Microwave absorption capacity of rice flour. Impact of the radiation on rice flour microstructure, thermal and viscometric properties

Mic owa e abso p ion capaci y o ice lou . Impac o he adia ion on ice lou mic os uc u e, he mal and iscome ic p ope ies Ma ina Villanue aa, Joanna Ha asyma, b, José Ma ía Muñozc, Felicidad Rondaa* a Depa men o Ag icul u e and Fo es y Enginee ing, Food Technology, College o Ag icul u al and Fo es y Enginee ing, Uni e si y o Valladolid, Spain b Bio-Re Lab, Depa men o Bio echnology and Foods Analysis, Ins i u e o Chemis y and Food Technology, Facul y o Enginee ing and Economics, W ocław Uni e si y o Economics, W ocław, Poland. c Depa men o Elec ici y and Elec onics, Uni e si y o Valladolid, Valladolid, Spain *Co esponding au ho : A . Mad id, s/n, 34004, Palencia, Spain, onda@ia .u a.es Abs ac The mic owa e adia ion he mal ea men o ice lou was s udied and i s impac on physical and s uc u al cha ac e is ic in ela ion o he ini ial mois u e con en (IMC) (20% and 30%) was e alua ed. To explain he undamen als o obse ed changes he mic owa e adia ion abso p ion capaci y o lou as well as empe a u e and mois u e change du ing he ea men we e e alua ed. The lou pa icle mo phological s uc u e as well as c ys allini y/amo phous egion a io changed a e he ea men . The lou he mal p ope ies also al e ed e ealing IMC signi ican impac on he gela iniza ion empe a u e, ha ised up o 3ºC, and he amylopec in e og ada ion ex en ha inc eased up o a 7% in he mos in ense mic owa e- ea ed lou s wi h espec o he na i e lou . Lowe peak, se back and b eakdown iscosi ies - ha dec eased wi h espec o he na i e lou up o 42%, 34% and 86% espec i ely-and highe pas ing empe a u es - ha inc eased up o 10 ºC- we e also obse ed. An excep ional mic owa e i adia ion e iciency esul ing in ice lou physical changes in signi ican ly sho e imes, 4–8 min, han con en ional hea -mois u e ea men p ocesses was concluded. Keywo ds: Mic os uc u e; Mic owa e ea men ; mic owa e abso p i i y; pas ing p ope ies; ice lou ; he mal p ope ies 1. In oduc ion Rice lou , due o i s low alle genici y is one o he mos u ilized aw ma e ials in glu en- ee p oduc ion. Howe e , he unc ional p ope ies o na i e ice lou a e insu icien o he c ea ion o highly de eloped and s able dough s uc u e. Fo imp o emen o ice lou unc ionali y se e al di e en modi ica ion p ocedu es we e employed including hyd ocolloids and ibe addi ion (Pe ez-Qui ce e al, 2017; Ronda e al., 2015), enzyme applica ion (Kim, 2016), p o ein en ichmen (Villanue a e al., 2015; Phong ai e al., 2017), milling and pa icle size classi ica ion (Yano e al., 2017), high p essu e p ocessing (Cappa e al., 2016) and hyd o he mal ea men in he excess o wa e (Bou ekoua e al., 2016). Mic owa e (MW) adia ion can deli e ene gy wi h high e iciency depending mainly on dielec ic p ope ies o a ea ed sample. The e o e mic owa e ea men (MWT) p o ides a as e me hod han con en ional hea ing o pe o m common hyd o he mal ea men (HMT). MW a e elec omagne ic wa es wi h equencies be ween 1 and 300 GHz ha pola and ionizable molecules (wa e and mine al sal s, mainly) may abso b e icien ly. The ene gy abso p ion akes place a a molecula le el, p oducing a apid inc ease in he empe a u e o all he sample olume, which signi ican ly di e en ia es MW and con ec ional he mal hea ing. MWT impac s udies on he physicochemical, s uc u al and unc ional p ope ies o ce eals and legumes s a ches we e ca ied ou , bu he e ec on lou s has been so a li le s udied. Ande son and Gu uya (2006) e alua ed he e ec o MWT o waxy and non-waxy ice s a ches a 20% wa e con en e ealing signi ican changes in iscosi y p ope ies a e mic owa e i adia ion exposu e. Ash a e al. (2012) s udied he e ec o MWT on he unc ional p ope ies o whea and ed bean lou and showed ha MWT imp o ed he wa e holding capaci y, oil abso p ion, emulsi ying and oaming abili y and p o eins solubili y index. Howe e , he e is a lack o p ocessing da a e.g. he mixing cha ac e izing and mic owa e adia ion dis ibu ion as well as mois u e e alua ion du ing he ea men which is c ucial o he p ope e alua ion o he mic owa es' impac . To de elop e ec i e mic owa e ea men s, he dielec ic p ope ies o aw ma e ials a e c i ical as hey measu e he abili y o s o e and abso b elec omagne ic ene gy. The dielec ic p ope ies o in e es a e he dielec ic cons an ɛ´ and loss ac o ɛ´´, he eal pa and imagina y pa , espec i ely, o he ela i e complex pe mi i i y (Guo e al., 2010): 𝜀 = 𝜀′+ 𝑗𝜀′′ (𝑗 = √−1) (Eq.1) The ɛ´ mainly e lec s he abili y o a ma e ial o s o e elec omagne ic ene gy and ɛ´´ ep esen s i s abili y o abso b i . The e o e he mic owa e a enua ion o a sample is ela ed o dielec ic losses (ɛ´´) o s udied lou while phase change is ela ed o dielec ic pe mi i i y (ɛ´) o lou . The measu emen o mic owa e dielec ic p ope ies o aw ma e ials as a unc ion o i s wa e con en s can be a use ul me hod o es ima e he e ec o mic owa e adia ion on o he p ope ies as well as o disc imina e bound wa e om he o al wa e con en hanks o i s di e en con ibu ion o dielec ic pe mi i i y and loss. As he mois u e is he unc ional a iable o MWT, i is c ucial o de e mine i s speci ic con ibu ion o lou hea abso p ion and physical modi ica ion du ing he mic owa e i adia ion. The mic owa e adia ion physical modi ica ion o ice lou and i s wa e con en e ec ha e no been s udied up un il now in spi e o he ac ha ice lou is a aw ma e ial mo e ex ensi ely used in glu en- ee p oduc s o mula ion. The main objec i es o his s udy we e o analyze he mic owa e adia ion abso p ion capaci y o ice lou as a unc ion o i s wa e con en and he mic owa e assis ed he mal ea men impac on he physical cha ac e is ic, he mal and pas ing p ope ies o ice lou . Mo eo e he p ocedu e o ob ain a uni o m dis ibu ion o MW adia ion wi hin he sample o a oid lou bu ning/da kening was designed, and wa e con en o he lou was con olled du ing he MWT o e alua e he ela i e impo ance o HMT and d y-hea - ea men (DHT). 2. Ma e ials and Me hods 2.1 Rice lou Indica ice a ie y comme cially a ailable lou He ba NAT 300 (He ba Ricemills S.L.U., Ta agona, Spain) was used o all expe imen s. The ini ial wa e con en was 13%, ash <0.9%, p o ein > 6.5%, a < 1% and glu en < 10 ppm. The lou g anulome y was as ollows: 1% <250 µm, 250 µm >10-20%>210 µm, 210 µm > 35–45% > 150 µm, 150 µm > 20–35% >100 µm and 100 µm <10–20% (da a p o ided by manu ac u e ). 2.2. Flou p epa a ion Ini ial ice lou wa e con en was measu ed wi h O icial Me hod AACC 44-19 (AACC, 2000) and he amoun o wa e added o ce ain wa e con en le els achie emen was calcula ed. Flou wa e con en le els we e se a 2.5%, 5%, 10%, 13%, 15%, 25%, 30% and 39% ± 0.5%. The wa e con en o 2.5% was ob ained by ice lou lyophiliza ion in F eeZone 1, Labconco (Kansas Ci y, USA) lyophilize . The calcula ed amoun o wa e was sp ayed on o he lou mixed in Teddy Bea mixe Mono Equipmen (Swansea, UK) wi hin 10 minu es. Wa e con en s o 5 and 10% we e ob ained by mixing calcula ed amoun s o 13% ice lou wi h lyophilized one. The p epa ed samples we e s o ed o 24 hou s a 4±2ºC o equilib a ion. The wa e ac i i y o lou s was measu ed wi h Tes o 650 Humidi y Me e p o ided wi h a high p ecision ela i e humidi y p obe TESTO (Lenzki ch, Ge many). De e mina ion was made in duplica e a 25ºC. 2.3. Mic owa e abso p ion capaci y o ice lou s Rice lou samples o di e en wa e con en s we e weigh ed and ca e ully homogenously dis ibu ed in Pe i dishes. Abso p ion was measu ed wi h Keysigh (Agilen ) E5071C ne wo k analyze wi h bo h po connec ed ia coaxial lines and a enua o s o wo coaxial wa eguide (SMA o WR340) ansi ions. The wo 40dB a enua o s we e placed be ween he coaxial lines and he wa eguide ansi ions o minimize he impedance misma ch be ween a coaxial line joining he analyze (50 ohms) and ansi ion ( he impedance depends on he measu ed sample) by educ ion o s a iona y wa es in hose lines wi h he goal o imp o ing he de e mina ion. The wa eguides we e aligned and aced each o he a a cons an dis ance and he 11 mm deep Pe i dishes, wi h homogenously dispe sed lou , we e placed be ween hem. The analyze was con igu ed o wo k be ween 2 and 3 GHz and o measu e he sca e ing coe icien S12. I was calib a ed wi h an emp y Pe i dish o 0 dB and 0º o phase angle. Abso p ion was measu ed a 2.5 GHz because is he same equency used by home mic owa e o ens and he only equency ha can be used wi hou special pe mi s. All samples we e measu ed in duplica e. In ou sys em –mois ened lou – wa e was esponsible o mic owa e abso p ion while lou played he ole o diluen . The applica ion o he Lambe -Bee law equi ed he no maliza ion o he measu emen o sample weigh since he op ical pa h could no be comple ely illed wi h he sample bu also included ai en apped be ween he lou pa icles. The mic owa e abso p ion was exp essed in e ms o a enua ion, calcula ed om he a io o he powe measu ed wi h he sample and he one ob ained wi h an emp y Pe i dish (in dB) and in e ms o phase change, calcula ed as phase shi o he ecei ed signal when placing he sample (in deg ees), by using he ollowing equa ions:  = 20 · 𝑙𝑜𝑔 𝑆12 (𝑓𝑖𝑙𝑙𝑒𝑑) 𝑆12(𝑒𝑚𝑝𝑡𝑦) (Eq.2)  = 𝑎𝑟𝑔 𝑆12(𝑓𝑖𝑙𝑙𝑒𝑑) 𝑆12(𝑒𝑚𝑝𝑡𝑦) (Eq.3) Whe e α is a enua ion,  is he phase shi , S12 is he sca e ing coe icien when he sample con aine is illed wi h a sample (S12( illed)) o emp y (S12(emp y)). In e ms o powe , he a enua ion can be ob ained om he o mula:  = 10 · 𝑙𝑜𝑔 𝑃 (𝑓𝑖𝑙𝑙𝑒𝑑) 𝑃(𝑒𝑚𝑝𝑡𝑦) (Eq.4) Whe e P( illed) is he powe de ec ed o he sample illed Pe i dish and P(emp y) is he powe de ec ed o he emp y Pe i dish. The ac ual alue o he complex pe mi i i y is di icul o measu e wi hou wa eguide sample holde s, which equi e, a hese equencies, an ino dina e amoun o sample ma e ial. 2.4 Mic owa e ea men The mic owa e ea men was p o ided wi h cus omized mic owa e o en (900 W) R342INW (Sha p, Sakai, Japan). P elimina y s udies we e unde aken o se ing he mic owa e ea men condi ions. Finally, 100 g o lou wi h wo le els o ini ial wa e con en (20% and 30%), we e placed in a polye hylene con aine closed wi h a plas ic ilm wi h a ew (4-5) needle made small holes and con inuously s i ed by an ex e nal de ice a a speed o 60-70 pm. The lou was exposed o mic owa e adia ion o 2, 4, 6, 8, 12 and 16min in cycles o 20s o exposu e and 40s o es . The lou empe a u e e olu ion du ing he MWT was measu ed wi h Tes o e m he mome e s ips o di e en scales, and 0.5ºC accu acy, om TESTO (Ba celona, Spain). Two s ips o di e en scale we e in oduced wi h each sample in o he polye hylene con aine and we e con inuously s i ed and in con ac wi h he sample du ing he es ablished ea men ime. Each measu emen was made in duplica e. 2.5. Scanning elec on mic oscopy (SEM) A mic oscope model Quan a 200-F (FEI, O egon, USA) was used o s udy he mo phological changes in he lou s. This mic oscope was equipped wi h an X- ay de ec o which allowed he analysis o samples o low conduc i i y wi hou p io me alliza ion. The samples we e di ec ly moun ed on s ubs and obse ed wi h an accele a ing ol age o 1.5 keV. 2.6. X-Ray Di ac ion The di ac ion assessmen was p oceeded using a B uke -D8-Disco e -A25 di ac ome e (B uke AXS, Rhein elden, Ge many) equipped wi h a coppe ube ope a ing a 40 kV and 40 mA, wi h CuKα adia ion o 0.154-nm wa eleng h. Di ac og ams o samples we e ob ained wi h scanning om 5° o 40°(2θ) a a a e o 1.2°/min, a s ep size o 0.02°, a di e gence sli wid h a iable o 5mm and a sca e sli wid h o 2.92° and a nickel il e 0.02 o exclude he Kβ adia ion. The c ys allini y o samples was de e mined om di ac og ams based on he ela ion be ween he global peaks a ea and he educed peaks a ea assigned o he c ys alline pa o he sample, and exp essed as a pe cen age. The “sea ch–ma ch” so wa e Di acEVA wi h PDF2-2004 and COD da abase was used o his pu pose. 2.7. Di e en ial Scanning Calo ime y Gela iniza ion and e og ada ion ansi ions we e assessed by DSC (DSC-822e, Me le Toledo, SAE). Flou samples, 6 mg, we e weighed in o aluminum pans (40μl) and dis illed wa e was added o achie e he a io 30:70 ( lou :wa e ). The samples we e scanned om 0 o 115°C a 5°C/min using an emp y pan as e e ence. The e og ada ion o s a ch was e alua ed in he samples p e iously gela inized in he DSC pans a e 7 days o s o age a (4± 2) °C ollowing he same p o ocol. The en halpy (ΔH) alues, J/g o solids, he onse and peak empe a u es (To and Tp), and he empe a u e ange (Rgel= 2·(Tp-To)) o he gela iniza ion peak, we e es ablished. Samples we e un in duplica e. 2.8. Pas ing P ope ies o Flou s Pas ing p ope ies we e s udied by using he Rapid-Visco-Analyze (RVA-4, Newpo Scien i ic P . L d., Aus alia) using ICC S anda d me hod 162. Un ea ed lou was also measu ed as con ol. The pas ing empe a u e (PT), peak ime (VT), peak iscosi y (PV), ough iscosi y (TV), b eakdown (BD), inal iscosi y (FV), and se back (SB) we e calcula ed om he pas ing cu e using The mocline .2.2 so wa e. The de e mina ion was ca ied ou in iplica e. 2.9. S a is ical analysis The S a g aphics Cen u ion .16 (Bi s eam, Camb idge, MN, USA) so wa e was used o MANOVA and ANOVA analyses. The Fishe ’s leas signi ican di e ence (LSD) es was adop ed o e alua e signi ican di e ences (p<0.05) among samples. Homogenei y o a iance was checked o each s udied a iable. 3. Resul s and Discussion 3.1 Mic owa e abso p ion capaci y o lou The mic owa e adia ion abso p ion capaci y o ice lou , measu ed in e ms o a enua ion, and he phase shi o adia ion when i passed h ough he samples as unc ion o hei wa e con en a e shown in Fig. 1A. The MW a enua ion da a a e also ep esen ed, simul aneously wi h he wa e con en o ice lou , e sus lou wa e ac i i y, aw, in Fig.1B. The MW a enua ion and phase shi inc eased wi h wa e con en acco ding o he equa ions: A enua ion(dB/g)=1.10 (  0.16)·10-5·W2 + 9.00 (  1.1)·10-4·W – 1.2 (  1.4)·10-3 R2 = 99.8 (Eq.5) Phase-shi (  )=0.0064(  0.0017)·W2+ 0.37(  0.12)·W + 20.6 (  1.5) R2 = 99.0 (Eq.6) Whe e W is he wa e con en exp essed in g/100 g solids. The s anda d e o o each eg ession coe icien is gi en in pa en heses. These esul s e eal ha he g ea e he o al amoun o wa e con ained in he lou he smalle is he signal eaching he ecei e . This is due, on he one hand, o he ac ha he e is a g ea e abso p ion o adia ion by he sample and on he o he hand, ha he p opo ion o inciden adia ion ha is e lec ed by he sample is g ea e , since i s dielec ic pe mi i i y is also g ea e . The combina ion o hese wo e ec s jus i ies he posi i e de ia ion om Bee ’s law ha shows he abso p ion cu e app oaching a quad a ic a he han a linea beha io . This ac canno be con i med, since i is possible ha he inc ease o he a enua ion is due o an inc ease in he e lec ed adia ion and no in he abso bed one. The independen e m o Eq.5 is no signi ican ly di e en om ze o which means a enua ion is ze o when he lou is comple ely d y. In consequence, i can be concluded ha lou d y ma e is unable o abso b he mic owa e adia ion e en hough lou could expe ience a as e hea ing unde MW- adia ion when i loses wa e (Lewandowicz e al., 1997). This e ec mus be due o he d ama ic educ ion in lou speci ic hea wi h he educ ion o i s wa e con en . Figu e 1. A enua ion o mic owa e adia ion by ice lou in unc ion o i s wa e con en and wa e ac i i y. A) A enua ion () and phase shi () o ice lou in unc ion o i s wa e con en . B) A enua ion () and wa e con en () e sus wa e ac i i y. 0 10 20 30 40 50 60 70 80 0.00 0.02 0.04 0.06 0.08 0.10 0.12 010 20 30 40 50 60 70 Phase shi (ϴ) A enua ion (dB/g) Wa e con en (g H2O/100 g solids) A) 0 10 20 30 40 50 60 70 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Wa e con en (g H2O/100g solids) A enua ion (dB/g) Wa e ac i i y B) 0 30 60 90 120 150 180 0 10 20 30 40 50 0 2 4 6 8 10 Flou empe a u e (ºC) Flou mois u e (%) T ea men ime (min) Figu e 1B shows a o al pa allelism in he e olu ion o wa e con en and a enua ion e sus aw. This indica es ha he mic owa e abso p ion capaci y o lou does no depend on wa e ac i i y since he a enua ion inc eased d as ically e en when aw ha dly a ied a ound aw=1, bu depends on he o al wa e con en o he lou . These esul s also indica e ha he a enua ion and he phase shi measu emen s may be a as , simple, and accu a e me hod o de e mining in line he mois u e con en o ice lou as hey allow a emo e and non-des uc i e measu emen o he lou , as concluded by Ince and Tu ne (1965), in biscui s in es iga ions and Okabe e al. (1973), in ice and whea g ains s udy. 3.2 Tempe a u e e olu ion in lou du ing he mic owa e ea men The e olu ion o he empe a u e and he wa e con en o he lou s du ing MWT a e shown in Fig.2. As can be seen, i dec eased in 8 min o 8% and 10% o he lou s mois ened o 20% and 30% espec i ely. These esul s sugges ha MWT in a non-he me ic con aine , is in ac , he combina ion o wo p ocesses: HMT, in he i s s age, and DHT in he las one. As can be seen in Fig.2 du ing he i s 80s o ea men he ene gy abso bed by he samples was mainly in ol ed in changing i s empe a u e, while a 80s bo h lou s a ained a small pla eau o cons an empe a u e, whe e he hea abso bed by he sample was in ol ed in boiling i s small amoun o ee wa e . A e ha , he empe a u e inc eased again o a ain a new pla eau, a e 4–5min o MW adia ion, whe e he empe a u e was cons an un il he end o he ea men . The maximum empe a u e achie ed by he samples was 15010ºC. In he i s 20s o ea men , he lou s wi h 20% and 30% wa e con en eached 46ºC and 60ºC, espec i ely. The highe mic owa e abso p ion capaci y could explain he highe empe a u e as was seen in ou p e ious wo k (Pé ez-Qui ce e al., 2016). Howe e , be ween 20s and 80s bo h samples showed simila empe a u e p o ile p obably due o he ac ha he highe ene gy abso p ion was compensa ed wi h he highe speci ic hea ha makes his lou need mo e abso bed hea o ge a simila change in empe a u e. Figu e 2. E olu ion o mois u e (,) and empe a u e (,) o he lou as a unc ion o mic owa e ea men o mois ened ice lou s a 20% (,) and 30% (,) ini ial hyd a ion le els. The boiling empe a u e o he lou wi h 20% ini ial mois u e was highe han ha o he lou wi h 30% because i s wa e ac i i y (Fig.1B), and in consequence i s wa e apo p essu e, was lowe in he o me , which means a highe empe a u e needed o a ain he ex e nal a mosphe ic p essu e and o each he boiling condi ions. A e 4min o MWT he wa e con en o he lou was o 5–10% (Fig.2), nea he alue co esponding o he ice lou monolaye wa e con en (Abebe & Ronda 2015) which co esponds o wa e igh ly bound. The inal long pla eau o cons an empe a u e p obably co esponded o a pe iod in which he hea abso bed by he sample (no oo much as he wa e amoun was eally low) was equal o he hea los by i owa ds he su ounding ha inc eased wi h he empe a u e o he sample. In ou p e ious wo k, whe e he sample was ea ed inside a he me ic con aine , a single and long empe a u e pla eau was ob ained below 100ºC, wi h wa e ac ing as ‘p o ec o ’ o he lou cons i uen s, which was used o explain he low impac o he MWT in such condi ions on lou unc ional p ope ies (Pé ez-Qui ce e al., 2016), di e en ly o wha we ha e obse ed in his case. 3.3. Mo phology o samples F om SEM images (Fig. 3) he impo an impac o MWT on lou pa icles mac os uc u e o samples mois ened a 20% and 30% can be concluded. Rice s a ch di e s by i s shape om o he ce eals and he g anules a e polygonal and a e packed e y igh ly in he ice g ain cells being en wined wi h globula p o ein bodies and lipids (Nawaz e al., 2016). The s a ch g anules o m polygonal mac os uc u es o en isible in SEM mic og aphs o ice ke nel (Si ugu i e al., 2009). A e milling o ice hese mac os uc u es appea mo e o less in ac in he lou (see Fig. 3-A1). Wi h he inc ease o wa e con en in lou s ea ed wi h MW, he cha ac e is ic o pa icle size dis ibu ion was na owed esul ing in mo e homogenous one (see Fig. 3-B1-C1) which was p obably caused by gluing he small pa icles oge he . The subsequen magni ica ion e ealed ha p ima ily ough and ayed pa icle shapes in na i e lou become mo e ounded and o oid (Fig. 3-A2-B2-C2) in ea ed samples which was also con i med p e iously by Takahashi e al. (2005) o sho g ain ice au ocla ed a 20% o mois u e con en . The pa icles' su ace (Fig.3-A3-B3-C3) appea s o be smoo he and aligned simila as epo ed by o he esea che s o sho ice g ain lou (Majzoobi e al., 2016) and ox ail mille lou (Amadou e al., 2014) when we e submi ed o con ec ional hyd o he mal ea men s. A highes magni ica ion s a ch g anules clus e s we e isible co e ed by p o ein bodies sp ead and adhe ed o e he su ace (Fig. 3-A4-B4-C4). The esul ing mac os uc u es (Fig. 3-A4-B4-C4) e ealed ha s a ch g anules in clus e s seem o be glued wi h neighbo ing ones and he slo s be ween hem isible a na i e lou we e shallow and illed in MW- ea ed ones. Such sealing could be he esul o amylose exuda ion du ing he he mal ea men o na i e lou as p e iously epo ed (Ca e a e al., 2015). Such beha io was no epo ed o isola ed s a ch ea men and p esen s he addi ional di e ence be ween HMT ea men o s a ch and lou . 3.4. X- ay di ac ion and c ys allini y o samples The X- ay di ac ion pa e ns o ice lou ea ed o 4 and 8 min a e p esen ed in Fig.4. All he ice lou samples p esen ed an A- ype di ac ion pa e n wi h c ys alline peaks a 10°, 15°, 17°, 18°, 23° and 26°, main ained a e he ea men . The e lec ion a 20°, which is usually connec ed wi h V-c ys allini y, was also obse ed in all ice lou al hough he peak inc eased in he MW- ea ed samples abou 14% in ones wi h he highes wa e con en and he longes ea men (30%-8min). 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