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C oss-linked me hyl cellulose ilms wi h mu a ui ex ac o an ioxidan and
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an imic obial ac i e ood packaging
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Ca ol López de Dicas illo*, Fe nanda Bus os, Abel Gua da, Ma ia José Galo o
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Food Packaging Labo a o y (Laben-Chile), Depa men o Science and Food Technology, Facul y o
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Technology, Cen e o he De elopmen o Nanoscience and Nano echnology (CEDENNA), Uni e sidad de
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San iago de Chile (USACH), San iago, Chile
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*Co esponding au ho : a[email p o ec ed]l
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ABSTRACT
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The use o biopolyme s as subs i u es o non-deg adable adi ional plas ics is an in e es ing
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al e na i e pa icula ly o sho - e m applica ions, such as ood packaging. Addi ionally,
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ac i e packaging has a ac ed much a en ion as an inno a i e echnology o ood
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conse a ion. Thus, he unc ionali y o biocomposi e ilms based on me hylcellulose (MC)
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and mu a ui (MU) (Ugni molinae Tu cz) ex ac was s udied. Mu a ui is a na i e
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Chilean be y and good sou ce o an ioxidan and an imic obial compounds. Fi s , a MU
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ex ac wi h he highes an ioxidan abili y and polyphenolic con en was selec ed, and ac i e
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MC ilms we e p epa ed by cas ing using glu a aldehyde (GA) o imp o e hei wa e
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esis ance. The e ec s o GA concen a ion and inco po a ion o MU ex ac on ma e ial
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p ope ies and an imic obial and an ioxidan ac i i ies we e examined. The addi ion o GA
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g ea ly dec eased swelling index, imp o ed mechanical p ope ies and an ioxidan and
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an imic obial ac i i ies achie ed highes po en ial when GA was added a lowes
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concen a ion.
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Keywo ds: Na u al ex ac s, ac i e packaging, elease, me hyl cellulose, c osslinking.
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Chemical compounds s udied in his a icle: 2,2´-azinobis(3-e hylbenzo hiazoline-6-
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sulphona e) (ABTS) (PubChem CID 90658258); polye hylene glycol (PubChem CID
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24762); glu a aldehyde (PubChem CID 3485); gallic acid (PubChem CID 370); T olox
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(PubChem CID 40634); Folin-Ciocal eu´s phenol eagen (PubChem CID 516996);
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anhyd ous sodium ca bona e (PubChem CID 10340).
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1. In oduc ion
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Du ing he las yea s, he esea ch on he de elopmen o ac i e ma e ials wi h
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an imic obial and an ioxidan p ope ies has inc eased eno mously wi h he pu pose o
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p o ec ood om oxida i e eac ions and mic obial g ow h. Fu he mo e, he applica ion o
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na u al ing edien s is a new end in he ood indus y and ood esea ch, i.e., na u al
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p ese a i es de i ed om na u al sou ces, ins ead o syn he ic subs ances and he educ ion
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o addi i es in oods. Na u al subs ances such as α- ocophe ol, essen ial oils and plan
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ex ac s ha e been inco po a ed in o polyme s o he p epa a ion o ac i e packages
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(Galo o, Gua da, & Lopez de Dicas illo, 2015; Gómez Es aca, Lopez de Dicas illo,
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He nandez Muñoz, Ca ala, & Ga a a, 2014). On he o he hand, he p oduc ion and he
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use o plas ics h oughou he wo ld ha e g own eno mously, wo sening en i onmen al
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impac and p oblems o he was e disposal. The use o biopolyme s as subs i u es o non-
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deg adable syn he ic polyme s is becoming a sus ainable al e na i e, pa icula ly in e es ing
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o sho - e m applica ions, such as ood packaging. Thus, he de elopmen o biodeg adable
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ac i e packaging con aining na u al ex ac s de i ed om plan s is one in e es ing s a egy
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la gely conside ed by he ood packaging indus y (Coope , 2013, Seydim & Sa ikus, 2006;
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Song, Lee, Al-Mijan, & Song, 2014). One al e na i e o de elop bio-based ma e ials is by
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ilm coa ing mul ilaye . A ilm coa ing is a hin polyme -based coa be ween 20-10 µm
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applied o a solid suppo . Biobased coa ings o e ex a ad an ages such as low cos s due o
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he educ ion on amoun o polyme , educing e ms o CO2 emissions, and he p ocessing
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empe a u es a e lowe , which is e y use ul o a oid he mal deg ada ion o ac i e agen s.
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Fo indus ial p ocesses, he echniques can be ex usion o co-ex usion o mul ilaye ilms,
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lamina ion, and mainly oll-d ying o he sol en emo al o he polyme solu ion
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(Debeau o , Quezada-Gallo, & Voilley, 1998; Va ianinen, Vaha-Nissi, M., & Ha lin,
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2014).
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Among he biopolyme s, anionic linea polysaccha ides de i ed om cellulose, such as
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me hyl cellulose (MC), a e e y p omising because hey a e en i onmen ally iendly due o
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hei biodeg adabili y. In he ood indus y, MC ilms p omise impo an po en ial o be used
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o packaging applica ions due o hei excellen ilm-making p ope ies, la ge a ailabili y,
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low cos , anspa ency, high-s eng h and easy abili y o be p ocessed (Aminabha i,
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Balundgi, & Cassidy, 2008; Coope , 2013; Rimdusi , Jingjid, Dam ongsakkul,
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Tip ipako n, & Takeichi, 2008). Me hyl cellulose a e polysaccha ides composed o linea
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chains o β(14) glucosidic uni s wi h me hyl subs i uen s ha p o ides ilms ha a e wa e
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soluble and oil-and g ease esis an and wi h e icien oxygen and lipid ba ie p ope ies
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(Pa k & Ruckens ein, 2001; Ga cía, Pino i, Ma ino, & Za i zky, 2004; Nispe os-
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Ca iedo, 1994).
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MC ilms, like mos ilms based on biopolyme s, a e highly sensi i e o en i onmen al
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condi ions and due o hei hyd ophilic na u e, physical p ope ies a e e y suscep ible o
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mois u e and biodeg adabili y. As a esul , se e al esea che s ha e de eloped new
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o mula ions h ough small chemical modi ica ions o hese polyme s, such as c osslinking
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p ocesses which p omo e co alen linkages be ween polyme chains. C osslinking is one o he
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mos popula me hods used o modi y wa e -soluble polyme s in o de o achie e desi ed
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p ope ies. MC can be c oss-linked by means o di e en me hods, such as adia ion o by using
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con enien chemical c oss-linke s consis ing on aldehydes, polyepoxy compounds, and e en
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ea ca echins (A ala, 2002; Wach, Mi omo, Nagasawa, & Yoshii, 2003; Yu, Tsai, Lin, Lin,
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& Mi, 2015).
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Glu a aldehyde, GA, is a widely used c oss-linke which o ms a s ong co alen
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a achmen on o a polyme su ace, p o iding he way o a igid s uc u e (He nández-
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Muñoz, Villalobos, & Chi al , 2004; Lee e al., 2005; Mansu , Sadahi a, Souza, &
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Mansu , 2008; Pa k, Bae, & Rhee, 2000). Some polyme cha ac e is ics could be al e ed
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by c osslinking such as pe meabili y, mechanical p ope ies and d ug eleasing. The e ec
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o addi ion o c oss-linke s on compounds ha a e desi ed o be eleased has been al eady
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s udied, bu mainly wi h pha maceu ical applica ions (Aiedeh, Taha, Al-Hia i, Bus anji, &
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Alkha ib, 2006; Ranjha, & Qu eshi, 2014; López de Dicas illo, Jo dá, Ca alá, Ga a a,
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& He nández, 2011a; Ma inez, Ca es, Ra i, Li, & Chaiko , 2014; Teng, Campello, &
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Wu, 2011).
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In he de elopmen o ac i e ma e ials i is impo an o each a con olled elease o ac i e
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componen s o he ood o p o ec i om oxida ion o mic obial spoilage, enhancing ood
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sa e y and shel li e. In his wo k, he e ec o c osslinking on he elease o an ioxidan
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compounds om ac i e packaging was e alua ed. Release o hese ac i e agen s will be
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comple ely dependen on he swelling deg ee o he polyme . Due o i s hyd ophillici y,
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me hyl cellulose was chosen in his wo k o be he polyme ma ix in he de elopmen o
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ac i e ma e ials o ood packaging sys ems (Cala ayud e al., 2013; Lopez de Dicas illo e
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al., 2011b). On he o he hand, GA was selec ed as c oss-linke agen due o i s p o en
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e ec i eness in o he wo ks and o a oid deg ada ion o phenolic compounds p opi ia ed by
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i adia ion (Beaulieu, D´Ap ano, & Lac oix, 1999, Hi ashima e al., 2013, Pa k e al.,
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2001; Rimdusi e al., 2008). And inally, polye hylene glycol was inco po a ed as
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plas icize . The use o plas icize is e y impo an on he ma e ials de elopmen wi h
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biodeg adable polyme s because hey dec ease he in e molecula in e ac ions among he
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unc ional g oups o he backbone chains, esul ing in inc eased lexibili y and ex ensibili y.
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In ood indus y, polye hylene glycol (PEG) has been widely used o MC p oduc s o
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olling, cas ing, o ex uding p ocesses because i p o ides se e al ad an ages due o
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chemical in e ac ions be ween MC and PEG s uc u es (Pa k e al., 2001; Sa ka , &
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Walke , 1995).
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Ugni Molinae, also known as “mu a”, “mu illa”, “uñi” o “Chilean c anbe y”, is a na i e
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plan om Chile, wes e n A gen ina, and ce ain egions o Boli ia. I is a wild sh ub o he
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My aceae amily ha bea s a oma ic ed globula ui ha is said o combine he swee ness
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o a s awbe y wi h he pungency o a gua a and he ex u e o a d ied bluebe y. P e ious
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s udies ha e shown mu a ui is composed by high le els o la an-3-ols, such as ca echin
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and epica echin, la onols, such as que ce in and que ce in-3-glucoside, and
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hyd oxycinnamic acid, such as ca eic acid-3-glucoside. The o he compounds we e
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an hocyanins, like cyanidin-3-glucoside and peonidin-3-glusocide, u in, gallic acid,
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que ci in, lu eolin, kaemp e ol, p-couma ic and my ice in, ha could a o d in e es ing
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an imic obial and an ioxidan ac i i ies o ood p o ec ion (Al a o e al., 2013; Junquei a-
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Gonçal es e al., 2015; Ruiz e al., 2010; Sch eckinge , Lo on, Lila, & Gonzalez de
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Mejia, 2010).
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2. Ma e ials and me hods
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2.1. Ma e ials and Reagen s
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Me hyl cellulose (MC) was ob ained om Reu e S. L. (San iago, Chile), 2,2´-azinobis(3-
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e hylbenzo hiazoline-6-sulphona e) (ABTS), Folin Ciocal eu phenol eagen , anhyd ous
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sodium ca bona e, Gallic acid, 6-hyd oxy-2,5,7,8- e ame hylch oman-2-ca boxylic acid
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(T olox) and polye hylene glycol (PEG) (a e age molecula weigh 190-210) we e pu chased
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om Sigma Ald ich Quimica S.A. Ugni Molinae ui , commonly known as mu a be y ui ,
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MU, was ob ained om “Na i o Li e”, an USDA and IMO o ganic g ade ce i ied company,
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whose ui s we e al eady d ied and milled.
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G am-posi i e bac e ia Lis e ia innocua ATCC33090 was ob ained om Labo a o y
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Mic obiologics (Uni e si y o Chile, Chile) and s o ed in T yp one soy b o h (TSB) a -80
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°C un il needed. Fo expe imen al use, he s ock cul u es we e main ained on T yp one soy
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aga (TSA) slan s a 4 °C, and o expe imen a ion, a loop ul o each s ain was ans e ed
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o 10 ml o TSB and incuba ed a 37 °C o 18 h o ob ain esh ea ly-s a iona y phase cells.
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2.2. Na i e F ui S udies - An ioxidan Ac i i y and Polyphenolic Con en
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Mu a ui powde was ex ac ed unde e hanol, e hanol 50% and dis illed wa e in o de
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o s udy he pola i y o he mos an ioxidan compounds and ind he ex ac wi h highes
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an ioxidan capaci y. The ex ac ion was ca ied ou a 40 °C du ing 3 h in an E lenmeye
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lask in a shaking incuba o a 150 pm. Then he mix u es we e cen i uged and he uppe
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phases we e e alua ed h ough ABTS me hod and Folin Ciocal eu es in o de o measu e
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an ioxidan capaci y (as adical sca enging capaci y) and polyphenolic con en , espec i ely.
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Folin-Ciocal eu me hod was done acco ding o he me hod o Single on e al., 1999, wi h
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some modi ica ions (Single on, O ho e , & Lamuela-Ra en ós, 1999). Gallic acid was
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used as he s anda d o he calib a ion cu e and polyphenol con en (PC) was exp essed as
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gallic acid equi alen s (GA).
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ABTS me hod was done acco ding o p e ious wo ks (Lopez de Dicas illo, Cas o-
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Lopez, Lasagabas e , Lopez-Vila iño, & Gonzalez-Rod iguez, 2013). ABTS assay is
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based on he inhibi ion o he adical ca ion 2,2´-azinobis(3-e hylbenzo hiazoline-6-
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sulphona e), ABTS+•, by an ioxidan s, which has a cha ac e is ic wa eleng h abso p ion
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spec um wi h maximum a 715 nm. This ca ionic adical is neu alized ei he by di ec
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educ ion ia elec on ans e o by adical quenching ia H a om ans e (P io , Wu, &
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Schaich, 2005). The pe cen age inhibi ion alues we e calcula ed using equa ion 1:
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% Inhibi ion= % I = (Acon ol – Asample) /Acon ol * 100 (1)
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Sca enging ac i i ies o he adicals we e exp essed as T olox equi alen s pe g am o
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mu a ui sample.
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2.3. Ob aining Na u al Ex ac
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In o de o ob ain a ui ex ac wi h high concen a ion o be inco po a ed o ilm
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de elopmen , mu a ui was ex ac ed wi h e hanol 50% (20 mg/mL) a 40 ºC du ing 3 h.
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The mix u e was cen i uged, il e ed and concen a ed o a inal concen a ion o 100 mg
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mu a/ mL.
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2.4. Films P epa a ion
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MC ilms we e p epa ed by solu ion-ex ension-e apo a ion (“cas ing”). This echnique
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has he ad an age o educing he he mal deg ada ion o he na u al ex ac wi h espec o
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con en ional ex usion and can be compa ed o ilm-coa ing echniques (Hong, Lee, & Son,
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2005; Va ianinen e al., 2014). 1 g o MC was dissol ed in 100 mL e hanol 70% by hea ing
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a 70 ºC (1% w/ ) wi h cons an s i ing un il o al dissolu ion. In o de o imp o e he wa e
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esis ance o MC ilms, he polyme was c oss-linked wi h glu a aldehyde a di e en
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concen a ions, 10, 15 and 20 % espec o polyme weigh . The pH o he mix u e was
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adjus ed o 3 using a HCl solu ion (1 M), and la e he solu ion was cooled o 40 ºC o a ound
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2 h unde agi a ion (Pa k e al., 2011; Plie a e al., 2006). Then, 233 µL o polye hylene
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glycol (PEG) (25% w/w o MC) was added as plas icize . In he case o he ac i e ma e ials,
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be o e he addi ion o PEG, addi ionally 2.5 mL o mu a be y ex ac (MU) (0.25:1 w . a io
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MU:MC) ob ained on p e ious sec ion was added o he mix u e. Films we e cas on a 20 cm
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diame e su ace pe i dish in a chambe a 55 ºC o e nigh . The inal ilms we e ca. 75-90
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μm hick.
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2.5. Physical Cha ac e iza ion o C oss-linked MC Films
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2.5.1. Scanning Elec onic Mic oscopy (SEM) s udies
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SEM mic og aphs o ac i e ilms we e ob ained om a JSM-5410 Jeol Scanning
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Mic oscope wi h accele a ing ol age a 10 kV. Fi s ly, ilms we e ac u a ed using Tensile
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Tes e because h ough c yo- ac u e was no possible o ob ain samples. A e , samples we e
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coa ed wi h gold palladium using a Spu e ing Sys em Humme 6.2 and SEM mic og aphs
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o he su ace and he c oss-sec ion o he ma e ials we e aken.
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2.5.2. Op ical P ope ies
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The ilm colo was de e mined wi h a Konica Minol a model CR-410 colo ime e . The
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ilm specimen was placed on he su ace o a s anda d whi e pla e, and he CIELAB colo
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space was used o de e mine he pa ame e s L*, a*, and b*. The colo was also exp essed
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also a educ ion o his peak. When compa ed o MC ilm, he p esence o he plas icize
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PEG was obse ed by he p esence o a new peak a 1350 cm-1 (C-H bending) (Shameli e
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al., 2012).
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Fig. 2B shows he FTIR o mu a ex ac , GA, MC and he ac i e ma e ial
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MC_10GA_MU as an example, since all ac i e ma e ials p esen ed he same spec a. I was
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possible o obse e mu a ex ac p esen ed a cha ac e is ic peak a a simila wa enumbe o
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GA. Thus, he inco po a ion o mu a ui ex ac in he case o ac i e ma e ials was
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pe cei ed only by he inc ease in abso bance o his peak a ound 1720 cm-1.
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3.2.4. Swelling Resul s
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Table 3 only p esen s swelling index (SI) esul s o c oss-linked ilms since MC ilms no
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c oss-linked we e quickly swelled and comple ely dissol ed in wa e wi hin 1 h.
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As i was expec ed, he inco po a ion o GA induced he chemical c osslinking o me hyl
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cellulose which was based on he gene a ion o co alen bonds ha main ained he in eg i y
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o he polyme ic ne wo k and educed polyme chain lexibili y and mobili y. C oss-linked
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MC ilms wi h and wi hou mu a ui ex ac we e highly s able when imme sed in wa e ,
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he shape did no change bu ilms swelled and hei su ace a ea inc eased. Fu he mo e, SI
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alues dec eased as GA concen a ion inco po a ion inc eased. Films wi h 20% GA showed
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e y low alues o SI, sugges ing ha he hyd ophillici y o c oss-linked ilms was g ea ly
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educed.
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On he o he hand, he inco po a ion o mu a ex ac dec eased he e iciency o he
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c osslinking p ocess and esul ed in a conside able inc ease on swelling index alues in he
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case o ac i e ma e ials. P obably some hyd oxyl g oups om an ioxidan compounds o
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mu a ex ac a e eac ing wi h glu a aldehyde molecules, dec easing c osslinking e iciency
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(Yu e al., 2015). GA, as a dialdehyde, can unde go a a ie y o eac ions, and he mos
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common a e nucleophilic addi ion eac ions. Taken in o accoun ha mu a ui ex ac is
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composed o la onoids and o ganic acids, he main eac ions would be be ween he ca bonyl
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g oups o GA molecule and he hyd oxyl g oups o hese molecules h ough nucleophilic
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addi ions o he ca bon-oxygen double bonds. Reac ions o aldehydes wi h alcohols p oduce
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ei he hemiace als (a unc ional g oup consis ing o one —OH g oup and one —OR g oup
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bonded o he same ca bon) o ace als (a unc ional g oup consis ing o wo —OR g oups
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bonded o he same ca bon), depending upon condi ions.
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3.2.5. The mal P ope ies
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The mal s abili y o MC and ac i e MC ilms we e e alua ed by TGA. The he mog ams
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and hei de i a i e o he weigh loss o all MC-based ma e ials a e shown in Fig. 3.
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The mog ams clea ly show he maximum decomposi ion o ma e ials occu ed a
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app oxima ely 361 °C, co esponding o me hyl cellulose deg ada ion (Rimdusi e al.,
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2012; Tjong, Xu, & Meng, 1999). I can be no iced ha he inco po a ion o plas icize
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inc eased he he mal s abili y a ound 20 °C (381 and 362 °C deg ada ion empe a u es o
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plas icized MC_PEG and unplas icized MC, espec i ely). On he o he hand, he
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inco po a ion o GA dec eased his e ec , and his e ec was no p opo ional o GA con en
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as maximum deg ada ion empe a u e alues o all c oss-linked ma e ials we e e y simila ,
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app oxima ely a 361 °C, as Fig. 3A and B show. In his case, c osslinking a e no gene a ing
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new bonds he mally mo e esis an o hea han ini ial bonds exis ing in MC ne wo k.
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In gene al, he he mal decomposi ion o c oss–linked MC based ilms ollowed mul is ep
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decomposi ion. The i s s ep was he e apo a ion o he esidual sol en om cas ing me hod
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(e hanol-dis illed wa e ) wi h i s maximum a ound 80 ºC (~3-6 % w ). This was ollowed by
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a decomposi ion p ocess a app oxima ely a 260 ºC, which co esponds o he new linkage
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deg ada ion o mo e he mo-sensi i e compounds, wi h lowe molecula weigh s
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co esponding o c osslinking p ocess. Finally he he mal MC deg ada ion p e iously
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men ioned.
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The inco po a ion o mu a ex ac did no o e any addi ional p o ec ion o he polyme .
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No mally he inco po a ion o an ioxidan s inc eases he mal polyme s abili y bu he
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opposi e e ec obse ed in his wo k was al eady seen in o he wo ks (A ie a, Lopez,
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Fe ándiz, & Pel ze , 2013, Lopez de Dicas illo, Alonso, Ca alá, Ga a a, & He nandez-
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Muñoz, 2010). A TGA s udy o me hyl cellulose wi h mu a ex ac wi hou c osslinking
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was ca ied ou o obse e he deg ada ion p ocesses. As Fig.3B shows, simila deg ada ion
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p ocesses we e displayed when compa ed o ac i e c oss-linked ma e ials. MU ex ac was
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also analyzed, showing a b oad deg ada ion band ha s a s a 120 ºC app oxima ely, wi h a
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maximum a app oxima ely 200 ºC. This deg ada ion can be associa ed o he
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“ca ameliza ion” p ocess o he suga s om he la onoids o MU ex ac , mainly la onols,
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such as my ice in and que ce in, which a e pa ially glycosyla ed (Shene e al., 2008). So,
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his peak a 250 °C can be associa ed o a c osslinking e ec o ca bonyl g oups om
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la onoids om his ui ex ac . This ac has been shown ecen ly in some wo ks (Yu e
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al., 2015; Benbe aieb, Ka bowiak, B achais, & Debeau o , 2015).
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3.2.6. Mechanical P ope ies
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The ensile p ope ies including elonga ion a b eak (EB), Young´s modulus (YM) and
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ensile s eng h (TS) o all he ilms de eloped we e e alua ed, and he esul s a e shown in
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Fig. 4. As i was expec ed, he alue o YM o MC_PEG dec eased conside ably due o i s
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plas icizing e ec . Ne e heless, as he inc ease o YM alues o all c oss-linked ilms
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shows, he inco po a ion o GA led o a ema kable inc ease in igidi y due o i s c oss-linke
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unc ion.
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Resul s e ealed c oss-linking p ocesses also had a signi ican e ec on inc easing he
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mechanical s eng h o he ilms. The MC chains mobili y dec eased due o he s ong
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in e ac ion be ween polyme ic ma ix and c oss-linke GA, enhancing he polyme s eng h
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bu educing he lexibili y o he co esponding ilms. This e ec esul ed in an enhancemen
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o TS alues and a ema kable educ ion in EB alues. Simila esul s we e obse ed when
423
MC was c oss-linked wi h ea-ca echins (Yu e al., 2015). Yu e al. showed he igid a oma ic
424
and he e ocyclic ings om la onoids can physically c oss-link MC. Such inc ease in TS
425
was also obse ed o gela in-soy p o ein ilms in he p esence o e ulic acid and que ce in
426
(Benbe aieb e al., 2015). In his wo k, la onols, such as que ce in and my ice in, om
427
mu a ex ac could be he eason o he highes alues o TS ob ained in he case o ac i e
428
ilms. The inco po a ion o MU ex ac had also a singula e ec inducing ilms o a
429
conside able inc ease on EB alues. This e ec could be due o he inc ease in polyme
430
chains mobili y caused by he p esence o some componen s om mu a ex ac be ween
431
polyme ic chains ha inc eased he lexibili y. This plas icizing e ec can be no iced also
432
om YM esul s. I is in e es ing ha when GA was a highes concen a ion his e ec was
433
diminished, as i some MU ex ac componen s we e eac ing wi h GA molecules.
434
435
20
3.3. An ioxidan ac i i y esul s
436
437
Fig. 5 p esen s he adical sca enging ac i i ies o MC ma e ials exposed o ABTS+·
438
solu ion exp essed as T olox equi alen s. As i was expec ed, ilms wi hou he inco po a ion
439
o MU ex ac did no show an ioxidan ac i i y, as Fig. 5 shows in he case o ilm wi h 20%
440
GA (MC_20GA), as an example.
441
The elease o an ioxidan componen s o MU ex ac om ma e ials ad anced owa ds
442
an equilib ium alue ha co esponded o 50.6, 40.4 and 32.4 % o he nominal alue o
443
ma e ials wi h 10, 15 and 20% GA, espec i ely. The ex en o elease a equilib ium depends
444
on he compa ibili y o he mig an wi h bo h he ood simulan and he polyme ic ilm. The
445
kine ics o all ac i e c oss-linked ma e ials p esen ed simila p o iles, ollowing an
446
“exponen ial g ow h o a maximum” ype p o ile. The inco po a ion o PEG, as plas icize ,
447
su ely acili a ed he elease o ac i e agen s because molecula and polyme chain
448
mo emen s we e enhanced. Se e al wo ks ha e used plas icize s o modi y polyme
449
p ope ies ela ed o he mass anspo o ac i e agen s (Lopez de Dicas illo, A es-Pe nas,
450
Cas o-López, Vila iño, & Gonzalez-Rod íguez, 2013; Siepmann, Sielpmann, Wal he ,
451
MacRae, & Bodmeie , 2008). The e ec o he GA concen a ion was clea ly no iceable,
452
diminishing an ioxidan ac i i y o ma e ials as GA concen a ion inc eased. This was
453
p obably due o he eac ions be ween an ioxidan compounds om na u al ex ac and GA
454
ha dec eased hei a ailabili y, and his ac was al eady e idenced by o he esul s, such as
455
mechanical p ope ies. An ioxidan ac i i y o ilms was p opo ional o an ioxidan s eleased
456
om ac i e biocomposi es o adical solu ion. This is he eason he kine ic p o ile o adical
457
sca enging ac i i ies o ma e ials p esen ed he same p o ile as common ac i e compound
458
elease om ac i e ma e ials (Lopez de Dicas illo e al., 2011a,b; Masche oni, Guilla d,
459
21
Nalin, Mo a, & Pie gio anni, 2010). Release o componen s om polyme ma ix is also
460
based on swelling deg ee o polyme s. As Table 2 indica es, highes swelling deg ee was
461
ob ained om ma e ials wi h 10% GA, as well as he highes an ioxidan ac i i y.
462
The ex en o he an ioxidan ac i i y can be cha ac e ized by he pa i ion coe icien , K,
463
which is de ined as he a io o he amoun o an ioxidan s e ained in he polyme ic phase
464
ela i e o he concen a ion o eleased an ioxidan s. As Fig. 5 shows, K coe icien s alues
465
ob ained we e e y simila and app oxima ely equal o alue 1, which co esponds when
466
equilib ium is eached ending up in a simila concen a ion o an ioxidan s in he polyme
467
han in he ood. Ne e heless, esul s showed highes an ioxidan ex en elease occu ed
468
when GA was lowes because as GA concen a ion inc eased, mo e an ioxidan compounds
469
we e e ained in he polyme s due o eac ions be ween an ioxidan molecules and GA.
470
471
3.4. An imic obial ac i i y esul s
472
473
Table 4 shows he an imic obial esul s ob ained o ac i e MC ilms de eloped wi h MU
474
ex ac agains Lis e ia innocua. The dilu ion me hod clea ly displayed ha ilms con aining
475
MU ex ac we e able o signi ican ly educe he g ow h o bac e ia om he i s day o
476
con ac . As obse ed in Table 4, he dilu ion me hod was use ul o quan i y he bac e ial
477
educ ion caused by ilms. Resul s showed a dec ease in mic obial g ow h o all samples
478
assayed including he blank ilm wi h highes GA con en . This ilm may con ain esidual
479
GA which can elease om he ilms o educe he g ow h o bac e ia because GA p esen s
480
some an imic obial ac i i y.
481
As i was expec ed, an imic obial esul s ollowed he same endency as an ioxidan
482
ac i i y. Films wi h lowes GA concen a ion p esen ed highes an imic obial powe ,
483

22
educing almos 4 logs, and esul ed in he mos e icien an imic obial ilm. In spi e o i s
484
in e es ing p ope ies, speci ic mig a ion es s should be ca ied ou be o e any applica ion o
485
ensu e ood sa e y.
486
487
4. Conclusions
488
489
In his wo k ac i e ilms based on me hyl cellulose (MC) and mu a ui ex ac (MU)
490
we e ob ained h ough cas ing p ocess. MC polyme was c oss-linked wi h glu a aldehyde
491
(GA) a di e en concen a ions owing o s udy he e ec o c osslinking deg ee on physical
492
p ope ies o he polyme and he elease o ac i e compounds. The mal p ope ies we e
493
sligh ly a ec ed by he inco po a ion o GA and MU, bu he he mal s abili y o he
494
de eloped ma e ials is s ill app op ia e o he in ended use. C osslinking p ocesses inc eased
495
mechanical s eng h and dec eased swelling index o de eloped ma e ials and he amoun o
496
ac i e agen s a ailable om MU ex ac in he polyme ma ixes. As GA concen a ion
497
inco po a ed inc eased, swelling index, an ioxidan and an imic obial ac i i ies o ac i e
498
ma e ials dec eased.
499
500
Acknowlegmen s
501
The au ho s acknowledge he Financial suppo o CONICYT h ough he P ojec
502
FONDEF “P og ama IDeA Ciencia Aplicada” (P ojec CA13I10334) and “P og ama de
503
Financiamien o Basal pa a Cen os Cien íficos y Tecnológicos de Excelencia” (P ojec
504
FB0807).
505
506
Re e ences
507
23
508
Aiedeh, K. M., Taha, M. O., Al-Hia i, Y., Bus anji, Y., & Alkha ib, H. S. (2006). E ec o ionic
509
c osslinking on he d ug elease p ope ies o chi osan diace a e ma ices. Jou nal o
510
Pha maceu ical Sciences, 96, 38-43.
511
512
Al a o, S., Mu is, A., Palma, R., Qui oz, A., Seguel, I., & Scheue mann, E. (2013). In luence
513
o geno ype and ha es yea on polyphenol con en and an ioxidan ac i i y in mu illa
514
(Ugni molinae Tu cz) ui . Jou nal o Soil Science and Plan Nu i ion, 13, 67-78.
515
516
Aminabha i, T. M., Balundgi, R. H., & Cassidy, P. E. (2008). A e iew on biodeg adable
517
plas ics. Polyme -Plas ics Technology and Enginee ing, 29, 235-262.
518
519
A ancibia-A ila, P., Toledo, F., We ne , E., Suhaj, M., Leon owicz, H., Leon owicz, M.,
520
Ma inez-Ayala, A., Pasko, P., & Go ins ein, S. (2011). Pa ial cha ac e iza ion o a new
521
kind o chilean mu illa-like be ies. Food Resea ch In e na ional. 44, 2054-2062.
522
523
A ie a, M. P., Lopez, P., Fe ándiz, S., & Pel ze , M. A. (2013). Cha ac e iza ion o PLA-
524
limonene blends o ood packaging applica ions. Polyme Tes ing, 32, 760-768.
525
526
Beaulieu, M.; D´Ap ano, M. B., & Lac oix, M. (1999). Dose a e e ec o gamma i adia ion
527
on phenolic compounds, polyphenol oxidase, and b owning o mush ooms (Aga icus
528
bispo us). Jou nal o Ag icul u al and Food Chemis y, 47, 2537-2543.
529
530
Benbe aieb, N.; Ka bowiak, T., B achais, C. H., & Debeau o , F. (2015). Coupling y osol,
531
que ce in o e ulic acid and elec on beam i adia ion o c oss-link chi osan-gela in ilms:
532
A s uc u e- unc ion app oach. Eu opean Polyme Jou nal, 67, 113-127.
533
534
Be gonzi, M., Bilia, A., Ba i, L., Mazzi, G., & Vincie i, F. (2007). S udies on he in e ac ions
535
be ween some la onols and cyclodex ins. Bioo ganic & Medicinal Chemis y Le e s, 17,
536
5744–5748.
537
538
24
Cala ayud, M., Lopez de Dicas illo, C., Lopez-Ca ballo, G., Velez, D., He nandez-Muñoz, P.,
539
& Ga a a, R. (2013). Ac i e ilms based on cocoa ex ac wi h an ioxidan , an imic obial
540
and biological applica ions. Food Chemis y, 139, 51-58.
541
542
Coope , T. A. (2013). De elopmen s in bioplas ic ma e ials o packaging ood, be e ages and
543
o he as -mo ing consume goods. In N. Fa me (Ed.), T ends Pack Food, Be e ages and
544
O he Fas -Mo ing consume goods (FMCG) (pp. 108-152). Woodhead Publishing, UK.
545
546
Debeau o , F., Quezada-Gallo, J. A., & Voilley, A. (1998). Edible ilms and coa ings:
547
omo ow´s packaging: a e iew. C i ical Re iews in Food Science, 38, 299-313.
548
549
Galo o, M. J., Gua da, A., Lopez de Dicas illo, C. An imic obial Ac i e Polyme s in Food
550
Packaging. In G. Ci illo, F. Iemma, & U. G. Spi izzi (Eds.), Func ional Polyme s in Food
551
Science, edi ion no1. Sc i ene Publishing Edi o ial, New Je sey, USA. 2015.
552
553
Ga cía, M. A., Pino i, A., Ma ino, M. N., & Za i zky, N. M. (2004). Cha ac e iza ion o
554
composi e hyd ocolloid ilms. Ca bohyd a e Polyme s, 56, 339-345.
555
556
Gómez Es aca, J., Lopez de Dicas illo, C., He nandez Muñoz, P., Ca ala, P., Ga a a, R. (2014).
557
Ad ances in an ioxidan ac i e ood packaging. T ends in Food Science & Technology. 35,
558
42-51.
559
560
Hause , C., Peñaloza, A., Rod iguez, F., Gua da, A., & Galo o, M. J. (2014). P omising
561
an imic obial and an ioxidan ex ac s o mu a lea es (Ugni molinae Tu cz): Shel -li e
562
ex ension and ood sa e y. Food Packaging and Shel Li e, 1, 77-85.
563
564
He nández-Muñoz, P., Villalobos, R., & Chi al , A. (2004). E ec o c oss-linking using
565
aldehydes on p ope ies o glu enin- ich ilms, Food Hyd ocolloids, 18, 403-411.
566
567
Hi ashima, F. K., Fabb i, A. D. T., Sag e i, J. M. A., Nunes, T. C. F., Gal ao, N. S., Lan e -
568
Ma quez, U. M., & Saba o, S. F. (2013). In luence o gamma i adia ion on phenolic
569
25
compounds o minimally p ocessed baby ca o s. 2013 In e na ional Nuclea A lan ic
570
Con e ence – INAC 2013. ISBN: 978-85-99141-05-2.
571
572
Hong, S., Lee, J., & Son, S. (2005). P ope ies o polysaccha ide-coa ed polyp opylene ilms
573
as a ec ed by biopolyme and plas icize ypes. Packaging Technology and Science, 18, 1-
574
9.
575
576
Junquei a-Gonçal ez, M. P., Yañez, L., Mo ales, C., Na a o, M., Con e as, R. A., & Zuñiga,
577
G. E. (2015). Isola ion and cha ac e iza ion o phenolic compounds and an hocyanins om
578
mu a (Ugni Molinae Tu cz.) ui s. Assesmen o an ioxidan and an ibac e ial ac i i y.
579
Molecules, 20, 5698-5713.
580
581
Lee, M., Lee, S., Ma, Y., Pa k, S., Bae, D., Ha, S., & Song, B. (2005). E ec o plas icize and
582
c osslinking agen on he physical p ope ies o p o ein ilms. Jou nal o Food Science and
583
Nu i ion, 10, 88-91.
584
585
Lopez de Dicas illo, C., Alonso, J. M., Ca alá, R., Ga a a, R., & He nandez-Muñoz, P. (2010).
586
Imp o ing he an ioxidan p o ec ion o packaged ood by inco po a ing na u al la onoids
587
in o e hylene- inyl alcohol copolyme (EVOH) ilms. Jou nal o Ag icul u al and Food
588
Chemis y, 58, 10958-10964.
589
590
López de Dicas illo, C., Jo dá, M., Ca alá, R., Ga a a, R., & He nández, P. (2011a).
591
De elopmen o ac i e poly inyl alcohol/β-cyclodex in composi es o sca enge undesi able
592
ood componen s. Jou nal o Ag icul u al and Food Chemis y, 59, 11026-11033.
593
594
Lopez de Dicas illo, C., Ne in, C., Al a o, P., Ca ala, R., Ga a a, R., & He nandez-Muñoz, P.
595
(2011b). De elopmen o new an ioxidan ac i e packaging ilms based on e hylene inyl
596
alcohol copolyme (EVOH) and g een ea ex ac , Jou nal o Ag icul u al and Food
597
Chemis y, 59, 7832-7840.
598
599
32
Table 3
723
Swelling esul s.
724
Sample
Swelling Index (SI)
MC_10GA
156 ± 4.8 e
MC_15GA
88.9 ± 7.6 b
MC_20GA
78.7 ± 0.9 a
MC_10GA_MU
237.7 ± 1.6
MC_15GA_MU
131.6 ± 2.3 d
MC_20GA_MU
105.6 ± 1.6 c
Lowe case le e s a- indica e signi ican di e ences in
725
swelling among he ma e ials.
726
727
728

33
Table 4
729
An imic obial ac i i y o de eloped ilms.
730
Reduc ion
Film
UFC/mL
% Reduc ion
Log Cycles
Con ol
7 x 107
-
-
MC_20GA
1 x 107
85,7
0,85
MC_10GA_MU
1 x 104
99,9
3,85
MC_15GA_MU
6,8 x 104
99,9
3,01
MC_20GA_MU
7 x 104
99.9
3
731
732
34
Figu e cap ions
733
734
Fig. 1. C oss-sec ion SEM images o he MC ilms de eloped: A: MC; B: MC_PEG; C:
735
MC_10GA; D: MC_10GA_MU; E: MC_20GA; F: MC_20GA_MU.
736
737
Fig. 2. FTIR spec a o : (A) i) MC; ii) MC_10GA; iii) MC_15GA; i ) MC_20GA; (B) i)
738
MC; ii) MC_15GA_MU; iii) mu a ex ac ; and i ) GA.
739
740
Fig. 3. A) TGA and de i a i e cu es (inse ) o he weigh loss o MC-based ma e ials
741
wi hou MU ex ac and GA; B) TGA de i a i e cu es o ac i e MC-based ma e ials and
742
MU ex ac .
743
744
Fig. 4. Young´s modulus (YM), Tensile s eng h (TS) and Elonga ion a b eak (EB) o MC
745
de eloped ma e ials (le e s a- indica e signi ican di e ences in each p ope y alues among he samples
746
in a mechanical p ope y).
747
748
Fig. 5. ABTS+· adical sca enge ac i i ies o mu a ui MC ilms.
749
750
35
751
752
A
E
C
D
B
F
36
753
37
754
755

38
756
757
758
MC MC_PEG 10GA 15GA 20GA 10GA_MU15GA_MU20GA_MU
YM (N/mm2)
0
200
400
600
800
1000
Young´s Modulus
MC MC_PEG 10GA 15GA 20GA 10GA_MU15GA_MU20GA_MU
TS ( N/mm2)
0
2
4
6
8
10
12
14
16
18
Tensile S eng h
MC MC_PEG 10GA 15GA 20GA 10GA_MU15GA_MU20GA_MU
EB (%)
0
10
20
30
40
50
60
70
Elonga ion a b eak
a
e
cd de
bb
c
aa
c
b
b
e
c
cc
a
e
d
c
bc ab
39
759
760
ime (hou s)
0,0 2,0 4,0 6,0 23,0 23,5 24,0 24,5
AA (mg T olox/g ilm)
0,0
0,3
0,6
0,9
3,0
4,0
5,0
MC_20GA
MC_10GA_MU
MC_15GA_MU
MC_20GA_MU
K = 3.1
K = 4
K = 4.8