 2003; Del Bubba et al. 2009). In the present study, it was aimed to investigate the changes in the total phenolic content and the phenolic composition of 6 different persimmon cultivars from Ordu, Turkey, during postharvest storage. Additionally, chemical composition was studied and the distribution of sugars and L-ascorbic acid content were presented.

Abstract: Chemical composition, total phenolic content, phenolic compounds, sugars, and L-ascorbic acid content of persimmon fruits of 6 different persimmon cultivars obtained from Ordu, Turkey, were evaluated in this study. Four astringent persimmon cultivars (Türkay, Hachiya, 07 TH 13, and Moralı) and 2 nonastringent persimmon cultivars (Tozlayıcı and Fuyu) were used for analysis. In order to determine total phenolic content in persimmon fruits, the Folin–Ciocalteu colorimetric method was used. High-performance liquid chromatography (HPLC) was used to identify and quantify the phenolic compounds, sugar, and L-ascorbic acid. Total phenolic content was higher in the astringent species than in the nonastringent species. Phenolic compounds identified and quantified in persimmons were gallic acid, chlorogenic acid, rutin, and catechin. Total phenolic content and phenolic compound concentrations decreased during storage. The sugar compounds found in persimmon cultivars were fructose and glucose. L-ascorbic acid content for all cultivars varied between 14.9 and 15.8 mg 100 g–1. The study showed that persimmon fruits are a good source of phenolic compounds, which are nutritionally important for their antioxidant activities and protective functions against diseases caused by oxidative stress.

Key words: High-performance liquid chromatography, L-ascorbic acid, persimmon, phenolic compounds, postharvest storage period

Received: 08.10.2012 Accepted: 23.02.2013 Published Online: 28.08.2013 Printed: 25.09.2013

Research Article

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2. Materials and methods2.1. Plant materialsFresh, mature, but unripe persimmon fruits belonging to 4 astringent cultivars (Diospyros kaki ‘Türkay,’ Diospyros kaki ‘Hachiya,’ Diospyros kaki ‘07 TH 13,’ and Diospyros kaki ‘Moralı’) and 2 nonastringent ones (Diospyros lotus ‘Tozlayıcı’ and Diospyros kaki ‘Fuyu’) were purchased from local producers in Ordu, Turkey.2.2. Sample preparationThe fruit samples were separated into equal groups. One group was used directly to determine chemical composition and total and individual phenolic contents of persimmon fruits. The rest were assayed at 7-day intervals during a 5-week storage period at room temperature. Türkay varieties were processed at 14-day intervals during an 8-week storage period due to their high amount of phenolic compounds. The persimmon fruits were crushed with a stainless steel knife and then the seeds were manually separated, and fruits were homogenized with an Ultra-Turrax (TP 18-10, Janke and Kunkel KG, IKA Werke, Staufen im Breisgau, Germany) for 2 min. The homogenized samples were kept at –20 °C until analysis.2.3. Determination of chemical compositionGeneral parameters were measured according to the following official methods (AOAC, 2000). Dry matter was determined by heating in a vacuum oven at 70 °C until a constant weight was obtained. The pH level was measured with a pH meter (WTW pH 537, Mettler Toledo, Germany). Titratable acidity was measured using 0.1 M NaOH up to pH 8.1 and was expressed as a percentage of malic acid. Soluble solid content was measured with an Abbe refractometer (ATAGO, Japan). For determination of total ash, samples were preburned with ethanol in order to prevent foaming, the temperature was gradually raised to 550 °C, and the samples were ashed for 24 h until they became white in color. For crude fiber analysis, samples were boiled with acid and base, respectively. Total fat was extracted with n-hexane (60 °C) over 6 h using a Soxhlet extractor. Protein content determined by micro-Kjeldahl method (James 1995) was calculated as total N × 6.25. 2.4. Determination of total phenolic contentThe Folin–Ciocalteu colorimetric method was used to determine the total phenolic content (Singleton and Rossi 1965). Homogenized samples were mixed with a methanol-water solution (80%, v/v) containing 1% hydrochloric acid (37%) according to a dilution factor of 1:5 (g mL–1). In order to avoid photodegradation and oxidation reactions, the mixture was shaken at 200 rpm over 4 h in a closed unit and centrifuged for 15 min at 6000 rpm. Supernatant was diluted according to the supernatant to pure water ratio of 1:60, and then 0.75 mL of Folin–Ciocalteu reagent (previously diluted 10-fold with distilled water) was mixed

with 100 µL of diluted solution and kept at 22 °C for 5 min. After adding 0.75 mL of sodium bicarbonate (60 g L–1), the mixture was allowed to stand at 22 °C for 90 min and absorbance was measured at 725 nm. Results were represented as milligrams of ferulic acid equivalent per kilogram of fresh fruit.2.5. Analysis of phenolic content High-performance liquid chromatography (HPLC) was used to determine the concentrations of individual phenolic compounds in persimmon fruits. The supernatant was filtered through a 0.45-µm Millipore membrane filter (Sartorius AG, Göttingen, Germany). The Shimadzu Class-VP HPLC System (Shimadzu Corp., Kyoto, Japan) used consisted of a SLC-10 A VP system controller and computer-controlled system with Class-VP software. A Shimadzu DGU-14A degasser, LC-10 ADVP Shimadzu pump, CTO-10 ASVP column oven, and an SPD-MIOA VP photo diode array (PDA) detector set at 280 nm were the other accessories used with the equipment. A reversed-phase ACE-5C18 (5 µm, 250 × 4.6 mm ID) column (ACE, Aberdeen, UK) was used for separation. The flow rate was 1.0 mL min–1, injection volume was 20 µL, and column temperature was 25 °C. The 2 mobile phases used for gradient HPLC elution were acetic acid (2.5%) and HPLC-grade methanol. The elution profiles were as follows: solvent A, 0–8 min, 65%; 8–8.5 min, 60%; 8.5–20 min, 44%; 20–30 min, 40%; 30–30.5 min, 35%; and 30.5–35 min, 20% (Artık et al. 1999). A 5-min post-run at initial conditions for equilibrium of the column was used. By using the PDA detector, the absorption spectra of each compound were determined online. Identification of chromatographic peaks in the samples was performed by comparing their retention times and UV spectra with those of their reference standards. Quantification was made from the peak area of each component and its corresponding calibration curve. 2.6. Analysis of L-ascorbic acidL-ascorbic acid contents of the samples were determined by HPLC. The homogenized persimmon samples were mixed with deionized water according to a dilution factor of 1:5 (g mL–1) in the magnetic stirrer. The mixed samples were filtered through Schleicher & Schuell no. 5893 black band filter paper and then through a 0.45-µm Millipore membrane filter (Sartorius AG), and were injected into the HPLC system for the determination of L-ascorbic acid content. During the application, samples were protected from direct sunlight. The Shimadzu HPLC system, equipped with a Shimadzu DGU-14A degasser, LC-10 ADVP Shimadzu pump, CTO-10 ASVP column oven, and SPD-MIOA VP PDA detector set at 210 nm, was used. A stainless steel Zorbax C18 (150 × 4.6 mm ID, 5 µm) column (Agilent Technologies, Palo Alto, CA, USA) was used for separation. The injection volume was

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20 µL and the column temperature was 25 °C. Next, 0.2 M of KH2PO4 (Merck) in deionized water solution was used as the mobile phase, which had a flow rate of 0.5 mL min–1. By using H3PO4 (Merck), the pH of the mobile phase was adjusted to 2.4 (Gökmen et al. 2000). Quantification was made from the peak area of the component and its corresponding calibration curve. 2.7. Analysis of sugarsThe HPLC system was used for determination of the sugars. The homogenized persimmon samples were mixed with deionized water according to a dilution factor of 1:5 (g mL–1) in the magnetic stirrer. The mixed samples were filtered through Whatman No. 42 filter paper and then through a 0.45-µm Millipore membrane filter (Sartorius AG), and were injected into the HPLC system for the determination of sugar content. The Shimadzu HPLC system, equipped with a Shimadzu DGU-14A degasser, LC-10 ADVP Shimadzu pump, CTO-10 ASVP column oven, and RID 10A Shimadzu refractive index detector, was used. A Zorbax carbohydrate analysis column (Agilent Technologies) with 150 × 4.6 mm ID (5 µm) at 30 °C was used for the determination of sugar composition. A 75:25 solution of acetonitrile and water was used as the mobile phase, which had a flow rate of 1.4 mL min–1.2.8. Statistical analysisThe data were analyzed as a completely randomized design by analysis of variance using Minitab 14.12.0 (Minitab Inc., State College, PA, USA). Mean separation was performed with the Tukey test at P < 0.05. Results of the analyses are the means of 2 replicates. 2.9. ChemicalsThe following standards were used for the determination of sugars, ascorbic acid, and phenolic compounds: fructose and glucose were obtained from Sigma-Aldrich (St Louis, MO, USA); L-ascorbic acid was from Merck (Darmstadt,

Germany); gallic acid, ferulic acid, chlorogenic acid, and (+)-catechin were obtained from Sigma-Aldrich; rutin (quercetin 3-rutinoside) was purchased from Wako Chem. Ind. Ltd. (Osaka, Japan); Folin–Ciocalteu reagent and other chemicals were from Merck; and methanol and acetonitrile, used as eluents, were either of analytical or HPLC grade and were obtained from Fluka (BioChemika-Fluka Chemie GmbH, Buchs, Switzerland). All reagents were of analytical or HPLC grade and were obtained from Merck.

3. Results3.1. Chemical composition of the persimmon fruits The chemical composition of the persimmon fruits before the postharvest storage period is presented in Table 1. Brix, pH, and the titratable acidity were higher in the astringent species than in the nonastringent species. However, the ash, crude fiber, moisture, protein, and total fat contents of the persimmon fruits were similar.3.2. Change in total phenolic content of persimmon fruitsThe change in total phenolic content of persimmon fruits during maturation is shown in Figure 1. At the beginning of the storage period, the total phenolic contents of Türkay, Hachiya, 07 TH 13, Moralı, Tozlayıcı, and Fuyu were 751.3, 379.2, 166.6, 153.5, 126.9, and 109.1 mg kg–1 fresh weight (fw) of fruits, respectively. It can be seen from the results that total phenolic contents were higher in astringent varieties than in nonastringent varieties. Maximum reduction in the amount of total phenolics was observed in Moralı, with a 60.9% reduction. This was followed by a 58.9% reduction in 07 TH 13, 57.5% reduction in Türkay, 54.4% reduction in Hachiya, 24.4% reduction in Fuyu, and 12.7% reduction in Tozlayıcı. It was concluded that during storage at 22 °C, the total phenolic content of astringent cultivars dropped

Table 1. Chemical composition of persimmon fruits.

Chemical composition Astringent species Nonastringent species

07 TH 13 Moralı Hachiya Türkay Tozlayıcı Fuyu

Brix (%) 21.2 18.5 18.2 19.9 17.0 16.2

pH 5.80 5.61 5.50 5.60 5.40 5.31

Titratable acidity (g kg–1) 0.46 0.40 0.38 0.37 0.30 0.28

Ash (%) 0.47 0.27 0.34 0.38 0.45 0.37

Crude fiber (%) 0.72 0.48 0.58 1.16 0.41 0.66

Moisture (%) 79.09 83.1 81.1 78.36 82.23 81.17

Protein (%) 0.59 0.39 0.58 0.51 0.43 0.56

Total fat (%) 0.05 0.05 0.05 0.07 0.06 0.05

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significantly to over 50% of its initial amount, while the reduction in total phenolic content remained under 25% of initial levels in nonastringent cultivars. The influence of storage time on the total phenolic content of persimmons was statistically significant at the studied levels (P ≤ 0.05), and after the storage period persimmon total phenolic contents decreased significantly compared with initial levels for all persimmons (P ≤ 0.05). 3.3. Change in phenolic content of persimmon fruitsA total of 4 phenolic compounds were identified and quantified in persimmon fruits: gallic acid, chlorogenic acid, rutin, and catechin. Gallic acid (3, 4, 5-trihydroxybenzoic acid) was determined as a major persimmon phenolic. Phenolic compounds were quantitatively measured before persimmons were stored, and the following amounts were recorded. Gallic acid ranged from 383.4 to 1.1 mg kg–1 fw in all persimmons, and among the 6 persimmons the highest amount of gallic acid was found in the Türkay cultivar; chlorogenic acid was detected in Hachiya, 07 TH 13, Moralı, Fuyu, and Tozlayıcı at 7.7, 32.8, 3.0, 3.0, and 21.5 mg kg–1 fw, respectively; rutin was detected in Hachiya and 07 TH 13 at 13.1 and 10.5 mg kg–1 fw, respectively; and catechin was detected in Moralı, Fuyu, and Tozlayıcı at 2.9, 2.7, and 7.1 mg kg–1 fw, respectively. Furthermore, the effects of a 22 °C postharvest storage period on the phenolic compounds of persimmon fruits were investigated (Figure 2).

The amount of each phenolic compound decreased during storage at 22 °C. The amounts of phenolic compounds declined with an increase in storage time (P ≤ 0.05), with the highest reduction (86% of initial amount) observed in the rutin content of 07 TH 13. Gallic acid contents decreased in the range of 37%–75% of their initial levels in fruits during postharvest storage. Rutin losses in Hachiya and 07 TH 13 were 35% and 86% of

their initial amounts, respectively; however, these changes were not significant (P > 0.05). At the end of the storage period, reductions in chlorogenic acid ranged from 33% to 76% of their initial levels. These reductions were statistically significant at the studied levels (P ≤ 0.05), with the exception of Hachiya (P > 0.05). Loss in the catechin content of Moralı, Fuyu, and Tozlayıcı varieties was 76%, 57%, and 62%, respectively. As the results demonstrate, concentrations of individual phenolics exhibited a significant decrease during the storage period. 3.4. L-ascorbic acid content of persimmon fruitsPersimmon is a rich source of L-ascorbic acid, which is an important antioxidant (Homnova et al. 1990). In this study, the concentration of L-ascorbic acid ranged from 14.9 to 15.5 mg 100 g–1 fw for astringent persimmons and was 15.4 and 15.8 mg 100 g–1 fw in the nonastringent Fuyu and Tozlayıcı varieties, respectively. Although the ascorbic acid content seemed to be higher in nonastringent varieties than in astringent ones, there were no statistically significant differences between astringent and nonastringent varieties in terms of L-ascorbic acid content (P > 0.05). 3.5. Sugar content of persimmon fruits The sugar compounds identified and quantified in this study were glucose and fructose. Glucose and fructose amounts in persimmon fruits are presented in Table 2. For the astringent cultivars, glucose ranged from 16.70 to 19.56 g kg–1 fw, and fructose was in the range of 10.62 to 13.97 g kg–1 fw. Glucose and fructose content in Fuyu and Tozlayıcı ranged from 22.42 to 19.62 g kg–1 fw and from 17.72 to 14.58 g kg–1 fw, respectively. These results suggest that glucose amounts are higher than fructose amounts for all varieties, and nonastringent cultivars contain more glucose and fructose than astringent cultivars.

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Figure 1. Change in total phenolic content of persimmon fruits with postharvest storage period at 22 °C.

Table 2. Glucose and fructose amounts in persimmon fruits.

Glucose (g kg–1) Fructose (g kg–1)

Astringent species

07 TH 13 18.77 13.97

Moralı 18.03 13.70

Hachiya 19.56 10.62

Türkay 16.70 12.31

Nonastringent species

Fuyu 22.42 17.72

Tozlayıcı 19.62 14.58

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4. DiscussionPersimmon is known as an excellent source of primary and secondary metabolites such as phenolic compounds, L-ascorbic acid, and sugars (Giordani et al. 2011). The chemical constituents of persimmons are often reported in the literature. The general composition of the fruits found in the current study was in accordance with previous findings on persimmon (Ito 1971; Aksu 1994; Celik and Ercisli 2008). In this study, the Brix, pH, and titratable acidity were higher in the astringent species

than in the nonastringent species (Table 1). Similarly, Ito (1971) reported concentrations of total soluble solids from 18.0 to 20.8 in astringent persimmon fruits and 16.2 in nonastringent persimmon fruits.

Similarly, total phenolic contents were higher in astringent varieties than in nonastringent varieties (Figure 1). Most studies in the literature comparing the total phenolic content of astringent and nonastringent persimmon fruits showed that the total phenolic content is higher in astringent persimmons than in nonastringent

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Figure 2. Changes in phenolic compounds of persimmon fruits with postharvest storage period at 22 °C: (♦) gallic acid; (■) chlorogenic acid; (▲) rutin; (●) catechin.

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persimmons (Suzuki et al. 2005; Jang et al. 2011; Li et al. 2011). Additionally, some authors determined changes in total phenolic content with postharvest storage. In agreement with studies on various persimmon cultivars (Sattar et al. 1992; Bibi et al. 2001; Karhan et al. 2003; Del Bubba et al. 2009), total phenolic content was found to decrease with storage.

Individual phenolic compounds in persimmon fruits and the influence of a 22 °C storage period on these compounds were also investigated (Figure 2). Gallic acid was determined as a major persimmon phenolic, in agreement with the results in Japanese persimmon reported by Suzuki et al. (2005) and Chen et al. (2008). Each phenolic compound decreased during the 22 °C storage period. Changes in total phenolic compounds in persimmon have been studied in general; however, changes in individual phenolic compounds of persimmon fruits during postharvest storage have not been widely reported in the literature. In agreement with reports for various persimmon cultivars, phenolic concentrations decreased along with the progress of ripening (Sattar et al. 1992; Bibi et al. 2001; Karhan et al. 2003). However, some authors observed a significant increment in the concentration of soluble tannins during the first period of fruit development and reported that it was related to the strong synthesis of proanthocyanidins. After this increment, soluble tannin concentrations showed a constant decrease with the progress of ripening (Del Bubba et al. 2009).

The literature showed that ascorbic acid content varied greatly. Giordani et al. (2011) critically reviewed more than 10 studies and reported that the mean value of ascorbic acid content in persimmons was 47 ± 39 mg 100 g–1 fw on average. Results from the current study were low compared with this result. However, the mean value of vitamin C content in the Hachiya cultivar was 12 ± 10.50 mg 100 g–1 in a study done in Turkey (Celik

and Ercisli 2008), and results of the current study were in agreement with this result. The widely varying ascorbic acid content of different persimmon cultivars may be due to environmental conditions, cultivar, and ripeness stage.

The amount of glucose was higher than the amount of fructose for all varieties, and nonastringent cultivars contained more glucose and fructose than astringent cultivars. Similarly, Giordani et al. (2011) found that glucose was the most abundant sugar in persimmon fruits and reported amounts ranging from 2.2 to 10.8 g 100 g–1 fw for astringent and nonastringent persimmons. Another sugar compound, fructose, was reported to range from 1.2 to 9.0 g 100 g–1 fw for astringent and nonastringent persimmons. However, no statistically significant differences between glucose and fructose were found in the fruits of astringent cultivars compared to nonastringent types (Giordani et al. 2011).

In conclusion, chemical composition, total phenolic content, phenolic compounds, sugars, and ascorbic acid content of the fruits of 6 different persimmon cultivars obtained from Ordu, Turkey, were determined in the present study. The influence of postharvest storage on the total phenolic content and phenolic compounds of persimmon were examined. Persimmons were found to be a good source of polyphenolic compounds including gallic acid, chlorogenic acid, rutin, and catechin. During the postharvest storage process, decreases in total phenolic content and phenolic compounds of persimmon were observed. The total phenolic content of astringent cultivars dropped to over 50% of the initial levels during storage, whereas the reduction was under 25% of initial levels for nonastringent cultivars. Similarly, persimmon fruit was a good source of L-ascorbic acid. There was no difference observed between astringent and nonastringent varieties in terms of L-ascorbic acid content. Persimmons contained high amounts of sugars, especially glucose and fructose. Persimmons have higher levels of glucose than fructose.

References

Aksu IM, Nas S, Gökalp HY (1994) Some physical and chemical characteristics of persimmon fruits grown in Artvin-Yusufeli valley. Gıda 19: 367–371 (in Turkish with an abstract in English).

AOAC (2000) Official Methods of Analysis of the Association of Official Analysis Chemists, 17th ed. AOAC International, Gaithersburg, MD, USA.

Artık N, Murakami H, Tomohiko M (1999) Determination of phenolic compounds in pomegranate juice by using HPLC. Fruit Processing 12: 492–499.

Baltacıoğlu C, Velioğlu S, Karacabey E (2011) Changes in total phenolic and flavonoid contents of rowanberry fruit during postharvest storage. J Food Quality 34: 278–283.

Bibi N, Chaudry MA, Khan F, Ali Z, Sattar A (2001) Phenolic and physico-chemical characteristics of persimmon during postharvest storage. Nahrung 45: 82–86.

Chen XN, Fan JF, Yue X, Wu XR, Li LT (2008) Radical scavenging activity and phenolic compounds in persimmon (Diospyros kaki L. cv. Mopan). J Food Sci 73: C24–28.

Celik A, Ercisli S (2008) Persimmon cv. Hachiya (Diospyros kaki Thunb.) fruit: some physical, chemical and nutritional properties. Int Food Sci Nutr 59: 599–606.

Del Bubba M, Giordani E, Pippucci L, Cincinelli A, Checchini L, Galvan P (2009) Changes in tannins, ascorbic acid and sugar contents in astringent persimmons during on-tree growth and ripening and in response to different postharvest treatments. J Food Compos Anal 22: 668–677.

574

BALTACIOĞLU and ARTIK / Turk J Agric For

Giordani E, Doumett S, Nin S, Del Bubba M (2011) Selected primary and secondary metabolites in fresh persimmon (Diospyros kaki Thunb.): a review of analytical methods and current knowledge of fruit composition and health benefits. Food Res Int 44: 1752–1767.

Gorinstein S, Kulasek GW, Bartnikowska E, Leontowicz M, Zemser M, Morawiec M, Trakhtenberg S (1998) The influence of persimmon peel and persimmon pulp on the lipid metabolism and antioxidant activity of rats fed cholesterol. J Nutr Biochem 9: 223–227.

Gorinstein S, Zachwieja Z, Folta M, Barton H, Piotrowicz J, Zember M, Weisz M, Trakhtenberg S, Martin-Belloso O (2001) Comparative content of dietary fiber, total phenolics, and minerals in persimmons and apples. J Agr Food Chem 49: 952–957.

Gökmen V, Kahraman N, Demir N, Acar J (2000) Enzymatically validated liquid chromatographic method for the determination of ascorbic and dehydroascorbic acids in fruit and vegetables. J Chromatogr A 881: 309–316.

Homnava A, Payne J, Koehler P, Eitenmiller R (1990) Provitamin A (alpha-carotene, beta-carotene and beta-cryptoxanthin) and ascorbic acid content of Japanese and American persimmons. J Food Quality 13: 85–95.

Ito S (1971) The persimmon. In: The Biochemistry of Fruits and Their Products (Ed. AC Hulme). Academic Press, New York, pp. 281–301.

James GS (1995) Analytical Chemistry of Foods. Blackie Academic and Professional, London.

Jang IC, Oh WG, Ahn GH, Lee JH, Lee SC (2011) Antioxidant activity of 4 cultivars of persimmon fruit. Food Sci Biotechnol 20: 71–77.

Karhan M, Artık N, Özdemir F (2003) Changes of major phenolic compounds, major carotenoids and L-ascorbic acid composition determined by HPLC in persimmon during ripening. Gıda 4: 349–353.

Li PM, Du GR, Ma FW (2011) Phenolics concentration and antioxidant capacity of different fruit tissues of astringent versus non-astringent persimmons. Sci Hortic Amsterdam 129: 710–714.

Sattar A, Bibi N, Chaudry MA (1992) Phenolic compounds in persimmon during maturation and on tree ripening. Nahrung 36: 466–472.

Scalbert A, Williamson G (2000) Dietary intake and bioavailability of polyphenols. J Nutr 130: 2073S–2085S.

Senter SD, Chapman GW, Forbus WR, Payne JR, Payne JA (1991) Sugar and nonvolatile acid composition of persimmons during maturation. J Food Sci 56: 989–991.

Singleton VL, Rossi JA Jr (1965) Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid reagents. Am J Enol Vitic 16: 144–158.

Suzuki T, Someya S, Hu F, Tanokura M (2005) Comparative study of catechin compositions in five Japanese persimmons (Diospyros kaki). Food Chem 93: 149–152.

Ünal H (2004) Determination of Phenolic Compounds and Ascorbic Acid Content of Persimmon Fruit. MSc, Ankara University, Ankara, Turkey (in Turkish).

Veberic R, Jurhar J, Mikulic-Petkovsek M, Stampar F, Schmitzer V (2010) Comparative study of primary and secondary metabolites in 11 cultivars of persimmon fruit (Diospyros kaki L.). Food Chem 119: 477–483.