Optimising harvest time of sour cherry cultivars on the basis of quality parameters

0139–3006/$ 20.00 © 2010 Akadémiai Kiadó, Budapest

Acta Alimentaria, Vol. 39 (1), pp. XX–XX (2010)DOI: 10.1556/AAlim.39.2010.1.6

Optimising harvest time of sour cherry cultivars on the basis of quality parameters

M. STÉGER-MÁTÉA1∗, G. FICZEKB, E. KÁLLAYC, G. BUJDOSÓC, J. BARTAA AND

M. TÓTHB

a Department of Food Preservation, Faculty of Food Science, Corvinus University of Budapest,H-1118, Budapest, Ménesi út 45. Hungary

b Department of Pomology, Faculty of Horticultural Science, Corvinus University of Budapest,H-1118, Villányi út 29-43. Hungary

cResearch Institute for Fruitgrowing and Ornamentals, Budapest, H-1223, Park utca 2. Hungary

The variation of some compositional quality parameters in connection with ripening time in the case of four sour cherry varieties (Prunus cerasus L. Mill.) was studied. Our aim was to optimize the harvest time on the basis of antioxidant capacity. The experiments were carried out in the Érd-Elvira orchards of the Research Institute for Fruitgrowing and Ornamentals (cultivars Érdi bőtermő, Kántorjánosi 3) and in orchards of the Agárd Frucht Ltd. in Agárd (cultivars Érdi jubileum, Maliga emléke). Anthocyanin, polyphenol and vitamin C contents as well as the water-soluble dry matter content of fruits were measured.

According to the results of quality parameter measurements it can be stated, that in case of the studied cultivars the optimal picking time for industrial processing is the second picking. At this time the anthocyanin, polyphenol and water-soluble dry matter content of the cultivars are optimal. In general, at the end of the ripening period the fruits shrink, fruit weight and juiciness decreases as a consequence of water loss, therefore determining optimal harvest time for the desired utilization purpose is very important. According to our results, out of the four studied cultivars, Érdi jubileum has the highest values regarding anthocyanin and polyphenol contents.

Keywords: sour cherry, anthocyanin, polyphenol, vitamin C, refraction

Total sour cherry (Prunus cerasus L. Mill.) production of the world is over 1 million tons and it is to be increasing in the following years. Sour cherry is popular mostly in Eastern Europe, the production of Hungary is determinant in the region. Sour cherry is considered to be our dominant fi eld of fruit growing because of its production value and export scale (KÁLLAY, 2003). About the half of our 13 000 hectares sour cherry orchards is 10 years old or younger, this means that the total yearly production of Hungary in the coming years can exceed 60 000 tons.

Hungary has a wide range of sour cherry cultivars. The most popular ones are Újfehértói fürtös (the growing area is 26% of all cultivars), Érdi bőtermő (24.5%) and Kántorjánosi 3 (24%). The proportion of Debreceni bőtermő (9%) and Érdi jubileum (2%) shows a slight increase. Cigánymeggy clones (5%), Pándy clones (4.5 %) and Meteor korai (1%) have a decreasing proportion in the Hungarian sour cherry production (KSH, 2003).

An outstanding feature of Hungarian cultivars is that beside their suitability for processing in canning industry, they also fi t well the needs of fresh market, because their acid–sugar ratio is optimal and the fruit taste is not bitter. Requirements of the canning industry are: uniform,

1 To whom correspondence should be addressed. Phone: +36 1 482 6034; fax: +36 1 482 6327; e-mail: [email protected]

65

Acta Alimentaria 39, 2010

STÉGER-MÁTÉ.: OPTIMIZING HARVEST TIME OF SOUR CHERRY

intensive colour, big fruit size, small seed, thin skin, hard fruit fl esh, optimal acid–sugar ratio, not to be susceptible to browning and not to contain larvae of cherry fruit fl y.

At the University of Michigan, investigations had been carried out for more than ten years regarding the effect of sour cherry on people’s health. They studied the American cultivar Montmorency and some others with high dry matter content originating from the Carpathian basin e.g. Érdi bőtermő and Újfehértói fürtös, which are produced in the USA under the names of Danube and Balaton, respectively. They have proven scientifi cally, that 17 components of sour cherry have antioxidant effects (WAND et al., 1999; BURKHARDT et al., 2001).

Sour cherry contains almost all of the most important vitamins. Its B1 (50μg/100g), B2 (20 μg/100 g), B6 (0.05 mg/100 g) and biotin (0.8 μg/100 g) contents are extremely high. Its mineral content is balanced, with a recordable potassium (186 mg/100 g), calcium (186 mg/100 g), magnesium (15 mg/100 g), iron (0.6 mg/100 g), as well as phosphorous (50 mg/100 g) content. Its copper content (0.057 mg/100 g) is one of the highest among fruits (BÍRÓ & LINDNER, 1999).

Studies on fruit samples proved, that there are signifi cant differences in certain compositional data (e.g. dry matter content, sugar, total acid, vitamin C content) according to ripening time (SANG et al., 2003.; STÉGERNÉ et al., 2003; KOVÁCS et al., 2008). In case of raw material containing biologically valuable components, it is especially important to follow up components during the ripening period. The quantity of certain components determines the character of the product (e.g. carbohydrate and acid content), as well as the extent of production costs (e.g. water-soluble dry matter content during juice concentrate or fi nal product processing). On the other hand, quantity of some inner components is an important fact in the aspect of product quality as well (e.g. vitamins, minerals) (DVARANAUSKAITE et al., 2006; HELYES & LUGASI, 2006; LECCESE et al., 2008).

Probably there will be a similar type of correlation with compounds having antioxidant effect, that recently gained great signifi cance in producing the so-called functional food (BÍRÓ & LINDNER, 1999; DIPLOCK et al., 1999; HIMELRICK, 2002; VERES et al., 2005; BRUNORI & VÉGVÁRI, 2007; MEIXNER et al., 2007; VÉGVÁRI et al., 2008).

Four sour cherry cultivars (Érdi jubilum, Érdi bőtermő, Maliga emléke, Kántorjánosi 3) were examined, and the correlation between some quality parameters and ripening time was studied in order to optimise the picking time on the base of antioxidant components.

1. Materials and methods

1.1. Experiment material

Samples were examined in 3 picking times during ripening period (Table 1), partly on in the orchard, partly in the laboratory. The fi rst picking date was before the optimal picking time, the second date was in the optimal picking time, while the third date was in an overripe state (after the optimal picking time). The optimal picking time means a period, when 80% of fruits can be shaken down without signifi cant juice lost.

66



Table 1. Cultivars investigated and dates of sampling in 2007

Name of variety Place of orchard Day of sampling and measuring

Érdi jubileum Agárd 05, 08, 12 June

Érdi bőtermő Érd-Elvira major 12, 15, 19 June

Maliga emléke Agárd 05, 08, 12 June

Kántorjánosi 3 Érd-Elvira major 15, 19, 22 June

Our investigations were carried out in two locations. On the experimental fi eld of the Research Institute for Fruit-growing and Ornamentals in Érd-Elvira major, cultivars Érdi bőtermő and Kántorjánosi 3, and in the orchard of Agárd Frucht Ltd. in Agárd, cultivars Érdi jubileum and Maliga emléke were examined. The orchards of Érdi jubileum was in its 9th, Érdi bőtermő and Kántorjánosi 3 in their 11th and that of Maliga emléke was in its 24th leaves in 2007, the year of examination. The soil of both area is calcareous chernozem plain soil, with a slight alkaline effect in the upper layer. Climatic features of the orchards are summarized in Table 2.

Table 2. Climatic features of the orchards in Érd-Elvira and in Agárd

Number of sunny hours (average)

Yearly mean temperature

Mean temperature of the vegetation period

Average yearly precipitation

Érd 2000 10.0 oC 16.8 oC 550–570 mm

Agárd 2050 10.5 oC 16.6 oC 550–600 mm

1.2. Sampling

Fruits of the examined cultivars were manually harvested, from 15 trees of each cultivar, from all the four quarters of trees. To determine the indicated parameters, from the average samples arrived to the laboratory, mixed fl esh of 15 kg fruits per sample was stored deep frozen until measuring. After defrosting and centrifugation; samples were taken from the supernatant refraction. We examined vitamin C, anthocyanin and polyphenol contents in 3 replicates.

1.3. Refraction

Determination of water-soluble dry matter content (refraction) was carried out according to the regulation Codex Alimentarius (1995) using a Zeiss-Abbé refractometer.

1.4. Determination of vitamin C content

Determination of vitamin C content was carried out in a spectrophotometer, at 500 nm in the presence of dichlorophenol-indophenol colouring agent after extraction with xylol, according to the HUNGARIAN STANDARD (1991).

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1.5. Determination of anthocyanin content

Determination of the colouring materials were made according to the method of FÜLEKI and FRANCIS (1968), using hydrochloric acid and ethanol for colour extraction, and measured at 530 nm with a U-2800A Hitachi spectrophotometer.

1.6. Determination of polyphenol content

Polyphenol content was determined spectrophotometrically, in the presence of Folin-Ciocalteu reagent at 765 nm, on the base of a calibration curve made with gallic acid, according to the method of SINGLETON and ROSSI (1965).

1.7. Statistical methods

For the statistical analysis of data, SPSS program was used. Statistical analysis was made by nonparametric methods, Kruskal-Wallis test and Mann-Whitney test. In case that on the base of a Kruskal-Wallis test based on rank numbers there was a signifi cant difference between samples at 95% signifi cance level, differences between groups were examined by pair comparisons (Mann-Whitney probe). On the base of the quality parameters and that of the processing industry’s demand, the optimal picking time is between the 2nd and 3rd picking times, therefore data of those picking times were presented in the statistical charts. We used box-plot diagrams to illustrate our results, which show minimum, maximum and median values.

2. Results and discussion

2.1. Anthocyanin content

The anthocyanin content of the fruit was studied by many authors, and the results show big variability according to both fruit species and cultivars. SASS-KISS and co-workers (2005) and SHIOW and co-workers (2008) reported similar results.

The chancing of anthocianin content of the examined sour cherry cultivars included in the research was different from each other during the ripening time (Table 3). In the fi rst

picking time anthocyanin content of varieties Érdi jubileum (76.5 mg l-1) and Kántorjánosi 3 (82 mg l-1) were almost equal. Anthocyanin content of both Érdi bőtermő and Maliga emléke was lower (43 mg l-1). However, as ripening proceeded, anthocyanin content of the varieties ranged differently.

Table 3. Quality parameters of sour cherry cultivars

Picking time Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3

Anthocyanin (mgl-1) x±sd

1 76,5±6,87 43±1,73 43±6,24 82±4,82

2 91,5±8,35 47,5±8,26 71,5±3,77 48±3,97

3 176±9,76 52±1,73 77,5±7,09 38,5±7,4

4 58±8,26 51±6,54

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Polyphenol (mgl-1) x±sd

1 160,4±2,21 139,6±6,7 117,6±7,76 163,3±11,59

2 176,2±5,96 120,1±4,6 170,3±12,81 140,3±4,1

3 276,4±22,3 164,8±4,77 186,6±7,11 148±7,87

4 164,8±11,1 147,9±10,78

Ascorbic acid (mg100g-1) x±sd

1 27,7±0,47 26,3±2,53 28±0,63 25,6±1,55

2 28,73±1,38 25,57±0,89 26,9±2,55 27,68±0,98

3 26,97±0,78 25,77±0,64 28,2±1,25 26,7±1,6

4 26,47±2,46 27,1±0,9

Water-soluble dry matter (%) x±sd

1 14,07±0,15 11,03±0,15 11,37±0,06 13,07±0,12

2 16,06±0,12 12,03±0,06 13,8±0,1 13,5±0,25

3 16,8±0,1 13,03±0,15 16,03±0,05 14,13±0,21

4 15,2±0,11 14,4±0,19

x:average; sd:standard deviation

In case of cultivar Érdi jubileum, a constant increase was experienced, at the 3rd picking time it reached 176 mg l-1, which was the highest value during ripening. The extent of increasing was the most intensive between the 2nd and the 3rd picking times (Fig. 1). Also an increase was noticed in case of Maliga emléke, but in a signifi cantly slower rate, its anthocyanin content at the time of the 3rd picking was 77.5 mg l-1, the second highest value.

180

160

140

120

100

80

60

40

180

160

140

120

100

80

60

40Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3 Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3

2nd picking 3nd picking

Ant

hocy

anin

, mg

1-1

Fig. 1. Range of anthocyanin content of the cultivars at the 2nd and 3rd picking time

Cultivar Érdi bőtermő showed a very moderate increase, its anthocyanin content at the 3rd picking time was only 52 mg l-1 and hardly increased. Among cultivars involved in the examination, only the Kántorjánosi 3 showed a decrease in anthocyanin content during ripening. Its value decreased from 82 mg l-1 (1st picking time) to 38.5 mg l-1 (3rd picking time), the rate of decrease was constant.

69



Statistically proved difference was found between the anthocyanin contents at the 2nd and 3rd picking times in case of cultivars Érdi Jubileum, Érdi bőtermő and Kántorjánosi 3 (Fig. 1). In case of Maliga emléke the difference was found between the 1st and 2nd picking times (Table 4).

Table 4. Differences in anthocyanin, polyphenol and water-soluble dry matter content, according to cultivar and maturity

Anthocyanin Polyphenol Refraction

Picking 1 2 3 1 2 3 1 2 3

Érdi jubileum 1 0 – + 0 + + 0 + +

2 0 + 0 + 0 –

3 0 0 0

Érdi bőtermő 1 0 – + 0 + – 0 + +

2 0 + 0 + 0 +

3 0 0 0

Maliga emléke 1 0 + + 0 + + 0 + +

2 0 – 0 – 0 +

3 0 0 0

Kántorjánosi 3 1 0 + + 0 – – 0 + +

2 0 + 0 – 0 +

3 0 0 0

+: signifi cant difference, –: no signifi cant difference

According to our results, considering the anthocyanin content, the cultivar Érdi jubileum can be highlighted, because it showed outstandingly high values both at the beginning and at the end of the ripening period. Cultivars Érdi bőtermő and Maliga emléke have a lower anthocyanin content. The lowest anthocyanin content was measured in case of Kántorjánosi 3.

2.2. Polyphenol content

The polyphenol content showed similar data to those obtained by others (KIM et al., 2005). The change in polyphenol content during the ripening period showed similar tendency to that of anthocyanin content. At the beginning of ripening time, at the 1st picking time the polyphenol content of cultivars Érdi jubileum (160.4 mg l-1) and Kántorjánosi 3 (163.3 mg l-1) was the highest. Érdi bőtermő (139.6 mg l-1) and Maliga emléke (117.6 mg l-1) had lower values, like in case of anthocyanin content (Table 3). As ripening period proceeded, polyphenol content of Érdi jubileum increased signifi cantly, in a high rate between the 2nd and 3rd picking times (Fig. 2). By the end of ripening time it reached 276.4 mg l-1. Polyphenol content of Maliga emléke also increased, but to a smaller extent, it reached 186.6 mg l-1 by the 3rd picking time.

70



300

270

240

210

180

150

120

Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3 Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3


Pol

yphe

nol,

mg

1-1

300

270

240

210

180

150

120

Figure 2. Range of polyphenol content of the cultivars at the 2nd and 3rd picking time

A smaller increase was experienced in case of Érdi bőtermő, its polyphenol content was 164.8 mg l-1 at the 3rd picking time. Similarly to the change of anthocyanin content, polyphenol content of Kántorjánosi 3 decreased during maturity from the souring value (163.3 mg l-1) to 148 mg l-1. An increase can be detected at the 4th picking time, but in this ripening period phase the variety is already not marketable.

Statistically proved difference was found in the change of polyphenol content between the 2nd and 3rd picking times in case of Érdi Jubileum and Érdi bőtermő (Fig. 2). In case of cv. Maliga emléke there is a signifi cant difference only between the 1st and 2nd picking times, while difference between 2nd and 3rd picking times was not statistically signifi cant (Table 4). In case of Kántorjánosi 3 the changes in polyphenol content are not subject to time.

According to our results cv. Érdi jubileum has an outstandingly high polyphenol content at the end of ripening period, while the lowest polyphenol content was measured in case of cultivars Érdi bőtermő and Kántorjánosi 3.

2.3. Vitamin C content

Vitamin C content of the varieties involved has not changed signifi cantly during the ripening period, a slight increase was experienced, only. First values were between 25.6–28.0 mg/100 g d.w.. At the 3rd picking time cv. Maliga emléke had the highest vitamin C content, then Érdi jubileum and Kántorjánosi 3. Érdi bőtermő had the lowest value (Fig. 3).

According to our results it can be stated, that there were no statistically signifi cant changes in vitamin C content of the examined sour cherry cultivars during the ripening period. There were also no signifi cant differences in the vitamin C content between the cultivars. It is supposed that the of vitamin C synthesis starts in the early stage of the ripening period. During colouring of fruits the synthesis of colouring materials are more important.

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20

24

28

3

2

1 2 3 4

Asc

orbi

c ac

id, m

g 10

0g

Picking time

Fig. 3. Vitamin C content of the cultivars during ripeningÉrdi jubileum, Érdi bőtermő, Maliga emléke, Kántorjánosi 3

2.4. Water-soluble dry matter contentWater-soluble dry matter content of the cultivars examined increased as ripening period proceeded (Table 3). Similar tendencies were shown by SHIOW and co-workers (2008), who studied the changing of dry matter content of raspberry. At the 1st picking time Érdi jubileum showed the highest value, and this cultivar has the highest water-soluble dry matter content of all (16.8%).

17

16

15

14

13

12Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3 Érdi jubileum Érdi bőtermő Maliga emléke Kántorjánosi 3


Wat

er-s

olub

le d

ry m

atte

r, %

17

16

15

14

13

12

Figure 4. Range of water-soluble dry matter of the cultivars at the 2nd and 3rd picking time

Also Maliga emléke had a high dry matter content, it increased intensively during ripening time (Fig. 4). The cv. Kántorjánosi 3 showed a very slow and slight increase. From the relatively high souring value (13.07 ref%) of dry matter content it increased to 14.4 ref%. A more dynamic increase was experienced in case of Érdi bőtermő, it increased from 11.03 to 15.2 ref%.

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The increase in water-soluble dry matter content of the examined varieties was statistically proved. There was a statistically proved difference between cultivars, too. An outstandingly high water-soluble dry matter content was measured in cultivars Érdi jubileum and Maliga emléke.

3. Conclusions

Antioxidant status of fruits can be well characterized by their vitamin C, polyphenol and anthocyanin contents. We have found, that the examined cultivars contained the antioxidant materials in the highest concentration at the end of the ripening period, between picking times 2 and 3.

According to our data, Érdi jubileum contained antioxidant materials (polyphenol, anthocyanin) in the highest concentration at the end of ripening period, it is followed by cultivars Maliga emléke, Kántorjánosi 3 and Érdi bőtermő. Our results are informative, further examinations are in progress to conclude more profound correlations.

*The research work was carried out in the framework of Regional University Knowledge Centre – Research

and Development in Foodstuff Chain (project number: RET-04/2006), with the support of the National Offi ce for Research and Technology.

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Optimising harvest time of sour cherry cultivars on the basis of quality parameters

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