Results of experimental storage of sour cherry ( Prunus cerasus L . ) fruit

Sour cherry yield of the world is around 1 million t/year produced by 75% in Europe 2005, where the majority is grown in the regions of Central and East-Europe. Sweet cherry is grown everywhere in Europe, whereas sour cherry is a preferred fruit of East Europe (Kállayné, 2003). Most sour cherry is produced in Germany (in the eastern territories), Poland and Serbia. In Asia, the main sour cherry producing countries are Turkey and Iran. The climate and features of the ground are excellent sites for sour cherry production (Inántsy, 2004). Turkey produces 100–140 thousand, Iran 60–65 thousand tons per year, and contribute significantly to the world market. Further important quantities are produced in North America, where USA Michigan State is most important (Kállayné, 2003). The majority of sour cherry is traded as a canned product, whereas many consumers of North and East Europe prefer it as a fresh fruit. This moment influences also the choice of variety. Most countries used to concentrate their production on a single variety. In extended parts of Europe, the main variety is ’Schattenmorelle’ and its selected clones or hybrids are grown (’Morellenfeuer’, ’Fanal’ stb.) (Nyéki et al., 2005). Cultivars and harvesting technologies are entirely determined by the claims of the processing industry (Inántsy, 2004). The near future promises a gradual shift on the wholesale markets, which will influence the policiy of choosing cultivars and growing practices. Hungary will certainly continue to be a leading producer for the canning industry, but the rate of fruit sold for fresh consumption will increase. This moment should be considered in planning of plantations (understock, planting system, harvesting technology, etc.) as indicated by Soltész (2004). In certain regions of the World, the variability of the sour cherry has been accumulated over historical times as it is an ancient fruit species of the Old World. Contemporary local cultivars represent already results of purposeful selection. One of those gene centres is obviously the Carpathian basin. The majority of cultivars grown in Hungary is derived from this source. Some of them are results of cross breeding (’Meteor korai’, ’Érdi bôtermô’, ’Érdi jubileum’, ’Érdi nagygyümölcsû’, ’Favorit’, ’Maliga emléke’, ’Piramis’ etc.), Results of experimental storage of sour cherry (Prunus cerasus L.) fruit


Introduction
Sour cherry yield of the world is around 1 million t/year produced by 75% in Europe 2005, where the majority is grown in the regions of Central and East-Europe.Sweet cherry is grown everywhere in Europe, whereas sour cherry is a preferred fruit of East Europe (Kállayné, 2003).Most sour cherry is produced in Germany (in the eastern territories), Poland and Serbia.
In Asia, the main sour cherry producing countries are Turkey and Iran.The climate and features of the ground are excellent sites for sour cherry production (Inántsy, 2004).Turkey produces 100-140 thousand, Iran 60-65 thousand tons per year, and contribute significantly to the world market.Further important quantities are produced in North America, where USA Michigan State is most important (Kállayné, 2003).
The majority of sour cherry is traded as a canned product, whereas many consumers of North and East Europe prefer it as a fresh fruit.This moment influences also the choice of variety.Most countries used to concentrate their production on a single variety.In extended parts of Europe, the main variety is 'Schattenmorelle' and its selected clones or hybrids are grown ('Morellenfeuer', 'Fanal' stb.) (Nyéki et al., 2005).
Cultivars and harvesting technologies are entirely determined by the claims of the processing industry (Inántsy, 2004).The near future promises a gradual shift on the wholesale markets, which will influence the policiy of choosing cultivars and growing practices.Hungary will certainly continue to be a leading producer for the canning industry, but the rate of fruit sold for fresh consumption will increase.This moment should be considered in planning of plantations (understock, planting system, harvesting technology, etc.) as indicated by Soltész (2004).
In certain regions of the World, the variability of the sour cherry has been accumulated over historical times as it is an ancient fruit species of the Old World.Contemporary local cultivars represent already results of purposeful selection.One of those gene centres is obviously the Carpathian basin.The majority of cultivars grown in Hungary is derived from this source.Some of them are results of cross breeding ('Meteor korai', 'Érdi bôtermô', 'Érdi jubileum', 'Érdi nagygyümölcsû', 'Favorit', 'Maliga emléke', 'Piramis' etc.), earlier, i.e. centuries ago selected ones are still maintained ('Pándy meggy', 'Cigánymeggy'), and they are also proofs of the wide range of variability.Other types, as the pipacsmeggy ('Korai pipacsmeggy', 'Pipacs 1') and bosnyákmeggy ('Csengôdi') are also derived from the same stocks.A special group of cultivars is represented by the accessions of NE-Hungarian origin ('Újfehértói fürtös', 'Debreceni bôtermô', 'Kántorjánosi', 'Éva', 'Petri'), which are considered to be proofs of a rich variability still unexploited from the point of view of research and development for the recent horticulture (Szabó, 2007).
The storage of sour cherry as a fresh fruit has been since long an unexplored question.SASS (1986) reported first about 'Pándy meggy' fruit being maintained in a store over 3-4 weeks with less than 8% loss of volume, which was copiously compensated be higher prices on the market.According to him, low temperature (between -0.5 and +0.5 °C) and an elevated CO 2 /O 2 ratio of the atmosphere are favourable.Storability of sour cherry is easier than that of sweet cherry.
Several authors report, that CO 2 concentrations between 10 and 15% and O 2 concentrations between 3 and 10% are adequate for cherry preservation (Bishop, 1990 andKader, 1992).Meheriuk et al. (1997) report optimal conditions for Sweet heart cherries preservation to be 5% CO 2 , 10% O 2 or 4% CO 2 , 6% O 2 .All these discrepancies could be derived from cultivar effects or different ripeness degree or other experimental variables but it seems clear, that no general recommendations for sour cherry conservation can be established and that each cultivar has to be individually and carefully studied.To achieve this goal, we have characterized post harvest changes that affect quality in those sour cherry cultivars.Therefore, it is necessary to design and optimize processing, storage, and transport conditions.

Material and method
The experiments have been performed at Kecskemét, the Faculty of Horticulture and at Újfehértó, Research and Extension Centre for Fruit Growing in cooled store rooms between 2005 and 2007.
Samples examined at Kecskemét were transported from plantations at Kecskemét (0 km), Szatymaz (70 km), Siófok (160 km) and Újfehértó (230 km).Hand picked fruit was immediately transported and selected as well as put in the store by filling plastic trays 10 kg each.
In the cool storage at Kecskemét all conditions of an up to date plant were given.The room secured an ULO-type technology with the following parameters: temperature of the store 2-3 °C oxygen content of the atmosphere 18.3-19.0%CO 2 content of the atmosphere 0.1-0.3%relative air humidity 90%.All experimental lots were measured exactly before put in the store.Each sample represented 200 fruits at least, and the mean volume per fruit was calculated.The state of maturity of the fruit was 90%.
For computing the loss of volume, the initial measurement served as a basis.In order to set a date of the time recommended for storage, not only the changes of quality were considered.The experiment was continued even beyond the date, when the commercial value deteriorated in order to follow up the dynamics of the process specific for each (species and) variety examined.
During the storing period, the lots of samples were supervised every 6 th -8 th day (i.e.weekly).Each time -the process of loss was traced -weighed with one gram accuracy.Subsequently, every fruit was checked one by one.The properties being checked are explained in the heading and remarks of tables, where the comparison of data is facilitated.
The soluble solid content of fruits was monitored twice at the beginning and the end of the experiment by a manual refractometer.The last inspection of volume and quality was performed at the final procedure.The volume of fruits decreased gradually, thus the single fruits lost also their diameter and entered occasionally to a lower size category.
At Újfehértó, the harvested lots of fruit were furnished straight to the cooling store, put into M 10 cases or into plastic trays (0.5 kg) and distributed between different temperatures and atmospheres.The loss of volume and incidence of decay (mould, withering etc.) was followed up, and the inner values were checked regularly.
In 2006 and 2007 experimental lots of cultivars and storing conditions each were placed into M 10 plastic cases and plastic trays.Other details are identical with those explained at Kecskemét.
In Iran sour cherries were manually harvested at commercial maturity and packaged in 5 trays and covered by polyethylene film.Each tray contained 500 g fresh fruits.
The harvested fruits under modified atmospheres (15% O 2 and 10% CO 2 ) and stored at about 0 o C and humidity 95% for 6 weeks.A fifth set of trays was left unpackaged and was used as control.The acidity, soluble solids, resistance to penetration force and color of Fruits were analyzed immediately after harvest and 42 days later (immediately after refrigeration).Statistical analyses were carried out using SPSS-software.Analysis of variance, with the test of least significant difference was performed for each MAP composition

Results and discussion
Results of the storing experiment of 2005 are summarised in Tables 1-6.This year happened to be an opportunity of checking also the effects of rainy weather at harvest time.The high incidence of rot due to mould obliged us to stop the experiment earlier by 2 weeks.Table 7 proved that the variety 'Kántorjánosi' resisted most to rotting, however, this cannot be interpreted directly as storability but rather as resistance to rain.The rate of fruits with small, superficial scares was low (14%) indeed, whereas in other cultivars incidence of this fault was 2-4 times higher.The due Soltész, M., Szabó, T., Nyéki, J., Davarynejad, G.H., Aryanpooya, Z. & Szabó, Z. conclusion of this year was that the harvest at rainy weather and any contact with water is risky.
Results of the experiments of 2006 at Kecskemét are presented in Tables 8-14.As the storage period of the cultivars was different, for the sake of comparison the losses of volume during the first 5 weeks are compared (Table 15).Except of the variety 'Dunavecse ½', the loss was similar in the rest of cultivars.No significant difference could be stated between the variety 'Érdi bôtermô' and the 5 local cultivars of NE-Hungary.The loss was between 6.4 and 7.7%.An important conclusion was the exceptionally (i.e.twice as) high loss of volume in the early ripening variety 'Dunavecse ½'.
We checked the relation between fruit size and loss of volume during the period of storing (Table 16).Mean volume of the fruit of 'Dunavecse ½' was 3.6 g.Its higher values of loss could be a consequence of early ripening as well as of smaller fruits.It is generally accepted that the smaller fruits have a higher relative rate of stone.In the fruit samples grown at Újfehértó, the fruit size did not correlate significantly with the loss of volume.Cultivars of fruit size between 4.8 and 6.9 g lost 6.4-6.9% of their volume.It should be remarked that the loss of volume was 1-2% alone due to the transport of 230 km.

Results of experimental storage of sour cherry (Prunus cerasus L.) fruit
In order to facilitate the comarison of cultivars, the scores of rotting have been also related to the storing period of 5 weeks (Table 17).After the first week, there was no significant difference between cultivars regarding the incidence of fruit rot.After a longer period of storing, 'Érdi bôtermô' produced exceptional results, i.e. 11.3% rot after 3 weeks and 50% rot after 4 weeks.It was a surprise to state that 'Dunavecse ½', which showed the most loss of volume did not rot at all.The presumable reason of this fact may be the sudden cooling of the harvested fruit into a cooled room of the farm.In Table 18, relation between the rate of scared fruits and the incidence of decay is demonstrated.The variety 'Dunavecse ½' being the most susceptible to be scared, all the same, it was the less afflicted by rot.The probable reason of this contradiction is the quick cooling after harvest on the spot.
Data raised after two weeks of storage on fruits harvested at July 12, 2006 at Újfehértó, are presented in Table 19, after 4 weeks storage in Table 20.The unequivocal conclusion indicates the decisive role of the temperature, less important being the composition of atmosphere (O 2 and CO 2 ) of the storing room.The best results are obtained in the check room, where the store was held at 2 °C.Fruits stored in M 10 cases, volume loss was higher and the rate of intact fruit was the lower than on the plastic trays.Under regulated conditions, the rate of withered fruits increased after 4 weeks.The cause of it should be cleared in the future.
The stored fruit was subsequently kept on room temperature (19-22 °C) in order to check its shelf life over one whole week.Relevant data appear in Table 21.
Results of the experiments 2007, Kecskemét are shown in Tables 22-33.For some cultivars, several tables are needed because the fruits grown at different sites were handled separately.The storing period of cultivars was Soltész, M., Szabó, T., Nyéki, J., Davarynejad, G.H., Aryanpooya, Z. & Szabó, Z.  variable because of their harvest times.For the sake of an objective comparison, the losses of volume after a 6 week period are taken, uniformly (Table 34).There was no significant difference between the cultivars, except 'Érdi bôtermô'.The coincident values of this variety grown at three different sites prove the validity of the observation.
Between the 5 cultivars of NE-Hungarian origin, no significant difference in loss of volume was found after 6week-long cold storage, the loss varied from 7.2 to 8.4%.The role of mean fruit size should be explored in the rate of loss in sour cherry too (Table 35).Between the stored samples of the cultivars, no significant difference could be stated, their mean value was 5-5.5 g.The conclusion was risked that differences in losses between cultivars of similar fruit size ought to be attributed to other causes (scares, distance of transport, speed of cooling).Data of decay after a 6-week-long storing period are compared in Table 36.After the first week spent in store, no difference was stated neither between cultivars nor sites of origin regarding the incidence of decay.Neither a two-week-long storage indicated difference between cultivars.First signs of variable susceptibility of cultivars to decay have been observed in storage after 3 weeks, and became subsequently more convincing.After 6 weeks, 'Érdi bôtermô' decayed at a rate of more than 60%.Less susceptible was 'Újfehértói fürtös' (where 43.5% of fruits rot).The rest of cultivars ('Debreceni bôtermô', 'Kántorjánosi', D clone, 'Petri', 'Éva') showed nearly similar data (22.5-30.0%)without significant difference.Table 37 will help to evaluate the role of scares on the fruit in the progress of decay.Table 38, on the other hand, claims to answer the question whether soluble solid content of the fruit may modify the process of loss as well as of decay during the storage?As example, the variety 'Érdi bôtermô' could be mentioned.Fruits of lower soluble solid content (harvested ripe but somewhat earlier) from Siófok loss less volume and were more sound than those harvested and taken to the store at a more advanced stage of ripening.Consequently, we have to be cautious with the date of harvest especially with the cultivars of earlier ripening.39.Similar to the previous year, it could be concluded that the best results are expected in a store with a normal atmosphere, at 2 °C temperature.The loss of volume was the highest and the rate of sound fruits the lowest in the earlier ripening variety 'Érdi bôtermô'.The role of atmosphere in storage suggested by an earlier paper with the variety 'Pándy meggy' (Sass, 1986) are not verified and need additional check.

Results of experimental storage of sour cherry (Prunus cerasus L.)
The changes of chemical composition (soluble solids, sugar, acid) in the stored fruits are visualised in Table 40.It could be stated that soluble solids, including sugars and acid content diminished substantially.We need to decide Soltész, M., Szabó, T., Nyéki, J., Davarynejad, G.H., Aryanpooya, Z. & Szabó, Z.  subsequently, what is the critical level of declining content of each constituent mentioned, which may cause commercial consequences in the quality of the commodity.The evolution of fruit characteristics before and after of storage is shown in Table 41.Significant differences have been found in the pH of fruits between two cultivars.
The pH significantly rose during the storage.No significant difference has been found in the soluble solids content between cultivars before and after storage.They remained almost constant during the experiment with values approximately 23 and 24 Brix, may be as a result of no water loss suffered by this samples.
Titratable acidity shows a similar behavior than in comparable experiments of previous studies in 'Bigarreau Burlat' cherry (Rem et al., 2000): It shows a gradual decrease after 42 days in samples.
Flesh firmness tests were showed no significant variation of Érdi jubileum before and after storage However, in the case of 'Érdi bôtermô' showed a significant decrease in the Flesh firmness.However, panel test and sensorial analysis shows that the fruits of mentioned cultivars to remain acceptable for consumers over 6 weeks.
In conclusion Packaging cherries in polypropylene micro perforated films allow a considerable extension of their post harvest shelf-life.Firmness decreased after 7 weeks.Titratable acidity declined steadily over the storage period.

Conclusions
Under Hungarian conditions we may risk the following statements as summarising our results: -For the purpose of storing, fruits ought to be picked by hand, absolutely, even for the shortest term planned for storage.-Care should be taken by all possible means to save the fruits from damages as physical scare and any adversities threatening throughout all phases of technology and environmental risks (weather, plant protection, harvest, transport, packing), because minimal scares may cause serious losses during storage.-All items containing more than 10% of scared fruits should be culled out carefully before putting them into the store, or excluded from storing for a longer time than 1 -2 weeks.-Rotting fruits ought to be eliminated at harvest or at least before storing because they are serving as inocula of decay.-Fruits should be cooled soon after being harvested, or the vehicles should be equipped with cooling engines being active during transport.-The fruit destined to be stored should represent high quality and perfect health.This is indispensable but not the sole criterium of success; there are also other conditions to be considered.-The main and decisive purpose of storing is to meet the claims of the fresh consumption.-One of the motives is certainly the intention of avoiding the concurrent offer of sellers and postpone the sale.-The purpose of storing is lastly the improvement of marketing conditions, i.e. to achieve better income by higher selling price.However, costs and losses of storage have to be subtracted carefully from the higher price in order to justify the postponed sale.-In Hungary, early ripening sour cherry cultivars are not suitable for being stored by two reasons, first, they are less tolerant to storing, on the other hand, the stored fruit will compete with the fresh fruit of the late ripening, high quality cultivars, thus the advantages of storing will be frustrated.-The potential value of storage will be enhanced gradually by the increasing popularity of eating fresh fruit in general.Closer attention is deserved for the information related to the suitability of cultivars.-Experiences related to conditions and techniques of storage are appreciated by entrepreneurs of commerceespecially during the hot summer time -as fruits are hardly kept on the shelf for more than 2 days without cooling equipment.

Table 1
Results of storing fruits of the sour cherry cultivar 'Kántorjánosi'

Table 5
Results of storing fruits of the sour cherry cultivar'Petri'  *(Kecskemét, 2005)*Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits without stem before storing Site of origin: Újfehértó Date of harvest: July 11 (rainy weather) Rate of fruits with slight and superficial injuries at the beginning: 35% Method of harvest: manual, without stem End of storing: July 28.Mean volume of fruits before storing: 6.4 g/fruit Mean volume of fruits at the end of storing: 6.1 g/fruit Rate of decayed fruits after storing and held in the store at July 28:

Table 7
Comparison of the results of storing sour fruits of different cultivars *(Kecskemét, 2005) *Remark: Site of origin: ÚjfehértóThe fruits are taken without stem Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits without stem before storingLoss of volume (%)Rate of decayed fruits after storing (%)

Table 6
Results of storing fruits of the sour cherry cultivar 'Éva' *(Kecskemét, 2005)*Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits without stem before storing Site of origin: Újfehértó Date of harvest: July 11 (rainy weather) Method of harvest: manual, without stem Rate of fruits with slight and superficial injuries at the beginning: 28.4% End of storing: July 28.Mean volume of fruits before storing: 6.8 g/fruit Mean volume of fruits at the end of storing: 6.6 g/fruit Rate of decayed fruits after storing and held in the store at July 28:

Table 8
Results of storing the sour cherry cultivar 'Dunavecse ½' *(Kecskemét, 2006) *Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits before storing

Table 11
Results of storing fruits of the sour cherry cultivar 'Újfehértói fürtös' *(Kecskemét, 2006) *Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits without stem before storing Site of origin: Újfehértó Date of harvest: July 11 Method of harvest: manual, without stem Rate of fruits with slight and superficial injuries at the beginning: 3.2%

Dates of the storing Loss of Rate of comestible Rate decayed
July 11 Method of harvest: manual, without stem Rate of fruits with slight and superficial injuries at the beginning: 3.4% End of storing: August 18 Mean volume of fruits before storing: 5.7 g/fruit Mean volume of fruits at the end of storing: 5.3 g/fruit

Table 13
Results of storing fruits of the sour cherry cultivar 'Éva' *(Kecskemét, 2006)*Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits without stem before storing B= Rate of slightly and superficially injured fruits without stem before storing Site of origin: Újfehértó Date of harvest: July 11 Method of harvest: manual, without stem Rate of fruits with slight and superficial injuries at the beginning: 4.3% End of storing: August 18 Mean volume of fruits before storing: 6.9 g/fruit Mean volume of fruits at the end of storing: 6.4 g/fruit

Dates of the storing Loss of Rate of comestible Rate decayed
July 11 Method of harvest: manual, without stem Rate of fruits with slight and superficial injuries at the beginning: 7.2% End of storing: August 18 Mean volume of fruits before storing: 5.6 g/fruit Mean volume of fruits at the end of storing: 5.2 g/fruit

Table 15
The loss of volume in sour cherry fruits of different cultivars during cool storage(Kecskemét, 2006)

Table 18
Relation between injuries of fruits and their decay during the storing period in sour cherry cultivars(Kecskemét, 2006) * Remark: Data refer to both sound as well as to superficially scared fruits

Table 20
Results of a four-week-long period of storage with sour cherry cultivars(Újfehértó, 2006)

Table 24
Results of storing fruits of the sour cherry cultivar 'Érdi bôtermô' *(Kecskemét, 2007)*Remark: Sound or slightly and superficially scared fruits are stored separately Legend: A= Rate of entirely sound fruits before storing B= Rate of slightly and superficially injured fruits before storing Site of origin: Siófok Date of harvest: July 14 Method of harvest: manual Rate of fruits with slight and superficial injuries at the beginning: 0.7% End of storing: August 10 Mean volume of fruits before storing: 5.7 g/fruit Mean volume of fruits at the end of storing: 4.9 g/fruit

Dates of the storing Loss of Rate of comestible Rate decayed
Table 25 Results of storing fruits of the sour cherry cultivar 'Debreceni bôtermô' *(Kecskemét, 2007) *Remark: Sound or slightly and superficially scared fruits without stem are stored separately Legend: A= Rate of entirely sound fruits before storing B= Rate of injured fruits before storing Site of origin: Újfehértó Date of harvest: July 28 Method of harvest: manual Rate of fruits with slight and superficial injuries at the beginning: 14.6% End of storing: August 10 Mean volume of fruits before storing: 5.8 g/fruit Mean volume of fruits at the end of storing: 5.3 g/fruit

Table 35
Relation between the size of fruit and the loss of volume during storage in fruits of different sour cherry cultivars(Kecskemét, 2007.)

Table 37
Relation between the injury of fruits and the incidence of decay during storage in sour cherry cultivars(Kecskemét, 2007)Table36Decay of during cool storage in sour cherry cultivars(Kecskemét, 2007)Remark: All samples are grown at Újfehértó and sound fruits were selected only before storing * Remark: Fruits were not selected before storage * Before storage, sound fruits were selected

Table 38
Relation between the content of soluble solids and the loss of volume in sour cherry fruits of different cultivars(Kecskemét, 2007)

Table 41
Effect of storage period on the quality and quantity characteristic of sour cherry cultivars