C. ◦ 2012 Society of Chemical Industry c 16 b It was found that both nitrogen and argon reduced These gas hydrates are stabilised relative to the 16 17–19 10 MPa) argon (Ar) and nitrogen (N) for 20 min. The effects Department of Biological Systems Engineering,Pullman, Washington WA 99164-6120, State USA University, Correspondence to: Min Zhang, School of Food Sciencenan and University, Technology, Jiang- 214122 Wuxi, Jiangsu, China. E-mail: [email protected] School of Food ScienceJiangsu, and China Technology, Jiangnan University, 214122 Wuxi, When certain gases such as neon, argon, krypton, xenon, ∼ ∗ radical-scavenging activities. a b nitrogen and oxygen are intemperature contact with and water under pressure favourable crystals called conditions, clathrate theygas hydrates molecules can or are gas trapped form withinmolecules hydrates a ice-like in framework stabilised of which cages byforces. the of water physical bonding via van der Waals malic dehydrogenase, whichto are specific browning keymetabolism. of enzymes fresh related fruits and vegetables and respiratory structureofpurewatericeandcanexistattemperatureswellabove tyrosinase and malic dehydrogenase activities, witha argon having more significant effectthe than enzymes nitrogen. related Aan to gaseous important browning role inhibitor in and of vegetables maintaining as respiration the a could replacement quality fortheir of have potential some health fresh chemical risks. fruits treatments with and •+ and ABTS However, • 2 and Shao-jin Wang ∗ a 4,10,11 2–3 days) because ∼ Minimal processing offers Pineapple is a very popular 1 3–6 C. ◦ Min Zhang a and MP product is the main form at 9 : 2250–2259 www.soci.org Argon is reported to be biochemically active, 92 A comparative study has been carried out on the 12–14 15 2012; MP pineapple has a commercial advantage in terms minimally processed pineapples; argon; nitrogen; high pressure; gas hydrate 7,8

2012 Society of Chemical Industry Argon and nitrogen as major components of the atmosphere c in modified atmosphere packagingto (MAP) reduce have microbial beenfresh growth produce. reported and improve quality retention of of weight reduction for transport, sincepeel bulky tissues inedible crown are and removed, J Sci Food Agric INTRODUCTION Minimally processed (MP) fruits represent oneexpandingsegmentsofthelightlytreatedrefrigeratedfoodmarket of the most rapidly owing to their increased functionality.

BACKGROUND: High-pressure (HP) inert gasrestrict intracellular processing water causes activity and inert enzymatic gas reactions.study, This and minimally technique water processed can be (MP) molecules used pineapples to to were preserve treated form fruits with clathrate and HP vegetables. hydrates ( In that this pineapples during shelf life Abstract antioxidant potential of minimally processed Zhi-shuang Wu, treatments on respiration, browning and Effects of high-pressure argon and nitrogen (wileyonlinelibrary.com) DOI 10.1002/jsfa.5612 Research Article Received: 6 March 2011 Revised: 20 October 2011 Accepted: 21 December 2011 Published online in Wiley Online Library: 24 February 2012 of these treatments on respiration,during browning 20 and days antioxidant of potential storage at of 4 MP pineapples were investigated after cutting and fruit throughout the world forproperties. its nutritive and health-promoting of quality loss, including pulp browning, accumulationthe of packaging, liquid off-flavours in and microbial growth. retail. However, its shelf life is very limited ( RESULTS: Lower respiration ratecontrol and samples. ethylene HP production Armaintained antioxidant were and capacity of found HP MP N pineapples. in Theyleakage. treatments did HP HP not effectively cause Ar- Ar a treatments reduced and significant had decline browningand HP in greater tissue maintenance and effects N-treated firmness of than or loss phenolic samples increase HP compounds in of N and compared juice treatments DPPH total with on phenols reduction and of respiration ascorbic rate acid and ethylene and production consumers highly nutritious, convenient and healthful fruitsmaintaining while freshness of the non-processed products. CONCLUSION: Both HP Ar and HP N processing had beneficial effects on MP pineapples throughout 20 days of storage at 4 probably owing towith its nitrogen and its enhanced possible interference solubility with enzymaticreceptor oxygen in sites. water compared MP fruits arewhole produce, because perishable ethylene production, respiratory and activity, enzymatic and non-enzymatic have browning and nutrient release shorter from cells are stimulated a by plant injuries. shelf life than effects of nitrogen and argon on the activities of tyrosinase and Keywords:

2250 2251 . 1 C C 2 − ◦ ◦ LL µ treatment, samples C and stored at 4 2 ◦ treatment, pineapple 2 wileyonlinelibrary.com/jsfa C. For high-pressure air treatment, ◦ C. The time required for pressurisation of the ◦ C. For high-pressure Ar or N ◦ of 99.7% purity were purchased from Wuxi Xinnan 2 The pressure vessel was rinsed and sanitised with 200 0) and after storage for 2, 5, 8, 11,900 14, 17 g and 20 of days. Approximately MP pineapplesevaluations and for 70 each trays treatment per sample weretotal were of used prepared, 420 resulting for trays. in day Ten a traysanalysed 0 at per each sample storage were time randomly (2, takenwhole 5, process and 8, was 11, conducted 14, in 17 triplicate and as replications. 20 days). The Experimental apparatus and procedure The high-pressure gasJiangnan University treatment (Jiangsu, China) apparatus and manufacturedScientific was by Huaan designed Research by Instrumentapparatus had Co. an operating Ltd temperature range (Jiangsu, from 0 China). to 50 The Gas Co. (Jiangsu, China). Gaspressuriser was injected from into the a plunger gasvessel. of The the cylinder on–off and valve on thenthe vessel the was entered turned feed off line after the the between required pressure pressure thereached, level had pump then been and the pressuretime. was At held the for end thedepressurised of required by the treatment opening experiments the theline. on–off system valve could on be the easily vessel outlet sodium hypochlorite solution. Pineapple wedgesthe were treatment placed vessel. in Thewas sealed vessel and vacuumised, containing then flushed with pineapples 99.7% pure wedges Ar or N vessel was about 5 min. Theand parameters of time the were operating pressure selected onnot shown). the Then depressurisation basis was of performed by preliminarypressure opening relief the tests valve at (results the gas outlettook on the only pressure vessel, a which fewwere seconds. immediately After packaged treatment in the a pineapple room wedges at 4 pineapples wedges werevessel placed was sealed in and theheld pressurised for to 20 treatment min 10 at MPa. vessel. 4 That The pressure was were pressurised by the plungerwas pump to held 10 MPa. for That 20 pressure min at 4 wedgeswerekeptinthevesselundernormalatmosphericpressure for 20 min at 4 for later analyses. at a maximumhigh-pressure working pressure gas of treatmentprimary 30 MPa. components system A of is the diagramsteel apparatus treatment of shown vessel, were the a in athermally plunger 500 controlled Fig. pump, mL bath. 1. a The stainless vacuum samplecircular The treatment pump viewing vessel and had windows a two back made and of was submerged Plexiglasoperating in on a temperature. water the The bath water frontthrough to a in ensure plastic and tube the the to desired a baththe small was thermally controlled temperature recirculated bath, where ofrefrigerator the or water heating wasmaximum via stabilised pressure of by a 32 MPa coolingA heater. was via used pressure A to a transducer plunger pressurisethe the was pump vessel. vessel fixed with pressure.displayed in a All on the temperature a vesselto control and lid high panel. pressure to pressure All datagas-tight monitor were parts connections were made of to of the thecould stainless system gas be inlet sealed steel. exposed by and The screwed outlet. flangesduring vessel and The neoprene high-pressure had vessel O-ring gas gaskets lid Huangyan processing. Qiujing A Vacuum vacuum Pumpconnected pump Factory, to Zhejiang, (2XZ-4, the China) vessel was building for the evacuating vacuum the state airAr of in the the and vessel. vessel N Commercially and available For normal atmospheric-pressure Ar or N 22 C. ◦ spores at suggested 2012 Society of Chemical Industry 24 c respectively at 1 − Behnke reported that argon sodium hypochlorite sodium hypochlorite bar 1 1 It is desirable to use 22 25 − − 1 . Bacillus cereus − 15 g each). The knife and 14 LL LL ∼ µ µ et al permeabilities of the sealing day 2 2 − m C by treatment with mixtures of ◦ 3 L.) harvested in Hainan (China) were and CO Argon and nitrogen form structure II 2 treatment (NAP N); (4) high-pressure air found that pressurised xenon treatments 19 2 26 . : 2250–2259 C overnight before processing. ◦ 92 1 et al ± C, argon and nitrogen clathrate hydrates can form ◦ 90 g per tray) from each treatment were placed 2012; ∼ Ananas comosus treatment (HP N). Four conditions must be met simultaneously within Pineapple crown leaves were removed and fruits were At 0 2 27 23 reported that the shelf life of asparagus spears could C for 5 min, rinsed with tap water and drained on a clean C for 20 days. They were analysed just before packaging (day 14 14,20,21 ◦ . ◦ C and 0% relative humidity. Samples were stored in darkness Cunderapressureof600 MPaowingtoargonclathratehydrate ◦ ◦ C. Samples ( Fruitsweresortedtoeliminatedamagedordefectivespecimens. There have been few reports dealing with the application of Treatments included six groups: (1) control (not treated); ◦ Effects of HP Ar and N treatments on shelf life of MP pineapples www.soci.org The shell colour stage was thateyes were where partially several filled with to yellow most colour, all of ofby the them green. surrounded shell paper towel. The fruits wereand then peeled cut manually into with 2 a cm sharp thick wedges knife ( cutting board were sanitised with 200 at 4 formation. Oshita J Sci Food Agric supplied by a localand distributor stored and at 10 transferred to the laboratory MATERIALS AND METHODS Raw material and sample preparation Pineapples ( The gas hydrate structures aredetermined identified structure as H. I, II and the recently 0 compressed (1.1 MPa absolute) argonpartial and pressure. xenon They (2 also : 9 found v/v) thatin many under micropores the appeared asparaguswith argon microstructure and xenon after remainingsuggesting the in a the positive treatment structure connection with asfresh process, keeping micropores, asparagus during spears the whole storage time. hydrates. one region in order for a gas hydrate towater, be high formed: pressure presence of and gas, low temperature. high-pressure (HP) argon (Ar) or nitrogen (N) treatment toMP preserve fruits. The aim of this studyAr was and to HP investigate N the treatments effects of onpotential HP respiration, of browning MP and pineapples antioxidant during 20 days of storage at 4 a pressurised low-costpreserve inert MP fruits. gas such as argon or nitrogen to 23 be extended to 12 days at 4 and remain stable at more than 8.7 and 14.3 MPa respectively. washed in an aqueous solution of 200 film (Su Zhou Deep Breaths Preservation TechnologyChina) Ltd, Jiangsu, were 110 and 500 cm on polypropylene trays, whichpackaging were machine (BG-2, Wenzhou then Chunlai Packaging thermosealed Machinery usingCo., Zhejiang, a China). The O were efficient in maintaining the quality of fresh-cutbroccoli carnation and owing to xenonhydration clathrate restrains the hydrate activity formation. ofenzymatic Clathrate intracellular reactions, so water vegetable and metabolism inhibits iset al retarded. Zhang treatment (HP air); (5) high-pressure Ar treatmentpressure (HP Ar); N (6) high- (2) normal atmospheric-pressure Ar treatment (NAP Ar); (3)atmospheric-pressure normal N solution for 3 min prior to use. addition accelerated the inactivation20 of that high-pressure inert gases inhibitgelatin) tyrosinase systems in by non-fluid decreasing (e.g. oxygenphysically availability rather altering than the by enzyme. Fujii at 4 - 1 β − 1 − uge; 12, C the clear catechol as : 2250–2259 ◦ 1 92 − perchloric acid. C for 1 h. The are the readings ◦ protein. 1 -phenylalanine in ∗ t L − 1 b 2012; − 1 phosphate buffer (pH − 1 and mg − ∗ t 1 for 10 min at 4 a − , g ∗ t L × protein. 1 C for 30 min. The reaction was for 15 min. To the supernatant -cinnamate was measured in a ◦ J Sci Food Agric − ethylene diamine tetraacetic acid g are the readings for fresh pineapple 1 mg − × trans 1 − ∗ initial b borate buffer (pH 8.8) with 5 mmol L HCl. The increase in absorbance at 290 nm 1 POD was extracted from 50 g of pineapple and 1 − 2 − . after pineapple wedge treatment. A 10 g pineapple sample was homogenised in t polyvinyl polypyrrolidone at 4 with some modification. A 10 g pineapple sample ∗ initial 31 et al . a 1 borate buffer (pH 8.8). The substrate was incubated , 32 . − 1 et al − ∗ initial et al C for 1 h and the reaction was stopped by adding L ◦ Peroxidase (POD) activity was measured by the procedure The assay of polyphenol oxidase (PPO) followed the method of UV–visible spectrophotometer (Precision Science InstrumentLtd, Co., Shanghai, China). One unit ofthe enzyme amount that activity caused was an defined increase as ofhour. 0.001 Results absorbance were units expressed per as units h Assay of enzyme activities The extractionammonia-lyase and (PAL) were activity carriedof out determination according Zhou to of the method phenylalanine at 40 due to the formation of phosphate buffer (pH 7) and 0.1 mL of 10 mmol L where 15 mL of 0.1 mol L was homogenised in 25 mL of 0.05 mol L mercaptoethanol, 2 mmol L of Oms-Oliu substrate and incubated at 30 at storage time 0.1 mL of 6 mol L 7) and the homogenate was filteredpaper. through After Whatman centrifugation no. at 1 9000 filter stopped by the addition of 0.8 mL of 2 mol L and 10 g L wedges without any treatment and Soares homogenate was then filtered through Whatman no. 1and filter paper centrifuged at(0.25 15 mL) 000 was added 2.75 mL of 60 mmol L 0.1 mol L PPO activity was measured inat the 395 UV–visible nm. One spectrophotometer unit of enzymethat activity caused an was increase defined of as 0.001 the absorbance units amount perwere hour. expressed Results as units h supernatant was collected asextract (0.5 the mL) enzyme was added extract. to The a mixture enzyme of 3.6 mL of 0.1 mol L 2 E ,H 2 2 (green / . and 1 ∗ 1 ] ∗ a 2 − ) b h , analysis was 2012 Society of Chemical Industry ∗ 1 www.soci.org Z-s Wu, M Zhang, S-j Wang L 2 − c ∗ initial b kg 2 − ∗ t (lightness), b ( ∗ L Colour was measured + 2 ) respectively and the column C. Ethylene production was 29,30 ◦ 1 ∗ initial − observer angle and calibrated a ◦ − ∗ t determination. Gas flows for N defines the magnitude of total colour a ( 2 E . + 1 2 − ) h and the column temperature maintained at (yellow chromaticity). The instrument was set 1 1 ∗ ∗ initial − b L − C for 1 h. A 1 mL headspace gas sample was taken − Lkg ◦ About 200 g of fresh-cut pineapple was placed in ∗ t µ L [( 28 = Schematic diagram of high-pressure gas-processing equipment: 1, gas cylinder; 2, pressure gauge; 3, on–off valve; 4, plunger pump; 5, pressure E C. Respiration rate was calculated as mg CO ◦ Ethylene concentration was determined using the same gas wileyonlinelibrary.com/jsfa and air were 47, 47 and 400 mL min transducer; 6, high-pressure vessel; 7, thermocouples; 8, water bath container; 9, thermostatic bath; 10, refrigerant compressor; 11, pressure ga Determination of respiration rate and ethylene production Respiration is a basicA physiological higher process respiration in ratedeterioration. all It means is living faster known tissues. that overallrespiration. wounding metabolism tissue induces and elevated Figure 1. relief valve; 13, on–off valve; 14, vacuum pump; 15, vent valve; 16, exhaust gas cylinder; 17, display panel. temperature was maintained at 50 55 with a gas-tight syringe through the septum, and CO up for illuminant D 65 and 10 a 1.5 L glassincubated jar, at 4 sealed using a cap with a rubber septum and with a standardTen pineapple white wedges calibration were analysedsamplingtime.Thusthereportedvaluesarethemeanandstandard plate for each before treatment at measurement. each deviation of 30 determinations. Numerical values of Browning evaluation Measurement of colour Tristimulus reflectance colorimetry was usedof to assess browning the extent of pineapple wedges. calculated as chromatograph equipped with athe flame same column ionisation as detector for and CO chromaticity) and with a Minolta CR-400 colorimeter (Konicaaccording to Minolta, the Tokyo, CIELAB colour Japan) parameters conductedusingagaschromatograph(GC-2010,Shimadzu,Kyoto, Japan) equipped with a thermal conductivitycolumn detector. (i.d. A 0.32 capillary mm) was used withrate helium as of carrier 30 gas at mL a min flow were considered for the evaluation of colour modificationcut of pineapples. fresh- The value difference and is expressed by the equation

2252 2253 • 1 − 100 final ). The 1 × Oand 1 ] − 2 − ), cysteine for 15 min 6H 1 · g 3 ABTS radical − control fresh weight )-scavenging • × 46 1 . − Abs C. After addition FeCl for 15 min. The / ◦ ) 1 In our experiment et al g − 45 L of extract or Trolox × µ sample Abs wileyonlinelibrary.com/jsfa − ) and oxalic acid (0.5 g L 1 control − [(Abs = acetate buffer (pH 3.6). A 3 mL aliquot of • C and prepared daily by mixing 2.5 mL 1 ◦ − C. Solvent blanks were run in each assay. The % 2,4,6-tris(1-pyridyl)-5-triazine (TPTZ) solution in is the absorbance of DPPH solution without any ◦ ) was generated by mixing ABTS (7 mmol L 1 HCl with 2.5 mL of 20 mmol L − with slight modifications. Fresh FRAP reagent was This explains why the use of multiple techniques to •+ 1 methanolic DPPH and 0.090 mL of distilled water. The 02 at 734 nm and equilibrated at 30 . 44 control 47 − 1 0 ), citric acid (0.5 g L − 1 ± − Each fruit sample was centrifuged at 22 100 C and filtered through Whatman no. 1 filter paper. A ◦ 41 70 . . -azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and  The determination of the DPPH free radical (DPPH at 4 ferric-reducing/antioxidant power (FRAP) methods and the results were correlated with totalevaluate phenol the and overall ascorbic antioxidant potential acid of contents MP pineapples. to DPPH free radical-scavenging assay Since most natural antioxidantsfunctional compounds, and several phytochemicals methods are coveringtion multi- various conditions oxida- shouldproperties. be tested to evaluate their antioxidant 0.01 mL aliquot of0.025 g the L supernatant was mixed with 3.9 mL of of 10 mmol L extract. ABTS radical cation decolourisation assay The ABTS assay was performed according to Re FRAP reagent was added toreadingat593 a nmwastakenintheUV–visiblespectrophotometer. test tube and a blank absorbance final concentration indark 25 mL) at room and temperaturefor keeping for up the 12–16 to mixture h 29 days). (the in mL A of reagent distilled the 3 was water g containing stable ascorbic pineapple acid sample (5 g was L homogenised in according to the equation % inhibition of DPPH prewarmed at 37 measure the antioxidant capacity of natural productsa has become common feature in recent publications. effect was carriedet out al according to the method of Alothman homogenate was vigorously30 shaken min. The and absorbance kept ofin the the in UV–visible sample spectrophotometer at darkness against 515 awithout for nm blank DPPH. of was methanol Results measured were expressed as % inhibition of DPPH homogenate was centrifugedsupernatant was at used for 15 antioxidant 000 ABTS activity solution measurement. was The diluted withof 0 distilled water to an absorbance 25 mL of 0.3 mol L the total antioxidant capacity of fresh-cutlife pineapples was during measured shelf using the 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2 inhibition of absorbance at 734 nma was function of calculated concentration and of antioxidants plotted and as Troloxreference for standard data. Total antioxidant activityTrolox was equivalent expressed antioxidant as mmol capacity (TEAC) kg of 2.95 mL of diluted ABTS solution to 5 standard in ethanol andmeasured at mixing 30 for 6 min, the absorbance was (FW). FRAP assay The FRAP assay wasand based Strain on the method proposed by Benzie 40 mmol L cation (ABTS concentration in 25 mL) with potassium persulfate (2.45 mmol L (0.5 g L where Abs 3 40 CO 2 sodium Na protein. 1 1 1 Moreover, − − − 2012 Society of Chemical Industry 38 c mg buffer (pH 6), metaphospho- 1 1 4 C and the clear − ◦ − PO 2 and enzyme extract methanol. The mixture 2 1 NaH O − 2 1 A 10 g sample of fresh-cut H − 43 These protective effects are 1 − and the total phenolic content C. The assay mixture consisted for 10 min at 4 ◦ 34,35 41 g . × /0.08 mol L 4 et al sample. : 2250–2259 1 HPO − 2 92 Na C due to oxidation of guaiacol was recorded in the ◦ 1 A 5 g sample of fresh-cut pineapple was crushed guaiacol, 4 mmol L for 15 min at 4 2012; − by alleviating oxidative stress, i.e. preventing free The absorbance at 595 nm was evaluated by graphic 1 42 g In MP fruits the tissues are primarily submitted to − sample. 33 × 1 36,37 39 − L) in a final volume of 3 mL. The change in absorbance at µ Soluble protein content in the crude enzyme of triplicate Effects of HP Ar and N treatments on shelf life of MP pineapples www.soci.org 470 nm and 25 and homogenised in 50 mL of 700 mL L radicals from damaging proteins, DNA and lipids. J Sci Food Agric was added andat the 765 mixture nm was wasThe measured held concentration in for of the total 2 UV–visible phenolic h.by compounds The spectrophotometer. was comparison determined absorbance withconcentrations the as absorbance standard. Results ofacid were gallic kg expressed as acid mg at gallic different Total phenolic compound evaluation The extraction of total phenolic compounds followedreported the method by Alothman Thus for MP fruits it is importantand to storage assess on the effects their of antioxidant processing potential. sample by homogenisation in 100 mL of 0.2 mol L supernatant was collected. Then 1 mL ofa extract was test transferred tube to and 1.5 mLmixed of thoroughly Folin–Ciocalteu for 6 reagent min. was Thereafter, added 6 and mL of 100 g L in the extract wasprocedure. determined according to the Folin–Ciocalteu oxidative stress, whichandaltersthecompositionandcontentofantioxidantcompounds, presumably causes membraneresultinginchangesinthetotalantioxidantactivityofthetissues. damage pineapple was homogenised in 100 mL of 30 g L Ascorbic acid evaluation Ascorbic acidnol/indophenol was titrimetric method. analysed according to the dichlorophe- Antioxidant potential Fruits and vegetables have been associated with thedegenerative prevention diseases of such as cancer, heart disease, inflammation, arthritis, immune systemand decline, cardiovascular brain diseases. dysfunction, cataracts interpolation on a calibration curve. UV–visible spectrophotometer. One unitdefined as of the amount enzyme that caused activity an increase of was 0.001units absorbance per hour. Results were expressed as units h ric acid. A 10 mLthe aliquot of distinct the rose filtrate pink wasexpressedasmgkg colour titrated persisted with dye for until 15–20 s. Results were considered in large part to becontain. related to The various antioxidants antioxidants they mightbenefits confer these health-protective extractions wasstandard. determined with bovine serum albumin as the antioxidant status of aprovideausefulindicatoroftheresultingoverallslicequality.When fruit is related to itsthe shelf postharvest life oxidative and stress may system’s exceeds capacity, the protection natural against active antioxidant oxygendeclines, species resulting (AOS) in AOS-induced injury translatedsuch into disorders as browning,quality. microbial contamination and poor sensory of 0.02 mol L 20 mmol L (150 was centrifuged at 3000 phosphate buffer (pHat 6.5). 6000 The homogenate was centrifuged Control NAP N NAP Ar HP air HP N HP Ar Control NAP N NAP Ar HP air HP N HP Ar or Ar in C: control, ◦ 2 : 2250–2259 92 b c a a a a a b b b c c 2012; a a a a b c C. Ethylene production a b b b c d ◦ a a a a b c a b b b c d c d C, with values of 0.0089, 0.0095, a b b b respectively. HP Ar- and HP N- ◦ J Sci Food Agric a ab b b c d 1 − h a b b b c c a b b b c c 1 standard deviation) in respiration rate of MP − standard deviation) in ethylene production of Storage time (days) ± c c ± a ab b b Storage time (days) Lkg a b b b c d µ 39 369 b a a a ab b a b b b c d 05 according to Duncan’s multiple range test. 05 according to Duncan’s multiple range test. . . 0061 0 0 0 6 12 15 18 21 . 012151821 < < 5 0 P P

0.01

25 20 15 10

0.011 0.009 0.008 0.007 0.006 0.005 0.004 0.003

2 Changes (mean Changes (mean

) h kg CO (mg rate

1 1

) h kg L ( production

− −

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1 1 − − Respiration Ethylene Figure 3 shows the effects of different treatments on ethylene The inhibitory effect of HP N or HP Ar treatment on the C. For each storage time, means with the same letter are not significantly ◦ production of MP pineapples stored at 4 untreated pineapple wedges;atmospheric-pressure NAP nitrogen N, fortreated pineapple 20 with min; wedges atmospheric-pressure NAP treatedwedges argon treated Ar, with with high-pressure for (10 pineapple MPa) 20 air min; forwedges wedges 20 treated min; HP HP with N, pineapple air, high-pressurepineapple pineapple (10 wedges MPa) treated nitrogen with for high-pressureFor 20 (10 each min; MPa) argon storage HP for time, Ar, different 20 at means min. with the same letter are not significantly MP pineapples of six4 treatments (see Fig. 2) during 20 days of storage at Figure 3. Figure 2. pineapples of six treatments during 20 days of storage at 4 0.0071 and 0 different at treated samples showed less ethylene productionsamples, than untreated with HPproduction Ar throughout treatment storage. resulting TheHP results in Ar indicated the and that least both HPthat ethylene HP N Ar treatment treatments had reducedtreatment. a No difference significantly ethylene was observed greater in production ethylene effect production and than and peak HP time N of untreatedwhich and NAP indicated N- that orinhibitory NAP effect NAP on Ar-treated ethylene N production samples, ofcold and MP storage. pineapples NAP during Ar treatments hadrespiration no rate and ethylenebe production of due MP pineapples to may gas hydrate formation and residual N of all samples maintained aoccurred stable at 11 pattern days. until The auntreated peak sharp and in increase treated ethylene with production HP ofafter air, samples 14, HP 11, N 17 and and HP 20 Ar days was at detected 4 C 48 ◦ FW. 1 C in a water 2012 Society of Chemical Industry − ◦ www.soci.org Z-s Wu, M Zhang, S-j Wang c O (200, 400, 600, 2 L of distilled water µ 7H C about 30 min after · ◦ 4 who reported that the 05). Similar results were 2 . by tilting the packages at 0 10 ± 27 . < C. A TA-XT2 texture analyser ◦ P et al ´ on standard deviation. ± 05. Values were expressed as mean of for asparagus spears with compressed . 0 14 ). FRAP values were expressed as mmol . 1 = − C and that HP Ar treatment was significantly C, which was followed by visual signs of P et al ◦ ◦ mol L for 5 min and recovering accumulated liquid with µ ◦ . The maximum penetration force was measured and FW. 1 1 − L aliquot of sample extract and 300 − µ kg + 2 Texture analysis Texture analysis was performed at 20 Fe a calibrated syringe. Results were expressed as mL kg more efficient than HP N treatment ( obtained by Zhang Juice leakage measurement Juice leakage from pineapple wedges was measuredthe according method of to Montero-Calder taken as firmness (N). Three trays wereto used at perform each the sampling time analyses, andrandomly five withdrawn wedges to for carry out each repetitions. replicate were wileyonlinelibrary.com/jsfa for cucumber with compressed Xe treatment. RESULTS AND DISCUSSION Respiration rate and ethylene production The respiration rate of all MP pineapples during shelf life at 4 A 100 were then added toto the the test FRAP reagent tube. and After 90 addition min of of incubation the at sample 37 respiration rate of fresh-cutby pineapple was storage significantly temperature affected after and 12 that days a at marked 5 increase occurred Statistical analysis All analyses were replicatedAll in data triplicate were at subjected eachInstitute, Cary, sampling to NC, time. analysis USA). The ofmeans significance variance of was using differences between determined SASsignificance (SAS by level of Duncan’s multipleall replicate range determinations test at a bath a secondchange absorbance in absorbance reading after at 90was min 593 compared from nm the with initial was a blankprepared standard taken. reading using curve. aqueous The The solutions calibration of curve FeSO was an angle of 20 (Stable Micro Systems5 kg Ltd, load Godalming, cellto UK) was penetrate employed. equipped the A0.5 with pineapple mm 2 s a mm wedge diameter sample rod at was a used test speed of removing samples from storage at 4 (1.1 MPa absolute) Ar and Xe treatment and by Zhan and Zhang microbial spoilage indicating thepineapples. end For samples of treated with post-cutting HP N lifeextended or to HP of Ar, 15 this MP days, stage since was throughout a the lower storage respiration period compared rate with was samplesand observed untreated treated with HP air, NAP Ntreated or NAP samples Ar showed (Fig. 2). the HP highest air-respectively and and throughout HP lowest the Ar- storage respiration time. rates There wasin no difference the respiration ratesamples. of untreated, The NAP results N-treatments demonstrated and could that NAP lower the Ar-treated both respirationduring HP rate storage of Ar at pineapple 4 and wedges HP N was rather low until 11 days (Fig.in 2). the From 14 respiration days rate a of sharpair, increase samples NAP untreated and N treatedthose and with observed HP NAP by Ar Marrero was and detected. Kader, The results agreed with 800 and 1000

2254 2255 - It L 51 Control NAP N NAP Ar HP air HP N HP Ar 05 according to . 0 a a a < a a b c a a a b b a a a a b c values than samples P E a a a b b a a b c a a a b b a a a a wileyonlinelibrary.com/jsfa a a b bc c d b b b c c a a a a a a a b b a a a a b b a a a b c d b a a a a a a a a b b a a a a b b a a a a b b standard deviation) in (a) PAL, (b) PPO and ± -cinnamic acid in the phenylpropanoid Storage time (days) Storage time (days) Storage time (days) values and lower b a a a a b b c c a a b b a a a a b b C. In each part, for each storage time, means with ∗ ◦ b trans a a a a b b a a a b b b c c a a b b and 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 ∗ 1 Browning reactions are generally assumed to be a

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1 1 1 1 1 1

− − − − − −

POD activity POD PAL activity PAL activity PPO (c) (a) (b) C. There was no difference between HP Ar and HP N treatments PAL, PPO and POD play an important role in the browning ◦ (c) POD activities of20 MP days of pineapples storage of at 4 six treatments (see Fig. 2) during the same letter are not significantly different at Duncan’s multiple range test. untreated and treated with HP air, NAP N orstorage NAP time. Ar This throughout suggested the that HP Arefficient and in HP preventing pineapple N wedge treatments surfaces were from browning at 4 Figure 5. had higher in colour retention of MP pineapples over the storage time. process of manyof fruits polyphenol and vegetables. synthesis PAL and is acts a key on enzyme the conversion of is well known that woundingThe induces effects of increased different enzyme treatments on activity. PAL,of PPO MP and POD pineapple activities wedges areshowed presented different in tendencies Fig. individually, 5.change with These over the activities different storage rates time. PAL of activityuntil increased the continuously end of storage (Fig. 5(a)), in agreement with the results phenylalanine to pathway. direct consequence ofto PPO form and quinones, which PODbrowning ultimately appearance actions polymerise of on to MP polyphenols produce fruit the and vegetable products. ∗ L values ∗ b HP N HP Ar Control NAP N NAP Ar HP air 2012 Society of Chemical Industry and c ∗ L areshowninFig.4. a a b b b b E After 5 days of shelf a ab b b b c C. This phenomenon (index of colour change) a a b b a a ◦ E 49 a a b b b c a b bc c c c and elevated PPO activity and b b c a a a a ∗ 9 b , a a b b b c a a b b b b a a a a b c ∗ 05 according to Duncan’s multiple . L 0 values and a marked increase in a a b b b c a a b b b b < b a a a a b ∗ b P a a b b b c a b b b c c a a b b b c standard deviation) in colour parameters (a) and ± ∗ Storage time (days) Another reason could be that HP Ar and : 2250–2259 a a b b b b Storage time (days) values, which could be due to the surface L a a b b b b MP pineapples treated with HP Ar and HP N Storage time (days) d c a b b b 92 E 30 14,48 a b b b c d a a b b bc c a ab b b b c (yellow chromaticity) and (c) ∗ 2012; b 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21 0 3 6 9 12 15 18 21

5 0

40 35 30 25 20 15 25 20 15 10 80 75 70 65 60 55 50

E * b * L Changes (mean ∆ (c) (a) (b) C. In each part, for each storage time, means with the same letter ◦ values were observed after 5 days at 4 E Effects of HP Ar and N treatments on shelf life of MP pineapples www.soci.org of MP pineapples ofat six treatments 4 (see Fig. 2) during 20 days of storage Browning evaluation Changes in the colour parameters HP N treatments renderedand thereby the reduced MP aerobic pineapple respiration(which and tissues relies ethylene anaerobic on formation oxygen).this Further hypothesis. studies are needed to validate could be induced by minimal processing. J Sci Food Agric micropores of pineapple wedges, which could restrainof the activity intracellular water andthe enzymes metabolism. in the fruits and slow down Figure 4. (lightness), (b) life, samples generally showed a slight increase in are not significantly different at may be the result of phenolic oxidation,enzymes which is to catalysed form by PPO coloured melanins, dehydration of pineapple wedges thattissue precedes the senescence. incidence of and decrease in In general, the colour of all samples became progressivelyand browner less pure yellowA than sharp that decrease of in recently cut fresh pineapples. range test. Control NAP N NAP Ar HP air HP N HP Ar 46%) and ∼ : 2250–2259 92 33%) and HP Ar During 20 days at ∼ who reported that 2012; a a b b b c 60 14 ., a a b b bc c et al b c a a b b 47%) and NAP Ar ( FW) and HP air-treated samples ∼ 1 J Sci Food Agric − c d a b c c For all samples, TAC determined by 35 for pineapple. The correlation between 59 FW). There was no difference in the b standard deviation) in ascorbic acid content a a b b b c -scavenging activities of MP pineapples 1 35 C. FW respectively, higher than in untreated ± − ◦ •+ 1 Its enediol structure plays an effective role Storage time (days) − a a a a b c 58 369 05 according to Duncan’s multiple range test. b b b c a b . 52%), a moderate reduction in wedges untreated 0 C, with HP Ar treatment showing a greater effect ◦ ∼ < 0 12151821 -andABTS P •

Changes (mean 400 300 200 100

FW) kg (mg acid Ascorbic

1 − C, there was a high reduction in ascorbic acid in wedges treated 48%) and treated with NAP N ( 30%), thus demonstrating that HP N and HP Ar treatments were Figure 7 shows that ascorbic acid content decreased with Ascorbic acid is one of the most effective antioxidants in fruits C. For each storage time, means with the same letter are not significantly ◦ ◦ ∼ ∼ increasing storage time for allacid degradation samples, through oxidative which processes. is due to ascorbic samples (362 mg gallic acid kg Figure 7. of MP pineapples of six treatments4 (see Fig. 2) during 20 days of storage at phenol content in HP N-443 and mg HP gallic Ar-treated acid samples kg was 409 and and vegetables since it suppressesof free radicals ascorbyl via radicals. the formation than HP N treatment. This result can beeffect of attributed HP to Ar the or inhibitory HP N treatment onto the phenol activity of degradation, enzymes related thus reducingpineapple the wedges loss at of 4 total phenols in with HP air ( ( (353 mg gallic acid kg different at duringcoldstoragearepresentedinFigs 8(a)andThe 8(b)respectively. DPPH andantioxidant ABTS capacity assays (TAC) showedresults of of Leong the and samples, Shui same in trends agreement in with total the compressed (1.1 MPa absolute) Ar and Xeon treatment had maintaining no effect the ascorbicFurther acid studies content are ofhighest reduction needed asparagus in ascorbic to spears. acid content found explainmay in be HP the air due wedges phenomenon. tothe HP The treatment oxidative and degradation oxygen oftreatments in had ascorbic the no significant acid. air effect on accelerating NAP retainingcontent the N of ascorbic pineapples acid and wedges. NAP Ar Total antioxidant capacity The DPPH in scavenging free radicals. the DPPH and ABTS methodsmechanism may result and partly also from theiraqueous/ethanolic because systems. similar both antioxidants are soluble in 4 total phenol content ofsamples throughout control the storage and time. HP NAPwere Ar effective N- and in HP retaining or N the treatments total NAP phenolicwedges content Ar-treated of at pineapple 4 a low reduction in wedges treated with HP N ( ( effective in reducing theThis loss differs of from ascorbic the acid results in of MP Zhang pineapples. C. C. 16 . ◦ ◦ FW 1 et al − NAP Ar Control NAP N HP air HP Ar HP N The total for peach 56 2012 Society of Chemical Industry PPO activity 50 . www.soci.org Z-s Wu, M Zhang, S-j Wang for cucumber Zhang C for 20 days c ◦ 48 et al 48 52–55 b d a c c c reported that Ar and 05 according to Duncan’s d b c c c a . 14 0 . c < b b b b c a et al P b b b d a c After 8 days of storage, with increasing standard deviation) in total phenolic com- can inhibit the activities of tyrosinase ab b b a a c 57 2 ± C. For each storage time, means with the same Storage time (days) ◦ ab bc b a a c for pineapple fruits stored at 6, 13 and 18 b b a a a c 31 . 036912151821

et al

Changes (mean 600 500 400 300 200

(mg gallic acid kg acid gallic (mg FW)

1 − Total phenolic compounds phenolic Total in micropores of pineapple wedge tissues suppressed enzyme The total phenolic compound content in control (untreated) 2 letter are not significantly different at wileyonlinelibrary.com/jsfa reported that Ar and N of Zhou Figure 6. pound content of20 MP days of pineapples storage of at six 4 treatments (see Fig. 2) during Antioxidant potential Total phenol and ascorbic acid contents Polyphenolic compounds arebecause very important of fruit theirmetal constituents antioxidant ions, activity inactivating lipid inhydroperoxide free chelating conversion radical into redox-active chains reactive and oxyradicals. preventing activity after HP Ar or HP N treatment. with compressed Xe treatment.attributed These to two results reasons. could One is possiblymay that form be gas HP hydrates Ar in and pineapple HPwater tissues, N activity which in treatments will the reduce fruit the tissue andof influence the protein enzymes, structure so enzyme activity is restrained. slices. The accumulation of phenolic8 compounds days during of the first storageinduced may by wounding be in promotedproductionofmajorphenoliccompoundsandthesynthesisofnew minimal by processing PAL andpolyphenolic results activity, substances. in which the is showed a clear increasestable (Fig. from 5(b)). POD 5 activity to decreasedstorage during and 11 the then days first increased and 8 (Fig. days 5(c)).inhibited then of HP PAL, Ar remained and PPO HP and N POD treatments activities of MP pineapples at 4 Xe remained in theand structure Xe as treatments, micropores suggesting a afterasparagus positive pressurised spears connection fresh. Ar for Another keeping reason mayN be that residual Ar or phenol content of MP pineapples stored at 4 and malic dehydrogenase. Zhang Similar results were obtained by Zhan and Zhang Increases in PAL activity in several fruitspineapple, and are vegetables, including induced by cold temperatures. wedges and thoseto treated storage with was HP 454, air, 420, HP 439 Ar and and 433 HP mg N gallic prior acid kg tissue senescence of pineapple wedges, totaldecreased polyphenol with content the oxidation of PPO in the presence of oxygen. multiple range test. respectively (Fig. 6). However, after 20 days of storage the total is presented inincreased Fig. during the 6. first few Total days of storage,after phenol reached a maximum content 8 days forstorage, and all in treatments agreement then with decreased the results during of the Zhu later period of

2256 2257 1 ´ − on FW 1 -and Cthe Care − • ◦ ◦ C. Similarly, FW) and HP ◦ 1 − C, and Montero-Calder ◦ wileyonlinelibrary.com/jsfa FW). The results indicated that 1 − C, samples treated with HP Ar or HP N ◦ The FRAP values of MP pineapples during 47 –TPTZ). + 2 FW), control samples (66% and 24 mmol TEAC kg found that the firmness (3 mm tip penetration test) 1 − 61 . reported no differences in the texture profile analysis -scavenging activities of 72% and 28 mmol TEAC kg –TPTZ) and producing a coloured ferrous tripyridyltriazine FW) or NAP Ar (65% and 25 mmol TEAC kg •+ 27 . + 1 et al 3 C. C. The firmness of samples after HP treatments decreased − The FRAP assay measures the reducing potential of an ◦ ◦ acids could be contributingantioxidants to TAC. present, This but implies furtherthis. a research Prior synergy is of to needed all storage, toair, TAC HP validate of N and pineapple HP Ar wedges was(Figs slightly treated 8(a) less than with and that HP 8(b)). of untreated However, wedges HP from day Ar 11, or samplestreated treated HP with with N HP air, had NAP higher N or TAC NAP than Ar. samples After 20 untreated days at and 4 parameters of MP pineapples5 throughout 20 days of storage at HP Ar or HP Npineapple treatment could wedges reduce during the cold degradation storage,hydrate of formation probably TAC of and due residual to gas Arinhibiting in the or micropores enzymes N related of to fruittreatment antioxidant tissues was degradation. more effective HP than Ar HP N treatmentof in the TAC retention over the entire storage period. antioxidant reacting(Fe with a ferric tripyridyltriazine complex et al FW) and samples treatedkg with NAP N (65% and 25 mmol TEAC slightly compared with thatbut no of difference was samples observed withoutduring in the storage the HP period (Table firmness 1). treatment, of The volume those offrom juice samples that pineapple leaked wedges ofover all treatments the increased significantly storageaccumulated juice time leakage inside (Table the 1).and HP container N- between There or control HP Ar-treated was samples.that The results no HP therefore showed difference Nfirmness in and and juice HP leakage4 of Ar MP treatments pineapples during had 20 days no at impact on tissue complex (Fe highest TAC was detected in HP Ar-treated samples (DPPH Gil were found to haveuntreated higher and ferric-reducing power treated thansuggested with that samples HP NAP Ar N orin HP or N ferric-reducing treatment HP power could retard of ArNo the MP significant decline and pineapples difference HP during inbetween air. cold ferric-reducing samples storage. power treated This with was HP Ar observed and HP N. Firmness and juice leakage The changes inof firmness different and treatments juice during leakage 20 of days MP of pineapples storage at 4 cold storage are shown inall Fig. samples 8(c). The decreased ferric-reducing withreducing power increasing power of storage of time. samplesdecreased more The untreated rapidly ferric- and from day treatedwith 5 HP with than N that HP and of air correlated samples HP with the treated Ar, loss of and ascorbic acid(Fig. this content 7). phenomenon of After MP could 20 pineapples days possibly at be 4 of whole andchange MP pineapples after of 9 days Tropical of Gold storage cultivar at did 5 not respectively),followedbyHPN-treatedsamples(69%and27 mmol TEAC kg air (64% and 24 mmol TEAC kg ABTS presented in Tableall 1. treatments The remainedobservation firmness coincided unchanged with the of over appearance ofkept pineapple the time their wedges, shape which and wedges (Table size 1). throughout the of 20 This days at 4 a b a c b c c a c c b c c d c c NAP N HP air HP Ar a c c b a 2012 Society of Chemical Industry c b c c a c c c b c c c c bc a bc c a b b b a b c b b b c Control NAP Ar HP N b b bc b b a b a b c a a b b b a b c a b bc a bc b a b b a c bc c a a a d a a b a a c bc a b b Storage time (days) b b c Storage time (days) c b a d a Storage time (days) a a a a standard deviation) in antioxidant capacity b a c a b ± b b b b c c c 258 a 25 : 2250–2259 a 28 a a a b a a b 92 a b b b b b c b c 011141720 0 8 11 14 17 20 05 according to Duncan’s multiple range test. a a 0 5 11 14 17 20 a . a a b a 0 b a 2012; < 5 4 3 2

60 70 80 90 45 40 35 30 25 20 4.5 3.5 2.5 P

-scavenging activity (%) activity -scavenging Changes (mean FW) kg power (mmol Fe (mmol power DPPH ) (mmol TEAC kg TEAC (mmol

· 1 2 1

− + −

Ferric-reducing/antioxidant -scavenging activity -scavenging

· ABTS + C by (a) DPPH, (b) ABTS and (c) FRAP assays. In each part, for each (b) (c) (a) ◦ Effects of HP Ar and N treatments on shelf life of MP pineapples www.soci.org storage time, meansdifferent of at bars with the same letter are not significantly J Sci Food Agric both methods decreased progressively over the storage time. After 8 days of storage thecould variation be in related TAC to was the relativelyfruit small, accumulation tissues which of (Fig. phenolic 6). compoundsnoticed A in after 8 sharp days, which variation was more in evidentand in TAC samples treated untreated of with HP all air sampleswith and the NAP was rapid N phenolic or degradation NAP (Fig.first Ar, 6). in However, 8 correspondence during days the oftrend storage, as TAC phenolic didthe content. not main antioxidants This show contributing the suggested todetermined by the same the that DPPH TAC and increasing ABTS of phenols methods, but, MP besidescompounds, were pineapples phenolic other bioactive compoundsthiols, carotenoids, such anthocyanins, tocopherol as and aromatic ascorbic amino acid, Figure 8. of MP pineapples ofat six treatments 4 (see Fig. 2) during 20 days of storage Vicia 42a 26ab 69ab 53a 78a 94ab 36a 67a 3e 5d 7c 8b 3ab 5g 2f ...... ´ andez F, 2 5 2 4 2 1 5 3 1 2 1 3 2 0 1 Postharv :177–184 :287–296 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 43 51 Food Control 2 5 3 6 2 7 8 : 2250–2259 ...... ) slices using 25 78 46 21 19 24 33 13 ...... 92 ´ es-Hern :113–118 (2008). :113–116 (2002). , ed. by Mortan JF. :1681–1687 (2009). 47 2012; 26 Trends Food Sci Technol 42 :530–534 (2007). Aust J Exp Agric C 27 ◦ Ananas comosus 14ab 19 73a 18 56b 18 33a 19 22ab 20 18a 18 78a 21 65a 20 5e 16 1d 24 9c 34 2b 41 8a 45 4g 4 5f 8 ...... 05) between means according . 5 3 2 4 5 3 3 3 1 2 1 2 2 0 0 0 Postharv Biol Technol ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± < 5 7 2 8 9 6 1 J Sci Food Agric ...... P 37 58 28 55 69 61 25 12 ...... ´ erola’ pineapple stored in controlled :686–691 (2008). ın-Belloso O, New advances in extending ´ Minimally Processed Refrigerated Fruits and Postharv Biol Technol Postharv Biol Technol Fruits of Warm Climates 41 Modified Atmosphere Packaging (MAP) and LWT – Food Sci Technol ˆ enc Technol Alim Camp :163–168 (2006). Ci 39 25ab 18 87ab 19 71a 17 41b 19 96a 18 53ab 20 32a 20 93ab 19 8e 16 5d 23 3bc 35 5b 42 6a 47 3g 5 4f 8 ...... , ed. by Wiley RC. Chapman and Hall, New York, NY, 3 4 3 2 2 6 4 1 1 1 2 1 3 0 1 ´ omez P, Aguayo E, Escalona V and Art ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 2 1 7 9 2 3 5 L.) during storage...... 42 23 34 78 16 51 12 73 ...... :508–514 (2009). :341–353 (2003). ´ es F, G during storagecontaining in 2% oxygen. argon, helium, andretards and oxygen nitrogen accelerates colour darkening in atmospheres faba faba bean ( asparagus spears with a compressed mix ofLWT–FoodSciTechnol argon and xenon gases. MAP of foods, in (2003). atmosphere for keeping qualityBiol of Technol fresh-cut pineapples. evaluation of fresh-cutatmosphere. ‘P of minimally processed pineapple fruit. fruits and vegetables, in Vegetables pp. 66–134 (1994). Sustainable sanitation techniques forof fresh-cut keeping plant quality commodities. and(2009). safety effects ofcontrolled atmosphere chemical on quality of fresh-cut dip banana. 20 and/or carrageenan coatingFlorida Flair and/or Books, Miami, FL, pp. 18–28 (1987). intermediate moisture pineapplehurdle ( technology. the shelf-life of fresh-cut14 fruits: a review. 7 Mortan JF, Pineapple, in 9 Budu AS and Joyce DC, Effect of 1-methylcyclopropene on the quality 3 Wiley RC, Preservation methods for minimally processed refrigerated 4 Soliva-Fortuny RC and Mart 5Art 6 Bico SLS, Raposo MFJ, Morais RMSC and Morais AMMB, Combined 8 Saxena S, Mishra BB, Chander R and Sharma A, Shelf stable 12 Jamie P and Saltveit ME, Postharvest changes in broccoli and lettuce 13 Nasar-Abbas SM, Plummer JA, Siddique KHM and White PF, Nitrogen 14 Zhang M, Zhan ZG, Wang SJ and Tang JM, Extending the shelf-life15 of Spencer KC, The use of argon and other noble gases for the 10 Marrero A and Kader AA,11 Optimal Antoniolli LR, temperature Benedetti BC, and Sigrist JMM modified and Silveira NFA, Quality 91a 18 51a 18 13a 20 25a 16 17a 20 72a 18 53a 19 86a 18 7e 17 8d 24 5c 36 2b 41 7ab 51 4g 5 5f 9 ...... 2 5 5 4 3 2 2 4 1 1 1 3 2 0 0 ın- ´ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 8 9 7 4 6 4 1 ...... 51 37 31 65 18 12 79 85 ...... -scavenging 2012 Society of Chemical Industry www.soci.org Z-s Wu, M Zhang, S-j Wang c •+ Innovat Food Sci Emerg 72a 21 16a 19 93a 20 74a 22 58a 23 49a 22 36ab 21 25a 20 1e 14 8d 22 1c 31 7b 39 9b 45 6g 3 5f 7 C...... ◦ 2 2 1 3 5 2 3 2 1 1 2 1 2 0 0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± -andABTS 3 9 6 8 7 3 5 ...... • 25 54 39 82 35 15 72 53 ...... :1085–1092 (2008). 106 C. They also inhibited the activity of ◦ standard deviation. For each parameter, different letters denote significant differences ( 23a 22 15a 20 52a 21 93a 20 74a 19 32a 23 27a 18 53a 22 5e 15 3d 21 5c 33 4b 40 6a 43 5g 3 8f 7 ...... FW) . . 1 2 3 1 2 4 3 2 0 1 2 3 1 ± 0 0 1 − ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Food Chem 8 7 2 1 5 5 3 ...... 46 35 81 54 63 45 37 16 ...... :356–362 (2009). 10 Changes in tissue firmness and juice leakage of MP pineapples of six treatments during 20 days of storage at 4 Belloso O, The rolefresh-cut of ‘Piel peroxidase de on Sapo’ the melonatmospheres. packaged antioxidant under potential different of modified minimally processed cactus pear packaging. Technol 00 0 0 00000 23 023 57 815 221 522 822 The results of this study suggest that combining short-time Days Control NAP N NAP Ar HP air HP N HP Ar Control, untreated pineapple wedges; NAPtreated N, pineapple with wedges atmospheric-pressure treated argon with forwedges atmospheric-pressure 20 nitrogen treated min; for with HP 20 high-pressure air, min;Data (10 NAP pineapple shown MPa) Ar, wedges are pineapple nitrogen mean treated wedges for with high-pressure 20 min; (10 MPa) HP air Ar, for pineapple 20 wedges min; treated HP with N, high-pressure pineapple (10 MPa) argon for 20 min. to Duncan’s multiple range test. Tissue firmness (N) Table 1. 11 23 14 34 17 42 20 48 11 21 14 20 17 19 20 20 Juice leakage (mL kg 1 Del Nobile MA, Conte A, Scrocco C and Brescia I,2 New strategies Oms-Oliu G, for Odriozola-Serrano I, Soliva-Fortuny R and Mart HP application with Arpreserving or MP N pineapples couldstudies could be and include a the probably effects promisingstability, of other method such treatments sensory for fruits. on microbial characteristics,technology Further for etc. further extending so the shelf life as of MP to products. provide a new wileyonlinelibrary.com/jsfa REFERENCES The authors thank theChina for National supporting this Natural research under Science contract 30972058. Foundation of ACKNOWLEDGEMENT CONCLUSIONS Both HP Ar andrespiration HP rate and N ethylene production treatments in MP (1020 pineapples MPa, days during 20 of min) reduced storage the at 4 activities and higher ferric-reducing power.HP Moreover, N treatments HP did not Ar influence tissue and firmness and juiceof leakage MP pineapples throughout 20 days at 4 PAL, PPO and PODbrightness and enzymes good and visual efficiently appearanceshelf of maintained life. MP surface Beneficial pineapples effects during ofwere HP expressed Ar as and reduced HP degradation Nand of treatments phenolic on ascorbic compounds TAC acid, increased DPPH

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