characterization of biodegradable films prepared with hake proteins and thyme oil

8/9/2019 Characterization of Biodegradable Films Prepared With Hake Proteins and Thyme Oil

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Characterization of biodegradable films prepared with hake proteins and thyme oil

C. Pires ⇑, C. Ramos, G. Teixeira, I. Batista, R. Mendes, L. Nunes, A. Marques

INRB, I.P./L-IPIMAR, Unidade de Valorização dos Produtos da Pesca e Aquicultura, Av. Brasília, 1449-006 Lisboa, Portugal

a r t i c l e i n f o

Article history:

Received 27 October 2010

Received in revised form 21 January 2011Accepted 18 February 2011

Available online 12 April 2011

Keywords:

Hake protein powder

Thyme oil

Biodegradable film

Mechanical properties

Water vapor permeability

Antioxidant activity

a b s t r a c t

Hake protein biodegradable films containing different thyme oil levels (0.025, 0.05, 0.1 and 0.25 ml oil/g

protein) were prepared and their physical, mechanical and antioxidant properties were studied. Dried

proteins were solubilized at pH 11 with NaOH and glycerol (59% of protein content) was added as plas-ticizer.

The addition of thyme oil levels reduced both the film thickness and water vapor permeability. Films

were homogeneous and transparent with a yellowish color. The optical properties of films were not gen-

erally affected by the thyme oil addition. Any clear trend between the mechanical properties of biode-

gradable films and thyme oil added was observed. Hake protein films exhibited some antioxidant

activity, which was improved by the addition of 0.25 ml of thyme oil/g of protein.

2011 Elsevier Ltd. All rights reserved.

1. Introduction

Packaging is used to protect the product from surroundings andto maintain the food product quality. Many materials are em-

ployed for the preparation of packaging but the majority is made

from plastics. Synthetic plastic packaging has come into wide-

spread use thanks to its good mechanical properties and effective-

ness as a barrier to oxygen and water. However, synthetic

packaging films represent a serious ecological problem due to their

non-biodegradability. As a consequence, in recent years, packaging

research has focused more on biodegradable and/or edible films

made from natural polymers. Such polymers may be protein, lipid

or polysaccharide-based and their chemical nature determines the

physical properties of the resulting films. Among these materials

proteins from different sources have been extensively employed

because of their relative abundance, film-forming ability and nutri-

tional qualities. Myofibrillar and sarcoplasmic fish proteins have

been also successfully used as reported by Cuq et al. (1995) on

the preparation of edible packaging films from sardine meats.

Transparent and flexible edible films were also made from blue

marlin myofibrillar proteins (Shiku et al., 2003). The properties of

films produced from surimi from threadfin bream (Prodpran and

Benjakul, 2005) and bigeye snapper (Chinabhark et al., 2007) were

also evaluated.

These films are generally good barriers against oxygen but poor

barriers against water vapor due to the hydrophilic character of

proteins. Thus, several lipids (fatty acids, waxes, oils, essential oils)

have been tested in order to improve the barrier properties of these

films. Essential oils improve the water barrier properties of filmsand also their food-protective function due to the antimicrobial

and/or antioxidant properties of these oils. Essential oils or extracts

from cinnamon, garlic, ginger, oregano, rosemary or thyme (Pra-

noto et al., 2005; Goméz-Estaca et al., 2009; Hosseini et al., 2009;

Atarés et al., 2010a,b) are by far the most used ones. These oils

are rich in volatile and nonpolar phenolic compounds, which are

significant contributors to their antioxidant properties.

Fish processing particularly the production of fish fillets and fish

portions generates a substantial amount of by-products with pro-

tein content similar to that of fish muscle. Thus, the recovery of

these proteins and their utilization to prepare biodegradable films

represents a valuable alternative for the upgrading of by-products

from fish processing industry.

The objective of this work was to prepare and characterize bio-

degradable films made with dried fish proteins recovered from

Cape hake by-products incorporated with different levels of thyme

oil.

2. Material and methods

2.1. Hake protein powder (HPP)

Hake proteins were recovered from frozen by-products result-

ing from the portioning (fish ‘sawdust’ and cut offs) of Cape hake

(Merluccius capensis) by alkaline solubilization following a method-ology previously described (Batista et al., 2006). The recovered pro-

0260-8774/$ - see front matter 2011 Elsevier Ltd. All rights reserved.doi:10.1016/j.jfoodeng.2011.02.036

⇑ Corresponding author. Tel.: +351 21 3027000; fax: +351 21 3015948.

E-mail address: [email protected] (C. Pires).

Journal of Food Engineering 105 (2011) 422–428

Contents lists available at ScienceDirect

Journal of Food Engineering

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j f o o d e n g

http://dx.doi.org/10.1016/j.jfoodeng.2011.02.036mailto:[email protected]://dx.doi.org/10.1016/j.jfoodeng.2011.02.036http://www.sciencedirect.com/science/journal/02608774http://www.elsevier.com/locate/jfoodenghttp://www.elsevier.com/locate/jfoodenghttp://www.sciencedirect.com/science/journal/02608774http://dx.doi.org/10.1016/j.jfoodeng.2011.02.036mailto:[email protected]://dx.doi.org/10.1016/j.jfoodeng.2011.02.036


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teins were freeze-dried and vacuum stored at 30 C until utiliza-

tion. The proximate composition of hake by-products (HB) and HPP

is shown in Table 1. The SDS–PAGE protein profile of HPP evi-

denced the presence of high molecular weight proteins (220 kDa)

as well as the typical actin fish protein (42 kDa) and also high num-

ber of other proteins in the 70–220 kDa range.

2.2. Characterization of thyme oil

The thyme oil (Sigma–Aldrich, St. Louis, MO) composition was

analyzed on an Agilent 6890 gas chromatograph interfaced to an

Agilent 5973N mass selective detector (Agilent Technologies, Palo

Alto, USA). A vaporization injector operating in the split mode

(1:50) at 250 C was used, into which a fused silica capillary col-umn (30 m length, 0.32 mm internal diameter, 0.25 lm film thick-

ness, HP-5MS, 5% diphenyl 95% dimethyl polydimethylsiloxane,

Agilent Technologies) was installed. Helium was used as carrier

gas. The transfer line, ion source and quadrupole analyzer temper-

atures were maintained at 280, 230 and 150 C, respectively. In the

full-scan mode, electron ionization mass spectra in the range 40–

400 Da were recorded at 70 eV electron energy. The acquisition

data and instrument control were performed by the MSD ChemSta-

tion software (G1701CA; version C.00.00; Agilent Technologies,

Santa Clara, CA, USA). The identity of each compound was assigned

by comparison of their retention index, relative to a standard mix-

ture of n-alkanes (Adams, 2001), as well as by comparison with themass spectra characteristic features obtained with the Wiley’s li-

brary spectral data bank (G1035B; Rev D.02.00; Agilent Technolo-gies, Santa Clara, CA, USA). For semi-quantification purposes the

normalized peak area abundances without correction factors were

used.

2.3. Film-forming solution preparation

Thirty grams of HPP was added to 2 L distilled water and the pH

of the protein suspension was adjusted to 11.0 with NaOH 1 M

with mechanical stirring. The suspension was centrifuged at

10,000 g for 15 min at 5 C to remove insoluble material. The pro-tein concentration of the soluble fraction was determined and glyc-

erol (Sigma–Aldrich, St. Louis, MO) was added at 59% (w/w) of

protein. The mixture was stirred gently for 30 min at room temper-

ature. For the preparation of thyme oil films 0.025, 0.05, 0.1 and0.25 ml oil/g protein was added to protein film-forming solution

and emulsified in a Polytron homogeneizer at 13,500 rpm for

2 min. Before casting all film-forming solutions were degassed un-

der vacuum for 20 min.

2.4. Film casting and drying

The film forming solutions were cast on square plastic dishes

(12 12 cm). The amount of film forming solution that would pro-

vide 4 mg of protein/cm2 was evenly spread over each dish. The

dishes were placed on levelled surfaces to obtaining films of homo-

geneous thickness. The solutions were dried in a drying chamber at

30 C and 50% relative humidity (RH) for 20 h. Dried films were

peeled off from the dishes and stored at room temperature at 57%RH in desiccators with saturated solutions of NaBr. Only homoge-

neous films with no phase separation or exudation, without insolu-

ble particles, and uniform color and no brittle zones checked by

visual and tactile analyses were used for the different trials.

2.5. Protein determination

The protein content of film forming solution was determined

using a FP-528 LECO nitrogen analyzer (LECO, St. Joseph, USA) cal-ibrated with EDTA according to the Dumas method (Saint-Denis

and Goupy, 2004). Each result is the mean of three determinations.

2.6. Thickness

Film thickness was measured using a Digimatic tube microme-

ter model BMD-25D (MITUTOYO MFG Co., Ltd., Japan). The results

were expressed as the mean of nine measurements in different

locations in five different films.

2.7. Mechanical properties

The films were conditioned at room temperature at 57% RH in

desiccators with saturated solutions of NaBr for 72 h prior to test-

ing. The puncture and tensile tests were performed using an In-

stron 4301 texturometer (Instron Engineering Corp., Canton, MA).

Puncture force (PF) is the maximal load that the film could sus-

tain before breaking when it is subjected to a puncture test. The

puncture deformation (Dl/l0), PD, is the ratio of total deformationat the breaking point to the initial dimension of the film. The Dl va-lue was calculated with the displacement of the probe at the break-

ing point. Puncture force and displacement of the probe were

determined directly from the force probe displacement curves

with the software from Instron Corporation, version 5.02, 1985–

1990. For the calculation of the puncture deformation it was con-

sidered that the stress was perfectly distributed along the film at

breaking point (Sobral et al., 2001). The films were fixed in a

10 10 cm cell and perforated with a 3 mm diameter plunger

moving at 60 mm/min. Each result is the mean of nine measure-ments in five different films.

Tensile strength (TS) represents the maximal load per original

cross-sectional area that film could sustain before breaking and

elongation at break (EAB) is the increase in length of film at break

when the film is subjected to a tensile loading. Rectangular films

strips of 10 2 cm were mounted to a self-aligning grip with 1

fixed and 1 movable grip. Initial grip separation was set at

50 mm and crosshead speed was 60 mm/min. The tensile strength

was calculated by dividing the maximum load (N) necessary to pull

film apart by cross sectional area (m2). Average thickness of film

strip was used to estimate de cross-sectional area of the samples.

Elongation at break (%) was calculated by dividing film elongation

at the moment of rupture by the initial grip length of samples mul-

tiplied by 100. The determination was done in 16 strips obtainedfrom four different films.

2.8. Water vapor permeability (WVP)

Water vapor permeability (WVP) values were measured using a

modified ASTM Method (1989) as reported by Gontard et al.

(1992). The edible films were sealed in cells containing silica gel

(0% RH) and the cells were stored in desiccators with distilled

water at 30 C. The cells were weighed at 1 h intervals during

2 days and WVP of the films calculated as follows:

WVP ¼ ðw xÞ

A t DP

where w is the weight gain of the cell (g), x is the film thickness (m), A is the area of exposed film (m2), t is the time of weight gain (s), DP

Table 1

Proximate composition of hake by-products (HB) and hake protein powder (HPP).

Sample Protein Moisture Fat Ash

HB 15.4 ± 0.40 82.90 ± 0.14 0.21 ± 0.196 1.87 ± 0.002

HPP 90.0 ± 0.81 5.31 ± 0.08 0.53 ± 0.023 1.44 ± 0.010

Results are the mean values (triplicate) ± standard deviation.

C. Pires et al. / Journal of Food Engineering 105 (2011) 422–428 423


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is the difference of partial vapor pressure of the atmosphere with

silica gel and pure water (4242.8 Pa, at 30 C) and w/t was calcu-

lated by linear regression from the points of weight gain and time.

All determinations were made at least in three different films.

2.9. Color, opacity and transparency

The films were applied in the surface of a white standard plate(L⁄ = 92.38, a⁄ = 1.0, b⁄ = 1.5) b) and the color parameters (L⁄, a⁄

and b⁄) were measured with a chromameter CR-410 (Minolta,Co., Ltd., Osaka, Japan). Chroma (C ⁄) and hue (h⁄), as well as thewhiteness (W ) of the films were calculated using the equations:

C ¼ ða2 þ b2Þ1=2

h¼ arctg ðb

=aÞ

W ¼ 100 ðð100 LÞ2þ a2 þ b

2Þ

1=2

The color of the films was expressed as the difference of color, DE ⁄

(García and Sobral, 2005).

DE ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiðDLÞ

2 þ ðDaÞ2 þ ðDb

Þ2

q

where DL⁄, Da⁄, Db⁄ are the differentials between the color param-

eter of the samples and the white standard used as the film

background.

Opacity was measured using the Hunterlab Method (2008) with

the same equipment for color measurement. The opacity (%) of the

samples was calculated from the reflectance measurements of each

sample with a black backing (Y black backing, L⁄ = 29.24, a⁄ = 0.54,

b⁄ = 0.76) and each sample with a white backing (Y white backing,L⁄ = 92.38, a⁄ = 1.0, b⁄ = 1.5).

Opacity ¼ Y black backingY white backing

100

where Y is the tristimulus value Y . The transparency value of the

films was calculated by the equation as reported by Shiku et al.

(2003):

Transparency value ¼ A600= x

where A600 is the absorbance at 600 nm and x is film thickness

(mm). According to this equation, higher transparency values indi-

cate lower transparency.Color, opacity and transparency tests were

made at least in five different positions of five different films.

2.10. DPPH radical-scavenging activity

2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging

activity was determined according to the method described by

Weng et al. (2009). Films were solidified in a mortar using liquid

nitrogen and ground with a pestle. Film powders (ca. 20 mg) in2 ml Tris–HCl buffer (0.1 M, pH 7.4) were added to 2 ml of 0.2 mM DPPH in ethanol and the mixture was shaken vigorously.

After a 30-min incubation at a room temperature in darkness,

when the steady state was achieved, the reaction mixture was cen-

trifuged at 4500 g for 10 min. The resultant absorbance of superna-tant was recorded at 517 nm in an UNICAM UV–vis UV2

spectrophotometer (ATI-UNICAM, USA). The controls contained

all reaction reagents except the film powder. Lower absorbance

indicates higher free-radical-scavenging activity. DPPH radical-

scavenging activity was calculated according to the following

formula

Radical-scavenging activityð%Þ ¼ 1 AbssampleAbscontrol

100

All determinations were made at least in triplicate.

2.11. Reducing power

The reducing power of films was determined according to the

method of Oyaizu (1988). Film powders (ca. 20 mg) in 2.0 ml dis-tilled water were added to 2.0 ml of 0.2 M phosphate buffer, pH

6.6 and 2.0 ml 1% potassium ferricyanide. The reaction mixture

was incubated at 50 C for 20 min and then 2.0 ml of 10% TCA

was added. The mixture was centrifuged at 1500 g for 10 min. A2.0 ml aliquot of the supernatant was mixed with 2.0 ml distilledwater and 0.4 ml of 0.1% ferric chloride. The absorbance of the

resulting solution was recorded at 700 nm after a 10-min reaction

in an UNICAM UV–vis UV2 spectrophotometer. The controls con-

tained all reaction reagents except the film powder. The results

are expressed as mg ascorbic acid/g of film. All determinations

were made at least in triplicate.

2.12. Statistical analysis

A general linear model, one-way ANOVA, was used to determine

significant differences ( p6 0.05) between the films. Multiple com-parisons were done by the Tukey HSD test. In the absence of homo-

geneity/normality conditions, a Kruskal–Wallis methodology wasapplied for the multiple comparisons. Statistical treatment was

done with the software STATISTICA from StatSoft Inc. (Tulsa,

OK, USA) version 5.1, 1996. For the hue values the test of Wat-

son–Williams was used to evaluate the differences between the

films (Zar, 1999).

3. Results and discussion

3.1. Thyme oil characterization

Thyme oil used in these trials was very rich in thymol (Table 2)

when compared with the data reported for the chemical composi-

tion of this essential oil (Hudaib et al., 2002; Arraiza et al., 2009).

The second more important constituent was carvacrol and its per-centage was also higher than that reported by the previous

authors. On the other hand, the percentage of their corresponding

precursors (p-cymene and c-terpinene) was relatively low. The

percentage of the first monoterpene accounted for only 0.4% and

c-terpinene was not detected. However, the thyme oil used in

the present work is a commercial product whereas the data pub-

lished dealt with the composition of natural thyme oil. Thyme oil

was chosen to incorporate in the protein films due to the antioxi-

dant properties of these terpenes which were recognized in several

works (Aeschbach et al., 1994; Yanishlieva et al., 1999).

3.2. Physical characterization of HPP films with added thyme oil

The alkaline solubilization of HPP at pH 11.0 was effective insolubilizing the fish proteins prior to film casting. In general, the

Table 2

Main constituents and compositional percentage of the volatiles in

thyme oil.

Components %

m-Thymol 75.4

Carvacrol 5.4

p-Cymene 0.4

trans-Caryophyllene 2.9

Oxygenated monoterpenes 82.6

Monoterpene hydrocarbons 7.1

Sesquiterpenes hydrocarbons 3.2

Others 1.6

Total identified 94.5

424 C. Pires et al. / Journal of Food Engineering 105 (2011) 422–428


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films prepared showed to be easy workable and resistant. They

were also homogeneous and had a good general aspect.

Films cast from 0.9% HPP film forming solution had an average

thickness of 0.028 mm (Fig. 1). It is worth mentioning that in spite

of using the same conditions for preparing all films, the addition of

0.1 and 0.25 ml oil/g protein significantly decreased ( p 0.05) within films was recorded.

In the case of PF and TS it was not observed any clear trend be-

tween their values and the level of thyme oil.

The studies published on the effect of lipid addition in the

mechanical properties of protein films have put into evidence very

diverse effects. In fact, as mentioned by Gontard et al. (1994), the

effect of lipid addition in films on their mechanical properties de-

pends on both the characteristics of the lipid and its capacity to

interact with the protein matrix. Thus, many works have reported

a decrease of TS as lipid concentration increases in films prepared

with wheat gluten (Gontard et al., 1994), sodium-caseinate (Chen,

1995), whey protein isolate (Shellhammer and Krochta, 1997), fish

water soluble proteins (Tanaka et al., 2001) and gelatin (Bertan

et al., 2005). In other works, the incorporation of lipids in the films

resulted in TS increase. This mechanical behavior was observed by

Chick and Hernandez (2002) and Fabra et al. (2009) in casein films

with added different lipids and by Atarés et al. (2010a) in soy pro-

tein isolate films with cinnamon oil added. However, the results re-

ported in those studies were achieved in films with higher lipid or

essential oil contents than those used in the present work. Thus,

the non correlation between mechanical properties and thyme

oil may be explained by their low level used together with the high

percentage of glycerol in these films. This plasticizer may reduce

the eventual interference of thyme oil added with protein chain-

to-chain interactions.

The results of the WVP tests of the films prepared are shown in

Fig. 2. Experimental results ranged between 3.5 and

5.9 1011 gm1 s1 Pa1. The addition of thyme oil significantly( p 0.05).

Table 3

Puncture force (PF), puncture deformation (PD), tensile strength (TS) and elongation

at break (EAB) of HPP films with different levels of thyme oil.

Thyme oil

(ml/g

protein)

PF (N) PD (%) TS (MPa) EAB (%)

0.000 5.82 ± 1.30a 54.56 ± 13.50a 6.16 ± 1.66a 147.9 ± 31.8a

0.025 8.49 ± 2.17b 115.41 ± 21.43b 6.67 ± 2.41a 129.8 ± 51.2a

0.050 5.35 ± 0.79a 99.63 ± 28.13b 4.13 ± 1.27b 119.1 ± 47.7a

0.100 9.10 ± 0.86b 93.78 ± 13.05b 5.61 ± 1.56a,b 146.3 ± 45.3a

0.250 3.30 ± 0.72a 87.87 ± 13.60b 4.33 ± 0.94a,b 111.2 ± 44.8a

Results are the mean values (PF and PD: nine measurements in five films; TS and

EAB: 16 measurements in four films) ± standard deviation. Different letters in thesame column indicate significant differences ( p < 0.05).

0.0E+00

1.0E-11

2.0E-11

3.0E-11

4.0E-11

5.0E-11

6.0E-117.0E-11

0.000 0.025 0.050 0.100 0.250

ml oil/g protein

W V P ( g m - 1 s - 1 P a - 1 )

a

b bc

d

Fig. 2. Effect of thyme oil concentration on water vapor permeability. Determina-

tions were performed in triplicate and results are the mean values ± standarddeviation.



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prepared in this work had relatively poor water barrier properties

when compared to synthetic polymer films (Shiku et al., 2003).

The water vapor transfer process in films depends on the hydro-

philic–hydrophobic ratio of the film constituents. Thyme oil used

in this study presented a significant polar fraction and thus

increasing levels of thyme oil in films decreased the WVP.

Tanaka et al. (2001) studied the effect of incorporated edible

oils (peanut oil, corn oil, salad oil and cod live oil) on the WVP of films prepared from fish water soluble proteins and in general

the incorporation of these oils also resulted in the decrease of

WVP. In contrast, the WVP of alginate-based films tend to increase

as higher amounts of garlic oil were incorporated (0.3–0.4%) ( Pra-

noto et al., 2005).

Color parameters of films prepared with different levels of

thyme oil are shown in Table 4. The color of HPP films was compa-

rable to that of films produced with fish muscle proteins (Prodpran

and Benjakul, 2005; Artharn et al., 2007; Chinabhark et al., 2007 )

and fish gelatin ( Jongjareonrak et al., 2006; Bao et al., 2009). On

the other hand, HPP films were whiter than those prepared with

mung bean proteins (Bourtoom, 2008), soy protein isolate (Prune-

da et al., 2008; Atarés et al., 2010a), hydroxypropylmethylcellulose

(Sánchez-González et al., 2009), sodium caseinate (Atarés et al.,

2010b), and chitosan (Siripatrawan and Harte, 2010).

HPP films with the different levels of thyme oil appeared clear

and transparent. They presented high L⁄ values and had a yellowish

color as indicated by the b⁄ values. This yellowish color may be dueto the presence of phospholipids in recovered proteins, which was

also reported by Trezza and Krochta (2000) in coatings prepared

with whey protein concentrate. However, the addition of oil did

not significantly affect ( p > 0.05) L⁄, a⁄ and b⁄ parameters, colorattributes (C ⁄ and h⁄), whiteness (W ) and total color difference(DE ⁄).

The effect of oil or vegetable extracts addition on the color

parameters of edible films depends very much on their origin.

Thus, the addition of different levels of oregano methanolic and

aqueous extracts to soy-based edible films resulted in a dark and

red film appearance (Pruneda et al., 2008). Similarly, the color of alginate-based edible films incorporated with garlic oil tends to

yellowish and darken (Pranoto et al., 2005).

The incorporation of cinnamon oil in chitosan-based films con-

siderably increased its total color difference, whereas such pro-

nounced effect was not recorded with thyme and clove oil

(Hosseini et al., 2009). Atarés et al. (2010a,b) also reported a con-

siderable effect of the incorporation of cinnamon oil in the color

of caseinate-based and soy protein-based edible films. However,

the latter authors did not observed a marked effect on the color

parameters of those films when ginger oil was added.

The transparency value of HPP films was around 1.8 (Fig. 3) and

similar to that reported for other films prepared with myofibrillar

fish proteins (Artharn et al., 2007; Benjakul et al., 2008) and with

fish skin gelatin ( Jongjareonrak et al., 2006). They had also a com-parable transparency value to that of synthetic films (Shiku et al.,

2003). However, HPP films were more transparent than those pre-

pared by Shiku et al. (2003) and Hamaguchi et al. (2007) from blue

marlin meat, as well as films prepared from Alaska Pollack surimi

(Shiku et al., 2004).

The addition of thyme oil decreased the transparency value of

HPP films being the film with 0.25 ml of thyme oil/g of proteinthe less transparent ( p 0.05).



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The DPPH radical-scavenging activity of thyme oil in the films

with lower levels (0.025–0.1 ml/g protein) was about 13% of the

free oil in the same experimental conditions. In the film with the

highest oil concentration (0.25 ml/g protein) its scavenging activity

attained 38% of the free oil. These results may be due to interac-

tions between the oil constituents and the protein matrix. Theinteractions between antioxidants and gelatin molecules in fish

skin gelatin films were previously suggested by Jongjareonrak

et al. (2008). Goméz-Estaca et al. (2009) also reported the occur-

rence of protein–polyphenol interactions in fish gelatin films.

The reducing power of HPP films was also lower than those pre-

pared by Weng et al. (2009). The films obtained by these authors

presented a reducing power of 2.2 mg of ascorbic acid/g of surimi

film whereas the reducing power of HPP films was 1.65 ±

0.14 mg ascorbic acid/g of film.

The addition of thyme oil increased the reducing power of HPP

films which attained 3.27 ± 0.20 mg ascorbic acid/g HPP film for

the level of 0.25 ml thyme oil/g protein. The reducing power of

thyme oil in the films with 0.025–0.1 ml/g protein was about 4%

of the free oil but it increased to about 14% in the film with0.25 ml of thyme oil/g of protein. These results such as those ob-

tained with DPPH suggest the occurrence of interactions between

oil constituents and proteins which affected the potential antioxi-

dant power of thyme oil.

4. Conclusions

Transparent biodegradable films were successfully prepared

from dried hake proteins recovered from by-products generatedduring portion production. These protein films represent an alter-

native for the utilization of that protein powder. The addition of

thyme oil levels reduced both the film thickness and water vapor

permeability. Optical properties of hake protein films were not

generally affected by the thyme oil addition. Oil addition signifi-

cantly increased the PD but not EAB. However, PF and TS of films

were not clearly affected by the addition of increasing levels of

thyme oil. Hake protein films exhibited some antioxidant activity,

which was improved by the addition 0.25 ml of thyme oil/g of pro-

tein. These results indicate that biodegradable HPP films contain-

ing thyme oil present a good potential for their utilization in

food packaging. Nevertheless further studies are required to evalu-

ate their performance in different types of foodstuffs.

Acknowledgments

This study was supported by Portuguese Foundation for Science

and Technology through the Research Project ‘‘FRESHFISH – Preser-

vation of fish products by using modified atmosphere packaging

and edible coatings with sea bass and sea bream as models (Ref.

PPCDT/DG/MAR/82008/2006)’’. The author A. Marques acknowl-

edge the Portuguese Foundation for Science and Technology for

supporting a Research contract (Program Ciência 2008). The

authors also express their gratitude to Prof. José Nogueira from

Faculty of Sciences in Lisbon for the thyme oil composition

analysis.

References

Adams, R.P., 2001. Identification of Essential Oil Components by GasChromatography/Quadrupole Mass Spectrometry, fourth ed. AlluredPublishing Corporation, Carol Stream, IL. p. 456.

Aeschbach, R., Lölliger, J., Scott, B.C., Murcia, A., Butler, J., Halliwell, B., Aruoma, O.I.,1994. Antioxidant actions of thymol, carvacrol, 6-gingerol, zingerone andhydroxytyrosol. Food Chem. Toxicol. 32 (1), 31–36.

ASTM E96-80, 1989. Standard Test Methods for Water Vapor Transmission of Materials. Annual Book of ASTM Standards, Philadelphia, PA, USA.

Arraiza, M.P., Andrés, M.P., Arrabal, C., López, J.V., 2009. Seasonal variation of essential oil yield and composition of thyme (Thymus vulgaris L.) grown inCastilla-La Mancha (Central Spain). J. Essent. Oil Res. 21, 360–362.

Artharn, A., Benjakul, S., Prodpran, T., Tanaka, M., 2007. Properties of a protein-based film from round scad (Decapterus maruadsi) as affected by muscle typesand washing. Food Chem. 103, 867–874.

Atarés, L., De Jesús, C., Talens, P., Chiralt, A., 2010a. Characterization of spi-based

edible films incorporated with cinnamon or ginger essential oils. J. Food Eng.doi:10.1016/j.jfoodeng.2010.03.004.Atarés, L., Bonilla, J., Chiralt, A., 2010b. Characterization of sodium caseinate-based

edible films incorporated with cinnamon or ginger essential oils. J. Food Eng.100, 678–687.

Bao, S., Xu, S., Wang, Z., 2009. Antioxidant activity and properties of gelatin filmsincorporated with tea polyphenol-loaded chitosan nanoparticles. J. Sci. FoodAgric. 89 (15), 2692–2700.

Batista, I., Pires, C., Nelhas, R., Godinho, V., 2006. Acid and alkaline-aided proteinrecovery from Cape hake by-products. In: Luten, J.B., Jacobsen, C., Bekaert, K.,Sabo, A., Oehlenschläger, J. (Eds.), Seafood Research from Fish to Dish. Quality,Safety and Processing of Wild and Farmed Fish. Academic Publishers,Wageningen, pp. 427–438.

Benjakul, S., Artharn, A., Prodpran, T., 2008. Properties of a protein-based film fromround scad (Decapterus maruadsi) muscle as influenced fish quality. LWT 41,753–763.

Bertan, L.C., Tanada-Palmu, P.S., Siani, A.C., Grosso, C.R.F., 2005. Effect of fatty acidsand ‘‘Brazilian elemi’’ on composite films based on gelatin. Food Hydrocolloids19, 73–82.

Bourtoom, T., 2008. Factors affecting the properties of edible film prepared frommung bean proteins. Int. Food Res. J. 15 (2), 167–180.

0

10

20

30

40

50

0.000 0.025 0.050 0.100 0.250

Thyme oil (ml/g protein)

R a d i c a l - s c a v e

n g i n g a c t i v i t y ( % )

a

b b

c

d

Fig. 4. DPPH radical-scavenging activity of films prepared with different levels of

thyme oil. Determinations were performed in triplicate and results are the mean

values ± standard deviation. Means with the same letter are not significantly

different ( p > 0.05).

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.000 0.025 0.050 0.100 0.250

Thyme oil (ml/g protein)

R e d u c i n g p o w e r ( m g a s c o r b i c a c i d / g f i l m )

a

a

a

a

b

Fig. 5. Reducing power of films prepared with different levels of thyme oil.

Determinations were performed in triplicate and results are the mean val-

ues ± standard deviation. Means with the same letter are not significantly different

( p > 0.05).


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Chick, J., Hernandez, R.J., 2002. Physical, thermal and barrier characterization of casein–wax based edible films. J. Food Sci. 67 (3), 1073–1079.

Chinabhark, K., Benjakul, S., Prodpran, T., 2007. Effect of pH on the properties of protein-based film from bigeye snapper (Priacanthus tayenus) surimi. Bioresour.Technol. 98, 221–225.

Chen, H., 1995. Functional properties and applications of edible films made of milkproteins. J. Dairy Sci. 78, 2563–2583.

Cuq, B., Aymard, C., Cuq, J.-L., Guilbert, S., 1995. Edible packaging films based on fishmyofibrillar proteins: formulation and functional properties. J. Food Sci. 60 (6),1369–1374.

Cuq, B., Gontard, N., Cuq, J.L., Guilbert, S., 1997. Selected functional properties of fishmyofibrillar protein–based films as affected by hydrophilic plasticizers. J. Agric.Food Chem. 45, 622–626.

Denavi, G., Tapia-Blácido, D.R., Añon, M.C., Sobral, P.J.A., Mauri, A.N., Menegalli, F.C.,2009. Effects of drying conditions on some physical properties of soy proteinfilms. J. Food Eng. 20, 341–349.

Fabra, M.J., Jimenez, A., Atarés, L., Talens, P., Chiralt, A., 2009. Effect of fatty acids andbeewax addition on properties of sodium caseinate dispersions and films.Biomacromolecules 10, 1500–1507.

Faraji, H., McClements, D.J., Decker, E.A., 2004. Role of continuous phase protein onthe oxidative stability of fish oil-in-water emulsions. J. Agric. Food. Chem. 52,4558–4564.

García, M.A., Pinotti, A., Martino, M.N., Zaritzky, N.E., 2009. Characterization of starch and composite edible films and coatings. In: Embuscado, M.E., Huber,K.C. (Eds.), Edible Films and Coatings for Food Applications. Springer, New York,pp. 169–210.

García, F.T., Sobral, P.J.A., 2005. Effect of the thermal treatment of the filmogenicsolution on the mechanical properties, colour and opacity of films based onmuscle proteins of two varieties of Tilapia. LWT 38, 289–296.

Gontard, N., Duchez, C., Cuq, L.-L., Guilbert, S., 1994. Edible composite films of wheatgluten and lipids: water vapour permeability and other physical properties. Int.

J. F ood Sci. Technol. 29, 39–50.Goméz-Estaca, J., Bravo, L., Gómez-Gullén, M.C., Alemán, A., Montero, P., 2009.

Antioxidant properties of tuna-skin and bovine-hide gelatin films induced bythe addition of oregano and rosemary extracts. Food Chem. 112, 18–25.

Gontard, N., Guibert, S., Cuq, J.L., 1992. Edible wheat gluten films: Influence of themain process variables on film properties using response surface methodology.

J. F ood Sci. 57, 190–195.Hamaguchi, P.Y., Yin, W.W., Tanaka, M., 2007. Effect of pH on the formation of

edible films made from muscle proteins of Blue marlin ( Makaira mazara). FoodChem. 100, 914–920.

Hosseini, M.H., Razavi, S.H., Mousavi, M.A., 2009. Antimicrobial, physical andmechanical properties of chitosan-based films incorporated with thyme, cloveand cinnamon essential oils. J. Food Process. Preserv. 33, 727–743.

Hudaib, M., Speroni, E., Di Pietra, A.M., Cavrini, V., 2002. GC/MS evaluation of thyme(Thymus vulgaris L.) oil composition and variations during the vegetative cycle.

J. Pharm. Biomed. Anal. 29, 691–700.

Hunterlab Method, 2008. Applications Note 9 (3), 2p. Jongjareonrak, A., Benjakul, S., Visessanguan, W., Tanaka, M., 2006. Effects of

plasticizers on the properties of edible films from skin gelatin of bigeye snapperand brownstripe red snapper. Eur. Food Res. Technol. 222, 229–235.

Jongjareonrak, A., Benjakul, S., Visessanguan, W., Tanaka, M., 2008. Antioxidativeactivity and properties of fish skin gelatin films incorporated with BHT and a-tocopherol. Food Hydrocolloids 22, 449–458.

Limpisophon, K., Tanaka, M., Osako, K., 2010. Characterisation of gelatin–fatty acidemulsion films based on blue shark (Prionace glauca) skin gelatine. Food Chem.122 (4), 1095–1101.

Oyaizu, M., 1988. Antioxidative activity of browning products of glucosaminefractionated by organic solvent and thin-layer chromatography. NipponShokuhin Kogyo Gakkaishi 35, 771–775.

Pires, C., Costa, S., Batista, A.P., Nunes, M.C., Raymundo, A., Batista, I., 2008.Physicochemical, functional and rheological properties of protein powdersprepared from Cape hake by-products. In: Guerrero, A., Muñoz, J., Franco, J.M.(Eds.), Rheology in Product Design and Engineering. Grupo Espanhol de

Reologia – Real Sociedad Espanola de Química (GER/RSEQ). Madrid, Spain, pp.111–114.

Pranoto, Y., Salokhe, V.M., Rakshit, S.K., 2005. Physical and antibacterial propertiesof alginate-based edible film incorporated with garlic oil. Food Res. Int. 38, 267–272.

Prodpran, T., Benjakul, S., 2005. Effect of acid and alkaline solubilization on theproperties of surimi based films. Songklanakarin J. Sci. Technol. 27 (3), 563–574.

Pruneda, E., Peralta-Hernández, J.M., Esquivel, K., Lee, S.Y., Godínez, L.A., Mendoza,S., 2008. Water vapor permeability, mechanical properties and antioxidanteffect of Mexican oregan-soy based edible films. J. Food Sci. 73 (6), C488–C493.

Saint-Denis, T., Goupy, J., 2004. Optimization of a nitrogen analyser based on theDumas method. Anal. Chim. Acta 515 (1), 191–198.

Sánchez-González, L., Vargas, M., González-Martínez, C., Chiralt, A., Cháfer, M., 2009.Characterization of edible films based on hydroxypropylmethylcellulose ad teatree essential oil. Food Hydrocolloids. doi:10.1016/j.foodhyd.2009.05.006.

Shellhammer, T.H., Krochta, J.M., 1997. Whey protein emulsion film performance asaffected by lipid type and amount. J. Food Sci. 62 (2), 390–394.

Shiku, Y., Hamaguchi, P.Y., Tanaka, M., 2003. Effect of pH on the preparation of edible films based on fish myofibrillar proteins. Fish. Sci. 69, 1026–1032.

Shiku, Y., Hamaguchi, P.Y., Benjakul, S., Visessanguan, W., Tanaka, M., 2004. Effect of surimi quality on properties of edible films based on Alaska Pollack. Food Chem.86, 493–499.

Siripatrawan, U., Harte, B.R., 2010. Physical properties and antioxidant activity of anactive film from chitosan incorporated with green tea extract. FoodHydrocolloids 24, 770–775.

Sobral, P.J.A., Menegalli, F.C., Hubinger, M.D., Roques, M.A., 2001. Mechanical, watervapor barrier and thermal properties of gelatin based edible films. FoodHydrocolloids 15 (4/6), 423–432.

Taguchi, K., Iwami, K., Ibuki, F., 1988. Antioxidant effects of wheat gliadin and hen’segg white in powder model systems: protection against oxidative deteriorationof safflower oil and sardine oil. Agric. Boil. Chem. 52, 539–545.

Tanaka, M., Ishizaki, S., Suzuki, T., Takai, R., 2001. Water vapor permeability of edible films prepared from fish water soluble proteins as affected by lipid type.

J. Tokyo Univ. F isheries 87, 31–37.Trezza, T., Krochta, J., 2000. Color stability of edible coatings during prolonged

storage. J. Food Sci. 65 (7), 1166–1169.

Weng, W.Y., Osako, K., Tanaka, M., 2009. Oxygen permeability and antioxidativeproperties of edible surimi films. Fish. Sci. 75, 233–240.

Yanishlieva, N.V., Marinova, E.M., Gordon, M.H., Raneva, V.G., 1999. Antioxidantactivity and mechanism of action of thymol and carvacrol in two lipid systems.Food Chem. 64, 59–66.

Zar, J.H., 1999. Biostatistical Analysis, fourth ed. Prentice-Hall, Inc., Upper SaddleRiver, New Jersey. pp. 616–663.

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characterization of biodegradable films prepared with hake proteins and thyme oil

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