lable at ScienceDirect

LWT - Food Science and Technology 57 (2014) 35e41

Contents lists avai

LWT - Food Science and Technology

journal homepage: www.elsevier .com/locate/ lwt

Quality of eggs coated with oilechitosan emulsion: Combined effectsof emulsifier types, initial albumen quality, and storage

Damir Dennis Torrico a, Wisdom Wardy a, Kennet Mariano Carabante a,Kairy Dharali Pujols a, Zhimin Xu a, Hong Kyoon No b, Witoon Prinyawiwatkul a,*a School of Nutrition and Food Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA 70803-4200, USAbDepartment of Food Science and Technology, Catholic University of Daegu, Hayang 712-702, Republic of Korea

a r t i c l e i n f o

Article history:Received 27 September 2013Received in revised form2 December 2013Accepted 22 December 2013

Keywords:Albumen qualityChitosanEmulsion coatingEgg qualityStorage

* Corresponding author. Tel.: þ1 225 578 5188; faxE-mail address: wprinya@lsu.edu (W. Prinyawiwat

0023-6438/$ e see front matter � 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.lwt.2013.12.035

a b s t r a c t

Effects of mineral oil:chitosan (MO:CH at 25:75) emulsions prepared with four different emulsifiers (2water- and 2 oil-miscible) as coatings on the internal quality (weight loss, Haugh unit, yolk index, andalbumen pH) of coated eggs were evaluated during 5 weeks at 25 � 2 �C and 20 weeks at 4 � 2 �C. Eggswith two initial albumen qualities [Haugh unit (HU): H ¼ 87.8 and L ¼ 70.9] were used. At 25 � 2 �C,Haugh unit, yolk index, and albumen pH of all coated eggs decreased with increased storage time. CoatedH- and L-eggs maintained an A-grade up to 4 weeks and 1 week, respectively. Weight loss of all coatedeggs remained below 1.35% after 5 weeks of storage at 25 � 2 �C. All coated eggs maintained an A-gradewith less than 2.5% weight loss during 20 weeks of storage at 4 � 2 �C. Emulsifier types marginallyaffected the internal quality of coated eggs regardless of storage temperatures.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

The United States (US) is one of the major producers of eggsworldwide. According to the USDA Economics, Statistics, andMarket Information System (USDA, 2013), the US production oftable eggs in 2012 was 6.68 billion dozen compared to 6.60 billiondozen in 2011. Eggs are highly susceptible to internal qualitydeterioration mainly due to loss of moisture and, to a lesser extent,carbon dioxide through the eggshell pores, causing undesirablequality changes in albumen and yolk, and the overall weight loss(Stadelman, 1995b). In the US, eggs are required to be refrigeratedat 7 �C or below to preserve the albumen and yolk quality, and toretard weight loss (Jirangrat, Torrico, No, No, & Printawiwatkul,2010; Wardy et al., 2011). Refrigeration can effectively reduce byhalf the weight loss of eggs compared to room temperature storage,and refrigerated eggs can maintain a quality grade of AA for at least4 weeks (Biladeau & Keener, 2009). However, in many countries(such as Thailand, Republic of Korea, and Brazil), refrigeration ofeggs is not required by law (Hong et al., 2012; Mizumoto &Zylbersztajn, 2004) and may be seldom practiced. Therefore,coating is alternatively an effective method to preserve egg internal

: þ1 225 578 5300.kul).

All rights reserved.

quality, and may help to reduce energy cost incurred by refrigera-tion of eggs during storage.

Coating materials have been applied to the eggshell surface forpreserving the internal quality of eggs. These materials includesynthetic polymers (Meyer & Spencer,1973), polysaccharides (Bhaleet al., 2003;Wardy, Pujols, Xu, No, & Prinyawiwatkul, 2014), proteins(Rhim, Weller, & Gennadios, 2004) and oils (Obanu & Mpieri, 1984;Waimaleongora-Ek, Garcia, No, Prinyawiwatkul, & Ingram, 2009).Our preliminary work demonstrated that an emulsion coatingprepared frommineral oil (MO) and chitosan solution (CH) at a ratioof 25:75 was able to extend egg shelf-life longer than was chitosansolution coating alone. Additionally, the drying time of the emulsionon the eggshell is considerably reduced compared to MO alone.

In addition to emulsion coatingmaterials, initial albumenqualityof eggs, emulsifier types used in emulsion preparation, and eggstorage conditionsmayaffect internal quality of eggs; however, veryfew studies have been done in this area. Sabrani and Payne (1978)observed a significant interaction (P < 0.05) between age of hens(eggs from younger vs. older hens, having different initial albumenqualities) and coating material (linseed oil) on internal egg qualityduring 24 days of storage at 28 �C. From the published literature,there is no information available on the interaction between theemulsifier types used for preparing emulsion coating and the initialalbumen qualities (expressed as Haugh unit) before coating andtheir combined effects on shelf-life of eggs during storage.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e4136

Therefore, the objective of this study was to evaluate the effectsof MO:CH (25:75) emulsion coatings prepared with four differentemulsifiers (2 water- and 2 oil-miscible) in preserving the internalquality of coated eggs (with two different initial albumen qualitiesbefore coating) during 5 weeks storage at 25 � 2 �C and during 20weeks of storage at 4 � 2 �C.

2. Materials and methods

2.1. Materials

Mineral oil (viscosity ¼ 34 mPa s; transparent, odourless andfood-grade) was obtained from Ste Oil Company� Inc. (San Marcos,TX, USA). Chitosan (molecular weight ¼ 223 kDa), acid soluble andwhite-coloured powder prepared from crab leg shell, was pur-chased from Biotech (Mokpo, Republic of Korea). Four emulsifiersincluded two oil-miscible types: (1) Tandem� 552K (a mixture ofmono and diglycerides, polysorbate, water and propyl gallate;Caravan� ingredients, Lenexa, KS, USA), (2) Tween 80 (Polyoxy-ethylene-20-sorbitan monooleate, reagent grade; Amresco� Inc.,Solon, OH, USA), and two water-miscible types: (3) TIC Pretest-ed�Ticaloid�210 S Powder (gum acacia and xanthan gum; TICGums�, Inc., White Marsh, MD, USA), and (4) Eficacia XE (Acaciagum purified and instantised; Colloides Naturels International,Rouen Cedex, France). These emulsifiers were previously screenedamong others in their ability to form a stable emulsion betweenmineral oil (MO) and chitosan (CH) at a ratio of MO:CH ¼ 25:75.

Faeces-free, white-shell eggs were obtained from two differentbatches of hens (52- and 54-weeks oldHylineW-36 hens; Cal-MaineFoods, Jackson, MS, USA). All eggs came from 2 different rows of thecagewithin the same facility. Five eggs fromeach rowwere randomlyassigned to each treatment (a total of 10 eggs; 5 eggs per each of thetwo replicates). After collection from the farm and screening for de-fects and desirable weight range (50e70 g), eggs with two differentinitial albumen qualities (expressed as Haugh unit) before coatingwere selected:H¼ eggs from 52-weeks old hens with Haugh unit of87.8, and L ¼ eggs from 54-weeks old hens with Haugh unit of 70.9.

Chitosan solution was prepared at 2 g/100 mL concentration bydissolving chitosan in 1mL/100mL acetic acid (Kim, Youn, No, Choi,& Prinyawiwatkul, 2009). Four MO:CH emulsions were prepared ata fixed ratio of 25:75 by adding 1 g/100 g of each of the fourdifferent emulsifiers as described in following procedures: Emul-sifiers Tandem� 552K and Tween 80 were added to MO and mixedusing a hand blender (Model # 59780R, Hamilton Beach� BrandsCanada, Inc., Picton, Ontario, Canada) at a low speed for 2 min at25 �C; the mixture stood for 30 min at room temperature, andsubsequently CH was added and mixed using the hand blender at ahigh speed for 6 min at 25 �C. Conversely, Tic Pretest-ed�Ticaloid�210 S Powder and Eficacia XEwere added to CH, mixedat a low speed for 2 min, stood for 30 min, and mixed with MO at ahigh speed for 6 min using a hand blender at 25 �C. The CH and allemulsions were prepared on the day of the coating experiment.

2.2. Coating treatment and storage of eggs

Eggs were individually weighed with a balance (TS400, OhausCorp., Florham Park, NJ, USA), coated withMO:CH (25:75) emulsionby using a sponge brush. Four coating treatments were evaluatedthroughout the storage periods: (1) TANDEM ¼ coating withemulsion containing Tandem� 552K, (2) TWEEN ¼ coating withemulsion containing Tween 80, (3) TIC ¼ coating with emulsioncontaining TIC Pretested� Ticaloid�210 S Powder, and (4)EFICACIA ¼ coating with emulsion containing Eficacia XE. Data fornoncoated eggs were not reported in this study. After coating, alleggs were allowed to dry overnight, then placed in a small-end

down position (Kim et al., 2009) on cardboard egg racks andstored at room temperature (25 � 2 �C) and in a cold room at4 � 2 �C. Based on previous (Jirangrat et al., 2010) and preliminarystudies which demonstrated that internal qualities of coated eggswould exhibit similar trends under refrigeration storage, only H-eggs were evaluated during refrigerated storage. For determinationof weight loss, Haugh unit, yolk index, and albumen pH, two rep-licates (five eggs/replicate) per each treatment (ten eggs total/treatment) were takenweekly for up to 5 weeks at 25� 2 �C, and at5-wk intervals for 20 weeks at 4 � 2 �C.

2.3. Determination of weight loss, Haugh unit, egg grade, yolkindex, and albumen pH

Weight loss (%) of the coated whole egg during storage wascalculated as {[initial whole egg weight (g) after coating at day0�whole egg weight (g) after storage]/initial whole egg weight (g)after coating at day 0} � 100. The weight of whole eggs wasmeasured with a balance (TS400S, Ohaus Corp., Florham Park, NJ,USA).

The height of albumen and yolk was measured with a tripodmicrometre (Model S-6428, B.C. Ames Inc., Melrose, MA, USA). Theyolk width was measured with a digital calliper (General Tools &Instruments, New York, NY, USA). The Haugh unit was calculated as100 log (H� 1.7W0.37 þ 7.57), where H is the albumen height (mm)and W is the weight (g) of egg. Egg grade was based on the UnitedStates Standards for Quality of Individual Shell Eggs (USDA, 2000)and Haugh unit. The yolk index was calculated as yolk height/yolkwidth (Stadelman, 1995a). After measurement of Haugh unit andyolk index, the albumen was separated from the yolk. The thin andthick albumen were mixed thoroughly prior to measuring pH witha pH meter (IQ150, IQ Scientific Instruments, San Diego, CA, USA).

2.4. Statistical analysis

For internal quality of eggs, mean � standard deviation valueswere reported based on ten measurements (two replicates; fiveeggs/replicate) per treatment. Data generated from the experimentat 25 � 2 �C were carried out in a Complete Randomized Design(CRD) [6 � 4 � 2 factorial: 6 storage time periods, 4 types ofemulsifiers (2 oil- and 2 water-based) and 2 initial albumen quali-ties before coating]. The Mixed model (PROC MIXED) was used todetermine differences amongmain effects and all their interactions,assigning the egg replication as a random variable at a ¼ 0.05.When main effects were significant, the Tukey’s Studentized Rangetest at a ¼ 0.05 was performed for post-hoc multiple comparisons.All analyses were done with the SAS software (SAS, 2003).

Multivariate Analysis of Variance (MANOVA) was used todetermine if significant differences exist among coated eggs whenall internal quality parameters are tested simultaneously. Descrip-tive discriminant analysis (DDA, Huberty, 1994) was used to deter-mine internal quality parameters responsible for the underlyingdifference among coating treatments. Principal Component analysis(PCA) was also performed to visualize the relationship among eggquality variables (weight loss, Haugh unit, yolk index, albumen pH)and the four emulsifiers (TANDEM, TWEEN, TIC, EFICACIA).

3. Results and discussion

3.1. Internal quality of eggs affected by coating materials duringroom temperature storage (25 � 2 �C)

3.1.1. Haugh unitThroughout storage of eggs, changes in albumen quality may

occur primarily due to storage conditions such as time,

Table 1ANOVA of main and interaction effects for Haugh unita, weight lossa, yolk indexa and albumen pHa of coated eggs at room temperature storage (25 � 2 �C).

Sourcea Dfb Haugh unit Albumen pH Weight loss Yolk index

F value Pr > F F value Pr > F F value Pr > F F value Pr > F

Storage period 5 203.4 <0.0001 50.8 <0.0001 75.4 <0.0001 205.1 <0.0001Initial quality 1 721.0 <0.0001 434.3 <0.0001 52.7 <0.0001 585.7 <0.0001Type of emulsifier 3 1.0 0.3984 1.7 0.1723 6.7 0.0002 2.5 0.0634Initial*Type 3 0.0 0.9996 5.0 0.0020 2.6 0.0535 1.8 0.1566Initial*Storage 5 8.3 <0.0001 50.0 <0.0001 3.4 0.0047 14.9 <0.0001Type*Storage 15 2.2 0.0072 2.7 0.0007 3.1 <0.0001 1.5 0.0986Initial*Type*Storage 15 0.5 0.9197 2.1 0.0114 2.2 0.0072 0.6 0.8682

a ANOVA ¼ Analysis of Variance. Complete Randomized Design: 6 � 4 � 2 ¼ 6 storage periods [0, 1, 2, 3, 4 and 5 weeks], 4 types of emulsifiers for preparing the coatingtreatments [Oil (TANDEM and TWEEN) andwater (TIC and EFICACIA) based], 2 initial albumen qualities of eggs before coating based on the Haugh unit (HU) [H¼ 87.76 HU andL ¼ 70.88 HU], and 2 replicates (five eggs per replicate). TANDEM ¼ coating with mineral oil:chitosan solution [MO:CH (25:75)] emulsion by using emulsifier Tandem� 552K;TWEEN ¼ coating with MO:CH (25:75) emulsion by using emulsifier Tween 80; TIC ¼ coating with MO:CH (25:75) emulsion by using emulsifier Tic Pretested�Ticaloid�210 SPowder; and EFICACIA ¼ coating with MO:CH (25:75) emulsion by using emulsifier Eficacia XE. Chitosan solution at 2 g/100 mL prepared in 1 mL/100 mL acetic acid.

b Df ¼ Degrees of freedom.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e41 37

temperature, and relative humidity (Li-Chan & Nakai, 1989).Regarding the Haugh unit (HU, an indicator of the albumen quality)of coated eggs, Analysis of Variance (ANOVA, Table 1) indicates thatmain effects including storage period and initial albumen qualitywere significant (P < 0.05), but the type of emulsifier was not sig-nificant (P � 0.05). Significant interactions were observed betweeninitial albumen quality and storage period and between type ofemulsifier and storage period (P< 0.05). As shown in Table 2, HU ofall coated eggs generally decreased with increased storage periods,although H-eggs consistently had higher HU (P< 0.05) compared toL-eggs throughout the 5-weeks storage (Table 2). The utmost dropin HU occurred during the first week of storage for all coated eggswith an average drop of 16.88 HU/week for H-eggs and 11.85 HU/week for L-eggs compared to 2.98e9.53 HU/week for H- and L-eggsduring the second week (Table 2). Robinson (1972) proposed thatthe natural thinning of egg albumen may be due to structuralmodifications of the protein ovomucin, particularly the b-ovomucincomponents which may be exposed to an alkaline pH. In this study,Haugh units of H-eggs (53.2e57.3) after 5 weeks were comparableto those of noncoated eggs (51.8e57.0) at week 1 (data not shown).

Table 2Haugh unit* (HU) and albumen quality egg grade* of coated eggs during 5 weeks of stor

Initialþ Type& Coating& Storage period

0 week 1 week

H Oil TANDEM 87.8 � 5.0A,a 72.0 � 4.6B,ab

AA AATWEEN 87.8 � 5.0A,a 71.4 � 4.6B,ab

AA AWater TIC 87.8 � 5.0A,a 73.6 � 3.9B,a

AA AAEFICACIA 87.8 � 5.0A,a 66.7 � 8.0B,b

AA A

L Oil TANDEM 70.9 � 8.0A,a 58.5 � 11.7AB,a

A BTWEEN 70.9 � 8.0A,a 60.6 � 5.8A,a

A AWater TIC 70.9 � 8.0A,a 60.0 � 6.9AB,a

A AEFICACIA 70.9 � 8.0A,a 57.1 � 11.1B,a

A B

*Means � SD of 10 measurements (two replicates; five eggs per replicate). AeEMeans wTukey’s Studentized Range (HSD) test. aebMeans with different superscripts within a co(P < 0.05) by Tukey’s Studentized Range (HSD) test. Egg grade was classified based on(firm) ¼ HU above 72; A (reasonably firm) ¼ 71e60; B (weak and watery) ¼ lower thanþInitial albumen qualities of eggs before coating: H ¼ 87.8 and L ¼ 70.9 HU.&See Table 1 for details.

Albumen quality of eggs can be classified into three grades: AA(firm) ¼ HU value >72; A (reasonably firm) ¼ 71e60; B (weak andwatery) ¼ lower than 60 (USDA, 2000). TANDEM, TWEEN andEFICACIA coated H-eggs preserved the AA/A grade up to 4 weeks. Incontrast, all coated L-eggs changed from A to B grade after 2 weekswhich remained until the end of 5 weeks (Table 2).

3.1.2. Albumen pHAnother important indicator of the albumen quality is the

albumen pH (Wardy et al., 2011). Freshly laid eggs contain 1.44e2.05 mg CO2/g of albumen (Biladeau & Keener, 2009; Keener,LaCrosse, & Babson, 2001) with an albumen pH of 7.6e8.7 (Rhimet al., 2004; Waimaleongora-Ek et al., 2009). During storage, CO2escapes through the eggshell pores resulting in an increasedalbumen pH value up to 9.6e9.7 (Kemps et al., 2007; Li-Chan &Nakai, 1989). ANOVA results (Table 1) showed that main effectsincluding storage period and initial albumen quality were signifi-cant (P < 0.05). All interactions observed among main effects werealso significant (P < 0.05) (Table 1). Two different patterns of thealbumen pH values throughout the storage time were observed for

age at 25 � 2 �C.

2 weeks 3 weeks 4 weeks 5 weeks

72.9 � 5.7B,a 61.1 � 6.9C,b 60.1 � 6.3C,a 57.3 � 5.2C,a

AA A A B65.3 � 6.4BC,b 67.7 � 3.0B,a 60.1 � 3.9CD,a 56.3 � 6.4D,a

A A A B68.1 � 4.7BC,ab 65.1 � 6.5CD,ab 58.8 � 4.6DE,a 54.4 � 4.1E,a

A A B B65.5 � 4.0B,b 64.3 � 3.6B,ab 63.9 � 7.1B,a 53.2 � 8.4C,a

A A A B

54.3 � 8.8B,a 38.0 � 10.2C,a 36.6 � 7.1C,a 39.4 � 12.5C,a

B B B B46.9 � 8.5B,a 43.8 � 12.6BC,a 33.7 � 12.4C,a 38.5 � 3.8BC,a

B B B B49.0 � 9.7BC,a 45.2 � 13.3CD,a 33.7 � 8.5D,a 34.3 � 9.1D,a

B B B B48.8 � 6.9BC,a 33.9 � 10.3D,a 37.7 � 9.4CD,a 39.1 � 10.3CD,a

B B B B

ith different superscripts in each row indicate significant differences (P < 0.05) bylumn and within a given initial HU before coating indicate significant differencesthe United States Standards for Quality of Individual Shell Eggs (USDA, 2000); AA60.

8.30

8.40

8.50

8.60

8.70

8.80

8.90

0 1 2 3 4 5

Albu

men

pH

Storage period (Weeks)

Albumen pH (H-eggs)

8.30

8.40

8.50

8.60

8.70

8.80

8.90

9.00

9.10

0 1 2 3 4 5

Albu

men

pH

Storage period (Weeks)

Albumen pH (L-eggs)

Fig. 1. Variations in albumen pH of coated eggs during 5 weeks of storage at 25 � 2 �C.Each point represents an average value of 10 measurements (two replicates; five eggsper replicate). For all data, the standard deviation values ranged from 0.04 to 0.25.Initial albumen qualities of eggs before coating: H ¼ 87.8 and L ¼ 70.9 HU. Solid linesrepresent oil based emulsifier treatments and dashed lines represent water basedemulsifier treatments. TANDEM (>) ¼ coating with mineral oil:chitosan solution[MO:CH (25:75)] emulsion by using emulsifier Tandem� 552K; TWEEN (,) ¼ coatingwith MO:CH (25:75) emulsion by using emulsifier Tween 80; TIC (6) ¼ coating withMO:CH (25:75) emulsion by using emulsifier Tic Pretested�Ticaloid�210 S Powder;and EFICACIA (B) ¼ coating with MO:CH (25:75) emulsion by using emulsifier Efi-cacia XE.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e4138

H- and L-eggs (Fig. 1). For instance, albumen pH values of coated H-eggs progressively decreased during the 5 weeks of storage. Incontrast, pH values of coated L-eggs increased during the firstweek, and thenmarginally decreased during the subsequent weeksof storage. The albumen pH values of all coated eggs in this studyranged from 8.38 to 9.02.

The behaviour of the albumen pH during storage differed be-tween H-eggs coated with emulsions prepared using oil- (TANDEMand/or TWEEN) vs. water- (TIC and/or EFICACIA) miscible emulsi-fiers (Fig. 1). The albumen pH of the former H-eggs decreased from8.81 (at week 0) to 8.47e8.58 after 3 weeks, and then increasedslightly to 8.53e8.62 after 5 weeks of storage. In contrast, thealbumen pH of the latter H-eggs progressively decreased from 8.81(at week 0) to 8.38e8.43 after 5 weeks of storage without anyincreasing trend. The observed decrease in albumen pH duringstorage in this study may be due to the continuing breakdown ofthe constituents in the egg white and/or a change in the bicar-bonate buffer system (Biladeau & Keener, 2009; Obanu & Mpieri,1984). Albumen pH values of all coated L-eggs were similar, hav-ing a noticeable rise of pH values in the first week (from 8.71 to8.93e9.02) and somewhat slight decrease after 4 weeks of storage(8.55e8.62, Fig. 1).

Ryu, No, and Prinyawiwatkul (2011) demonstrated that albumenpH of noncoated eggs can increase drastically from 8.81 at week0 to 9.37 after 5 weeks of storage at 25 �C. In this study, albumen pHvalues of coated H- and L-eggs after 5 weeks of storage at 25 �C(Fig. 1) were lower than those of noncoated eggs reported by Ryuet al. (2011) and our noncoated eggs (9.29e9.33; data notshown), which suggests that 25:75 MO:CH emulsion coating candelay loss of carbon dioxide via eggshell pores by acting as a gasbarrier (Obanu & Mpieri, 1984; Stadelman, 1995b), and this effect isindependent of the type of emulsifier used (oil and/or watermiscible, although they act differently, Fig. 1).

3.1.3. Weight lossANOVA results (Table 1) showed that all main effects including

storage period, initial albumen quality and type of emulsifier (oiland/or water miscible) were all significant (P < 0.05). Significantinteractions were observed (P< 0.05) for all effects, except betweeninitial albumen quality and type of emulsifier (P � 0.05). For allcoated eggs, weight loss gradually increased (P < 0.05) withincreased storage periods (Table 3). Significant variations of weightloss existed between H- and L-eggs during storage at room tem-perature (25 � 2 �C).

Temperature, humidity, air movement and storage time cancause loss of water through the porous shell, resulting in loss of eggweight (FAO, 2003). Weight loss of all coated eggs remained below1.35% during the entire 5-weeks storage period at 25 � 2 �C. Ac-cording to FAO (2003), a weight loss of 2e3% is common in mar-keting eggs and is hardly noticeable to consumers. This studydemonstrated that 25:75 MO:CH emulsion coatings (irrespective ofinitial HU before coating and the type of emulsifier used) cansimilarly offer protective barriers against the loss of moisturethrough the eggshell during 5 weeks of storage at 25 � 2 �C, thusminimizing weight loss of eggs (<1.35%, Table 3).

3.1.4. Yolk indexOverall, the yolk index (an indicator of the spherical nature of

egg yolk) of all coated eggs decreased with increased storage pe-riods (Table 3). This decrease was affected by storage and initial HUof eggs before coating (interaction between initial albumen qual-ities*storage periods, P < 0.05, Table 1). During storage of eggs, theyolk index decreases as a result of a progressive weakening of thevitelline membranes, reduction of the total solids, a progressivetransition of egg yolk rheological properties from pseudoplasticityto Newtonity, and liquefaction of the yolk, which are caused mainlyby osmotic diffusion of water from the albumen (Hidalgo, Lucisano,Comelli, & Pompei, 1996; Obanu &Mpieri, 1984; Stadelman, 1995a).Emulsifier types (oil vs. water miscible) did not significantly affectyolk index during storage (P� 0.05, Table 1). For H-eggs, yolk indexdecreased from 0.48 (week 0) to 0.33e0.36 (week 5). Yolk indexvalues of L-eggs were significantly (P< 0.05) lower than those of H-eggs throughout storage, and decreased from 0.40 (week 0) to0.29e0.32 (week 5) (Table 3).

Based on MANOVA results, overall differences existed amongfour coating treatments (Wilks’ Lambda P-value < 0.05, data notshown) when all parameters (Haugh unit, weight loss, yolk index,and albumen pH) were considered simultaneously. DDA showedthat the Haugh unit and yolk index were the two most criticalcriteria differentiating among all coated egg treatments with thepooled within canonical structure r’s values of 0.530 and 0.512,respectively, in the first dimension (Can 1) of the linear discrimi-nant functions. Regarding the second dimension (Can 2), albumenpH (r ¼ 0.864) contributed the most to the overall differences. Thebiplot (Fig. 2) shows the relative positions of the four coatingtreatments and egg quality parameters. All treatments weregrouped at the centre (origin) of two dimensions (D1 and D2)

Table 3Weight loss (%)* and yolk index* of coated eggs during 5 weeks of storage at 25 � 2 �C.

Initialþ Type& Coating& Storage period

0 week 1 week 2 weeks 3 weeks 4 weeks 5 weeks

Weight lossH Oil TANDEM e 0.28 � 0.05B,b 0.57 � 0.52AB,a 0.81 � 0.54A,a 0.67 � 0.24AB,b 0.49 � 0.25AB,c

TWEEN e 0.52 � 0.25B,a 0.47 � 0.09B,a 0.63 � 0.18B,a 1.35 � 0.87A,a 1.16 � 0.31A,a

Water TIC e 0.33 � 0.15C,ab 0.44 � 0.12BC,a 0.67 � 0.23A,a 0.61 � 0.10AB,b 0.67 � 0.19A,bc

EFICACIA e 0.43 � 0.25B,ab 0.48 � 0.12B,a 0.58 � 0.10AB,a 0.75 � 0.51AB,ab 0.92 � 0.40A,ab

L Oil TANDEM e 0.14 � 0.11B,a 0.36 � 0.36AB,a 0.35 � 0.20AB,a 0.47 � 0.17AB,a 0.61 � 0.47A,a

TWEEN e 0.14 � 0.07C,a 0.30 � 0.18BC,a 0.58 � 0.40AB,a 0.64 � 0.28A,a 0.64 � 0.25A,a

Water TIC e 0.19 � 0.17B,a 0.40 � 0.48AB,a 0.28 � 0.12AB,a 0.57 � 0.28A,a 0.55 � 0.22A,a

EFICACIA e 0.27 � 0.21B,a 0.29 � 0.18B,a 0.38 � 0.24B,a 0.36 � 0.20B,a 0.85 � 0.39A,a

Yolk indexH Oil TANDEM 0.48 � 0.01A,a 0.39 � 0.03B,a 0.38 � 0.03BC,a 0.38 � 0.03BC,a 0.36 � 0.03BC,a 0.35 � 0.03C,a

TWEEN 0.48 � 0.01A,a 0.38 � 0.03BC,a 0.38 � 0.03BC,a 0.40 � 0.02B,a 0.35 � 0.02C,a 0.36 � 0.04BC,a

Water TIC 0.48 � 0.01A,a 0.40 � 0.02B,a 0.39 � 0.02B,a 0.39 � 0.03B,a 0.35 � 0.03C,a 0.33 � 0.02C,a

EFICACIA 0.48 � 0.01A,a 0.39 � 0.03B,a 0.38 � 0.04B,a 0.40 � 0.03B,a 0.36 � 0.03B,a 0.36 � 0.04B,a

L Oil TANDEM 0.40 � 0.02A,a 0.36 � 0.02B,a 0.35 � 0.02B,a 0.32 � 0.02C,a 0.31 � 0.02C,a 0.32 � 0.03C,a

TWEEN 0.40 � 0.02A,a 0.35 � 0.02B,a 0.32 � 0.02BC,b 0.32 � 0.03C,a 0.32 � 0.03C,a 0.31 � 0.02C,a

Water TIC 0.40 � 0.02A,a 0.36 � 0.02B,a 0.32 � 0.01C,b 0.30 � 0.03CD,a 0.30 � 0.02CD,a 0.29 � 0.02D,a

EFICACIA 0.40 � 0.02A,a 0.37 � 0.02B,a 0.33 � 0.01C,ab 0.31 � 0.02C,a 0.31 � 0.02C,a 0.32 � 0.02C,a

*Means � SD of 10 measurements (two replicates; five eggs per replicate). AeDMeans with different superscripts in each row indicate significant differences (P < 0.05) byTukey’s Studentized Range (HSD) test. aecMeans with different superscripts within a column and within a given initial Haugh unit (HU) before coating indicate significantdifferences (P < 0.05) by Tukey’s Studentized Range (HSD) test.þInitial albumen qualities of eggs before coating: H ¼ 87.8 and L ¼ 70.9 HU.&See Table 1 for details.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e41 39

which altogether accounted for 83.72% of the variation. Besides,Haugh unit and yolk index were negatively correlated with thealbumen pH and weight loss in the first dimension (D1, 50.60%) ofthe biplot.

3.2. Internal quality of eggs affected by coating materials duringrefrigerated temperature storage (4 � 2 �C)

The most profound factor that affects the quality deteriorationrate of eggs is storage temperature. The deteriorating rate of qualityslows downwhen the storage temperature is closer to the freezingpoint (Stadelman, 1995b). As presented in Table 4, HU of all coatedH-eggs slowly decreased with increased storage periods (from 87.8at week 0 to 66.1e68.6 at week 10, and to 61.4e64.4 at week 20) atrefrigerated temperature (4 � 2 �C). All coated H-eggs maintainedconsistently an A grade during 20 weeks of storage at 4 � 2 �C(Table 4) compared with 4 weeks of storage at 25 � 2 �C (Table 2);

TANDEM TIC

TEWEEN EFICACIA

pH

Weight Loss

Haugh Unit

Yolk Index

-15

-10

-5

0

5

10

15

20

-25 -20 -15 -10 -5 0 5 10 15 20 25 30

Dim

ensi

on 2

(33.

13 %

)

Dimension 1 (50.60 %)

Biplot (axes D1 and D2: 83.72 %)

Fig. 2. The PCA product-attribute bi-plot involving the principal component 1 (50.60%variance explained) and the principal component 2 (33.13% variance explained).pH ¼ Albumen pH.

this implied the synergistic protective effects of emulsion coatingand refrigerated storage. Similar to HU, albumen pH valuesdecreased progressively from 8.81 to 8.25e8.63 after 20 weeksstorage at 4 � 2 �C. Weight loss (%) of all coated H-eggs after 10weeks at 4 � 2 �C were comparable to those after 5 weeks at25 � 2 �C (0.38e0.99% vs. 0.49e1.16%, Tables 3 and 5); this alsoimplied the synergistic protective effects of emulsion coating andrefrigerated storage. Weight loss of all coated H-eggs remainedbelow 2.5% after 20 weeks of storage at 4 � 2 �C (Table 5).

Generally, the yolk index of all coated H-eggs decreased duringrefrigerated storage but the rate of decrease was retarded by theeffect of the low temperature (Jirangrat et al., 2010). After 20 weeksof storage, yolk index merely decreased from 0.48 to 0.37e0.38 at4 � 2 �C (Table 5). The type of emulsifier used did not significantlyaffect the Haugh unit, albumen pH, weight loss, and/or yolk indexduring refrigerated storage (P � 0.05, Tables 4 and 5). Studies bySamli, Agma, and Senkoylu (2005) demonstrated that albumen pHof refrigerated eggs (5 �C) was lower compared to that of eggsstored at 21 �C or 29 �C. They further reported that yolk indices ofeggs from old laying hens decreased with increased storage time,however, this decrease was slower at 5 �C than at 21 �C and 29 �C.This indicates that migration of water from the albumen to the yolkis a function of storage temperature with a faster migration rateoccurring at higher temperatures (Stadelman, 1995b).

4. Conclusions

This study demonstrated that a 25:75 MO:CH emulsion coating,regardless of the initial albumen quality before coating and the typeof emulsifier used for preparing the emulsion, could preserve bothalbumen and yolk quality of coated eggs at 25 � 2 �C. Additionally,coated eggs exhibited grade A quality during 20 weeks of storage at4 � 2 �C as a result of synergistic effects of refrigeration andemulsion coating. The type of emulsifier (oil vs. water miscible)used for preparing the emulsion coatings marginally affected theHaugh unit, albumen pH, weight loss, and/or yolk index of coatedeggs during room temperature storage but did not significantlyaffect these internal quality parameters at refrigeration.

Table 4Haugh unit* (HU), albumen quality egg grade* and albumen pH* of coated eggs during 20 weeks of storage at 4 � 2 �C.

Type& Coating& Storage period

0 week 5 weeks 10 weeks 15 weeks 20 weeks

Haugh unitOil TANDEM 87.8 � 5.0A,a 68.9 � 2.9B,b 68.6 � 3.6B,a 66.5 � 4.9B,ab 64.4 � 4.1B,a

AA A A A ATWEEN 87.8 � 5.0A,a 72.2 � 4.8B,ab 66.1 � 3.8C,a 68.0 � 3.3BC,a 63.4 � 3.5C,a

AA AA A A AWater TIC 87.8 � 5.0A,a 75.5 � 6.4B,a 66.5 � 3.5C,a 63.9 � 5.3C,ab 62.7 � 3.6C,a

AA AA A A AEFICACIA 87.8 � 5.0A,a 71.1 � 4.00B,ab 66.6 � 7.0BC,a 62.8 � 2.8C,b 61.4 � 5.6C,a

AA A A A A

Albumen pHOil TANDEM 8.81 � 0.10A,a 8.54 � 0.09B,a 8.48 � 0.10BC,a 8.40 � 0.13CD,a 8.27 � 0.11D,b

TWEEN 8.81 � 0.10A,a 8.45 � 0.07C,ab 8.49 � 0.12BC,a 8.42 � 0.13C,a 8.63 � 0.12B,a

Water TIC 8.81 � 0.10A,a 8.42 � 0.06B,b 8.45 � 0.06B,a 8.44 � 0.09B,a 8.25 � 0.07C,b

EFICACIA 8.81 � 0.10A,a 8.49 � 0.10BC,ab 8.54 � 0.12B,a 8.42 � 0.07C,a 8.27 � 0.07D,b

*Means � SD of 10 measurements (two replicates; five eggs per replicate) from H-eggs (H ¼ 87.8 HU). AeDMeans with different superscripts in each row indicate significantdifferences (P < 0.05) by Tukey’s Studentized Range (HSD) test. aebFor Haugh unit or albumen pH, means with different superscripts within a column indicate significantdifferences (P< 0.05) by Tukey’s Studentized Range (HSD) test. Egg grade was classified based on the United States Standards for Quality of Individual Shell Eggs (USDA, 2000);AA (firm) ¼ HU above 72; A (reasonably firm) ¼ 71e60; B (weak and watery) ¼ lower than 60.&See Table 1 for details.

Table 5Weight loss (%)* and yolk index* of coated eggs during 20 weeks of storage at 4 � 2 �C.

Type& Coating& Storage period

0 week 5 weeks 10 weeks 15 weeks 20 weeks

Weight lossOil TANDEM e 1.08 � 2.46A,a 0.57 � 0.25A,a 1.23 � 0.41A,a 1.60 � 1.18A,a

TWEEN e 0.40 � 0.08C,a 0.79 � 0.33BC,a 1.30 � 0.54B,a 2.45 � 1.36A,a

Water TIC e 0.49 � 0.17B,a 0.99 � 0.62AB,a 1.42 � 0.73A,a 1.53 � 0.59A,a

EFICACIA e 0.70 � 0.42B,a 0.38 � 0.02B,a 1.61 � 0.62A,a 1.92 � 0.96A,a

Yolk indexOil TANDEM 0.48 � 0.01A,a 0.39 � 0.02B,a 0.39 � 0.04B,a 0.39 � 0.02B,a 0.38 � 0.04B,a

TWEEN 0.48 � 0.01A,a 0.40 � 0.02B,a 0.38 � 0.03B,a 0.40 � 0.03B,a 0.38 � 0.04B,a

Water TIC 0.48 � 0.01A,a 0.41 � 0.02B,a 0.38 � 0.04C,a 0.38 � 0.03BC,a 0.38 � 0.02BC,a

EFICACIA 0.48 � 0.01A,a 0.41 � 0.01B,a 0.38 � 0.02BC,a 0.37 � 0.02C,a 0.37 � 0.02C,a

*Means � SD of 10 measurements (two replicates; five eggs per replicate) from H-eggs (H ¼ 87.8 HU). A-CMeans with different superscripts in each row indicate significantdifferences (P < 0.05) by Tukey’s Studentized Range (HSD) test. aFor weight loss or yolk index, means with different superscripts within a column indicate significantdifferences (P < 0.05) by Tukey’s Studentized Range (HSD) test.&See Table 1 for details.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e4140

References1

Bhale, S., No, H. K., Prinyawiwatkul, W., Farr, A. J., Nadarajah, K., & Meyers, S. P.(2003). Chitosan coating improves shelf life of eggs. Journal of Food Science, 68,2378e2383.

Biladeau, A. M., & Keener, K. M. (2009). The effects of edible coatings on chicken eggquality under refrigerated storage. Poultry Science, 88, 1266e1274.

FAO. (2003). Egg marketing e A guide for the production and sale of eggs. In FAOagricultural services bulletin (Vol. 150).

Hidalgo, A., Lucisano, M., Comelli, E., & Pompei, C. (1996). Evolution of chemical andphysical yolk characteristics during the storage of shell eggs. Journal of Agri-cultural and Food Chemistry, 44, 1447e1452.

Hong, S. H., Ra, D. K., Yun, G. R., Joung, Y. J., Nam, J. H., Cheong, E. H., et al. (2012).Investigation for freshness and nutritive components of the egg sold in Incheon.Korean Journal of Veterinary Service, 35, 119e128.

Huberty, C. J. (1994). Applied discriminant analysis. New York: Wiley and Sons.Jirangrat, W., Torrico, D. D., No, J., No, H. K., & Printawiwatkul, W. (2010). Effects of

mineral oil coating on internal quality of chicken eggs under refrigeratedstorage. International Journal of Food Science and Technology, 45, 490e495.

Keener, K. M., LaCrosse, J. D., & Babson, J. K. (2001). Chemical method for deter-mination of carbon dioxide content in egg yolk and egg albumen. Poultry Sci-ence, 80, 983e987.

Kemps, B. J., De Ketelaere, B., Bamelis, F. R., Mertens, K., Decuypere, E. M., DeBaerdemaeker, J. G., et al. (2007). Albumen freshness assessment by combining

1 *In the references represents that “this work provides basis for our currentstudy.”

visible near-infrared transmission and low-resolution proton nuclear magneticresonance spectroscopy. Poultry Science, 86, 752e759.

Kim, S. H., Youn, D. K., No, H. K., Choi, S. W., & Prinyawiwatkul, W. (2009). Effect ofchitosan coating and storage position on quality and shelf life of eggs. Inter-national Journal of Food Science and Technology, 44, 1351e1359.

Li-Chan, E., & Nakai, S. (1989). Biochemical basis for the properties of egg white.Critical Reviews in Poultry Biology, 2, 21e58.

Meyer, R., & Spencer, J. V. (1973). The effect of various coatings on shell strength andegg quality. Poultry Science, 52, 703e711.

Mizumoto, F. M., & Zylbersztajn, D. (2004). Coexistence of institutional arrange-ments: analysis of the Brazilian egg chain. In A conference paper presented at the14th annual world food and agribusiness forum & symposium. Montreux,Switzerland: International Food and Agribusiness Management Association(IAMA). June 12e15, 2004.

*Obanu, Z. A., & Mpieri, A. A. (1984). Efficiency of dietary vegetable oils in preser-ving the quality of shell eggs under ambient tropical conditions. Journal of theScience of Food and Agriculture, 35, 1311e1317.

Rhim, J. W., Weller, C. L., & Gennadios, A. (2004). Effect of soy protein coating on shellstrength and quality of shell eggs. Food Science and Biotechnology, 13, 455e459.

Robinson, D. S. (1972). Egg white glycoproteins and the physical properties of eggwhite. In B. M. Freeman, & P. E. Lake (Eds.), Egg Formation and production (pp.65e86). Edinburgh: British Poultry Science.

*Ryu, K. N., No, H. K., & Prinyawiwatkul, W. (2011). Internal quality and shelf life ofeggs coated with oils from different sources. Journal of Food Science, 76, S325eS329.

Sabrani, M., & Payne, G. G. (1978). Effect of oiling on internal quality of eggs storedat 28 and 12 �C. British Poultry Science, 19, 567e571.

Samli, H. E., Agma, A., & Senkoylu, N. (2005). Effect of storage time and temperatureon egg quality in old laying hens. The Journal of Applied Poultry Research, 14,548e553.

D.D. Torrico et al. / LWT - Food Science and Technology 57 (2014) 35e41 41

SAS. (2003). SAS/STAT user’s guide. Version 9.1. Cary, NC: SAS Institute Inc.Stadelman, W. J. (1995a). Quality identification of shell eggs. In W. J. Stadelman, &

O. J. Cotterill (Eds.), Egg science and technology (4th ed.) (pp. 39e66). New York:The Haworth Press.

*Stadelman, W. J. (1995b). The preservation of quality in shell eggs. InW. J. Stadelman, & O. J. Cotterill (Eds.), Egg science and technology (4th ed.) (pp.67e79). New York: The Haworth Press.

USDA. U.S. Department of Agriculture. (2000). United States standards, grades, andweight classes for shell eggs. AMS 56.210. Washington, DC: AMS, USDA.

USDA. US Department of Agriculture. (2013). USDA economics, statistics, andmarket information system. Retrieved June 22, 2013, from Poultry Reportshttp://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do;jsessionid¼6ED8593F72EDA1799912FAB94D9CE7FB?documentID¼1028.

Waimaleongora-Ek, P., Garcia, K., No, H. K., Prinyawiwatkul, W., & Ingram, D. (2009).Selected quality and shelf-life of eggs coated with mineral oil with differentviscosities. Journal of Food Science, 74, S423eS429.

*Wardy, W., Pujols Martínez, K. D., Xu, Z., No, H. K., & Prinyawiwatkul, W. (2014).Viscosity changes of chitosan solution affect physico-functional properties andconsumer perception of coated eggs during storage. LWT e Food Science andTechnology, 55, 67e73.

*Wardy, W., Torrico, D. D., Jirangrat, W., No, H. K., Saalia, F. K., & Prinyawiwatkul, W.(2011). Chitosan-soybean oil emulsion coating affects physico-functional andsensory quality of eggs during storage. LWT e Food Science and Technology, 44,2659e2668.