title: Microwave-assisted isomerisation of lactose to lactulose and Maillard conjugation of lactulose and lactose with whey proteins and peptides.
abstract: Lactose was isomerised to lactulose by microwave heating and purified by a methanolic procedure to a product with approximately 72% lactulose content. Afterwards, lactose and the lactulose-rich product (PLu) were conjugated with either whey protein isolate (WPI) or its antioxidant hydrolysate (WPH) through microwaving. Lactose had a higher Maillard reactivity than PLu, and WPH was more reactive than WPI. The browning intensity of WPI-sugar systems was however higher than that of WPH-sugar pairs. Atomic force microscopy showed larger (up to ≈103 nm) particles for WPI-PLu conjugates compared to WPH-PLu counterparts (up to ≈39 nm). The Maillard conjugation progressively increased the radical-scavenging activity of WPI/WPH-sugar pairs with increasing conjugation time and improved the foaming properties of WPI and WPH. The WPI/WPH-sugar conjugates showed higher solubility and emulsification index than unreacted counterpart pairs. For native WPI, β-lactoglobulin was not degraded by in vitro gastric digestion, whereas for WPH-PLu conjugates degraded completely.
authors.affiliation: Department of Food Science and Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Nooshkam
authors.affiliation: Department of Food Science and Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Electronic address: a.madadlou@ut.ac.ir.
authors.forename: Ashkan
authors.initials: A
authors.lastname: Madadlou
mesh_terms: D000975:Antioxidants; D007536:Isomerism; D007782:Lactoglobulins; D007785:Lactose / Q000737:chemistry; D007792:Lactulose / Q000737:chemistry*; D015416:Maillard Reaction; D008872:Microwaves / Q000627:therapeutic use*; D010455:Peptides / Q000737:chemistry*; D000067796:Whey; D000067816:Whey Proteins / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D007782:Lactoglobulins; D010455:Peptides; D000067816:Whey Proteins; D007792:Lactulose; D007785:Lactose
keywords: Digestibility; Functional properties; Lactulose; Maillard reaction; Whey protein hydrolysate; Whey protein isolate