title: Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.
abstract: The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s).
authors.affiliation: School of Health Sciences, University of Ballarat, Mount Helen, VIC 3353, Australia.
authors.forename: M Amdadul
authors.initials: MA
authors.lastname: Haque
authors.forename: Peter
authors.initials: P
authors.lastname: Aldred
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Barrow
authors.forename: Benu
authors.initials: B
authors.lastname: Adhikari
mesh_terms: D005503:Food Additives / Q000737:chemistry*; D006358:Hot Temperature; D006874:Hydrostatic Pressure; D007700:Kinetics; D007768:Lactalbumin / Q000737:chemistry; D007782:Lactoglobulins / Q000737:chemistry; D008894:Milk Proteins / Q000737:chemistry*; D011489:Protein Denaturation; D000067816:Whey Proteins
chemical_list: D005503:Food Additives; D007782:Lactoglobulins; D008894:Milk Proteins; D000067816:Whey Proteins; D007768:Lactalbumin