Food Processing & Technology Jambrak et al., J Food Process Technol 2012, 3:3 http://dx.doi.org/10.4172/2157-7110.1000145 Research Article Open Access Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures Anet Režek Jambrak1*, Doriane Lerda2, Ranko Mirčeta1, Marina Šimunek3, Vesna Lelas1, Farid Chemat2, Zoran Herceg1 and Verica Batur1 1 2 3 Faculty of Food Technology and Biotechnology, University of Zagreb, 10000 Zagreb, Pierottijeva 6, Croatia UMRA 408 INRA, University of Avignon, Safety and Quality of Products of plant origin, 33 Rue Louis Pasteur, 84029 Avignon cedex, France Vindija D.O.O, Medimurska 6, 42000 Varazdin, Croatia Abstract The aim of this study was to determine the effect of high power ultrasound on functional properties of ice-cream model mixtures. Mixture composed of sucrose, glucose, whole milk powder, whey protein concentrates (WPC) and distilled water was ultrasonically treated according to different parameters. Amplitude of ultrasounds, percentage of WPC in the sample and time of treatment are the three variables considered. Effect of ultrasound parameters on rheological properties (measurement of coeficient of consistency), thermal properties (measurement of initial freezing point) and foaming properties (measurement of maximal foam capacity) was observed. Experiment was designed using model called Central Composite Design (CCD) permitting to consider the signiicant factors for each property, and results were analyzed and process was optimized through response surface methodology-RSM. Through study, optimal conditions of ultrasound treatment (amplitude, treatment time and percentage of WPC) by which experiment should be performed were obtained. The factor “percentage of WPC” is signiicant from a rheological and thermal point of view. Regarding foaming properties, the signiicant factor that is to say affecting most the value of the maximum foam capacity is the duration of ultrasound treatment. Keywords: High power ultrasound; Ice-cream model mixtures; Response surface methodology; Physical properties; Optimization Introduction Sonication technology can improve the process through reduced processing time, higher throughput and lower energy consumption [14]. Ultrasound technology is based on mechanical waves at a frequency above the threshold of human hearing (>16 kHz). hese waves travel either through the bulk of a material or on its surface at a speed which is characteristic of the nature of the wave and the material through which it is propagating [1,5]. Ultrasound can be divided into diferent frequency fields: high frequency low energy diagnostic ultrasound in the MHz range and low frequency high-energy power ultrasound in kHz range [6]. Ultrasound can be used in conjunction with pressure treatment (manosonication), heat treatment (thermosonication) or both (manothermosonication) [6]. Usually, the high frequency ultrasounds are used as an analytical technique for quality assurance, process control or non destructive inspection. For example, high frequency ultrasounds is useful to control characteristic values like low rate or to determine food properties [6]. For low frequency high-energy power ultrasounds, application in food industry is relatively new. he main use of this kind of ultrasound treatment is made in the field of extraction where ultrasounds permit to improve the yield and to decrease the necessary time. Innovative researches appeared since past years to propose new applications of ultrasounds in food industry [1,7-10]. Ultrasound efects on liquid systems are mainly related to the cavitation. his phenomenon is that ultrasound is propagated via a series of compression and rarefaction waves induced on the molecules of the medium passed through [5]. Ice cream is an aerated water and suspension of crystallized fat in highly concentrated sugar solution containing hydrocolloids, casein micelles and proteins. he importance of the fat structure and colloidal aspects of ice cream are widely recognized today, as fat structure is the underlying explanation for dryness of ice cream at extrusion from J Food Process Technol ISSN:2157-7110 JFPT, an open access journal the barrel freezer, malleability, and shape retention during meltdown, and smooth-eating texture [11]. he basic steps in the manufacturing of ice cream are generally as follows: blending, pasteurization, homogenization, aging the mix, freezing, packaging and hardening [12]. he temperature is a very important parameter to consider for the production of ice-cream. Cooling and/or freezing as a means of preservation of food has been used for hundreds of years through the use of natural ice or overwinter storage. One very important area related to freezing in the food industry is the formation of ice crystals during the freezing of water present in the food material. Sonication is thought to enhance both the nucleation rate and rate of crystal growth in a saturated or super cooled medium by producing a large number of nucleation sites in the medium throughout the ultrasonic exposure. Acoustic cavitation also occurs and acts as nuclei for crystal growth or by the disruption of nuclei already present. In freezing, this phenomenon would lead to ine ice crystals and shortening of the time between the onset of crystallization and the complete formation of ice, thus reducing damage to cellular structure. Ultrasound could be useful tool to obtain better physical and functional properties of treated material but caution should be taken care if oils of fats are present in the system. Chemat et al. [13] reported an increase in deterioration of *Corresponding author: Anet Režek Jambrak, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000 Zagreb, Pierottijeva 6, Croatia, Tel: +385-1-4605-035; Fax: +385-1-4605-072; E-mail: arezek@pbf.hr Received December 10, 2011; Accepted January 21, 2012; Published January 24, 2012 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Copyright: © 2012 Jambrak AR, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Volume 3 • Issue 3 • 1000145 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Page 2 of 6 sonicated sunlower oil samples processed for 2 min (20 KHz, 150 W). he ultrasound assisted lipid oxidation is attributed to the cavitation phenomenon, which afected structural and functional components leading to lipid oxidation. he collapse of cavitation bubbles in the emulsions result in formation of energy accumulated hot spots having temperatures above 5000ºC and pressure of 500 MPa which caused lipid oxidation by mechanisms like the thermal efect, due to free radicals generated during sonication and mechanical forces created by micro-streaming and shock waves. Furthermore intense mechanical stress and agitation owing to shear and turbulence during sonication lead to oxygen inclusion and distribution within the material which will increase the rate of lipid oxidation. Furthermore it has shown that oxygen availability in the system is related to an increase in lipid oxidation during the time. he objective of this study was to investigate the efect of high power ultrasound and ice-cream model mixtures on functional and physical properties. Efect of ultrasound processing parameters (amplitude, treatment time and percentage of WPC) on rheological properties (measurement of coeicient of consistency), thermal properties (measurement of initial freezing point) and foaming properties (measurement of maximal foam capacity) was observed. Materials and Methods Samples Samples were prepared according to three diferent recipes resumed in Table 1. here was 3 diferent mixtures varied according percentage (%) of whey protein concentrate (WPC), and denoted A (10% WPC), B (12% WPC) and C (14% WPC). Model mixture, composed by sucrose, glucose, whole milk powder, whey protein concentrate (WPC) and distilled water, was ultrasonically treated according to diferent parameters. Experiment has been designed by Central Composite Design (CCD). Untreated samples were denoted as A, B and C, and ultrasound treated one as A1-A16. Composition of Whey Protein concentrate-WPC (“Meggle” GmbH, Wasserburg, Germany) is protein: 60%; water: 3.0%, ashes: 6.0%, lactose: 25.0%, fat: 6.0%; Whole Milk Powder - WMP (“DUKAT”, Zagreb, Croatia) is: protein: 26.3%; fat: 26.1%; lactose: 39.8%; ashes: 3.0%; water: 4.8%; Sucrose (Viro Tvornica Secera, Virovitica, Croatia) and Glucose. Each sample was prepared in a 400 mL glass and homogenized by vigorous hand mixing followed by a magnetic stirring for 15 min. he final volume of samples was 300 mL. Experimental methodology In this study, experiment was designed in STATGRAPHICS Centurion (StatPoint technologies, Inc, VA 20186, USA) sotware. Experiment consists of 16 experimental trials (Table 2). he variables were percentage (%) of whey protein concentrate (WPC),-X1 (%), amplitude-X2 (%) and treatment time-X3 (min). he operating variables were considered at three levels namely, low (-1), central (0) and high (1). Central composite design has been created: 23+ star which study the efects of 3 factors in 16 runs. he design has been run in a single block. he order of the experiments has been fully randomized. his provides protection against the efects of lurking variables. Repetition experiments were carried out ater other experiments followed by order of runs designed by program. Response (output) values were for rheological properties: values of consistency coeicient, J Food Process Technol ISSN:2157-7110 JFPT, an open access journal for thermal properties: values of initial freezing point and for foaming properties: values of maximal foam capacity. In order to optimize the ultrasound treatment and investigate efects of above variables on rheological properties, thermal properties and foaming properties, central-composite face centered design with the variables at three levels was used in the experiment (Table 2). Design matrix for the experiment and the regression model proposed for response was given below [14]: Y = β 0 + ∑ βi X i + ∑ βii X i2 + ∑ βij X i X j 3 3 3 i =1 i =1 i〈 j (1) where β0 is the value of the ixed response at the central point of the experiment which is the point (0, 0, 0); βi, βii and βij are the linear, quadratic and cross-products coeicients, respectively. While demonstrating the signiicant efects 3-dimensional itted surfaces were drawn [15,16]. he model was itted by multiple linear regressions (MLR). Experimental results were analyzed by response surface methodology (RSM). Calculations were done at 95% of conidence level. Analysis of variance (ANOVA) was carried out to determine any signiicant diferences (p<0.05) among the applied treatments. Ultrasound treatments hree parameters were varied according STATGRAPHICS computer sotware, namely, amplitude of ultrasound (50, 75 and 100%), percentage of WPC (10%, 12% and 14%) in the sample and time of treatment (3, 6 or 9 minutes) (Table 2). Ater sample homogenization, samples were treated by ultrasounds 20 kHz probe: S-4000 (Misonix Sonicators, Newtown, Connecticut, SAD) and samples were denoted as A1-A16. he probe with a titanium tip of 12.7 mm in diameter was RECIPES Sucrose A B C 10. 0% 10. 0% 10. 0% Glucose 8.0% 8.0% 8.0% Whole Milk Powder (WMP) 8.0% 6.0% 4.0% Whey Protein Concentrate (WPC) 10.0% 12.0% 14.0% Water 64.0% 64.0% 64.0% Table 1: Composition of the different samples. Samples % of Amplitude WPC (%) Time (min) Power (W) Energy (J) Ti (°C) Tf (°C) A1 14 100 3 100 19.145 19 34 A2 12 75 6 82 30.954 19 43 A3 10 100 3 103 18.884 20 34 A4 12 75 6 79 29.467 20 42 A5 10 50 3 62 11.041 20 28 A6 14 50 9 60 34.423 20 45 A7 14 100 9 99 60.125 19 61 A8 12 50 6 62 23.048 20 37 A9 12 75 3 83 15.101 18 30 A10 14 75 6 78 29.627 19 41 A11 10 50 9 57 32.674 19 42 A12 10 75 6 78 29.168 19 40 A13 12 100 6 102 37.825 20 48 A14 14 75 9 76 42.952 20 50 A15 10 100 9 92 54.358 18 56 A16 14 50 3 63 11.436 19 28 Table 2: Treatments, values of three parameters: amplitude, time and percentage of WPC; power, energy input and temperature before (Ti) and after treatment (Tf). Volume 3 • Issue 3 • 1000145 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Page 3 of 6 introduced in the sample (300 mL) so that the same part of probe was immersed in the liquid (about 2 cm) and the tip was at the “center” of the mix. law, in addition with linear least square method for regression analysis. τ = ηapp γ (5) Determination of acoustic power Determination of thermophysical properties of ice-creams model mixtures he most widely accepted method for determining the power from an acoustic horn into an aqueous solution is the calorimetric technique described by Margulis and Maltsev [17]. his method involves taking a known volume of sample and applying ultrasound (for ca.3 min) while monitoring the change in temperature with time for various ultrasonic amplitudes. he ultrasonic power can be readily determined from the following equation: ∂T (2) P = m × Cp × ∂t Where P is the ultrasonic power (W), m is the mass of the sample (kg), Cp is the speciic heat capacity and dT/dt is change in temperature during sonication of sample in time. Parameters of thermophysical properties were determined using data logger apparatus (KTT 300, Kistock, KIMO) that measures temperature of referent material (quartz sand) and examined material (ice-cream model mixtures). Instrument is connected and operated through computer with sotware (Kilog, KIMO, France). Measurements were performed continuously in the temperature interval from -30ºC to 0ºC, with intervals of measurements of 0.01ºC. he apparatus had high frequency of sampling (10 measurements per second). Distilled water was used as calibration substance for the static correction (0.88ºC) of the initial freezing point. As results, initial freezing temperature and initial thawing temperature for each sample were obtained. Results and Discussion Foaming properties of ice-creams model mixtures For determination of foaming properties samples were prepared as described in section 2.1 and then ultrasonically treated as described in section 2.3. Ater ultrasound treatment, suspensions were whipped at room temperature with blender (TIP 3228, Gorenje, Slovenia) equipped with a wire whip beater at maximum speed setting for up to 15 min to determine maximum foam expansion. Whipping was interrupted every 5 minutes during the run in order to determine foam expansion. Foam expansion was determined by level-illing a 100 mL plastic weighing boat with foam and then weighed. Foam expansion was calculated using the expression: Foam expansion (%) = Unwhipped suspension wt (g) - foam wt (g) × 100 Unwhipped suspension wt (g) (3) Foam stability was determined by transferring 100 mL of maximum expansion foam into a pyrex ilter funnel with dimensions of 7.5 cm inner top diameter, 0.4 cm inner stem diameter and 7.0 cm stem length. A small plug of glass wool was placed in the top of the funnel stem to retain the foam but allow drainage of the liquid. he time required (min) for drainage of the entire foam was determined for index of foam stability [18]. Determination of rheological properties of ice-creams model mixtures Torque measurements were carried out on the 10% (w/w) model dispersions using a Rheometric Viscometer (Model RM 180, Rheometric Scientiic, Inc., Piscataway, USA) with the spindle (no. 3; Ø=14 mm; l=21 cm). Shear stress against the increasing shear rates from lowest value of 0s-1 to 1290s-1 as well as downwards was applied. Volume of the beaker was 36 mL. he samples were kept in a thermostatically controlled water bath for about 15 minutes before measurements in order to attain desirable temperature of 25ºC. Measurements were done in triplicates for each sample. he shear rate versus shear stress was interpreted using the Rheometric computer program. he values for n and k were obtained from plots of log shear stress versus log shear rate, according to the power law equation: log τ = log k +n log γ (4) Where τ is the shear stress (Pa); γ is the shear rate (s-1); n is the low behavior index, and k is the consistency index (Pa sn). Apparent viscosity (ηapp) was calculated at 1290 s-1 using Newtonian J Food Process Technol ISSN:2157-7110 JFPT, an open access journal he inluence of ultrasound parameters (amplitude and treatment time) and percentage of WPC on rheological, thermophysical (DTA) and foaming properties of ice cream model mixtures have been analyzed. Diferent results were interpreted according to Central Composite Design (CCD) and response surface methodology (RSM) permitting to consider the signiicant factors for each property. Actual power of ultrasound in the study was from 57-103 W cm-2 (Table 1). In order to test the model signiication and suitability, analysis of variance (ANOVA) were carried out. In Table 3 phase transition temperatures (initial freezing and melting temperatures) for ice-cream model mixtures are shown. here is obvious signiicant inluence (p<0.05) of percentage of whey protein concentrate in ice-cream model mixtures, on initial freezing and melting temperatures. here is statistically signiicant inluence (p<0.05) in decreasing of initial freezing temperatures for ice-cream model mixtures containing 14 Sample Initial freezing temperature (°C) Top of freezing curve (°C) Initial melting temperature (°C) Top of melting curve (°C) A - 2.7 - 8.5 - 7.9 - 1.4 B - 2.7 - 8.0 - 7.0 - 2.4 C - 1.6 - 7.7 - 6.8 - 0.8 A1 - 1.4 - 7.3 - 7.1 - 1.3 - 1.3 A2 - 1.7 - 8.0 - 7.1 A3 - 2.5 - 7.7 - 6.8 -1.4 A4 - 2.7 - 7.9 - 6.1 - 1.7 A5 - 2.3 - 7.0 - 6.7 - 1.8 A6 - 2.0 - 7.5 - 6.7 - 1.9 A7 - 1.7 - 8.1 - 7.3 - 1.2 A8 - 2.6 - 8.1 - 6.5 - 1.6 A9 - 1.6 - 8.0 - 7.4 - 1.2 A10 - 1.6 - 7.6 - 6.6 - 0.8 A11 - 2.6 - 7.0 - 6.2 - 1.7 A12 - 2.4 - 7.4 - 6.4 - 1.8 A13 - 2.0 - 8.1 - 7.2 - 1.7 A14 - 1.9 - 7.8 - 7.5 - 1.5 A15 - 1.9 - 7.5 - 6.7 - 1.7 A16 - 2.1 - 8.0 -6.7 - 1.6 Table 3: Initial and inal freezing and melting temperatures of ice-cream model mixtures (untreated and treated). Volume 3 • Issue 3 • 1000145 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Page 4 of 6 % of WPC. Amplitude of ultrasound and treatment time have not shown signiicant inluence (p>0.05) in changes of initial freezing temperatures (Table 4). Ultrasound can promote ice nucleation due to cavitations and enhance heat and mass transfer due to microstreming agitation [7]. his might be due to the accumulated thermal efect which is proportional to acoustic duration. Data for foaming properties are given in Table 4. For untreated samples, for increase in percentage of WPC in ice-cream model mixture there is increase in foam capacity (%) for 14% WPC samples. here is increase in foam capacity (%) for prolonged mixing time (5 to 15 min). Also, increase in foam stability index (sec) and maximum foam stability (min) for higher WPC percentage (14%). Ater ultrasound treatment of ice-cream model mixtures, there is signiicant reduction in foam capacity (%) for all samples. here are interesting data where no foaming properties could be observed for samples A1, A5, A8, A9 and A16 ater ultrasound treatment. From Table 5 there is statistically signiicant (p<0.05) inluence of treatment time on foaming capacity. Whey protein concentrates exhibited diferent foaming properties due to the presence of carbohydrates and fat in its composition. Foaming values for both foam capacity and stability were generally lower because of WPC composition. Lactose and fat amount reduced the ability of whey proteins to propagate at air-water interface. Foam stabilities are reduced for all treatments and all model systems ater ultrasound treatment as compared to untreated ones (Tables 6), because of the formation of foams with larger foam lamellas what makes them more fragile [8]. On contrary, for samples A13, A14 and A15 there is increase in foam stability index ater ultrasound treatment. his could be explained for prolonged ultrasound treatment time and highest amplitude for these samples. Ultrasound applied might is causing Foam capacity (%) Sample Mixing time 5 min 10 min 15 min Foam stability index (sec) A 98.01 100.02 103.2 75 63.51 B 110.20 115.20 118.6 78 68.62 C 120.03 121.4 128.3 98 70.35 74.31 76.19 78.89 20 3.2 78.01 78.58 81.07 14 2.7 A6 78.90 83.80 84.10 120 24 A7 81.65 83.36 83.73 329 56.81 A10 71.78 76.74 82.04 30 2.23 A11 76.94 78.26 78.42 24 4.45 A12 73.79 76.91 77.40 22 3.28 A13 80.22 83.35 83.78 342 53.45 A14 80.30 83.15 81.68 360 60.58 A15 80.58 81.74 82.55 141 22.32 A1 * A2b A3* Ab A5* A8* A9* A16* *no foaming of samples Table 6: Foaming properties. T = 20°C 25 untreated sample A Sum of Squares Df Mean Square F-Ratio P-Value A : WPC 0.841 1 0.841 5.93 0.0508 B : Amplitude 0.441 1 0.441 3.11 0.1283 C : time 0.004 1 0.004 0.03 0.8721 0.00226489 1 0.00226489 0.02 0.9036 AA AB 0.03125 1 0.03125 0.22 0.6554 AC 0.03125 1 0.03125 0.22 0.6554 BB 0.193174 1 0.193174 1.36 0.2875 BC 0.03125 1 0.03125 0.22 0.6554 CC 0.205674 1 0.205674 1.45 0.2738 Total error 0.85094 6 0.141823 Total (corr.) 2.5375 15 R2 = 66.4654 %. R2 (adjusted for df) = 16.1636 %. Table 4: Analysis of variance (ANOVA) for initial freezing temperature. Sum of Squares Df Mean Square F-Ratio A : WPC Source 13.225 1 13.225 0.03 P-Value 0.8794 B : Amplitude 766.325 1 766.325 1.45 0.2734 C : time 16849.4 1 16849.4 31.95 0.0013 AA 651.208 1 651.208 1.23 0.3090 AB 2.53125 1 2.53125 0.00 0.9470 AC 5.88245 1 5.88245 0.01 0.9193 BB 1289.19 1 1289.19 2.44 0.1690 BC 1.7672 1 1.7672 0.00 0.9557 CC 1414.53 1 1414.53 2.68 0.1526 Total error 3164.66 6 527.443 Total (corr.) 24878.1 15 R2 = 87.2793 %. R2 (adjusted for df) = 68.1983%. Table 5: Analysis of variance (ANOVA) for foaming properties. J Food Process Technol ISSN:2157-7110 JFPT, an open access journal shear stress (Pa) 20 Source Maximum foam stability (min) 3 min, A = 100% (A3) 15 3 min, A = 50 % (A5) 10 9 min, A = 50 % (A11) 6 min, A = 75 % (A12) 5 9 min, A = 100 % (A15) 0 0 500 1000 shear rate (1/s) 1500 Figure 1: Shear stress versus shear rate behavior of untreated and ultrasound treated samples prepared with 10% of WPC. homogenization efect. Mechanical homogenization process tended to increase the foaming power. he homogenization efect of ultrasound usually disperses the protein and fat particles more evenly, which may improve the foaming stability [19]. his could later prevent collapse of foam and promote production of more stable foam. In Figures 1, 2 and 3 shear stress versus shear stress relationship is shown for samples containing 10, 12 or 14% of WPC. From calculations, and from low behavior values it could be concluded that all systems (non-treated and ultrasound treated) had dilatant (n>1), non-newtonian behavior (data not shown). In Table 7 analysis of variance (ANOVA) showed that percentage of WPC had statistically signiicant (p<0.05) inluence on rheological parameter (consistency coeicient). Combined 3D and contour plots representing the linear and quadratic efects of the independent variables are shown in Figures 4, 5 and 6. he analysis of variance (ANOVA) showed that the resultant quadratic polynomial models adequately represented the experimental Volume 3 • Issue 3 • 1000145 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Page 5 of 6 In Table 8 optimized values for each examined factor is given. T = 20°C Estimated Response Surface Amplitude=75,0 consistency coefficient (Pa s n) rheology data. he signiicance of experimental factors which afect the treatment process may be quantiied from the model coeicients, multiple determinations and probabilities that were generated from STATGRAPHICS sotware. he predicted response models were signiicant for all examined parameters (p<0.0001) and itted well with the experimental data with low RMSE and high regression coeicients (R2). he predicted values were within the 95% prediction limit. (X 0,00001) 37 27 17 7 untreated sample B 25 -3 10 6 min, A = 75 % (A2) 11 12 20 Shear stress (Pa) 6 min, A = 75 % (A4) 15 6 min, A = 50 % (A8) 3 14 4 5 7 8 9 time WPC Figure 4: Surfaces obtained with RSM study: rheological parameter (consistency coeficient Pa sn) behavior in function of time of treatment, % of WPC and estimated response surface at amplitude = 75%). 10 3 min, A = 75 % (A9) 5 6 min, A = 100 % (A13) 0 Estimated Response Surface time=6,0 9 min, A = 75 % (A14) 1000 Shear rate (1/s) 1500 °C 500 Figure 2: Shear stress versus shear rate behavior of untreated and ultrasound treated samples prepared with 12% of WPC. T = 20°C 25 untreated sample C 20 -1,6 initial freezing temperature 0 Shear stress (Pa) 13 6 -1,8 -2 -2,2 -2,4 -2,6 -2,8 10 11 3 min, A = 100 % (A1) 15 9 min, A = 50 % (A6) 10 9 min, A = 100 % (A7) 12 13 14 50 60 70 80 90 100 Amplitude WPC Figure 5: Surfaces obtained with RSM study: initial freezing temperature behavior in function of amplitude applied, % of WPC and estimated response surface (time = 6 min). 6 min, A = 75 % (A10) 5 Estimated Response Surface Amplitude=75,0 3 min, A = 50 % (A16) 0 200 400 600 800 1000 Shear rate (1/s) 1200 1400 Figure 3: Shear stress versus shear rate behavior of untreated and ultrasound treated samples prepared with 14% of WPC. Source Sum of Squares Df Mean Square F-Ratio P-Value A : WPC 1.34282E-7 1 1.34282E-7 13.91 0.0097 B : Amplitude 3.42576E-8 1 3.42576E-8 3.55 0.1086 C : time 1.27092E-8 1 1.27092E-8 1.32 0.2949 0.9043 AA 1.51862E-10 1 1.51862E-10 0.02 AB 2.25888E-8 1 2.25888E-8 2.34 0.1769 AC 4.11989E-8 1 4.11989E-8 4.27 0.0843 BB 6.62778E-9 1 6.62778E-9 0.69 0.4390 BC 1.88277E-8 1 1.88277E-8 1.95 0.2120 0.84 0.3957 CC 8.0738E-9 1 8.0738E-9 Total error 5.79096E-8 6 9.6516E-9 Total (corr.) 3.55415E-7 15 R2 = 83.7065 %. R2 (adjusted for df) = 59.2662%. Table 7: Analysis of variance (ANOVA) for rheology. J Food Process Technol ISSN:2157-7110 JFPT, an open access journal foaming Foamproperties capacity (%) 0 120 100 80 60 40 20 0 10 6 11 12 WPC 13 14 3 4 7 8 9 5 time Figure 6: Surfaces obtained with RSM study: foaming properties behavior in function of time, % of WPC and estimated response surface at ixed amplitude (75%). Optimum value is obtained and predicted according data obtained. Optimum value for consistency coeficient was obtained with the following treatment: percentage of WPC = 14%; amplitude = 100%; time = 9 min. Optimum value for initial freezing temperature was obtained with the following treatment: percentage of WPC = 14%; Volume 3 • Issue 3 • 1000145 Citation: Jambrak AR, Lerda D, Mirčeta R, Šimunek M, Lelas V, et al. (2012) Experimental Design and Optimization of Ultrasound Treatment: Functional and Physical Properties of Sonicated Ice Cream Model Mixtures. J Food Process Technol 3:145. doi:10.4172/2157-7110.1000145 Page 6 of 6 a) rheological parameter (optimum value of consistency coeficient = 0,000562348 Pa sn) Factor Low High Optimum WPC 10.0 14.0 14.0 Amplitude 50.0 100.0 100.0 Time 3.0 9.0 9.0 Optimum value was obtained with the following treatment: Percentage of WPC = 14%; - Amplitude = 100%; Time = 9 min. b) Thermophysical parameters (optimal value of initial freezing temperature = -1,36436°C Factor Low High WPC 10.0 14.0 Optimum 14.0 Amplitude 50.0 100.0 84.7005 Time 3.0 9.0 3.0 Optimum value was obtained with the following treatment: Percentage of WPC = 14%; - Amplitude = 84.7005%; Time = 3 min. c) Foaming properties (optimal value of maximal foam capacity = 105,915%) Factor Low High Optimum WPC 10.0 14.0 14.0 Amplitude 50.0 100.0 79.8809 Time 3.0 9.0 8.8885 Optimum value was obtained with the following treatment: Percentage of WPC = 14%; Amplitude = 79.8809%; Time = 8.885 min. Table 8: Optimized values of rheological (a) thermo physical (b) and foaming properties (c) at optimal processing parameters (ultrasound amplitude and treatment time and % of WPC). amplitude = 84.7005%; time = 3 min. Optimum value for foaming capacity was obtained with the following treatment: percentage of WPC = 14%; amplitude = 79.8809%; time = 8.885 min. Conclusion Amplitude of ultrasound, percentage of WPC in the sample and time of treatment are the three variables considered to efect rheological properties (measurement of coeicient of consistency), thermal properties (measurement of initial freezing point) and foaming properties (measurement of maximal foam capacity). Experiment was adequately designed using model called Central Composite Design (CCD) and results were analyzed and process was optimized through Response surface methodology-RSM. here is obvious signiicant inluence of percentage of whey protein concentrate in ice-cream model mixtures, on initial freezing and melting temperatures. here are interesting data where no foaming properties could be observed for samples A1, A5, A8, A9 and A16 ater ultrasound treatment. here is statistically signiicant inluence of treatment time on foaming capacity. Percentage of WPC had statistically signiicant inluence on rheological parameter (consistency coeicient). Optimum value is obtained and predicted according data obtained. Optimum value for consistency coeficient, for initial freezing temperature and for foaming capacity was obtained with statistical analysis. References 1. Chemat F, Zill-e-Huma, Khan MK (2011) Applications of ultrasound in food technology: Processing, preservation. and extraction. 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