Aerated Properties of Ultrasonic Treated Whey Protein Foam for Cake Making

Transcription

1 Proceedings of the 2014 International Conference on Food Properties (ICFP2014) Kuala Lumpur, Malaysia, January 24 26, 2014 Aerated Properties of Ultrasonic Treated Whey Protein Foam for Cake Making 1 Tan, M.C., 1 Chin, N.L.*, 1 Yusof, Y.A., 1 Taip, F.S., and 2 Abdullah, J. 1 Department of Process and Food Engineering, Faculty of Engineering, Universiti Putra Malaysia, UPM Serdang, Selangor, Malaysia. 2 Plant Assessment Technology Group, Malaysian Nuclear Agency (Nuclear Malaysia), Bangi, Kajang, Selangor, Malaysia. *Corresponding author: Tel.: ; Fax: address: chinnl@eng.upm.edu.my Abstract Ultrasound treated whey protein suspension was aerated to foams which in turn was used in batter for making cakes. The effects of using ultrasound at 20 khz for a range of 5 to 25 minutes on 20% concentration of whey protein concentrates were investigated. The aerated properties of foam, batter and cake i.e. foam overrun, batter density and cake density were found to be highly inversely correlated with foam drainage, batter viscosity and cake volume measurements. The ultrasound treatment shows improvement in the aerated properties of foam and the quality of batter and cake where it has increased foaming capacity and stability, increased batter viscosity and cake volume despite lower densities measured in batters and cakes. Keywords Whey Protein Concentrate, Ultrasound, Foam, Batter, Cake 1. Introduction Aeration is important in enhancing the appearance, texture and digestibility of aerated bakery products. Foam is represented in the form of highly aerated confectioneries [1], especially foam style cakes which rely greatly on the foaming and aeration properties for their structure and volume [2]. Hence, foams used in cake making must be stable enough to support its weight and capable to hold other ingredients such as flour and sugar until heat coagulation occurs in the oven for a stable protein matrix development [3]. In cake making, the viscosity of batter is critically controlled as it affects the volume of final cake product. During baking, batter with higher viscosity can retain more air bubbles in the batter by retarding the rise of bubbles to the surface and preventing the entrapped air from coalescing hence reducing shrinkage of cake [4]. The objective of this research is to investigate the use of ultrasonic treatment in improving the aeration properties of foams to be used in a batter and cake systems. The protein suspension is whey protein concentrate at 20% concentration. The ultrasound treatment was done by a 400 W probe operating at 20 khz applied to protein concentrates for 5, 15 or 25 minutes before it was whipped into foams and subsequently used in batter for cake baking. 2. Materials and Methods 2.1 Materials The ingredients used for cake making were commercial low protein flour (Brand Gold Key, FFM Berhad, Selangor, Malaysia), whey protein concentrate (Textrion PROGEL 800, DMV International, BA Veghel, Netherlands), caster sugar (Tien Swee Trading Sendirian Berhad, Kuala Lumpur, Malaysia), and salt (Seng Hin Brothers Enterprises Sendirian Berhad, Selangor, Malaysia).

2 Tan, M.C., Chin, N.L., Yusof, Y.A., Taip, F.S., and Abdullah, J. 2.2 Protein Suspension Preparation and Ultrasound Treatment 20% (w/w) aqueous suspensions of powdered whey protein concentrate were prepared by dispersing 50 g of dry matter into 200 g of distilled water in a 500 ml beaker and stirred using a mechanical stirrer (RW20 DZM n S2, IKA Works (Asia) Sendirian Berhad, Malaysia) at 355 rpm for 20 minutes until homogenous suspensions were obtained. The protein suspensions were then treated with ultrasonic waves for 5, 15 or 25 minutes using a 20 khz-400 W high intensity ultrasound probe (Digital Sonifier Model 450, Branson Ultrasonics Corporation, Danbury, Connecticut, USA) at 60% amplitude. The probe with vibrating titanium tip of 1 inch was immersed in half level at the center of the liquid suspension. The control samples were those without ultrasonic treatment, zero minutes treatment time. 2.3 Cake Preparation The adapted formulation of Angel food cake [5] used is given in Table 1. The treated protein suspension was loaded into a table top mixer (5K5SSS, Kitchen Aid Inc., St. Joseph, Michigan, USA) and whipped for 15 minutes at 330 rpm until it was fully foamed. Sugar was then added into the foam during the extended mixing of 4 minutes. Mixing continues for another 4 minutes at a reduced of 160 rpm where pre-mixed salt with flour was added to obtain cake batter. The mixing speed of cake batter at the final 15 second was increased back to 330 rpm. 450 g of cake batter was poured into the cake pan of 20 cm diameter and baked at 170 o C with oven heat levels setting of 20% (top): 30% (side): 10% (bottom) for 40 minutes in an electronic baking oven (ST-02, Salva Industrial, Spain). Baked cakes were inverted on a wire rack immediately and cooled for 5 minutes before removing it from the tins. The cakes were left in ambient for 1 hour for further cooling [6, 7] before cake analyses. Ingredients Table 1: Angel food cake formulations Mass of cake loading (g) Flour 100 Sugar 250 Salt 3 Protein suspension 250 Total Mass Foaming Capacity Foaming capacity was determined based on the mass of 100 ml of protein suspension in a 100 ml cylinder, and the mass of foam filled and leveled in a 100 ml plastic weighing boat. The average foaming capacity was taken from three samples from each batch of whipped foam. Foaming capacity is expressed in terms of percentage of overrun as given in Equation 1 [8]. Mass suspension Mass foam Overrun (%) 100 (1) Mass 2.5 Foaming Stability Foaming stability was determined from foam drainage at room temperature. A small plug of glass wool was placed at the top of the funnel stem of a filter funnel with dimension 7.5 cm inner top diameter, 0.4 cm inner stem diameter and 7.0 cm stem length to retain 100 ml of fresh whipped foam whilst allowing drainage of liquid [9] for 20 minutes. The average drainage of three samples was taken from every batch of whipped foam. 2.6 Batter Density A standard cup of volume 114 cm 3 was filled with batter and leveled before weighing. Batter density was calculated following Equation 2 [7,10-12] and the average of four samples were taken from every batch of cake batter mix. foam 2.7 Batter Viscosity Batter viscosity was measured using a rheometer (AR-G2, TA Instruments, New Castle, USA) with a 40 mm diameter serrated plate-plate geometry set at a constant gap height of 2.4 mm at 25 o C [13]. Batter was sheared by linearly increasing shear rate from 0 to 100 s -1 in 5 minutes. Batter viscosities at shear rate 5.5 s -1 were compared. The experiments were conducted in duplicate.

3 Foam Overrun (%) Foam Drainage (ml) Foam Overrun (%) Tan, M.C., Chin, N.L., Yusof, Y.A., Taip, F.S., and Abdullah, J. 2.8 Cake Volume and Density The volume of cake was measured using coriander seeds displacement method [7,10,14] cm 3 of coriander seeds was first filled into a 6220 cm 3 container before a cake was placed on it and then overfilling the remaining space with more seeds. The container was tapped and its surface leveled using a ruler. The total volume of seeds used was equal to the mass of seeds divided by kg/m 3, the pre-determined density of seeds as in Equation 3. The volume of cake was obtained by minus the volume of the container to the volume of seeds as in Equation Statistical Analyses The effect of ultrasound treatment on the aerated properties of foam and quality of batter and cake was determined using single factor ANOVA using Microsoft Excel 2010 (Window 7, Microsoft Corporation, USA). 3. Results and Discussion 3.1 Foaming Capacity and Stability Foaming capacity which is expressed in percentage of overrun, indicates the amount of air incorporated in the foam. Figure 1a shows that the ultrasound treated whey protein concentrate suspensions have higher overruns than the control. Foam overruns were increased gradually from the control by 7%, 12% and 15% with increasing sonication time from zero to 5, 15 and 25 minutes respectively. Previous study also found that foaming capacity of soy protein concentrate and soy protein isolate suspension were increased after being treated with 20 khz of ultrasonic waves at intensity of Wcm -2 for 30 minutes [9]. Foam stability was measured after it attained the least flow. Figure 1a shows that the drainage of foam was 21%, 45% and 35% less than the control when sonication time increased by 5, 15 and 25 minutes respectively. The results suggest that ultrasound treatment was capable in improving the stability of foam and more incorporated bubbles were retained in the foam system giving a higher overrun. The ANOVA results indicate that the ultrasound treatment had significant effects on foaming capacity and stability at P< Figure 1b shows that the foam overrun and foam drainage are inversely related when the coefficient of determination is Foam Overrun Foam Drainage R²= Foam Drainage (ml) Figure 1: Overrun and drainage of foam treated for different sonication time, and correlation between foam overrun and drainage 3.2 Batter Density and Viscosity Figure 2a shows that ultrasound sonicated whey protein suspension can produce lower batter densities by 3.4%, 3.8% and 4.5%, and higher viscosities by 11%, 19% and 31% for 5, 15 and 25 minutes treatment time respectively.

4 Cake Density (kg/m 3 ) Cake Volume (cm 3 ) Cake Density (kg/m 3 ) Batter Density (kg/m 3 ) Batter Viscosity (Pa.s) Batter Density (kg/m 3 ) Tan, M.C., Chin, N.L., Yusof, Y.A., Taip, F.S., and Abdullah, J. Density is an indicator of the amount of air incorporated into batter system [11], where a lower density indicates higher air incorporation. The ANOVA results show that ultrasound treatment effects were more significant on batter density at P<0.001 than for batter viscosity at P<0.1. The batter density and viscosity are also inversely related with coefficient of determination of (Figure 2b) Batter Density Batter Viscosity R²= Batter Viscosity (Pa.s) Figure 2: Density and viscosity of batter treated at different sonication time, and correlation between batter density and batter viscosity 3.3 Cake Volume and Density Ultrasound treated whey protein suspension can produce higher cake volume by 3.4%, 7.6% and 18% and lower cake density by 5.5%, 8.9% and 18% with 5, 15 and 25 minutes treatment time compared to the untreated. The ANOVA results indicate that the ultrasound treatment s effects on both cake volume and density were significant up to P<0.05. The improved cake quality is in the form of increased cake volume and lower density as shown in Figure 3b. This proves that a comparatively smaller and more evenly distributed air bubble structures within the cake structures Cake Density Cake Volume R²= Cake Volume (cm 3 ) Figure 3: Density and volume of cake treated at different sonicated time, and correlation between cake density and cake volume

5 Tan, M.C., Chin, N.L., Yusof, Y.A., Taip, F.S., and Abdullah, J. 4. Conclusion The ultrasound treated whey protein suspension is able to produce foams with higher foaming capacity and stability. These foams bring benefits to producing batters with higher viscosity and cakes with higher volumes and lower density which altogether produce positive impact on cake consuming appeal. Ultrasonic treatment may be applied in the bakery industry as to enhance the overall qualities of whey protein replacement in eggless cake. References 1. Pernell, C. W., Foegeding, E. A., Luck, P. J., and Davis, J. P., 2002, Properties of Whey and Egg White Protein Foams, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 204, Conforti, F. D., 2006, Cake Manufacture, appears in Bakery Products: Science and Technology, Hui, Y. H. (ed.), USA: Blackwell, Indrani, D., and Rao, G. V., 2008, Function of Ingredients in The Baking of Sweet Goods, appears in Food Engineering Aspects of Baking Sweet Goods, Sumnu, S. G. and Sahin, S. (eds.), USA: Taylor & Francis Group, Sahin, S., 2008, Cake Batter Rheology appears in Food Engineering Aspects of Baking Sweet Goods, Sumnu, S. G. and Sahin, S. (eds.), New York, USA: Taylor & Francis Group, LLC, Yamazaki, W. T., and Lord, D. D., 1971, Soft Wheat Flour Products, appears in Wheat Chemistry Technology, Pomeranz, Y. (ed.), Saint Paul, Minnesota, USA: American Association of Cereal Chemists, Incorporated, Gómez, M., Oliete, B., Rosell, C. M., Pando, V., and Fernández, E., 2008, Studies on Cake Quality Made of Wheat-Chickpea Flour Blends, LWT Food Science and Technology, 41, Tan, M. C., Chin, N. L., and Yusof, Y. A., 2011, Power Ultrasound Aided Batter Mixing for Sponge Cake Batter, Journal of Food Engineering, 104, Patel, M.T., and Kilara, A., 1990, Studies on Whey Protein Concentrates. 2. Foaming and Emulsifying Properties and Their Relationships with Physicochemical Properties, Journal of Dairy Science, 73(10), Jambrak, A.R., Lelas, V., Mason, T.J., Kresic, G., and Badanjak, M., 2009, Physical Properties of Ultrasound Treated Soy Proteins, Journal of Food Engineering, 93, Tan, M. C., Chin., N. L., and Yusof, Y. A., 2010, A Box-Behnken Design for Determining the Optimum Experimental Condition of Cake Batter Mixing, Food and Bioprocess Technology: An International Journal, DOI: /s Allais, I., Edoura-Gaena, R. B., Gros, J. B., and Trystram, G., 2006, Influence of Egg Type, Pressure and Mode of Incorporation on Density and Bubble Distribution of a Lady Finger Batter, Journal of Food Engineering, 74, Allais, I., Edoura-Gaena, R. B., and Dufour, E., 2006, Characterisation of Lady Finger Batters and Biscuits by Fluorescence Spectroscopy Relation with Density, Color and Texture, Journal of Food Engineering, 77, Mleko, S., Kristinsson, H. G., Liang, Y., and Gustaw, W, 2007, Rheological properties of foams generated from egg albumin after ph treatment, LWT Food Science and Technology, 40, Sahin, S., and Sumnu, S. G., 2006, Physical Properties of Foods, Springer Science Business Media LLC, New York,