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Meat Science 80 (2008) 599–606

MEATSCIENCE

Characteristics of meat emulsion systems as influenced by differentlevels of lemon albedo

C. Sarıc�oban *, B. Ozalp, M.T. Yılmaz, G. Ozen, M. Karakaya, M. Akbulut

Selcuk University, Agriculture Faculty, Food Engineering Department, Konya 42049, Turkey

Received 5 June 2007; received in revised form 25 December 2007; accepted 7 February 2008

Abstract

The effect of the addition of lemon albedo on the functional properties of emulsions was studied by using a model system. Oil/water(O/W) model emulsion systems were prepared by the addition of two types of lemon albedo (raw and dehydrated) at five concentrations(0.0%, 2.5%, 5.0%, 7.5% and 10%) to mechanically deboned chicken meat. The emulsion capacity, stability, viscosity and flow propertiesof the prepared model emulsions were analyzed. In addition, the colour parameters of cooked emulsion gel were determined. The addi-tion of lemon albedo increased the emulsion capacity (EC) and the highest EC value was reached with 5% of albedo added. However,further increase in the albedo concentration caused an inverse trend in the EC values. A similar trend was observed in the emulsion sta-bility (ES) values. Dehydrated albedo (DA) addition caused higher EC and ES values than did raw albedo (RA). DA increased the L*, a*

and b* values of the cooked emulsion gels. Emulsion viscosity (EV) values were positively correlated with an increase in albedo concen-tration and the highest EV value was obtained from the emulsions with 10% albedo. Albedo addition did not change the flow propertiesof the emulsions and, in addition, increased the pseudoplasticity. As a consequence, the use of lemon albedo might be a potential dietaryfiber source to enhance the functional and technological properties for frankfurter-type meat products.� 2008 Elsevier Ltd. All rights reserved.

Keywords: Model system; Lemon albedo; Fiber; Emulsion characteristics; Pseudoplasticity

1. Introduction

The increasing price of meat and processed meat prod-ucts have caused the food industry to evaluate utilizationof all protein sources, including some products such asmechanically deboned chicken meat (MDCM) in chickensausages (Babji & Lim, 1993). Nowadays, 1000 ton ofred and white meats are mechanically deboned and usedin the production of further processed meat products.MDPM is frequently used in the formulation of commi-nuted meat products; therefore, incorporation of MDPMinto emulsified meat products has opened additional mar-kets for meat from chicken frames and necks (Mielnik,Aaby, Rolfsen, Ellejaer, & Nilsson, 2002). Emulsion typemeat products are popular meat products consumed by

0309-1740/$ - see front matter � 2008 Elsevier Ltd. All rights reserved.

doi:10.1016/j.meatsci.2008.02.008

* Corresponding author. Tel.: +90 332 223 2927; fax: +90 332 241 0108.E-mail address: cscoban@selcuk.edu.tr (C. Sarıc�oban).

millions of consumers world-wide. However, increasingconcerns about the potential health risks related withthe consumption of high fat foods has led the food indus-try to develop new formulations or modify traditionalproducts to make them healthier. The most common ofthese modifications has been fat reduction. Diets prevail-ing in industrialized countries are characterized by anexcess of energy dense foods rich in fats and sugar anda deficiency of complex carbohydrates which constitutethe majority of dietary fiber (Papadina & Bloukas,1999). Epidemiological research has demonstrated a rela-tionship between this type of diet and the emergence ofseveral chronic diseases such as colon cancer, obesity, car-diovascular diseases and several other diseases (Beecher,1999; Best, 1991; Kaeferstein & Clugston, 1995), andtherefore an increase in the level of dietary fiber inthe daily diet has been recommended (Eastwood, 1992;Johnson & Southgate, 1994).

600 C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606

Albedo is a white, spongy and cellulosic tissue (Fernan-dez-Gines, Fernandez-Lopez, Sayas-Barbera, Sendra, &Perez-Alvarez, 2004) component of citrus fruits, and couldbe considered as a potential fiber source. Dietary fibersources such as albedo are not only desirable for theirnutritional properties but also for their functional andtechnological properties (Thebaudin, Lefebvre, Harring-ton, & Bourgeosis, 1997). In this respect, the use of fiberhas been successful in improving cooking yield, reducingformulation cost, and enhancing texture in food products(Akoh, 1998; Iyengar & Gross, 1991; Jimenez-Colmenero,1996).

Fiber is appropriate in meat products and has previ-ously been added to meat products to increase the cookingyield because of its water and fat-binding properties (Cof-rades, Guerra, Carballo, Fernandez-Martın, & Jimenez-Colmenero, 2000). Various types of fiber and albedo havebeen studied alone or combined with other ingredientsfor the formulation of reduced-fat meat products, mainlyground and restructured products (Aleson-Carbonell,Fernandez-Lopez, Perez-Alvarez, & Kuri, 2005; Desmond,Troy, & Buckley, 1998; Fernandez-Gines et al., 2004; Man-sour & Khalil, 1999) and emulsion type meat products(Aleson-Carbonell, Fernandez-Lopez, Sayas-Barbera, Sen-dra, & Perez-Alvarez, 2003; Chang & Carpenter, 1997). Itstechnological effects on foods differ according to the quan-tity and nature of dietary fiber (Thebaudin et al., 1997).Several researches have focused on this aspect. In general,the effect of various types and concentrations of albedo(0%, 2.5%, 5.5%, 7.5% and 10%) on the properties of emul-sion type meat products have been studied in the finalproduct. However, studying the mentioned functionaleffects of the albedo using a quick and effective methodol-ogy could provide more precise knowledge. In this respect,model system studies have frequently been preferred due tothe fact that they are convenient, economical; require min-imum time and are reproducible (Karakaya, 1990). In gen-eral, some functional properties of emulsion systemsprepared with lemon albedo such as emulsion capacity, sta-bility and gelation properties have not been well docu-mented. In addition, no study has appeared of theseproperties by using a model system. In this research, thelevels of 0.0%, 2.5%, 5.0%, 7.5% and 10% were selectedand studied based on other studies related to the additionof albedo into the comminuted meat products. Therefore,the objective of this research was to study the effect ofaddition of lemon albedo (raw and dehydrated) on thefunctional properties of emulsions to determine its appro-priate addition levels in frankfurter-type meat products.

2. Materials and methods

2.1. Materials

Albedo was obtained directly from commercial lemons(Citrus limon var. verna) in a pilot plant. Two types ofalbedo were used in this work: raw albedo (RA) obtained

directly from lemons and dehydrated raw albedo (DRA)obtained by drying raw albedo in an oven at 50 �C during48 h. The purpose of the dehydration was to improve thealbedo shelf life by the reduction in water content, whichalso favours handling by decreasing the storage costs. Bothmaterials were vacuum-packed in polyethylene vacuumpouches (2 kg). In order to restrict the activity of endoge-neous enzymes degrading pectin in the RA, the pouchesincluding RA or DA were immediately frozen at �30 �Cuntil analysis to provide the same processing conditionsfor RA and DA in spite of the low water activity of DA.When needed, frozen albedo pouches were placed at refrig-erator temperature (4 �C) during 24 h for defrosting. Toobtain a product with an appropriate particle size (1–3 mm, visually determined), an homogenizer (WaringCommercial Blendor�, USA) was used.

Mechanically deboned chicken breast meat (MDCBM)was obtained from a commercial firm (Beypi Co., BoluTurkey). Chicken meats were processed through a BeehiveRSTC-06 (Weiler, USA) separator. Each batch ofMDCBM was vacuum-packed as 10 kg of blocks, frozenat �30 �C and then stored at �18 �C at the processingplant until analyses.

2.2. Preparation of model system emulsions

Analytical grade NaCl and K2HPO4 (Merck, Darmstadt,Germany) were used. A NaCl (2.5%)–K2HPO4 (0.25%)combination was prepared and dissolved in water. Twotypes (raw and dehydrated albedo) and five concentrations(0.0%, 2.5%, 5.0%, 7.5% and 10%, the percentages relatedto 25 g of meat sample) of lemon albedo were used in thisstudy. Although upper concentrations exceeding the 10%level were also tested, only the results for the concentrationsup to 10% as used previously in studies of comminuted meatproducts with albedo are reported because the upper limitsdid not produce remarkable results for the emulsion proper-ties studied. In addition, each concentration was adjustedand equalized to each other so that the same dry matter con-tent of these albedo types at each concentration could beachieved. For each treatment, 25 g of meat plus 100 mL ofcold (0–4 �C) salt–phosphate solution (SPS) plus corre-sponding concentrations and types of lemon albedo wereplaced into a blender jar and comminuted for 2 min at13,000 rpm to obtain slurry. The resulting 12.5 g of slurryand 37.5 mL of additional SPS were transferred to anotherblender jar and homogenized for 10 s at low speed(5000 rpm) and 50 mL of refined corn oil was added at first.The blender was brought under to the model system withthe water-jacketed burette containing oil maintained at11 �C. Oil was added at 1.0 mL/s until the total amount ofoil (dispensed plus original) reached 100 ml. The emulsionswere prepared by mixing the oil into the dispersions at theconcentrations indicated and then, emulsifying with a War-ing Blender (Waring Commercial Blendor�, USA) at13,000 rpm during oil addition at 11 �C. All emulsions sam-ples were studied in triplicate with two replications.

C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606 601

2.3. Chemical and physicochemical analysis

Moisture (hot air oven), protein (Kjeldahl), fat (ether-extraction), ash (muffle furnace) and crude fiber contentswere determined using standard methods of the AOAC(2000). Moisture (g water/100 g sample) was determinedby drying a 3 g sample at 105 �C to constant weight. Protein(g protein/100 g sample) was analyzed according to theKjeldahl method. Factor 6.25 was used for conversion ofnitrogen to crude protein. Fat content (g fat/100 g sample)was determined by using a Soxhelet fat extraction appara-tus. Ash content (g ash/ 100 g sample) was determined byashing at 550 �C for 2 h. Crude fiber (g brute fiber/100 gsample) of lemon albedo was determined by the Weendemethod. The pH values of the samples were measured witha pH meter (WTW 315 i set model, Weilheim, Germany)following the instructions outlined by Ockerman (1985).

2.4. Colour determination of model system emulsions

Colour measurements were carried out on the emulsionscooked in a water bath until the geometric centre of themodel emulsions reached 72 �C. The inner temperaturewas monitored using a thermocouple probe (Omega Engi-neering, INC, Stamford, CT) positioned in the geometriccentre. When the endpoint temperature was reached, thecooked emulsions were immediately chilled by tap water.Colour measurements were performed at 13 �C using achroma meter CR-400 (Konica Minolta, Inc., Osaka,Japan) with illuminant D65, 2� observer, Diffuse/O mode,8 mm aperture of the instrument for illumination and 8mm for measurement. The instrument was calibrated witha white reference tile (L* = 97.10, a* = �4.88, b* = 7.04)before the measurements. The L*, a* (±red–green) and b*

(±yellow–blue) colour coordinates were determinedaccording to the CIELab colour space system. Chroma(C*) and hue-angle (h�) were calculated by the followingformula: C� ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

a�2 þ a�2p

, h� = tan�1 (b*/a*). Americanmeat science association guidelines for colour measure-ments were followed (Hunt et al., 1991). Measurementswere made directly upon the emulsion samples and carriedout five times, one on the middle and four on the differentparts of the cooked emulsion samples.

2.5. Emulsion capacity (EC) of model system emulsions

EC was determined by using a model system describedby Ockerman (1985). End point was determined asdescribed by Webb, Ivey, Craip, Jones, and Monroe(1970). To measure EC, the emulsions were prepared asdescribed above, namely, 12.5 g of slurry and 37.5 mL ofSPS were transferred to a blender jar and homogenizedfor 10 s at low speed (5000 rpm) and 50 mL of refined cornoil was added at first. The blender was brought under tothe model system with the water-jacketed burette contain-ing oil maintained at 11 �C. The blender rate was13,000 rpm during emulsifying. Oil was added at 1.0 mL/s

until the breaking point of the emulsions. The electricalconductivity of the emulsion was monitored by the ohm-meter (YX-360 TRN Multitester Fuse & Diyote Protec-tion, Sunwa, Moscow, Russia) connected to a millivoltrecorder (Labsco Laboratory Supply Com. Ollmann &Co. KG, Louisville, KY). At the breaking point, the con-ductivity suddenly dropped and oil addition was stopped.The total amount of emulsified oil was measured and calcu-lated by considering the first 50 mL oil added. EC was cal-culated as millilitres of oil in per gram of protein afterprotein (Kjeldahl) contents of the meat samples were deter-mined (Ockerman, 1985).

2.6. Stability of model emulsions

Emulsion stability (ES) of the newly formed emulsionswas determined using a model system described by Ocker-man (1985). In the ES determination, an emulsion wasformed as described above, but the emulsion forming pro-cess was stopped when the total amount of oil (dispensedplus original) reached 100 mL. Then, 20 g emulsion wasweighed into cellulose nitrate test tubes with a cap andtransferred to a water bath (Nuve, BM 402 model, Turkey)at 80 �C until the internal temperature reached to 72 �C.The test tubes were centrifuged for 15 min at 900g (Hettich,Micro 22R model, Germany) and were drained into a vol-umetric cylinder for 12 h to collect the unbound oil andwater. ES was calculated as a percentage (%) from theamount of separated oil (SO) plus separated water (SW)released by the emulsion (Ockerman, 1985).

2.7. Emulsion viscosity and flow properties of model system

emulsions

The apparent viscosity of solutions was measured at20 �C using Lab Line viscometer, Model No 4535 (LabLine Instruments, Inc., MELROSE PARK, ILL., UK).Appropriate spindle (No. 7) was used to get all readingswithin the scale. Viscometer readings were recorded at sixdifferent rotational speeds (2.5, 5, 10, 20, 50, 100 rpm).All data were taken after 60 s in each sample. For this anal-ysis, approximately 25 g of the newly formed emulsion wastransferred into a cellulose nitrate test tube in order for theemulsion to just cover the immersion grooves on the spin-dle shafts. The temperature was kept constant at 20 �Cusing a thermostatically controlled water bath. The flowcurves, apparent viscosity versus rotational speed of allemulsions studied were plotted by increasing speed rate.The data were fitted to the well-known power-law model(Eq. (1)) which is used extensively to describe the rheolog-ical properties of non-Newtonian liquids in theoreticalanalysis as well as in practical engineering applications(Barnes, Hutton, & Walters, 1989). The flow behaviourindex (n), consistency index (k) values and determinationcoefficients (r2) were obtained by fitting the rotationalspeed versus apparent viscosity values to power-law modeland calculated by employing linear regression analysis.

602 C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606

ga ¼ kcðn�1Þ ð1Þwhere g is the apparent viscosity (mPa s), k (Pa sn) is theconsistency index, c is the rotational speed (s�1) and n

(dimensionless) is the flow behaviour index. For n < 1,the model is pseudoplastic (shear-thinning);for n > 1, themodel is dilatant (shear-thickening).

2.8. Statistical analysis

Each parameter was tested in triplicate samples with tworeplications. Conventional statistical methods were used tocalculate means and standard deviations. Collected datawas subjected to statistical analyses using MINITAB forWindows Release 13� (MINITAB, 2000). Multifactoranalysis of variance (ANOVA) was used to evaluate theeffect of albedo type (raw and dehydrated) and concentra-tion (0.0, 2.5, 5.0, 7.5 and 10%) on the parameters studied.When a significant (p < 0.05) main effect was found, themean values were further analyzed using Duncan MultipleRange Test (MstatC, 1986).

3. Results and discussion

3.1. Chemical and physicochemical properties of albedo

Chemical and physicochemical analysis results of albedo(raw and dehydrated) and mechanically deboned chickenbreast meats (MDCBM) are presented in Table 1. Thelower pH value of dehydrated albedo (DA) could be attrib-uted to the relative increase in the concentration of organicacids present in DA as a result of dehydration; therefore,provoking a decrease in pH values of DA. Lightness

Table 1Chemical and physical properties of lemon albedo types and MDCBM

Type of albedo Moisture (%) Ash (%) Fibre (%) pH

RA 62.5a 2.98b 31b 4.66DA 6.2b 4.50a 85a 4.08MDCBM 62.5 1.04 – 6.76

RA, raw albedo; DA, dehydrated albedo; MDCBM, mechanically deboned cha,b Means with no common superscripts are significantly different (p < 0.05).

Table 2Effects of albedo type and concentration on EC, ES, pH and colour paramete

Concentration (%) Emulsion properties C

pH EC ES L

0.0 (Control) 7.12a 326.2d 72.1b 782.5 7.09ab 345.6c 79.2a 825.0 7.06bc 388.9a 81.1a 837.5 7.02cd 361.0b 80.4a 8410 6.99d 348.6c 79.8a 82Albedo type

RA 7.09x 348.6y 75.3y 81DA 7.02y 359.6x 81.8x 82

Means in a column with no common superscripts are significantly different (p <types. RA, raw albedo; DA, dehydrated albedo; EC, emulsion capacity; ES, e

decreased and redness increased (p < 0.05) when albedowas dehydrated. The decrease in albedo lightness (L* val-ues) by dehydration was thought to result from thedecrease in water content. For some foods, lightness wasreported to be dependent on moisture content (Hutchings,1999). The increase in redness (a* values) of DA could bedue to relative increase in the concentration of carotenoidcompounds, which promoted the redness value (Fernan-dez-Lopez, Perez-Alvarez, Sayas-Barbera, & Lopez-Sant-ovena, 2002). Dehydration had no effect on theyellowness (b*) values. These results were very similar tothose of Aleson-Carbonell, Fernandez-Lopez, Sendra,Sayas-Barbera, and Perez-Alvarez (2004) who also foundhigher moisture, pH, and L* values, but lower ash, fibre,a* values of raw lemon albedo as compared to those ofdehydrated lemon albedo.

3.2. pH and emulsion capacity (EC) of model system

emulsions

Table 2 shows the pH and EC results for emulsion sam-ples prepared with RA and DA at different concentrations.The pH values in emulsions with RA were higher thanthose in emulsions with DA, which could be due to thelower pH value of DA (Table 1). Furthermore, an increasein the concentration of albedo decreased (p < 0.01) the pHvalues of the emulsions (Table 2), which could be due to thepresence of some organic acids in albedo (Braddock, 1995).The lowest pH value was obtained for samples with 10%albedo.

The EC values of samples with albedo were higher(p < 0.01) than that of the control sample. Albedo addition

L* a* b* Protein (%) Fat (%)

a 75.47a �3.17b 16.37a 0.37b –b 72.04b 4.19a 18.30a 1.88a –

47.35 21.00 13.32 17.23 18.10

icken breast meat.

rs of model system emulsions

ooked emulsion gel colour

* a* b* Hue-angle� Chroma

.9c �2.1a 8.9b 76.6a 9.2ab

.1b �2.1a 9.6a 77.3a 9.8a

.4ab �2.0a 8.8b 77.3a 9.1b

.1a �1.8a 8.9b 78.3a 9.2ab

.5ab �2.1a 9.5a 77.5a 9.7ab

.5y �2.3x 8.7y 75.5y 9.0y

.9x �1.8y 9.6x 79.3x 9.7x

0.01). a–c: difference between concentrations, x– y: difference between albedomulsion stability.

C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606 603

increased the EC values of model emulsions (O/W), whichwas in accordance with the information by Lario et al.(2004) who reported that lemon albedo has a high waterand oil holding capacity. These functional properties oflemon albedo result from its soluble components, mainlypectin, which may constitute up to 25% of the tissue (Mese-guer, 2002). The lemon albedo concentrations studied weredirectly related to quantities of albedo used already in stud-ies of comminuted meat products. In addition, higher con-centrations exceeding the 10% level were tested in thisstudy; however, only the results for the concentrations upto 10% were reported in this study in that higher levelsdid not produce the remarkable results for capacity andstability of the emulsions. EC increased with both typesof albedo addition; however, this increase was not linearand reached a peak at the concentration of 5% albedofor both types. Fig. 1 explicitly shows the phenomena seenin the EC values of the samples with albedo. After thislevel, a trend to decrease in EC values was observed. Thisdecrease, dependent on albedo concentration, could bedue to the relationship between pH and EC. Cheftel,Cuq, and Lorient (1985) reported that pH was one of themost important parameters affecting emulsion characteris-tics. pH influences the emulsification properties of the pro-teins, in other words, EC values of the meat species. At theisoelectric point (pI) of proteins, hydrophobic interactionsbetween lipids and proteins are enhanced. Myofibrillar pro-teins have better emulsifying properties at pH values fur-ther away from the pI (Cheftel et al., 1985). In this study,increase in albedo concentration was determined todecrease pH values (Table 2) and consequently EC values;therefore, decreasing pH values caused proteins toapproach the isoelectric point where they had the leastEC (Cheftel et al., 1985) in spite of the effect of albedoaddition to increase EC until 5% of concentration.

Samples with DA had higher (p < 0.01) EC values whencompared to samples with RA. This was thought to result

320

330

340

350

360

370

380

390

0.0 2.5 5.0 7.5 10.0

EC

(m

L o

il /g

pro

tein

)

Albedo concentration (%)

Emulsions with RAEmulsions with DA

*

*

* *

*

*

Fig. 1. Emulsion capacity (EC) of model system emulsions prepared withdifferent albedo types and concentrations. RA, raw albedo; DA,dehydrated albedo. Values marked with * indicate a significant(P < 0.01) difference between the emulsions with RA and DA at eachalbedo concentration.

from more acidic nature of DA whose pH value (4.08) wasdetermined to be further away from the isoelectric point ofmyofibrillar proteins (pI = 4.8–5.2) when compared to thatof RA (4.66) (Cheftel et al., 1985). Furthermore, fat hold-ing capacity was reported to be affected by fiber processingmethod and consequently their chemical and physicalstructure, which was also related to the soluble dietary fibercontent (Borroto, Larrauri, & Cribeiro, 1995; Griguelmo-Miguel & Martin-Belloso, 1999).

3.3. Stability of model system emulsions

Emulsion stability is an indicator of unseparated fat andmoisture retained by meat proteins. Albedo has a goodpotential for moisture retention (Lario et al., 2004). Theparallel result was reached in this model system study,which demonstrated that albedo addition increased(p < 0.01) the emulsion stability (ES) values of the samples.Nevertheless, the increase in albedo concentration did notinfluence the ES values (Table 2). The results for ES inthe samples with DA were similar to those for EC, in otherwords, samples with DA showed higher (p < 0.01) ES val-ues than did samples with RA. The reason could beexplained by the similar fact that water and fat holdingcapacity was affected by fiber processing method. Fig. 2illustrates the same trend in ES values of samples withRA, which increased until the 5% of concentration, andthen decreased after this concentration level. The possiblereason could be attributed to the same phenomena seenin EC values in which the linear pH decrease (Table 2)might cause a decrease in ES values at the albedo concen-trations, higher than 5%. The relationship between pH andwater retaining capacity of protein has been well estab-lished by Warriss, Wilkins, and Knowles (1999). However,ES values of samples with DA did not reach a peak at the5% of concentration, continuing to increase at higher con-centrations,up to at the highest albedo concentration(Fig. 2).

70.0

72.0

74.0

76.0

78.0

80.0

82.0

84.0

86.0

0.0 2.5 5.0 7.5 10.0

ES

(%

)

Albedo concentration (%)

Emulsions with RAEmulsions with DA

Fig. 2. Emulsion stability (ES) of model system emulsions prepared withdifferent albedo types and concentrations. RA, raw albedo; DA,dehydrated albedo.

700

2200

3700

5200

6700

8200

9700

11200

12700

14200

0 10 20 30 40 50 60 70 80 90 100

App

aren

t Vis

cosi

ty (m

Pa.s

)

Speed (rpm)

0% RA 2.5% RA 5% RA 7.5% RA 10% RA

Fig. 3. Flow curves of model system emulsions prepared with differentconcentrations of raw albedo (RA).

500

4000

7500

11000

14500

18000

21500

25000

28500

0 10 20 30 40 50 60 70 80 90 100

App

aren

t Vis

cosi

ty (m

Pa.s

)

Speed (rpm)

0% DA2.5% DA5% DA7.5% DA 10% DA

Fig. 4. Flow curves of model system emulsions prepared with differentconcentrations of dehydrated albedo (DA).

604 C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606

3.4. Colour of cooked emulsion gels

Table 2 shows also colour parameters of the cookedmodel emulsions. Addition of any type of albedo at anyconcentration increased (p < 0.01) lightness (L* values)and this increase was more prominent in the samples withDA. Emulsion samples with DA had higher L* values whencompared samples with RA. The reason why samples withDA showed the higher lightness could be due to the higherEC and ES values of these samples. Some authors reportedthat the increase in fat and/or water in meat productsresults in a lighter products (Perez-Alvarez & Fernandez-Lopez, 2000).

The higher L* values of the samples with 5.0%, 7.5% and10% of albedo were thought to be caused by the same fact,namely, the higher fat and water retention properties in thesamples with these levels of albedo. The redness of thecooked emulsion gels prepared with different levels ofalbedo showed negative values although DA and MDCBMeach alone showed redness value of 21.00 and 4.19, respec-tively (Table 1). This could be explained by the addition ofrefined corn oil to prepare the emulsions, which possiblygave rise to these negative a* values. Nas, Gokalp, and Un-sal (1998) reported the lovibond colour value of the refinedcorn oil to be 40 yellow-4.0 red maximum indicating thegreenish colour of refined corn oil, which was thought todecrease the redness values of the cooked emulsions. Theredness (a* values) and hue-angles (h�) were not modifiedby albedo addition (at any concentration); however, sam-ples with DA were slightly redder and more vivid(p < 0.01) (higher a* and chroma values) than cooked emul-sion gels with RA. A possible explanation could be anincrease in the concentration of carotenoid compounds,which contributed the redness value (Fernandez-Lopezet al., 2002). Hue-angle and chroma values were higher inthe samples with DA (higher brownness and saturation)than those in the samples with RA, which indicatedbrowner and more vivid colour properties of samples withDA. Addition of albedo at any concentration had no stableeffect on the yellowness (b* values) behaviour of the sam-ples. On the other hand, samples with DA showed higheryellowness than did samples with RA. This increase in b*

values could be related to the incorporation of yellow com-ponents present in albedo, which occur in higher amountsin the concentrated dehydrated albedo than in raw albedo(Fernandez-Lopez et al., 2004).

3.5. Emulsion viscosity and flow behaviour of model system

emulsions

ANOVA results revealed that addition of albedo at anyconcentration increased (p < 0.01) the emulsion viscosity(EV) at all rotation speeds, e.g. 2.5, 5, 10, 20, 50 and100 rpm. Fig. 5 illustrates this increase in EV values ofthe samples at different rotation speeds with respect toalbedo level. The effect of albedo was evident for all sam-ples with varied rotation speeds. For instance, EV of the

control sample (no added albedo) at 10 rpm was initially3300 mPa s and increased to 7683 mPa with 10% of albedolevel. This effect could be partly due to the effect of albedoto increase EC values, an indicator of the amount of emul-sified oil (Table 2). As the oil was emulsified, the proteinmatrix extended in the emulsion, which resulted in anincrease in the viscosity (Smith, 1988). Increase in EV isdesired in the high fat emulsion type products, becausehigher EV gives an increased elasticity to emulsion typemeat products (Yapar, Atay, Kayacier, & Yetim, 2006).In general, no difference was seen between samples withDA and RA with respect to the EV values (data notpresented).

The apparent viscosity (AV) of the model system emul-sions with RA and DA was graphically plotted in Figs. 3and 4, which illustrate AV data of each emulsion as a func-tion of rotational speed (c). Table 3 shows the flow behav-iour index (n), consistency index (k) constants and

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

22000

0.0 2.5 5.0 7.5 10.0

Em

uls

ion

vis

cosi

ty (

m P

a.S

)

Albedo concentration (%)

2.5 rpm5 rpm

10 rpm20 rpm

50 rpm100 rpm

Fig. 5. Emulsion viscosity (EV) of model system emulsions prepared withdifferent albedo types and concentrations.

Table 3Consistency index, flow behavior index and determination coefficientvalues of model system emulsions prepared with different types andconcentrations of albedoa

Albedoconcentrations(%)

Raw albedo Dehydrated albedo

n

Indexk Index(mPa sn)

r2 n

Indexk Index(mPa sn)

r2

0.0 (Control) 0.41 14149 0.990 0.41 14,149 0.9902.5 0.29 23718 0.992 0.49 15,573 0.9715.0 0.35 26170 0.995 0.33 19,423 0.9647.5 0.33 23257 0.996 0.31 25,781 0.99110 0.44 23066 0.995 0.15 61,482 0.999

a k and n (dimensionless) values were obtained by fitting rotationalspeed–viscosity data to power-law model, g = kc(n�1), where g is theapparent viscosity, k is consistency index and n is flow behaviour index.

C. Sarıc�oban et al. / Meat Science 80 (2008) 599–606 605

apparent viscosity values (AV) by power-law equation ofthe all emulsions. The AV versus c data for the emulsionsat temperature of 20 �C were well fitted to the Ostwald-de-Waele model or power-law model with high determinationcoefficients (r2 = 0.964–0.999). The values of n of emulsionsamples were found to be less than unity. These modelemulsions showed a non-Newtonian flow in which AVdecreased with speed. Therefore, it can be said that allemulsion samples exhibited a typical shear-thinning behav-iour, as also can be clearly seen in Figs. 3 and 4, thus, theseO/W model emulsions can be regarded as pseudoplasticfluids. For all the emulsion samples with DA tested, thepseudoplasticity increased as the concentration increased:the k values rose, but n values fell. However, the modelemulsions with RA did not behave in a similar fashion:the consistency values of samples with RA showed anincrease followed by a decrease, showing a peak at the5% of concentration (Table 3), as seen in the trendobserved in the EC values (Table 2).

4. Conclusions

Albedo addition increased the lightness of the emulsionsamples. Dehydrated albedo addition gave rise to higherL*, a* and b* values than did raw albedo addition. In thisresearch, the model system revealed that addition of albedoincreased emulsion capacity (EC) and stability of the model(O/W) emulsions. However, the EC of O/W emulsions wasnegatively affected by further increase exceeding 5% level inalbedo concentration. The addition of albedo as a dehy-drated form yielded better results in terms of the emulsionparameters. Emulsion viscosity (EV) was positively affectedby an increase in the albedo concentration. Increase in EVis desired in the high fat emulsion type products. Accord-ingly, when high fat emulsion type products are produced,the advantage of albedo addition should be taken into con-sideration to produce better product. Albedo addition didnot change the flow behaviour type of the model systememulsions, and even increased the pseudoplasticity. As aconsequence, lemon albedo at 5% level, is a potentiallygood source of dietary fiber for frankfurter-type meatproducts to enhance these emulsion properties.

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