Heat stability and acid gelation properties of calcium-enriched reconstituted skim milk affected by ultrasonication.
The aggregation of proteins after heating of calcium-fortified milks has been an ongoing problem in the dairy industry. This undesirable effect restricts the manufacture of calcium rich dairy products. To overcome this problem, a completely new approach in controlling the heat stability of dairy protein solutions, developed in our lab, has been employed. In this approach, high intensity, low frequency ultrasound is applied for a very short duration after a pre-heating step at ⩾70 °C. The ultrasound breaks apart whey/whey and whey/casein aggregates through the process of acoustic cavitation. Protein aggregates do not reform on subsequent post-heating, thereby making the systems heat stable. In this paper, the acid gelation properties of ultrasonicated calcium-enriched skim milks have also been investigated. It is shown that ultrasonication alone does not change the gelation properties significantly whereas a sequence of preheating (72 °C/1 min) followed by ultrasonication leads to decreased gelation times, decreased gel syneresis and increased skim milk viscosity in comparison to heating alone. Overall, ultrasonication has the potential to provide calcium-fortified dairy products with increased heat stability. However, enhanced gelation properties can only be achieved when ultrasonication is completed in conjunction with heating.
Advanced Food Systems Research Unit, College of Health and Biomedicine, Victoria University, VIC 3030, Australia.
Jayani
J
Chandrapala
School of Chemistry/Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
Don
D
Bui
School of Chemistry/Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
Sandra
S
Kentish
School of Chemistry/Department of Chemical and Biomolecular Engineering, University of Melbourne, VIC 3010, Australia.
Muthupandian
M
Ashokkumar
D000818:Animals; D002118:Calcium / Q000008:administration & dosage*; D002136:Calcium, Dietary / Q000008:administration & dosage; D002364:Caseins / Q000737:chemistry; D004355:Drug Stability; D004548:Elasticity; D005511:Food Handling / Q000379:methods; D005527:Food, Fortified; D057141:Food, Preserved; D005782:Gels / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry; D010316:Particle Size; D012996:Solutions; D013010:Sonication; D014783:Viscosity; D000067816:Whey Proteins
D002136:Calcium, Dietary; D002364:Caseins; D005782:Gels; D008894:Milk Proteins; D012996:Solutions; D000067816:Whey Proteins; D002118:Calcium