Effect of power ultrasound pre-treatment on the physical and functional properties of reconstituted milk protein concentrate

Abstract This work investigated the impact of power ultrasound (PUS) pretreatment on the physical and functional properties of reconstituted milk protein concentrate (MPC) 80. Ultrafiltered/diafiltered (UF/DF) milk protein retentates were treated with PUS (12.50 ± 0.31 W and 50% amplitude) for 0.5, 1, 2, and 5 min prior to spray drying. Results revealed that the particle size (D50) reduced from 28.45 μm to 0.13 μm after 0.5 min of sonication. Solubility increased significantly from 35.78% to 88.30% after 5 min of PUS pre-treatment. Moreover, the emulsifying activity index (EAI) of MPC samples increased significantly as the time of ultrasonic treatment was prolonged. Additionally, the emulsion stability index (ESI) initially increased after ultrasound treatment for 1 min. Surface hydrophobicity was greatly increased with more hydrophobic groups exposed to the environment. PUS pre-treatment also promoted an increase in the storage modulus ( G ′) of the MPC solutions. Viscosity significantly decreased after PUS pre-treatment. This result was confirmed by the microstructure of the powder, with small particles formed and trapped in dents of large particles. However, sodium-dodecyl sulfate–polyacrylamide gel electrophoresis showed no significant change in protein molecular weight.

[1]  P. Sanguansri,et al.  High shear treatment of concentrates and drying conditions influence the solubility of milk protein concentrate powders , 2012, Journal of Dairy Research.

[2]  J. Wagner,et al.  Coalescence of o/w emulsions stabilized by whey and isolate soybean proteins. Influence of thermal denaturation, salt addition and competitive interfacial adsorption , 2002 .

[3]  David Julian McClements,et al.  Food Emulsions: Principles, Practice, and Techniques , 1998 .

[4]  A. Davenel,et al.  Rehydration of casein powders: effects of added mineral salts and salt addition methods on water transfer , 2002 .

[5]  J. Weiss,et al.  Structural and functional changes in ultrasonicated bovine serum albumin solutions. , 2007, Ultrasonics sonochemistry.

[6]  Muthupandian Ashokkumar,et al.  Selected Applications of Ultrasonics in Food Processing , 2009 .

[7]  A. Carr.  The functional properties of milk protein concentrates : a thesis presented for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand , 1999 .

[8]  Pieter Walstra,et al.  Dairy Science and Technology , 2005 .

[9]  V. V. Mistry,et al.  Effect of Lactose and Protein on the Microstructure of Dried Milk , 1992 .

[10]  Zoran Herceg,et al.  Influence of novel food processing technologies on the rheological and thermophysical properties of whey proteins , 2008 .

[11]  E. Dumay,et al.  High-Pressure Unfolding and Aggregation of .beta.-Lactoglobulin and the Baroprotective Effects of Sucrose , 1994 .

[12]  Linda K. Weavers,et al.  Sonolysis of synthetic sediment particles: particle characteristics affecting particle dissolution and size reduction. , 2002, Ultrasonics sonochemistry.

[13]  D. Mulvihill,et al.  Emulsifying and foaming properties of acidic caseins and sodium caseinate , 1988 .

[14]  Muthupandian Ashokkumar,et al.  Ultrasonic processing of dairy systems in large scale reactors. , 2010, Ultrasonics sonochemistry.

[15]  Ulrich Kulozik,et al.  Quantitative assessment of thermal denaturation of bovine alpha-lactalbumin via low-intensity ultrasound, HPLC, and DSC. , 2006, Journal of agricultural and food chemistry.

[16]  Timothy J. Mason,et al.  Physical properties of ultrasound treated soy proteins , 2009 .

[17]  E. Dickinson,et al.  Emulsion stabilization by ionic and covalent complexes of β-lactoglobulin with polysaccharides , 1991 .

[18]  U. Kulozik,et al.  Influence of a thermal treatment on the functionality of hen’s egg yolk in mayonnaise , 2007 .

[19]  Timothy J. Mason,et al.  Effect of ultrasound treatment on solubility and foaming properties of whey protein suspensions , 2008 .

[20]  J. Raso,et al.  Influence of different factors on the output power transferred into medium by ultrasound. , 1999, Ultrasonics sonochemistry.

[21]  J. Weiss,et al.  Interfacial properties and structural conformation of thermosonicated bovine serum albumin , 2006 .

[22]  Y. Mine.  Recent advances in the understanding of egg white protein functionality , 1995 .

[23]  Dietrich Knorr,et al.  Applications and potential of ultrasonics in food processing , 2004 .

[24]  Oscar E. Pérez,et al.  Comparative study of high intensity ultrasound effects on food proteins functionality , 2012 .

[25]  G. Barbosa‐Cánovas,et al.  Microstructure of fat globules in whole milk after thermosonication treatment. , 2008, Journal of food science.

[26]  Jayani Chandrapala,et al.  Effects of ultrasound on the thermal and structural characteristics of proteins in reconstituted whey protein concentrate. , 2011, Ultrasonics sonochemistry.

[27]  A. Pilosof,et al.  Molecular and functional modification of hydroxypropylmethylcellulose by high-intensity ultrasound , 2009 .

[28]  J. Kinsella,et al.  Emulsifying properties of proteins: evaluation of a turbidimetric technique , 1978 .

[29]  S. Nakai,et al.  Relationships of Hydrophobicity and Net Charge to the Solubility of Milk and Soy Proteins , 2006 .

[30]  K. Duangmal,et al.  Structure and functional properties of modified threadfin bream sarcoplasmic protein , 2008 .

[31]  D. Dalgleish.  Adsorption of protein and the stability of emulsions , 1997 .

[32]  Zhengxiao Guo,et al.  High-speed observation of the effects of ultrasound on liquid mixing and agglomerated crystal breakage processes , 2007 .

[33]  E. Dickinson.  Properties of emulsions stabilized with milk proteins: overview of some recent developments , 1997 .

[34]  J. Cheftel,et al.  Determination of sulfhydryl groups and disulfide bonds in heat-induced gels of soy protein isolate , 1988 .