effect of short-term air storage after removal from controlled-atmosphere storage on apple and...

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Research ArticleReceived: 6 July 2009 Revised: 30 October 2009 Accepted: 30 October 2009 Published online in Wiley Interscience: 12 January 2010

(www.interscience.wiley.com) DOI 10.1002/jsfa.3851

Effect of short-term air storage after removalfrom controlled-atmosphere storage on appleand fresh-cut apple qualityPeter MA Toivonen,∗ Paul A Wiersma, Cheryl Hampson and Brenda Lannard

Abstract

BACKGROUND: One of the realities of apple distribution for long-term stored fruit is that a controlled-atmosphere (CA) storageroom will be unsealed and fruit held in air storage and marketed over several weeks. This work was conducted to determine theeffect of post-CA air storage of whole fruit on potential shelf life for fresh-cut apple slices.

RESULTS: Fresh-cut slices of ‘Spartan’ and ‘Delicious’ apples held in post-CA air storage for 2 or 4 weeks showed the leastchanges in cut surface color as compared with those made from apples immediately on removal from CA. Shelf life was mostimproved by post-CA air storage in the ‘Spartan’ apples, which were more advanced in maturity as compared with the ‘Delicious’apples. Internal ethylene concentration, firmness, and respiration changed significantly with post-CA air storage, suggesting arelationship between physiological status of the whole fruit and shelf life of slices made from that fruit.

CONCLUSION: The results support the hypothesis that apples had suppressed physiological activity in CA storage and aresusceptible to accelerated deterioration upon cutting. Holding fruit for 2 weeks in air storage allowed recovery of physiologicalactivity, which resulted in greater resistance to deterioration in response to fresh-cut processing.Copyright c© 2010 Crown in the right of Canada. Published by John Wiley & Sons, Ltd

Keywords: respiration; controlled atmosphere; fresh-cut; phenolics; ethylene; Malus × domestica

INTRODUCTIONFresh-cut apple slices were amongst the first minimally processedfruit or vegetable products to be dependent on the supplyof freshly harvested and long-term stored raw product.1 Asa consequence, the effects of inherent changes in the fruitphysiology and condition during storage may impact on thequality and shelf life of the fresh-cut product. During the conductof quality research for fresh-cut apples, unexplainable variationsin shelf life potential became prevalent at the time of year whenapples used for slicing were removed from controlled atmosphere(CA) storage as opposed to air storage.1

Low oxygen levels in CA storage are known to enhancestorage life of whole apples through inhibition of oxygen-dependent processes, including ethylene production, respirationand ripening.2,3 Flavour volatile production is also an oxygen-dependent process which is inhibited by low oxygen storageatmospheres.4,5 The effect of short air storage periods after removalof apples from CA has been shown to enhance regenerationof flavour volatile production, which is inhibited under lowoxygen storage atmospheres in CA.4 Also, it is known that asfruit mature and ripen on the tree, flavour volatiles increase.5 Inregard to fresh-cut apple slice shelf life, recently we found that‘Granny Smith’ apples harvested before their optimal maturitywere much more susceptible to cut surface-associated browningand decay-associated secondary browning, and we concludedthat susceptibility to both types of browning was associated withmaturity of the fruit and its physiological state.6 These resultsand the literature regarding volatiles regeneration prompted a

preliminary experiment to evaluate the effect of holding apples,removed from controlled atmosphere, in air storage for varyinglengths of time to allow them to re-aerate before slicing. Two to fourweeks in post-CA air storage resulted in significant improvementin shelf life of ‘Spartan’ apple slices.7 This preliminary experimentled to the hypothesis that physiological status of the fruit afterlong-term CA storage was correlated to a greater susceptibility offresh-cut slices to decay and cut-surface color change and thatpost-CA aeration could modulate the susceptibility.

Therefore the objective of this research was to determinewhether the time of holding in air storage post-CA had an effecton whole apple quality and physiology and on consequent qualityof fresh slices made from those apples.

MATERIALS AND METHODSPlant material and storage regimesApples (Malus × domestica Borkh.), cvs ‘Spartan’ and ‘Delicious’were harvested on 21 and 27 September 2007, respectively,from research blocks at the Pacific Agri-Food Research Centreat Summerland, British Columbia. Six boxes of ‘Spartan’ apples

∗ Correspondence to: Peter MA Toivonen, Agriculture and Agri-Food Canada,Pacific Agri-Food Research Centre, Box 5000, Summerland, BC, Canada V0H1Z0. E-mail: [email protected]

Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre,Summerland, British Columbia, Canada V0H 1Z0

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were sealed in commercial storage on 27 September 2007 heldat 0 ◦C and having a CA target of 1.5 kPa O2 + 1.5 kPa CO2. Sixboxes of ‘Delicious’ apples were sealed in a commercial storageon 8 October 2008 held at 0 ◦C and having a CA target of 0.7 kPaO2 + 1.5 kPa CO2. On 31 March 2008 both cultivars were removedfrom CA storage and placed in a 1 ◦C cold room at the PacificAgri-Food Research Centre at Summerland, British Columbia. Theholding periods in air storage before cutting were 0, 2 and 4 weeksand are designated as ‘weeks post-CA’.

Experimental descriptionOn 0, 2, and 4 weeks post-CA, two boxes of each cultivar weretaken from 1 ◦C air holding to a pilot plant area for washing,slicing, dipping and packaging. Whole apples were washed incool distilled water containing 100 mg L−1 sodium hypochlorite(Javex-5, Colgate-Palmolive, Toronto, Ontario, Canada), rinsedbriefly under running distilled water and allowed to drain forseveral minutes in a stainless-steel colander. Apples in groupsof five fruit were then sliced and cored using a hand-operatedFood Prep bench-top corer/wedger (Ditto Dean, Rocklin, CA, USA),fitted with an eight-slice wedging/coring head. Immediately aftercutting slices were rinsed in cool distilled water for 30 s and thendipped in a commercial anti-browning solution (70 g L−1 NatureSeal AS1; Mantrose-Haueser, Westport, CT, USA) for 2 min. Sliceswere then allowed to drain for 2 min before packaging and sealingin 20 × 25 cm zip-lock bags (measured oxygen transmission rate= 16.42 nmol s−1 m−2 Pa−1; Lakeside Plastics, Salmon Arm, BritishColumbia, Canada). The whole process from initial whole fruitwashing to packaging was completed in approximately 1 h, afterwhich the packaged slices were placed in a 5 ◦C walk-in storageroom for 3 weeks.

A subset of five replicates, comprised of two apples for eachcultivar, was assessed for internal ethylene concentration foreach post-CA time. A subsample of five replicates, comprised offour apples each, was assessed for firmness as described below.Another subset of five replicates, comprised of two apples for eachcultivar, was analyzed for respiration rates as described below.A third subset of five replicates of three apples was sliced andtreated as above and then immediately assessed for surface coloras described below. After 3 weeks of storage, slices were removedfrom their packages and both an instrumental measurement ofsurface color and a visual assessment of the severity of secondarybrowning were made on all slices as described below.

Physiological and quality measurementsApple slice L∗, a∗, and b∗ values were determined at three pointsalong each side of the cut surface using a Minolta chroma-meter(CR300; Minolta, Ramsey, NJ, USA). The six values taken fromeach slice were averaged and these average values for all theslices within a replicate were averaged to give a single value perreplicate. The initial lightness (L∗ values) is reported for the slicesfrom each cultivar, after each post-CA air holding period. A secondset of readings of surface color of the slices was made after 3 weeksin the package. The background color of the unaffected area on theslices was then evaluated using a Minolta chroma-meter (CR300).The difference between the initial color and the color of slicessamples after 3 weeks’ storage was calculated using the L∗, a∗, andb∗ values using the total color difference calculation (�E):8

�E = [(L∗t1 − L∗

t0)2 + (a∗t1 − a∗

t0)2 + (b∗t1 − b∗

t0)2]0.5

where t0 indicates readings at the time of cutting and t1 indicatesreadings 3 weeks after cutting.

The severity of secondary browning, which is browningassociated with the onset of fungal spore germination on the cutsurfaces,1 was made using a three-point scale: 1 = no secondarybrowning; 2 = few, minor localized secondary browning areasvisible; and 3 = moderate to severe occurrence of localizedsecondary browning. The scores for all slices in a single packagewere averaged to yield a single value for that package (replicate).

Fruit firmness was tested using a Fruit Texture Analyzer (FTAGS-14, Guss Manufacturing (Pty) Ltd, Strand, South Africa). Fruitwere sampled directly from the storage room, warmed for 3 h andthen the skin was removed from opposite sides of each fruit (thesun and shade sides) and measurements made using an 11 mmMagness–Taylor probe.

Internal ethylene concentration (IEC) of five replicates of twoapples for each cultivar was measured after the fruit had been heldat 20 ◦C for 24 h as described previously.9 Briefly, a 1 mL gas samplewas withdrawn with a syringe from the seed cavity of each appleand injected into a gas chromatograph (Model 5880A, Hewlett-Packard, Palo Alto, CA, USA) equipped with a flame ionizationdetector and a 2.1 mm OD × 1.52 m stainless-steel column packedwith F-1 activated alumina ranging in particle size from 0.177 to0.250 mm (Supleco, Bellefonte, PA, USA). Injector, detector andoven temperature were set at 200, 250 and 130 ◦C, respectively,and the carrier gas was nitrogen at 25 mL min−1.

Respiration was measured using a flow-through, computer-controlled apparatus, reported previously.10 Apple fruit wereplaced individually in 1 L plastic jars with tight-fitting lids andput into a 20 ◦C incubator (Model 307; Fisher Scientific Canada,Nepean, Ontario, Canada). Jars were continuously flushed with airat a rate of 1.5 L h−1. The output of each jar was connected to anautomated solenoid switching system. Every 5 min the samplerwas advanced to the output from the next jar and the CO2

detector was flushed with gas from a new sample. The level ofCO2 was detected with a �P infrared instrument (Type DPIP-CD-1900-0; Analytical Development Co., Hoddesdon, UK) and loggedby computer. Samples were analyzed over a 24 h period. Rates ofCO2 production are expressed as mL kg−1 h−1.

A previously developed in vitro method and fractionationprotocol11 was used to produce phenolic fractions of solublebioaccessible digestate. A 5 g aliquot of frozen apple powder,containing both peel and flesh, was first thawed and then madeinto slurry in 10 mL saline solution (140 mmol L−1 NaCl plus5 mmol L−1 KCl). An 8 mL aliquot of the slurry was added to 8 mLof simulated gastric fluid (SGF, 3.2 g L−1 pepsin, 2.0 g L−1 NaCl and7 mL of 12 mol L−1 HCl, pH 1.2) and the mixture was incubated ina 37 ◦C shaking water bath set at 60 rpm for 30 min. The gastricdigestate was then pH adjusted with the addition of 0.4 mL of0.2 mol L−1 NaOH. The pH-adjusted digestate was then added to16 mL simulated intestinal fluid (SIF, 10.0 g L−1 pancreatin and6.8 g L−1 KH2PO4, pH 6.8) and incubated in a 37 ◦C shaking waterbath for 60 min. The final digestate was centrifuged at 5000 × gat 20 ◦C for 30 min in an Allegra 64R centrifuge (Beckman CoulterCanada, Inc., Mississauga, Ontario, Canada). A 3.5 mL aliquot ofthe resultant supernatant was transferred to the top well of acentrifugal size exclusion filter device (Amicon Ultra-4. 10 kDa cut-off, Millipore Corp., Billerica, MA, USA) and centrifuged at 5000 × gin an Allegra 64R centrifuge for 30 min at 20 ◦C. An aliquotof the resultant filtrate was analyzed for antioxidant capacityand represented the total antioxidant capacity of the digestate.Phenolic antioxidant capacity was estimated by separating thenon-phenolic component11 as follows and then subtracting fromthe total capacity. A 2 mL aliquot of the filtrate was added to a

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preconditioned SPE cartridge (Oasis HLB, 3 mL volume loaded with60 mg of exchange resin, Waters, Milford, MA, USA). The cartridgehad been preconditioned with 1 mL of methanol and then rinsedwith two 1 mL aliquots of distilled water.

Reducing capacity was measured with Folin–Ciocalteu reagentby the method of Singleton and Rossi.12 A 6 mL volume ofdistilled water, 1 mL extract solution and 1 mL Folin–Ciocalteureagent (Sigma-Aldrich Canada Ltd, Oakville, Ontario, Canada)were mixed in a 25 mL capped test tube. After exactly 3 min,1.0 mL saturated sodium carbonate solution (71 g L−1) and 1 mLdistilled water were added and the mixture was agitated. Thetest tubes were left to incubate for 1 h at room temperature.The absorbance was measured at 725 nm, with a Cary 100 BioUV-visible spectrophotometer (Varian Canada), against a blankprepared in the same way with distilled water in the place ofthe extract. The results were expressed in terms of gallic acidequivalents (GAE) as mg GAE kg−1, on a fresh weight basis, oncethe extract concentration was determined against an equationobtained from analysis of standard quantities of gallic acid.

Experimental design and statistical analysisThe basic experimental design consisted of three treatments (0,2 and 4 weeks of holding in air after controlled atmospherestorage), each having five replicates and for two apple cultivars.In whole apple measurements, either two or three fruit were usedas subsamples per replicate. In sliced apple measures, a packagecontained 24 slices, which was equivalent to three apples, wasconsidered a replicate for the two quality assessments made after3 weeks of slice storage. Data were analyzed using PROC ANOVA(SAS version 9, SAS Institute, Cary, NC, USA). Data were summarizedin figures as means ± standard errors.

RESULTS AND DISCUSSIONFruit quality post-CAThe statistical analysis determined that declines in firmness overthe weeks post-CA were significant (P = 0.0138) and that thedifferences between the two cultivars were highly significant(P < 0.0001). There was no significant interaction term. ‘Delicious’apples were much firmer than ‘Spartan’ apples immediatelyafter removal from controlled atmosphere (0 weeks post-CA) andcontinued to be much firmer over the two ensuing post-CAsampling times (Fig. 1). A part of this large difference is probablyrelated to the fact that the ‘Delicious’ apples were harvested2 weeks earlier than target date (27 September 2007 instead of12 October 2007), based on estimated optimal maturity. ‘Spartan’apples were harvested within a week of the optimal harvest time,on 21 September 2007 instead of 28 September 2007, based onthe estimated maturity for those fruit at the Pacific Agri-FoodResearch Centre research blocks.

The maturity differences between the ‘Spartan’ and ‘Delicious’apples are clearly demonstrated by the internal ethylene concen-tration (IEC) data (Fig. 2). ‘Spartan’ IEC values were significantlyhigher than ‘Delicious’ values (P < 0.0001) and IEC increase wassignificant with post-CA storage time (P < 0.0001). The interactionterm (cultivar × post-CA) was not significant.

The respiration data (Fig. 3) show similar trends to the IEC data.Cultivar and post-CA terms were highly significant (P < 0.0001),as was the interaction term (P < 0.0001). Respiration of ‘Spartan’was slightly, but significantly, higher on immediate removal fromcontrolled atmospheres; however, the respiration rates at 2 and

Figure 1. Firmness of whole apple fruit measured on fruit immediatelyafter removal from 6 months controlled atmosphere storage (0 weeks postCA) and also at 2 and 4 weeks after holding in air storage (post CA). Valuesrepresent the means of five replicates ± standard errors.

Figure 2. Internal ethylene concentration (IEC) of whole apple fruit after24 h conditioning at 20 ◦C. IEC was measured on fruit immediately afterremoval from 6 months controlled atmosphere storage (0 weeks post CA)and also at 2 and 4 weeks after holding in air storage (post CA). Valuesrepresent the means of five replicates ± standard errors, when the errorbars are not obscured by the data point symbol.

4 weeks post-CA rose much higher than for ‘Delicious’. ‘Delicious’respiration increased gradually with weeks of storage post-CA(Fig. 3). That differences in respiration increase with weeks post-CAsupports the conclusion that ‘Spartan’ apples were more matureand undergoing climacteric ripening on removal from controlledatmosphere storage. In contrast, the ‘Delicious’ apples were muchless mature and were not undergoing rapid ripening after removalfrom controlled atmosphere storage.

An increasingly important aspect of quality in fruits is functionalvalue.13 The Folin–Ciolcalteu reaction (FCR) measures totalreducing power which, in apples, is attributed predominantly tophenolic compounds and so is often considered a good estimateof total phenolics in methanol extracts of fruits. However, it shouldbe kept in mind that other constituents such as vitamin C andsugars can also react with the FCR reagent.12 Analysis of the FCRreducing capacity for the methanol extracts of the fruit showedthat ‘Delicious’ had much higher estimated total phenolics content

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Figure 3. Respiration rates of whole apple fruit over 24 h at 20 ◦C asmeasured by CO2 production on fruit immediately after removal from6 months controlled atmosphere storage (0 weeks post CA) and also at 2and 4 weeks after holding in air storage (post CA). Values represent themeans of five replicates ± standard errors, when the error bars are notobscured by the data point symbol.

Figure 4. Total phenolics, as estimated by the Folin–Ciocalteu reducingcapacity assay in methanol extracts and in the soluble fraction of in vitrodigestates from whole apple fruit measured on fruit immediately afterremoval from 6 months controlled atmosphere storage (0 weeks post CA)and also at 2 and 4 weeks after holding in air storage (post CA). Valuesrepresent the means of five replicates ± standard errors, when the errorbars are not obscured by the data point symbol. Note: FCR reducingcapacity is expressed in mg gallic acid equivalents (GAE) kg−1 fresh weight.

than ‘Spartan’ (Fig. 4; P < 0.0001). This is not unexpected, sinceother authors have shown that ‘Delicious’ has a much higher totalcontent of phenolics than many other commercially grown applecultivars.13 Total phenolics content was not significantly affectedby post-CA air storage (P = 0.9310), nor was there a significantinteraction between cultivar and weeks post CA.

Since there is always the question as to what the biologicalsignificance of total phenolic content is,13 it was imperative toevaluate the bioaccessibility of the phenolics in in vitro digestates.

Figure 5. Cut surface lightness (L∗ value) of fresh-cut slices made fromwhole apple fruit immediately after removal from 6 months’ controlledatmosphere storage (0 weeks post CA) and also at 2 and 4 weeks afterholding in air storage (post CA). Values represent the means of fivereplicates ± standard errors, when the error bars are not obscured by thedata point symbol.

Previous work has shown that bioaccessible phenolics are only afraction of the total measured in raw product.11,14 This is becausethe matrix of the fruit tissue can bind phenolics during digestion.15

Therefore it was important to assess the actual potential availabilityof phenolics for absorption after digestion in order to assesswhether bioaccessibility of phenolics paralleled total estimatedphenolics in methanol extracts of the apples. An in vitro modeldigestion was performed on the whole apples to obtain anestimate of bioaccessibility of the phenolics in the apples asshown previously.11 The phenolics content of the soluble digestatefraction was estimated using the FCR reducing capacity test.This method is more accurately labelled as the Folin–Ciocalteureaction (FCR) reducing capacity assay, as opposed to the generallyaccepted ‘total phenolics’ assay, since many non-phenolics reactpositively in the assay.16 The data show that the soluble digestatefraction showed a much smaller difference between ‘Delicious’ and‘Spartan’, although it was still significant (P = 0.0005). There wasno significant effect for weeks post CA (P = 0.6375), nor was therea significant interaction term in the analysis. These results indicatethat weeks post CA do not have a detrimental effect on functionalvalue of the apples, and that when assessed on the bioaccessibilitybasis the phenolics content was only slightly different betweenthe two cultivars.

Fresh slice colorThe initial color of fresh slices made from the two cultivars wasassessed at the time of slicing (Fig. 5). The L∗ value of ‘Spartan’ wassignificantly higher than ‘Delicious’ (P = 0.0006), in keeping withits ‘whiter’ flesh color than ‘Delicious’. The initial color changedslightly but significantly (P = 0.0095) with weeks post CA. Therewas no significant interaction term in the statistical analysis. Slicesmade at 2 weeks post CA were slightly lighter in color than thosesampled at 0 and 4 weeks post CA.

Slice quality after 3 weeks in packageThe quality of the apple slices from both cultivars was assessedafter 3 weeks storage at 5 ◦C in package. Change in slicecolor was assessed both instrumentally and using a rating for


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Figure 6. Total colour change (�E) after 3 weeks in package at 5 ◦Cas compared with initial cut surface colour of fresh slices made fromwhole apple fruit immediately after removal from 6 months controlledatmosphere storage (0 weeks post CA) and also at 2 and 4 weeks afterholding in air storage (post CA). Values represent the means of fivereplicates ± standard errors.

decay-associated secondary browning. For both approaches ofassessment the cultivar and post-CA terms were significant, as wasthe interaction term in the ANOVA analysis.

The background color of the cut surfaces in the sliced fruit at3 weeks storage in package changed the least from initial valuesin the slices made from ‘Spartan’ apples held 2 or 4 weeks or‘Delicious’ apples held 4 weeks post CA before cutting (Fig. 6).The background color of ‘Delicious’ apples slices showed muchgreater change than ‘Spartan’ slices when comparing slices made0 and 2 weeks post CA. ‘Delicious’ apple slices showed the greatestdifference in total color change between 0 and 4 weeks post CA.These results show that the more mature ‘Spartan’ fruit wereless subject to color change over 3 weeks in package and thissuggests that more immature fruit are subject to greater levels ofsurface browning despite the application of anti-browning dipsafter slicing. This is congruent with the results obtained in thepreviously published work with maturity effects on slice browningin ‘Granny Smith’ apples.2

The severity of secondary browning was greater in ‘Delicious’than in ‘Spartan’ apple slices at all three post-CA sampling times(Fig. 7). Secondary browning declined only slightly with increasingtime post CA for ‘Delicious’ apple slices. In contrast, there was asignificant decline in secondary browning severity with increasedtime post CA for ‘Spartan’ apple slices (Fig. 7). These results showthat, for whole apples, time in air storage after removal fromcontrolled atmosphere storage (post CA) can significantly reducethe severity of secondary browning for apple slices made fromthose apples. The effect appears to be greater for apples harvestedat a more advanced maturity.

Relationship of ripening to slice shelf lifeThe association of reduced secondary browning, a phenomenonassociated with fungal spore germination,1 with ripening in thewhole apples when held under post-CA air storage suggests a link-age between physiological and biochemical activity and resistanceto fungal infection. A ripening inhibitor, 1-methylcyclopropene,has been shown to increase decay in apples,17 which suggeststhat ripening enhances decay resistance in apples. There has

Figure 7. Severity of secondary browning after 3 weeks in package forfresh slices made from whole apple fruit immediately after removal from6 months controlled atmosphere storage (0 weeks post CA) and also at 2and 4 weeks after holding in air storage (post CA). Values represent themeans of five replicates ± standard errors, when the error bars are notobscured by the data point symbol.

been a hypothesis that 1-methylcyclopropene can inhibit wound-associated ethylene effects18 and it is possible that the effects ofpost-CA air holding may allow apples to recover their inherentdecay resistance mechanisms that are associated with ripening.What that mechanism may be it is not clear at this moment, butone possibility is suggested by the literature. Fan et al.19 foundthat hexanal application to apple fruit increased ester formationand inhibited spore viability of blue mould spores. In other work,volatile production in apples has been putatively linked to ethy-lene action, which is associated with ripening.20,21 Hence it maybe that ripening enhances volatile production and thus inhibitsfungal development on cut surfaces of slices made from thoseapples. Since the ‘Delicious’ apples were much less mature andtheir ripening lagged well behind ‘Spartan’ (Fig. 2), resistance didnot develop to the same degree as indicated by the ratings forsecondary browning (Fig. 7). Another possibility, phenolic accu-mulation, can be ruled out as a mechanism since phenolic levelsdid not change significantly over the post-CA treatments (Fig. 4).In contrast, the total colour change, a direct consequence of re-sponse to cutting, was not influenced by ripening and appearedto be primarily associated with time post CA (Fig. 6). This suggeststhat general adaptability to cutting stress is modulated by post-CAaeration as opposed to being modulated by the ripening process.

CONCLUSIONSThe results demonstrate that holding apples in air storage for 2 or4 weeks after removal from CA storage results in better shelf lifefor fresh-cut slices made from those apples compared with fruitthat is sliced immediately after removal from CA. This improvedshelf life of the slices was associated with increases in respirationand IEC and a slight decline in firmness for the whole apples whichwere held in post-CA air storage. Those apples held in cold airstorage for 2 or 4 weeks post CA showed better colour stabilityover 3 weeks of storage in the package at 5 ◦C, and in more maturefruit there was also a significant reduction in severity of secondarybrowning. These results parallel what is known about the effects ofCA storage, in that the fruit metabolism is significantly restrictedunder CA conditions.22 It may be that fruit in such a state aremore susceptible to deterioration in response to cutting and have

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weakened defence against the invasion of tissue by fungi which arethe responsible agents in the secondary browning phenomenon.Therefore, the results of this paper suggest that shelf life variationfor fresh-cut apples observed previously1 was at least partiallydetermined by the time post-CA history of the apples used tomake those slices. Another positive aspect of this approach is thatthe post-CA air storage did not appear to have any affect on thefunctional quality of the apples as measured by total estimatedphenolics of the raw tissue or the bioaccessible phenolics of in vitrodigests.

ACKNOWLEDGEMENTSThe authors would like to acknowledge the Okanagan Tree FruitCooperative in Kelowna, British Columbia, for allowing the useof their commercial storage facilities for our samples and theassistance of Dan Worley for placing and removing fruit into andfrom the storage rooms as required for this work.

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multi-disciplinary research. Can J Plant Sci 86:1361–1368 (2006).2 Knee M, Effects of controlled atmosphere storage on respiratory

metabolism of apple fruit tissue. J Sci Food Agric 24:1289–1298(1973).

3 Knee M, Physiological responses of apple fruits to oxygenconcentrations. Ann Appl Biol 96:243–253 (1980).

4 Altisent R, Graell J, Lara I, Lopez L and Echeverrıa G, Regenerationof volatile compounds in Fuji apples following ultra low oxygenatmosphere storage and its effect on sensory quality. J Agric FoodChem 56:8490–8497 (2008).

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12 Singleton VL and Rossi JA, Colorimetry of total phenolics withphosphomolybdic and phosphotungstic acid reagents. Am J EnolVitic 16:144–158 (1965).

13 Tsao R, Yang RJ, Young C and Zhu H, Polyphenolic profiles in eightapple cultivars using high-performance liquid chromatography(HPLC). J Agric Food Chem 51:6347–6353 (2003).

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17 Janisiewicz WJ, Leverentz B, Conway WS, Saftner RA, Reed AN andCamp MJ, Control of bitter rot and blue mold of apples byintegrating heat and antagonist treatments on 1-MCP treatedfruit stored under controlled atmosphere conditions. PostharvestBiol Technol 29:129–143 (2003).

18 Toivonen PMA, Application of 1-MCP in fresh-cut/minimal processingsystems. HortScience 43:102–105 (2008).

19 Fan L, Song J, Beaudry RM and Hildebrand PD, Effect of hexanal vaporon spore viability of Penicillium expansum, lesion developmenton whole apples and fruit volatile biosynthesis. J Food Sci71:M105–M109 (2006).

20 Schaffer RJ, Friel EN, Souleyre EJF, Bolitho K, Thodey K, Ledger S, et al,A genomics approach reveals that aroma production in apple iscontrolled by ethylene predominantly at the final step in eachbiosynthetic pathway. Plant Physiol 144:1899–1912 (2007).

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