5种杏仁发育过程中的一些物理化学变化

Food Sci Technol Res 16 1 71 78 2010 Some Physical and Chemical Changes during Fruit Development of Five Common Apricot Prunus armeniaca L Cultivars G khan durmaz1 Mustafa am2 T rkan KuTLu3 and Ya ar Hi iL4 1 Department of Food Engineering Inonu University 44280 Malatya Turkey 2 Department of Food Engineering Erciyes University 38039 Kayseri Turkey 3 Department of Chemistry Inonu University 44280 Malatya Turkey 4 Department of Food Engineering Ege University 35100 zmir Turkey Received July 14 2009 Accepted October 22 2009 Five apricot Prunus armeniaca L cultivars were examined throughout fruit development period to monitor the changes in quality characteristics including hardness Brix color titratable acidity and pH Changes in the amount of sugars fructose glucose and sucrose and organic acids citric malic and quin ic were also determined by HPLC The predominant sugar of cultivars found to be glucose at the initial ripening stages however sucrose or glucose became predominant at the end of fruit maturation Sugar acid rate was found to be the highest in Hasanbey HB cultivar during unripe period while Kabaas KA showed the highest value at full ripeness Low soluble solid containig varieties of Zerdali ZD and HB reached fruit maturity earlier than the other cultivars So anc SO measured as the hardest fruit at maturity while ZD was the softest cultivar Chroma as a measure of color was found to be well corelated with maturity level rather than L value In the course of ripening total acid content decreased along with the increasing amount of total sugar for all cultivars Keywords apricot fruit development HPLC organic acids sugars quality characteristics To whom correspondence should be addressed E mail gdurmaz inonu edu tr Introduction Apricot is a stone fruit and a member of Rosaceae family Turkey is one of the biggest apricot producer countries with the total annual production of about 538 000 tons of fresh apricot Durmaz and Alpaslan 2007 Apricot tree showed great adaptation to Anatolia especially Malatya region which provides 90 of total dried apricot production of Tur key where 7 10 of the world s fresh apricots and 80 85 dried apricots are produced Hac sefero ullar et al 2007 It is well known and widely accepted that the knowledge of the qualitative and quantitative distribution of sugars and acids in fruits vegetables honeys and several other natural matrices are of primary importance for a number of reasons Katona et al 1999 Qualitative and quantitative composi tion of organic acids and soluble sugars has been often re garded as indicator of fruit quality traits In addition these compounds are useful to evaluate fruit maturity ripeness and storage conditions moreover these conditions could be used as chemical markers in distinguishing different cultivars Bartolozzi et al 1997 Information on physical and chemical changes during fruit development is available for many fruits such as per simmon Glew et al 2005 banana Mustafa et al 1998 muskmelon Villanueva et al 2004 guava Jain et al 2003 papaya Gomez et al 2002 peach Wu et al 2005 pomegranate Kulkarni and Aradhya 2005 and strawberry Kafkas et al 2006 However little is known regarding the physical and chemical changes that take place during fruit development from bloom to harvest of apricot fruit Cell wall composition of apricots during development periods were studied Femenia et al 1998 Microstructural changes dur ing four stages of apricot ripening were studied Kov cs et al 2008 To authors knowledge there is no study reporting the changes of individual sugar and organic acid composition of apricot fruit Unlike some fruits such as pear cherry etc apricot is edible prior to full ripeness like some varieties of apple and plum thereby the compositional changes that take place during the ripening process must be revealed In the present study we report the changes in some physical and chemical properties including sugar and organic acid contents of com mercially important apricot cultivars during the development period of the fruit Materials and Methods Fruit collection and sample preparation The selected cultivars for this study were preferred as they are commonly cultivated varieties Hac halilo lu HH and Kabaa KA are well suitable for drying due to their high content of dry matter and sugar On the other hand So anc SO and Hasanbey HB are partially suitable for drying and also for fresh consumption Zerdali ZD however is a wild type apricot and because of its juicy flesh and sour taste it is gen erally consumed as fresh G l et al 2006 Asma et al 2007 Fruits were picked in 2007 from the orchard of Malatya Horticulture Research Institute Full blooming was observed at 13 14 March First fruit collection was performed at 27 April when measurable fruit formation occurred 3 g of fruit Table 1 Each cultivar was collected from at least three different trees and branches for homogenous sam pling Fruits were collected in plastic bags and immediately brought to the laboratory For the analysis of sugars and or ganic acids the fruits were cut into small pieces frozen and lyophilized in a freeze dryer Armfield UK Other analyses were carried out just after the fruit sampling Determination of physical parameters and quality char acteristics Fruit firmness was determined using a texture analyzer Lloyd UK equipped with a cylindrical probe with a diameter of 2 mm The instrument was set to test the speed 1 mm s 1 depression limit 3 mm and trigger 0 01 N Data was processed by using Nexygen software Lloyd UK and hardness were expressed as N Apricot skin color parameters of L a and b values Color space coordinates Cielab were determined by using a chromameter Minolta CR20 Japan and the chroma index C was calculated by using Eq 1 Mart nez Romero et al 2003 C a 2 b 2 1 2 1 L defines the lightness and a and b define the red greenness and blue yellowness respectively Fruit and seed weight were measured by using a precision balance Gec Av ery UK and the kernel rate was calculated pH total soluble solid content expressed as Brix unit and titratable acidity expressed as malic acid equivalent were determined by using the conventional methods described by Cemero lu and Acar 1986 Extraction of sugars and organic acids Extraction of sugars and organic acids was performed according to the method of Kafkas et al 2006 with slight modification For the extraction of sugars 1 g of lyophilized sample was weighed and 20 ml of aqueous ethanol 80 v v added into a screw capped vial Suspension was shaken for 15 min at 80 and filtered through a 0 45 m filter this procedure was repeated thrice Extracts were combined and evaporated to dryness in a water bath with nitrogen gas purging The residue was dissolved in 2 ml of distilled water and passed through a 0 45 m filter before injection For the extraction of organic acids 1 g of freeze dried sample was weighed into a screw capped vial 20 ml of meta phosphoric acid 3 was added and the mixture was shaken at room temperature After 30 min of regular shaking the mixture was filtered through a 0 45 m filter and the vol ume was adjusted to 25 ml using meta phosphoric acid 3 Analysis of sugars and organic acids Organic acids were analyzed with Hewlett Packard 1050 series pumping g durmaz et al Table 1 Fruit sampling dates and corresponding stages for apricot cultivars Picking date Corresponding stages for cultivars Hac halilo luKabaa So anc HasanbeyZerdali 27 April11111 11 May22222 25 May33333 08 June44444 22 June55555 29 June 66 06 July666 13 July777 Fruits were picked two weeks intervals during the ripening But after 5th stage Hasanbey and Zerdali after 6th stage Hac halilo lu Kabaa and So anc cultivars reached their full ripeness and picked one week after previous picking dates 72 system a Waters 486 UV detector Reverse phase separations were carried out with a 250 3 2 mm i d 5 m LiChrospher RP 18 column The mobile phase was 0 2 M KH2PO4 pH adjusted to 2 4 with H3PO4 at a flow rate of 0 8 ml min 1 Other parameters were as follows injection volume 10 20 L column temperature 30 and detection wavelength 214 nm All organic acids were identified by matching the re tention time and spiking tests Malic citric and quinic acids were quantified by the external standard method described in AOAC 1999 Sugars were analyzed with the same HPLC equipment using refractive index detector on a 250 4 6 mm i d 5 m Zorbax NH2 analytical column at 30 Elution was carried out using 75 aqueous acetonitrile at a flow rate of 1 5 ml min 1 as the mobile phase Sugars were identified both by comparison of their retention times and spiking with authen tic standards Sugars and organic acids were expressed on a dry weight basis Statistical analysis Analysis of variance ANOVA was applied to the data Means corresponding to different stages of ripening were compared using Duncan s multiple range test P 0 05 using SPSS program version 10 1 Results and Discussion Quality characteristics that determine the acceptability and quality of apricot cultivars during the ripening period are summarized in Fig 1 and Fig 2 Physical properties of apricot cultivars between subsequent stages indicated statisti cally significant differences P 0 05 Fruit weight of five cultivars increased approximately 7 11 fold throughout the fruit development period Fig 1 The cultivar HB showed the best profile for fruit weight during fruit development in proportion to the other cultivars which is in agreement with the previous report Hac sefero ullar et al 2007 Fruit weight is an important quality characteristic in respect of the harvest yield and consumer acceptance The percentage of kernel in fruit mass decreased along with fruit development and reached its minimum level at the last stage for all culti vars Fig 1 The percentage of kernel was minimum for HB 1 67 0 33 and maximum for SO 2 59 0 22 at full ripe ness Double kernel formation that contributes to the kernel mass was observed for SO Apricot kernel is an important edible except ZD by product of apricot production Durmaz and Alpaslan 2007 and this data could be important in esti mating the kernel rate of different apricot cultivars Another quality characteristic that establishes the apri cot fruit s appeal is sourness which can be measured by means of determination of pH total titratable acidity and quantification of individual acids present in fruit According to our results ZD was found to be an outstandingly acidic cultivar in comparison with other apricot cultivars tested Acidity plays an important role in selecting proper preserva Changes in Apricot during Fruit Development Fig 1 Some physical and chemical changes throughout apricot fruit development Results are the mean of at least three replicates Cultivars Hac halilo lu Kabaas So anc Hasanbey Zerdali 73 tion method for fruits Due to the increasing concentration of organic acids in fruit mass with decreasing water content ZD is expected to become extremely sour after dried When HH KA SO and HB showed pH values between 4 50 and 4 70 at full ripeness ZD indicated a pH value of 3 41 Fig 1 Similar pattern as expected was observed for total titratable acidity which was expressed as equivalent of malic acid ZD showed 0 8 malic acid equivalent titratable acidity which is approximately 2 5 4 0 times higher than the values ob tained for other cultivars Fig 1 Titratable acidity and pH values indicated sharp changes between 4th and 5th fruit picking stages except pH value of ZD Brix values of fruits were varied between 6 5 0 14 and 10 1 0 07 at the first fruit sampling Fig 2 Following 6 weeks Brix values were lower than the initial values until a sudden increase observed at the 5th stage and it increased as much as 15 Brix for HH KA and SO at full ripeness However Brix values at maturity were 13 5 0 06 and 11 5 0 10 for HB and ZD respectively This finding supports the preference of HH KA and SO for drying and ZD and HB for fresh consumption It s well known that higher dry matter and Brix values increase the yield during drying process At the same time high content of soluble matter directly related to the sugar content and increase the quality of the final dried product Ak n et al 2008 Azodanlou et al 2003 handled apricots for quality assessment and used near to ripe ripe and over ripe fruits for Brix determination and measured between 11 7 and 13 2 Brix units In another study 37 apri cot varieties cultivated in Spain were tested and soluble solid content of ripe fruits reported to vary in the range of 10 4 17 0 Ruiz et al 2005 However the change of this parame ter in apricot fruit throughout the development period is be ing reported for the first time in this study At the 1st fruit picking stage the fruits hardness ranged from 12 18 1 22 to 14 79 0 76 N for different apricot cultivars Fig 2 Throughout the fruit development period the hardest fruit was recorded at the 2nd stage for ZD with a value of 19 96 0 64 N After this stage all cultivars started to soften except HB which started to soften after the 3rd stage Fruits reached the softest state when they were fully mature ZD was the softest and SO was the hardest variety at this stage with hardness values of 4 06 0 54 and 5 41 0 79 N respectively Textural alterations go along with the color flavor and compositional changes during fruit developmental stages and determine the fruit quality and acceptability Jain et al 2003 Relatively harder apricot cultivars such as SO KA and HH at maturity are preferred for long term storage and drying because of their durability against harvest dam ages and other processes On the other hand softer cultivars such as ZD appeal to consumers owing to their softer and g durmaz et al Fig 2 Some physical and chemical changes throughout apricot fruit development Results are the mean of at least three replicates Cultivars Hac halilo lu Kabaas So anc Hasanbey Zerdali 74 juicy flesh Fruit color is an important indicator for fruit ripeness and harvest date of some fruits Ninio et al 2003 Beside spe cific yellow orange color of the apricot is positively corre lated to carotene content Ruiz et al 2005 In this study color values of the fruit skin were measured and the Chroma index was calculated instead of giving a and b values sepa rately for clarity Fig 2 Early ripening varieties HB and ZD reached their highest L values at full ripeness Other varieties lost their lightness and the L value showed a sharp decrease towards the end of the ripening period This may be due to the partly red areas that appear on the fruit skin at near mature stage Chroma index increased in the course of fruit development and reached the highest value at the last stage for all cultivars except SO which showed a slight decrease after the 6th stage These results showed that an increase in the Chroma index rather than the L value is well correlated with the ripening stages The main organic acids of apricot cultivars were reported to be citric and malic acids Gurrieri et al 2001 Campo et al 2006 while quinic succinic and ascorbic acids were found to be present in small amounts Bartolozzi et al 1997 In agreement with these reports in our study citric and malic acids were determined as principal organic acids of apricot cultivars while quinic acid was found in small amounts Changes in the same organic acids of different apricot cultivars showed similar trends throughout fruit develop ment period The level of citric malic and quinic acids sig nificantly changed in all cultivars Table 2 Citric acid was found to be the predominant organic acid of HH SO HB and ZD whereas malic acid was the predominant acid in KA at maturity Except quinic acid at early stages ZD was found to contain all organic acids in higher quantities compared to the other cultivars at every stage of maturity In some fruits such as tomatoes apples grapes and pears malic acid accu mulates in early developmental stages and then decreases to 50 during ripening due to respiration Glew et al 2005 According to our results the level of malic acid found to reach the maximum level at either the 1st or 2nd stages and then decreased to the minimum level at either the 6th or 7th stages for the apricot cultivars analyzed Citric acid content of apricot cultivars was at minimum level in the 1st stage of development and reached to its maximum at either 4th or 5th stages and then decreased in subsequent stages Quinic acid concentration of cultivars decreased continuously from first to the last stages except for SO which showed the maxi mum level at the fourth stage and then reached the minimum level at the 7th stage Similar results for quinic acid were ob served for Coffea canephora Coffea Arabica Rogers et al 1999 and peach Wu et al 2005 Sugars are basic parameters in evaluating fruit market quality attributes Genetic and environmental factors may affect the qualitative and quantitative composition of the sugar fractions by altering the activity of the enzymes in volved in synthesis and breakdown processes Linge and Dunlap 1987 The level of individual sugars of each tested apricot cultivar significantly changed along with the fruit development period Table 2 At the initial stages of apricot development glucose was prevalent among the sugars for all cultivars Glucose remained the predominant sugar dur ing the development stages for HH SO and KA whereas the predominant sugar of HB and ZD was sucrose at matu rity The level of sucrose fluctuated between the 1st and the 4th stages and boosted at the 5th stage for all cultivars The maximum sucrose level was measured at the last stage of rip ening period for all cultivars Changes in fructose level fol lowed a similar trend Fructose level showed fluctuation up to the 3rd stage and then gradually increased and reached the maximum level at the last stage for all cultivars The cultivar ZD showed the lowest total sugar content among cultivars although it was found to contain higher sucrose content com pared to HH KA and SO at maturity This was the r