title: Lactose-hydrolyzed milk is more prone to chemical changes during storage than conventional ultra-high-temperature (UHT) milk.
abstract: The enzymatic hydrolysis of lactose to glucose and galactose gives rise to reactions that change the chemistry and quality of ambient-stored lactose-hydrolyzed ultra-high-temperature (UHT) milk. The aim of the present study was to investigate and compare chemical changes in lactose-hydrolyzed and conventional UHT milk during a 9 month ambient storage period. Several complementary analyses of volatiles, free amino acids, acetate, furosine, and level of free amino terminals were concluded. The analyses revealed an increased level of free amino acids and an increased formation rate of specific compounds such as furosine and 2-methylbutanal in lactose-hydrolyzed UHT milk compared to conventional UHT milk during storage. These observations indicate more favorable conditions for Maillard and subsequent reactions in lactose-hydrolyzed milk compared to conventional UHT milk stored at ambient temperature. Furthermore, it is postulated that proteolytic activity from the lactase-enzyme preparation may be responsible for the observed higher levels of free amino acids in lactose-hydrolyzed UHT milk.
authors.affiliation: Department of Food Science, Aarhus University , Kirstinebjergvej 10, DK-5792 Aarslev, Denmark.
authors.forename: Therese
authors.initials: T
authors.lastname: Jansson
authors.forename: Morten R
authors.initials: MR
authors.lastname: Clausen
authors.forename: Ulrik K
authors.initials: UK
authors.lastname: Sundekilde
authors.forename: Nina
authors.initials: N
authors.lastname: Eggers
authors.forename: Steffen
authors.initials: S
authors.lastname: Nyegaard
authors.forename: Lotte B
authors.initials: LB
authors.lastname: Larsen
authors.forename: Colin
authors.initials: C
authors.lastname: Ray
authors.forename: Anja
authors.initials: A
authors.lastname: Sundgren
authors.forename: Henrik J
authors.initials: HJ
authors.lastname: Andersen
authors.forename: Hanne C
authors.initials: HC
authors.lastname: Bertram
mesh_terms: D000447:Aldehydes / Q000032:analysis; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation; D005690:Galactose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006358:Hot Temperature; D006868:Hydrolysis; D043322:Lactase / Q000378:metabolism; D007785:Lactose / Q000378:metabolism*; D008239:Lysine / Q000031:analogs & derivatives / Q000032:analysis; D015416:Maillard Reaction; D008892:Milk / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000596:Amino Acids; C018948:furosine; C547093:2-methylbutanal; D043322:Lactase; D005947:Glucose; D007785:Lactose; D008239:Lysine; D005690:Galactose