hrfr irba otmnto ed ob iiie and minimized inactivated. be be must to pathogen the needs 2009). (Mandrell contamination greens microbial leafy ready-to-eat Therefore other prepackaged, and Iceberg and containing lettuce salads Iceberg A ready-to-eat 2009). Mandrell ded 2008; the others of and of in Cruz number one outbreaks (Da being foodborne States. of toxins, United cases the and nevertheless, in involved pathogens is, vegetables for leafy It main vehicle restaurants. a and self-service as sandwiches, in known salads, found in items ingredient other traditional a being etables, Lettuce 1996). handling, (Beuchat field, ( distribution the in and Pathogen occur packaging, 2009). on can processing, others pathogens produce and fresh human (Lynch of of produce contamination fresh presence inside the even by or food- caused of illnesses frequencies increased borne by increase accompanied this However, is years. consumption recent in in countries developed in ing ute erdcinwtotpriso sprohibited is permission without reproduction Further 10.1111/j.1750-3841.2010.01786.x doi: Fan author to inquiries Direct 600 U.S.A. Center, 19038, of Research [email protected]). PA Dept. (E-mail: Wyndmoor, Regional U.S. Lane, with Eastern Mermaid are Service, E. Fan Research and Huang Agricultural Agriculture Author of Agriculture, Preservation China. for 300384, Center Tianjin Products,Products, Research Technology Agricultural of and Storage Engineering and Physiology National with Postharvest is of Guan Laboratory Author Key 6/22/2010. Tianjin Accepted 4/19/2010, Submitted 20100426 MS Introduction Fan Xuetong and Huang, Lihan Guan, Wenqiang Package Atmosphere Modified Storage in during Lettuce Iceberg Fresh-Cut of Deterioration Quality Caused Dodecyl Sulfate Sodium with Combination in Acids C atc sativa Lactuca osmto ffehctfut n eealshsbe increas- been has vegetables and fruits fresh-cut of Consumption 00Isiueo odTechnologists Food of Institute 2010 Keywords: Abstract: h fet fL n A ncmiainwt D a oprdwt ircai n hoie nteinactivation the on chlorine) and acid citric with compared (as SDS with investigated combination study 4 in present The SAS lettuce. and Romaine of on LA pathogens of human effects inactivating in the effective was (SDS) sulfate dodecyl fsgiesadsfeigatr7ad1 trg.I per httecmie ramnscue nices nthe in increase an caused treatments combined the development that to appears CO due It higher by storage. unacceptable indicated d sensorially as 14 were lettuce and fresh-cut samples of 7 SAS-treated rate after and respiration softening LA- and lettuce. sogginess of of texture and quality visual 02%,adcti cd(prxmtl .5)i obnto ihSSrdcdpplto of population reduced SDS SAS with (0.5%), LA combination storage. in during 0.25%) developed (approximately pieces lettuce acid of browning citric edge and cut (0.25%), inhibited treatments acid the side, positive oteltue hrfr,cmae oclrn,L n A ncmiainwt D aelmtdcmeca value commercial limited have SDS storage. damage with during without combination deterioration CFU/g in quality log SAS to 0.94 and due of LA lettuce reduction Iceberg chlorine, a fresh-cut to achieved for compared chlorine Therefore, while respectively, lettuce. CFU/g, the log to 0.58 and 0.87, 0.41, ◦ .coli E. .Rslssoe htL 05 o3)adSS(.5 o07% ih00%SScue ermna fet on effects detrimental caused SDS 0.05% with 0.75%) to (0.25% SAS and 3%) to (0.5% LA that showed Results C. .coli E. saogtems ihycnue rs-u veg- fresh-cut consumed highly most the among is ) 17H n esr ult ffehctIeegltuei oie topeepcae uigsoaeat storage during packages atmosphere modified in lettuce Iceberg fresh-cut of quality sensory and O157:H7 hoie ircacid, citric chlorine, eetsuissoe htsdu cdslae(A)adlvlncai L)i obnto ihsodium with combination in (LA) acid levulinic and (SAS) sulfate acid sodium that showed studies Recent 17H ubek aebe ikdt shred- to linked been have outbreaks O157:H7 R .coli E. 17H,fehctltue euii cd oimai sulfate acid sodium acid, levulinic lettuce, fresh-cut O157:H7, etc n05 ircai r05 atcai ouinfr2min 2 for solution acid lactic 0.5% or acid citric Iceberg of 0.5% dipping that in reported lettuce been lactic has 2002; and It others 2009). acid, others and vegetables Venkitanarayanan and malic Rosa 1996; and acid, Farber citric fruits and as fresh-cut (Zhang such acid in acids Common use organic vegetables. for mainly are available and acids fruits of fresh-cut types some on populations 2009). Akbas and Olmez others 2009; and Feng Francisco and 2001; Herdt others 2009; and bacteria (Sapers pathogenic lettuce of fresh-cut inactivation on the in efficacy fresh-cut their to on studied determine been use have for agents need chemical a sanitizers washing Different is alternative vegetables. there evaluate restrictions Thus, and regulatory 1998). identify others new to and to consumers (Richardson lead future by may the in concerns and raised use have re- chlorine upon matter, against trihalomethanes organic of with formation and action as populations such bacterial effects, reducing adverse in its chlorine of Vel efficacy 2009; limited Feng and oth- Herdt and 1998; (Beuchat pathogens ers common CFU of (where reduction CFU/g unit) log very forming 1 is than produce less fresh achieving effec- of limited, population its microbial but reducing cross-contamination, in prevent tiveness sanitize to to mainly and washes water lettuce in washing used widely to been 50 has hypochlorite, ppm) (sodium 200 veg- Chlorine 2009). 2009; on Feng others bacteria and and Keskinen Herdt pathogenic 2002; of determine others inactivation and to (Venkitanarayanan etables the studied Dif- in been populations. efficacy have microbial their agents reducing chemical in washing step ferent important an is ing 2 rai cd aesont eefciei euigbacteria reducing in effective be to shown have acids Organic packag- to prior and cutting after produce fresh-cut Washing n oe O lower and o.7,N.8 2010 8, Nr. 75, Vol. 2 nmdfidamshr akgs nthe On packages. atmosphere modified in r ora fFo Science Food of Journal zuzadohr 09.The 2009). others and azquez ´ .coli E. H5:7by OH157:H7 = colony- S435

S: Sensory & Food Quality , 2 TM /24 h severe; 2 On each = extremely none. ,andCO fair, slightly 2 /24 h. The = = 2 = analyzer (DuralTrak slight; 1 2 in packages. = 14 cm and there were 2 × in the headspace of packages and CO 2 excellent, essentially free from 2 = and CO Firmness was evaluated with a TA- using a Multivac C450 packaging 2 okorai 2008). Overall visual quality 2 moderate; 2 C. S ◦ and CO = 2 Visual quality was assessed immediately after SDS) Approximately 0.25% (w/v) 3.17 + good, minor defects, not objectable; 5 = 0.05% SDS 0.75% (w/v) 1.86 0.05% SDS 0.5% (w/v) 1.96 0.05% SDS 0.25% (w/v) 2.15 poor, excessive defects, limit of salability; 1 0.05% SDS0.05% SDS 0.5% (w/v) 1.0% (w/v) 3.04 2.93 0.05% SDS 3.0% (w/v) 2.77 0.05% SDS 2.0% (w/v) 2.83 moderately severe; 3 + + + + + + C until analysis. Sensory evaluation, headspace O + Firmness measurement. Analysis of headspace O Visual quality. Pieces from 8 heads of lettuce were randomized at first. Then an = ◦ = Chlorine (sodium hypochlorite)FIT (citric acid 0.01% (w/v) 6.50 acid in thedetermined diluted by FIT titrating solutionhydroxide. 10 Table was 1 mL shows estimated the diluted list to FITand of pH treatments be with of and each 0.1 0.25% concentrations solution. N Allusing as dipping deionized sodium solutions water were at prepared daily 4 XT2i Texture Analyzer (Texture TechnologiesN.Y., U.S.A.) Corp., equipped Scarsdale, with a(TA-91). Kramer Lettuce Shear pieces press with (25and 5 g) then blades were the placed 5-bladethe in bottom plunger of the was the holder press movedfrom at down holder, each 2 to mm/s. replicated There bag 1 wasa for one cm total measurement firmness of below 4 measurements, measurements resultingrecorded each and in treatment/sampling area under day. Force the was curve wasExpert calculated software using (version the Texture 1.22, Texture Technologies Corp.). SAS day of quality analysis, O bag sizes100 were g approximately cut 15 uumed lettuce and per flushed bag. with The N packaged slices were then vac- machine (Multivac Inc., Kansas4 City, Mo., U.S.A.), and stored at were analyzed using a portable O Table 1–Concentration and pHpresent of study. washing solutions used in the Washing solutionsWaterLA LA LA Concentration ofSAS acids pH 6.26 in the packages were measuredwere at 4 1, replicates 7, for and each 14 treatment. d of storage. There Barnsteed Intl., Dubuque,treatment, Iowa, the U.S.A.) samples at were rinsed 100of in rpm. deionized 1:10 water After with (sample:water) a the fordrained ratio and 1 dried min. in a Theinto hand polypropylene lettuce held, plastic manual pieces film salad were bagsS.C., spinner then U.S.A.) and (PDF961, with placed Cryovac, an Duncan, oxygen transmission of 7000 mL/m and carbon dioxide transmission of 21000 mL/m 4 defects; 7 to moderately objectionable defects,3 lower limit ofpoor, sales not appeal; usable.and Cut sogginess/watery edge were rated tissue on browning, a surface scale of browning, 5 to 1: 5 was rated on a 9 to 1 scale: 9 902 D, Quantek Instruments,in the Grafton, packages Mass., afterquality U.S.A.). analysis. gas Samples analysis were then used forheadspace subsequent analysis of packages by a 3-memberand trained panel others (Kader 1983; Fan and aliquot (300g) of samples was submergedsolutions in while 1500 mL agitated of on one of a the shaker (Model M49125, Bigbill LA SAS C ◦ H, LA) with SDS 2 CO 2 O157:H7. Therefore, the CH 2 Iceberg lettuce was purchased Vol. 75, Nr. 8, 2010 E. coli r Fresh-cut lettuce was submerged in O157:H7 and the sensory quality of C(O)CH 3 O157:H7 populations by 6.7 log CFU/g E. coli E. coli and Journal of Food Science 2.5 cm. The lettuce slices were then dipped in solutions as × In recent years, some new types of acids, which have been Treatment procedure. Preparation of lettuce pieces. There is no study directly comparing different acid sanitizers Lettuce treated with acids . . . the following 10 solutions:0.75% deionized [w/v]), water, in SAS combination (0.25%, with1.0%, 0.50%, 0.05% 2.0%, (w/v) 3.0% SDS, [w/v]) LA insodium (0.5%, combination hypochlorite with (final 0.05% (w/v)at chlorine SDS, pH concentration 6.5, 0.01% FITas (w/v) (citric suggested acid by as the active ingredient, manufacturer). diluted The 88 concentration times of citric dramatically increased the bactericidal activity of thesea 2 combination chemicals; of 3%Salmonella LA acid and 1% SDS for 20 s reduced both objective of the presenteffects of study LA was and towith SAS chlorine compare in and and combination citricthe identify with acid, the inactivation SDS 2 of in commercially comparison used sanitizers, on S436 Materials and Methods Effect of sanitizers on quality could be as effective as chlorineon for reducing fresh-cut microbial populations Icebergcommercialized lettuce sanitizer, (Akbas is and asodium Olmez dodecyl mixture sulfate 2007a). of (SDS) FIT, in mainly aqueous a citric solution. aciddesignated and by the U.S.generally Food recognized and as Drug safe Administrationas (GRAS), alternative (FDA) sanitizers as have for also decontaminationFan attracted of and fresh-cut interest others products. (2009) foundsulfate that (NaHSO4, it SAS) is to possible controlgrowth to browning of while use inhibiting microorganisms sodium the acid that on has apple been slices.a used SAS as processing is a aid ain pH (Anonymous compound dressings, control 2008). agent, sauces, Currentsyrups. leavening marinades, uses Zhao agent, and fillings, for and others beverages, SASbining (2009) cheeses, levulinic are have recently acid and reported (CH that com- produce processing laboratory. Thewere outer removed from the 3 lettuce or head and 4 discarded.(Model A leaves lettuce SKK2 cutter and KutLett, core U.S.A.) was Silver used King to slice Refrigeration the2.5 lettuce Inc., into pieces Minn., withdescribed a below.SAS final and size FIT of (citric acidprovided as active by ingredient) were Jones-Hamilton Co.HealthPro (Walbridge, Ohio, Brands U.S.A.) and Inc.LA (Cincinnati, and SDS Ohio, were U.S.A.), purchasedU.S.A.). from respectively. Sigma-Aldrich Bleach (St. (6% Louis, sodium Mo., company hypochlorite) (Oakland, was Calif., U.S.A.). from the Clorox through a local supermarket and immediately transported to 4 on fresh-cut Romaine lettuce.tuce However, treated sensory with quality SASketo of has acid, let- not can beenrenewable be feedstocks, studied produced and after the at antimicrobial storage.been properties low LA, of reported cost LA (Anonymous a have and 2007). Thehumans in safety has high of been LA widely yield tested, andthe from and SDS U.S. they for FDA have been as designatedsubstance GRAS by or for adjunct direct andCode multipurpose addition of additives, to Federal respectively food Regulations (21 (FDA [CFR] as 2009). 172.515; flavoring 21 CFR 172.822) (citric acid, SAS, andsory LA) quality in and inactivation terms of of their effect on both sen- fresh-cut Iceberg lettuce in modifiedcold atmosphere storage. packages during

S: Sensory & Food Quality D,02%SAS 0.25% SDS, .%(/)ppoei :0iceet oafia iuino 10 of dilution final sterile a to the in increments of diluted 1:10 aliquot in serially 1-mL peptone and A (w/v) removed ho- 0.1% rpm. was then 260 solution at and wash Seward, min lettuce PW 400, 1 (Model 0.1% for circulator England) mL stomacher London, 20 a using with by bags mogenized transferred stomacher immediately Fol- were sterile experiments. samples to quality the sensory treatments, preliminary the the lowing of base the of on inactivate concentrations to The used min. 5 sanitizers for test temperature ambient at rpm 100 n i-re o nalmnrflwbooia od(Model hood biological flow laminar drained a then in and h Nuare min 2 MU-425-600, immediately 15 for for were inoculum air-dried (60g) mL and pieces 300 Lettuce the PW. in suspensions 0.1% cell immersed washed mL adding above-mentioned by 3 270 prepared the resuspended into was of mL) each and of (300 BD), mL Inoculum (PW, PW. 10 water 0.1% mL peptone 30 sterile in 0.1% mL 10 0m ri er nuinBoh(H,B) n nuae at incubated and BD), (BHI, Broth Infusion 37 Heart to Brain transferred was mL strain 30 each from (SMAC, plates U.S.A.) Agar Md., Sorbitol–MacConkey Sparks, on BD, colony isolated an of loop (3) and 933; strain O157:H7 strains (1) These Pa. included Wyndmoor, Center, USDA of the Research at Regional others isolates maintained Eastern collection and culture Three the Wang from (2010). selected of were Huang procedure and the (2007) following determined was eebc acltdt con o iuinadwih ftissue of weight and dilution for buffer, account wash to of calculated milliliter back per were CFUs of representing colonies obtained, values colorless/translucent typical and coli E. h, 24 for incubator 0 p hoie n30m ekr o i ihgnl agi- gentle with min Bigbill M49125, 5 (Model for shaker beakers a mL on LA 300 tation in (0.5% 50 chlorine) solutions ppm in test 100 submerged and CFU/g. then control) log were (as 6.5 water g) about of (10 be mL samples to lettuce estimated was Inoculated pieces lettuce lated of level The ments. eaae01m lqoso aho h iuin rm10 from dilutions the of each of aliquots 0.1-mL Separate r a m n d7 4 d7 14d 7d 1d 14d 2.9 ( different significantly not are column same b within letters same the a by followed Means Treatment 7d Storage 2.8 Chlorine SAS 0.75% 1d Water Treatment O on treatment sanitizer of 2–Effect Table coli Escherichia . . . acids with treated Lettuce ltsprdlto.TeSA ltswr nuae na37 a in incubated were plates SMAC The dilution. per plates 10 etiuain(2400 centrifugation I 1.2 Treatment FIT .%LA 0.5% .%LA 1.0% .%LA 2.0% .%LA 3.0% .0 SAS 0.50% SAS 0.25% h ubr r means are numbers The Sand NS h fetvns fsntzr ninactivating in sanitizers of effectiveness The − ◦ 5 vrih ihml hkn.Ec utr a avse by harvested was culture Each shaking. mild with overnight C eewtdanadsraepae noSA lts 2 plates, SMAC onto plated surface and withdrawn were 17H nSA ltswr one.Tepaecount plate The counted. were plates SMAC on O157:H7 ∗∗∗ + + + + × niaen infiac rsgicneo ramn,soae n neato ewe ramn n trgsat storages and treatment between interaction and storage, treatment, of significance or significance no indicate + + + .5 D 2.7 SDS 0.05% .5 D 2.0 SDS 0.05% .5 D 2.0 SDS 0.05% .5 D 2.3 SDS 0.05% trg NS storage .5 D 1.4 SDS 0.05% .5 D 1.0 0.9 SDS 0.05% SDS 0.05% .coli E. + 17H nciaintests inactivation O157:H7 ± .5 D,FTdltd8 ie ihwater, with times 88 diluted FIT SDS, 0.05% 17H SAFI 55-5 (2) 45753-35; USDA/FSIS O157:H7 tnaddvain fmas( means of deviations standard .coli E. × TM g lmuh in,USA)bfr treat- before U.S.A.) Minn., Plymouth, , o 0mna 4 at min 10 for 17H ouaino h inocu- the on population O157:H7 .coli E. .coli E. ± ± ± ± ± ± ± ± ± ± 17H tanA28C.A A9218-C1. strain O157:H7 .a6.4 0.7a .a4.8 0.5a .a8.4 1.6a 1.9a .a5.3 1.4a .a9.5 1.4a .a5.6 0.3a .a7.4 5.1 9.0 0.6a 0.4a 0.7a 17H eedetermined were O157:H7 a ◦ ) ahdtiewith twice washed C), TM n 2 = n CO and ante nl, at Intl.,) Barnsteed , 4). 8.4 .coli E. .coli E. O ± ± ± ± ± ± ± ± ± ± 2 ∗∗∗ ∗∗∗ .c4.4 2.0 1.3c 2.3abc .a 7.6 1.9ab .a 7.7 3.0ab .b 3.2 0.4bc . 3.9 a 4.2 .b 5.2 1.2bc .ac2.0 5.6 8.6 3.2abc 1.5bc 2.9a 2 % CO (%) b ata rsue fpcae rs-u etc trda 4 at stored lettuce fresh-cut packaged of pressures partial O157:H7 O157:H7 + 0.05% .coli E. − 2 ◦ to C 5 P . < .%ad29 nalpcae fe fsoae n then and day storage, to of 7 day d From 7. 1 day at after O 9.5% packages 14, and 4.8% all between to in increased 2.9% and 0.9% ihlwcnetain 05 o2)o AhdlwrO lower had LA of 2%) to (0.5% treated concentrations Samples period. low storage the with of rest the throughout and 7 day ntepcaewr bevddrn trg.O storage. during observed were package the in etc,a fetdb ipn ramnsadsoaetm t4 at time storage and treatments dipping by affected as lettuce, Inc., Inst. (SAS 9.1 All and U.S.A.). SAS model. N.C., using treatment Cary, linear performed between general were the interaction analyses using statistical as conducted were well time as storage time treatment storage of effects Overall and period. storage each during treatments ahtetet n o O low and treatments wash r hw nTbe2 nrae nteO the in Increases 2. Table in shown are a esta h muto xgndfue notefimbags. film the into diffused oxygen of O package amount When the the in than lettuce less the was by consumption oxygen that indicated ooti F e rmtsu aus h et eerepeated were tests The values. tissue gram times. per 4 CFU obtain to CO CO higher ape rae ihwtr hoie n %L ipae higher displayed LA 14. 3% day and on O 3.9% chlorine, to water, 2.1% with between treated values the Samples to 1 day on 1% around asaetesm,i ece qiiru.Tecagsi O in changes The equilibrium. reaches it same, the are bags a opsto npackages in composition Gas Discussion and Results analysis Statistical a rsmbydet hne nrsiainrt.Prilpressure Partial rate. O respiration in in differences changes to due The packages presumably death. atmosphere was modified cell the to in due composition probably gas were in difference LA 3% by treated sample the ifs hog h l otelwpesr ie(hti,isd of inside is, (that side low-pressure the bags).TheincreaseinO to film the through diffuse lot0 fe aumn n uhn ihN with flushing and vacuuming after 0% almost nteohrhn,CO hand, other the On A(e olwn eto) h ihrO 3% higher by the caused section), tissue following lettuce (see of LA injury severe the from Judged water. 0.05). 2 ± ± ± ± ± ± ± ± ± ± hne ngscnetaini akgso rs-u Iceberg fresh-cut of packages in concentration gas in Changes of effect the test to used was test difference significant least The n oe CO lower and 2 .b 1.3 1.5 3.3bc 1.6c .a 1.0 0.4ab .a 1.2 2.5ab .c1.3 3.9c .b 1.3 2.2bc .ac1.3 2.8abc .c1.4 1.3 1.3 2.1c 4.7abc 3.0a eesi h asrflc eprto yaisi epneto response in dynamics respiration reflect bags the in levels 2 eesdcesd ecigvle ewe .%t 8.6%. to 2.0% between values reaching decreased, levels 2 2 osmto n h muto O of amount the and consumption eescmae ihtoetetdwt hoieand chlorine with treated those with compared levels o.7,N.8 2010 8, Nr. 75, Vol. 2 cosfimbg raeadiigfrefrO for force driving a create bags film across 2 ocnrto hnteohrtetet from treatments other the than concentration ± ± ± ± ± ± ± ± ± ± 2 .a2.3 2.3 0.2a 0.2a .a1.6 0.1a .a1.5 0.1a .a2.5 0.2a .a2.6 0.1a .a2.4 0.1a .a2.4 2.8 1.9 0.1a 0.2a 0.2a P eesi l akgskp nraigfrom increasing kept packages all in levels 2 < 2 eesi h asdrn h rt7d 7 first the during bags the in levels .0 ees respectively. levels, 0.001 hg CO /high r ora fFo Science Food of Journal 2 ± ± ± ± ± ± ± ± ± ± paety rai acids organic Apparently, . 2 2 ∗∗∗ ∗∗∗ ∗∗∗ .b 3.0 3.7 0.6bc 0.4abc .d2.1 0.1d .d2.3 0.5d .a 3.5 0.1ab .a 3.4 0.3ab .a 3.0 0.2ab .ac3.9 2.9 2.0 0.6abc 0.1a 0.4cd n CO and 2 n oe CO lower and (%) 2 2 ◦ o pt 4d. 14 to up for C ovle between values to ifsdit the into diffused 2 2 nrae from increased concentrations 2 eesin levels ± ± ± ± ± ± ± ± ± ± 2 0.7abc 0.6ab 0.1bc 0.3bc 0.3a 0.8a 0.9abc 0.6a 1.0abc 0.7c 2 S437 2 and and ◦ C, to

S: Sensory & Food Quality < P 0.05) 0.4ab 0.5a 0.2ef 0.2e 0.2a 0.3d 0.3b 0.3f 0.4d 0.0bc 0.5bc 0.3abc 0.5d 0.0g 0.6c 0.4cd 0.3abc 0.2ab 0.2g 0.3e okorai extremely S ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± < = P excellent, 1 = 0.05) lower sogginess okorai 2005). Texture S < 0.9bc 5.1 0.2def 3.1 0.5ab 5.2 0.4ef 3.0 0.1de 2.4 0.2a 4.9 0.2de 3.1 0.5b 4.5 0.3f 2.7 0.4cde 3.3 0.5bcd 5.0 0.4bc 4.2 0.2ab 4.5 0.3de 3.6 0.0g 1.3 0.2e 4.5 0.3cd 3.8 0.5a 5.0 0.3bcd 5.1 0.1g 1.4 ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ P ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.05) better than other samples. < 0.05), and cut edge browning of P < P C for up to 14 d. ◦ 0.0a 2.7 0.4c 2.8 0.0a 2.8 0.1c 2.6 0.0a 1.9 0.1a 4.7 0.0a 2.0 0.4b 3.9 0.1de 2.4 0.0a 2.1 0.0a 2.5 0.1c 3.5 0.0a 2.9 0.4ef 3.0 0.2fg 1.0 0.0a 1.6 0.3a 3.2 0.0a 3.4 0.0a 2.4 0.1g 1.0 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± none. 0.001. = < P 0.5d 1.0 0.8ab 2.2 0.5cd 1.0 0.9a 2.0 0.2e 1.0 0.1d 3.3 0.7d 1.0 0.3cd 2.7 0.3a 1.8 0.3b 1.0 0.5b 1.0 0.2cd 2.4 0.3bc 1.0 0.6a 1.6 0.8cd 1.4 0.7a 1.0 0.1a 3.1 0.4a 1.0 0.4d 1.0 0.7bc 1.0 severe, 1 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Firmness may be decreased by loss of cell turgor as a result of Sogginess and texture represent the crispness that is also an 0.05). Overall visual quality was rated on a 9 to 1 scale: 9 = increased with increasing LA concentration fromalso 0.5% increased to 3%. the SAS sogginessof of the the sogginess lettuce increased pieces with and increasing SAS the concentration. severity water loss during storage (Akbasance and of Olmez sogginess 2007a). The indicatesand resulting appear- the in loss leakage of of cellof turgor electrolytes samples (Fan had from and an cells sogginess inverted increased, relationship texture with of sogginess the scores. samples As decreased. On day 1, and others 2009). A rapiding increase in in all cut samples edge were andfound observed surface during to brown- storage. be LA more treatmentpared effective was in to reducing other cut treatmentlettuce edge ( decreased browning com- with increasedconsistently LA affect concentration. the browning SAS ofthe did lettuce effect of not during SAS the on the storagedependent browning of and between lettuce 0.25% was not and concentration 0.75%. important quality parameterfreshness as of the consumers product (Fillion associate and2005). Kilcast Effect it 2002; of Fan with different and sanitizerssamples the on were the shown in sogginess Table 3 and and texture0.05) 4, of changes respectively. Significant in ( sogginess were observed inin lettuce different samples dipped acid solutions.induce Water sogginess and of fresh-cut chlorine lettuce during treatmentperiod, the did and entire were 14-d not significantly storage ( FIT treatment resulted in significantlyscores ( than those of LAscores and of SAS on the daysduring samples 7 and storage, treated 14. and with The sogginess sogginess LA of samples were significantly among ( the highest < P < P b 0.5e 2.5 1.5ab 4.3 0.4e 2.8 0.7abc 4.9 0.5f 1.4 0.1cd 2.6 0.5e 2.2 0.2de 3.2 0.2cd 4.5 0.6de 3.6 0.2c 3.8 0.2de 3.2 0.1cd 3.5 0.2bcd 4.8 0.2e 3.1 0.4a 5.0 0.3bcd 5.0 0.5b 4.6 0.2e 2.5 0.5a 3.6 ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ∗∗∗ ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 6.1 4). = n O157:H7 produced no- Surface browning (1 to 5) Sogginess/watery (1 to 5) Overall visual quality (9 to 1) Cut edge browning (1 to 5) a 0.4ef 4.3 0.0a 3.1 0.2de 4.3 0.0a 2.7 0.2g 2.3 0.0a 2.2 0.4f 3.9 0.0a 1.8 0.0a 2.3 0.1cd 4.4 0.4c 5.3 0.0a 1.8 0.2b 5.0 0.0a 2.4 0.0a 1.3 0.1ab 7.3 0.0a 2.4 0.5g 4.1 0.0a 3.3 0.0a E. coli Vol. 75, Nr. 8, 2010 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± r C are shown in Table 3. On day 1, sig- ◦ 0.05) were observed in the visual quality standard deviations of means ( < ± P 0.05) better overall visual quality than those treated < 0.05% SDS 7.2 0.05% SDS 1.0 0.05% SDS 7.6 0.05% SDS 1.0 0.05% SDS 1.0 0.05% SDS 6.5 storage storage P 0.05% SDS 6.8 0.05% SDS 1.0 0.05% SDS 7.2 0.05% SDS 1.0 0.05% SDS 7.8 0.05% SDS 1.0 0.05% SDS 8.5 0.05% SDS 1.0 + + + + + + × × + + + + + + + + Journal of Food Science 0.05) in the edge and surface browning. During 14 d storage, indicate significance of treatment, storage day, and interaction between treatment and storages at > In addition to possessing suitable antimicrobial activities, a san- For lettuce, browning is considered to be the critical factor in P ∗∗∗ The numbers are means Lettuce treated with acids . . . 0.50% SAS 0.50% SAS 0.25% SAS 0.25% SAS Treatment 3.0% LA 3.0% LA 2.0% LA 2.0% LA Treatment FIT 1.0 1.0% LA FIT1.0% LA 8.0 0.5% LA 0.5% LA Chlorine 1.0 Chlorine 8.7 0.75% SAS a b S438 Storage Treatment Means followed by thepoor. same Cut letters edge within browning, surface same browning, column and are sogginess not were rated significantly on different a ( scale of 5 to 1: 5 Treatment Water 1.0 0.75% SAS Storage Table 3–Effect of sanitizers on sensoryTreatment quality of packaged fresh-cut lettuce stored at 4 Water 1d 7d 9.0 14d 1d 7d 14d Change in sensory quality of fresh-cut lettuces during storage (FIT and LA) andof SAS fresh-cut caused lettuce. the The increase gasthat in composition chlorine the in did not respiration the significantly rate packages increasecut showed respiration lettuce rate of compared fresh- withagreed water with treatment other (control). authors Thisno (Baur result and difference others 2005), inwashed who the with observed chlorine respiration or rate tap water. when Iceberg lettuce was nificant changes ( and sogginess of samples,( while there waswater- no and chlorine-treated significant lettuce change maintained significantly ( 0.05) better overall visualLA, quality and SAS. than Samples samples treatednificantly with treated ( FIT, with 0.5% and FIT, 1% LA had sig- itizer must be able toincluding maintain visual produce quality, cut quality. edge Sensory browning, attributes surfacesogginess browning, of and fresh-cut lettucethe after dipping storage treatments period and at during 4 with 2% and 3% LA, andtration all increased SAS-treated from samples. 0.25% As to SAS 0.75%,quality concen- generally did the overall not visual resulted change, in while a significant the decrease increase in overall in visual quality LA of concentration lettuce. perceived loss of quality, and it isthe reported that most some effective sanitizers activity with ticeable against discoloration of Iceberg and Romaine lettuce (Keskinen

S: Sensory & Food Quality I 155.8 168.7 Treatment FIT Chlorine SAS 0.75% SAS 0.50% SAS 0.25% LA 3.0% LA 2.0% LA 1.0% LA 0.5% ncltdo h rs-u cbr etc scmae othe to log compared (0.94 on reduction as CFU/g) highest lettuce the achieved Iceberg Chlorine sig- (water). fresh-cut dip control 5-min the a on with inoculated sanitizers the ( All nificantly 5. Table in presented are of tivation .%LA 0.5% ae 5.90 ( significantly are column same the in treatments. letters a the among different different by followed Means Water different with treatment min 5 after sanitizers. lettuce Iceberg oculated 5– Table different significantly d not 14 are column b same within letters a same the ( by followed Means Treatment d Storage 7 182.1 d 1 Water Treatment 4 at stored lettuce Iceberg fresh-cut of Texture 4– Table sanitizers different with inoculated of Inactivation treatments. SAS 3 significant a in resulted SAS and LA, FIT, ( chlorine, and solutions water different ( in significantly change dipping not after did lettuce fresh-cut of texture the . . . acids with treated Lettuce pt 4d. 14 to up ewe ramn n trgsat storages and treatment between ramn LgCUgtsu)(o F/ tissue) CFU/g (Log tissue) CFU/g (Log Treatment o lo o h eoeyo nue el.Hne h o re- log the considering Hence, overestimated bacteria. be cells. even injured injured may possible sanitizers of does the recovery by that the ductions medium for selective a allow SMAC, not the using numerated CFU/g. were log 1 than less were reduc- CFU/g of log 0.58 population with and Treatments 0.87 wash. in of water resulted tion FIT the and to SAS comparison 0.25% in CFU/g log inactivating in effective least hoie(0 p)4.96 5.32 ppm) (100 Chlorine acid) citric (0.25% FIT SAS 0.25% nrae ihteicesn A ocnrto fe storage ( d difference significant 7 samples no after was of concentration there texture although SAS increasing The the treatments. with caused other increased treatment than LA loss sogginess, texture on larger treatment of effectiveness the P h ubr r means are numbers The means are numbers The P Sand NS < h fet fdfeettpso cd n hoieo inac- on chlorine and acids of types different of effects The < 0.05). .5 euto ntxueo as7ad1.Smlrto Similar 14. and 7 days on texture in reduction 0.05) ∗∗∗ .coli E. + + + + + × niaen infiac rsgicneo ramn,soae n interaction and storage, treatment, of significance or significance no indicate shrci coli Escherichia + + + + .5 D 153.8 168.9 SDS 0.05% 179.3 SDS 0.05% 167.5 SDS 0.05% SDS 0.05% .5 D 5.49 SDS 0.05% P trg NS storage .coli E. .5 D 166.1 SDS 0.05% 156.8 SDS 0.05% 172.2 SDS 0.05% .5 D 5.05 SDS 0.05% .coli E. vntog l aiiessgicnl eue the reduced significantly sanitizers all though Even . < .coli E. .5 eue h ubrof number the reduced 0.05) ± ± 17H ncltdIeegltuesamples lettuce Iceberg inoculated O157:H7 17H ouain hl .%L a the was LA 0.5% while populations O157:H7 tnaddvain fmas( means of deviations standard ( means of deviations standard 17H nIeeglae,tereductions the leaves, Iceberg on O157:H7 17H ouainrdcino in- on reduction population O157:H7 P < ± ± ± ± ± ± ± ± ± ± .coli E. P shrci coli Escherichia ouainReduction Population .0 ees respectively. levels, 0.001 .coli E. 18b146.8 21.8ab 165.1 31.6ab 152.3 9.8ab 140.3 18.9ab 138.5 6.0ab 75 145.3 17.5b 137.6 10.5ab 135.5 12.8ab 152.3 19.8ab 24.4a > ± ± ± ± ± .5.Hwvr oprdwith compared However, 0.05). .8a 0.08 .5 0.94 0.58 0.87 0.41 0.35d 0.26bc 0.37cd 0.20b a 17H,rdcn ny0.41 only reducing O157:H7, ntelettuce the on etr (g Texture 183.8 a ± ± ± ± ± ± ± ± ± ± ∗∗∗ n n ∗∗∗ 17H populations O157:H7 = = P 17c165.4 11.7bc 189.0 11.7ab 182.4 12.9bc 152.7 16.2c 155.4 21.0c 07 145.2 10.7c 148.7 19.2c 146.5 24.8c 157.5 9.6bc 201.2 20.7a b 4). 4). > × .coli E. .5 mn the among 0.05) s) ± ± ± ± 0d O157:H7 0.28a 0.18bc 0.32ab 0.12c ± ± ± ± ± ± ± ± ± ± P 1.1bc 8.4ab 12.6abc 26.5c 37.2c 16.6c 27.4c 24.9c 23.4c 10.1a ◦ < Cfor 0.05) eknnadohr 09.I hssuy esta o CFU/g log 1 than less study, this in 2007b; In Olmez reduction 2009). and (Akbas others lettuce and fresh-cut Keskinen produce. of quality ef- treated the detrimental with- on the had CFU/g fects sanitizers of log many that characteristics 5 showed to sensory studies However, 3 the by affecting loads be out pathogen should reducing vegetables fresh of of capable (Abbot treatments nutrients sanitizing and Ideally, texture, flavor, 1999). unattrac- as such an consider attributes shows never major product will other consumer food potential phytonutrients a a quality, on visual if general effects fact, tive In adverse quality. no sensory have and also but populations, manufacturers’ or injury tissue in results recommendation. on the based for selected tested were was sanitizer each coli for concentration one solution Only Vel to 2002; by lettuces others of pathogens and ratio levels,(Venkitanarayanan of and inoculums inactivation solutions, strains, sanitizer the of bacterial temperature in of role sensitivity a include play weresanitizers study may present Other that the treatments. disinfectant factors in the lettuce from protected of and pieces internalized cut the on inoculated achieved ppm) of 200 CFU/g Keskinen log and 1 example, (100 about chlorine For that studies. found (2009) earlier others many and to similar was study effective. least the in was effective acid, most the was acid, inorganic reducing an SAS, that acids, showed the results our among However, 2007b). Olmez others plasma than and and Akbas penetrate (Buchanan inhibitory 2004; interior cell’s and more the lipophilic acidify are thus are and acids membrane they organic because weak acids 2009). that others inorganic and reported Rosa 2008; is (Eswaranandam others It and force Kreske motive 2004; proton others and of reduction perme- and/or membrane cell ability altering by transport by ions, substrate pH metal of of disruption intracellular chelation the molecules, acid of undissociated decrease of ionization pH, the medium to the attributed of be reduction could activity antimicrobial Their properties. eedpe nbceiliouu o i n re o only the for of dried many and that pieces min possible lettuce is 1 It for 5-cm-long min. in inoculum (2009), in 20 bacterial dipped while others in were drying and dipped h size Zhao were 2 of cm by followed study 3 min the to 15 for 2 inoculum present in is O157:H7 the (2009) pieces In procedure. others lettuce inoculation and study, Zhao bacterial of the results that in in and treating differences discrepancy study with the present for compared the reason between lettuce likely The Iceberg faster lettuce. washing much Romaine decreased to levels and used chlorine Buchanan lettuce. when that of showed types (2004) 2 Romaine the others from on load Sharma those and organic (Patel and attachment to 2010) bacterial compared in difference inactivated to due be lettuce to harder were Perhaps, (2009). 2.0 of of in reduction resulted wash CFU/g chlorine ppm log 100 2007a), Olmez and (Akbas etc.I sucerwyterdcinof reduction 4.6 the why a provided unclear LA min is 5 It for lettuce. SDS of reduction 0.05% CFU/g that with log reported who combined (2009) LA others and 0.5% Zhao by reported those than n eetdsntzrms eefciea euigmicrobial reducing at effective be must sanitizer selected Any of reduction The antimicrobial important have to shown been have acids Organic .coli E. nciainsuyi h rsn td.Teeconcentrations These study. present the in study inactivation + D norsuydfee rmta fZa n others and Zhao of that from differed study our in SDS .coli E. 17H yL ntepeetsuywsmc less much was study present the in LA by O157:H7 .coli E. o.7,N.8 2010 8, Nr. 75, Vol. 17H ouaino etc hl A keto a LA, while lettuce on population O157:H7 .coli E. 17H a bando rs-u lettuce fresh-cut on obtained was O157:H7 .coli E. .coli E. 17H ncltdo cbr lettuce Iceberg on inoculated O157:H7 .coli E. .coli E. 17H yclrn norpresent our in chlorine by O157:H7 17H nltue naohrstudy another In lettuce. on O157:H7 17H ncltdo Romaine on inoculated O157:H7 r TC292 h reduction The 25922. ATCC ora fFo Science Food of Journal .coli E. zuzadohr 2009). others and azquez ´ .coli E. 17H htwere that O157:H7 17H by O157:H7 .coli E. S439 E.

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The growingMandrell burden RE. of 2009. foodborne Enteric outbreaks human due pathogens associated with fresh produce: sources, transport Olmez H, Akbas MY. 2009. Optimization of ozonePatel treatment J, of Sharma fresh-cut M. green 2010. leaf Differences lettuce. in attachment J of Richardson SD, Thurston AD, Caughran TV, Collette TW,Rosa Patterson RM, KS, Jonathan Lykins MM, BW. Angel 1998. SL, Robert SF, Olga MB. 2009. Use of malic acid andSapers other GM, Miller RL, Pilizota V, Mattrazzo AM. 2001. Antimicrobial treatments for minimally on Listeria monocytogenes and . Available from: http://findarticles.com/ Escherichia coli artBody;col1. Accessed May 1, 2010. Vol. 75, Nr. 8, 2010 O157:H7 and adverse effects on = r O157:H7 by 0.41 log CFU/g, 0.87 Prepared Foods E. coli E. coli O157:H7 populations on fresh-cut Iceberg E. coli Journal of Food Science We thank Kimberly Sokorai and Aaron Williams for techni- Chlorine (100 ppm) achieved the highest (0.94 log CFU/g) 15:207–25. 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Conclusions after treatment with the sanitizers.in Importantly, combination both with LA SDS and caseding SAS severe of sogginess lettuce and after tissue 7 soften- andresulted 14 in d of the storage. least FIT (citric injuryin acid) this to treatment study. lettuce Compared tissues withdid among water not the treatment, cause acids detrimental 100 used effect ppmstudy. on chlorine fresh-cut lettuce in our present cal assistance, Dr.sis, John Drs. Philips Geralding Sapers for the and advice manuscript, Joshua on GurtlerInc. Jones-Hamilton for for Co. statistical and critically providing analy- SASnames HealthPro review- Brands and or FIT, commercial respectively.the Mention products purpose of in of trade this providingply specific recommendation publication or information is endorsement andAgriculture. by solely does the for not U.S. Department im- of log CFU/g, and 0.58 logments CFU/g were of obtained after 0.5% 5 LA,and min SAS-treated treat- 0.25% fresh-cut SAS, Iceberg andceptable lettuce due FIT were to wash, sensorially the respectively. development unac- after LA of sogginess 7 and and tissueLA 14 softening and d SAS storage. incommercial Overall, combination use our on with fresh-cut results SDS Iceberg demonstratedfectiveness had lettuce in because that limited inactivating of potential their for inef- reduction of lettuce. Reductions of product quality. The results demonstrated theical limitation washes of in chem- inactivating foodborneNovel pathogens safety in intervention fresh technologies produce. ensure need the safety to of be fresh developed fruits to and vegetables. Baur SR, Klaiber G, Wei H, Hammes WP, Carle R. 2005. Effect of temperature and chlorination Beuchat LR. 1996. Pathogenic microorganisms associatedBeuchat LR, Nail with BU, Adler fresh BB, Clavero MRS. produce. 1998. Efficacy of J spray application Food of chlorinated Prot

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