title: Impact of blanching and packaging atmosphere on the formation of aroma compounds during long-term frozen storage of leek (Allium ampeloprasum Var. Bulga) slices.
abstract: The content of aroma compounds and the catalytic activity of lipoxygenase (LOX), alliinase, hydroperoxide lyase (HPL), and alcohol dehydrogenase (ADH) were analyzed in unblanched and blanched 15-mm leek slices packed in atmospheric air (21% O2) or 100% nitrogen (0% O2) three times during 12 months of frozen storage (12 M). The total amount of sulfur compounds and the total amount of aldehydes were greatly influenced by storage time, atmosphere, and blanching [concentration of sulfur compounds in fresh unblanched (UNB) slices = 1.35 mg/L, fresh blanched (B) slices = 1.09 mg/L, UNB 21% O2 12 M = 0.656 mg/L, UNB 0% O2 12 M = 2.11 mg/L, B 21% O2 12 M = 1.14 mg/L, B 0% O2 12 M = 1.59 mg/L]. B 0% O2 was closest to the original ratio between sulfur compounds and aldehydes after 12 months. The activities of HPL and alliinase were totally lost after 12 months, and ADH showed minimal activity, whereas LOX (UNB 0% O2) showed approximately 25% of the original activity. LOX was the most and HPL the least heat labile enzyme investigated.
authors.affiliation: Department of Food Science and LMC, Centre of Advanced Food Studies, The Royal Veterinary and Agricultural University, Rolighedsvej 30, 1958 Frederiksberg C, Denmark. gni@kvl.dk
authors.forename: Ghita Studsgaard
authors.initials: GS
authors.lastname: Nielsen
authors.forename: Lone Melchior
authors.initials: LM
authors.lastname: Larsen
authors.forename: Leif
authors.initials: L
authors.lastname: Poll
mesh_terms: D000446:Aldehyde-Lyases / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D018857:Food Packaging / Q000379:methods*; D005615:Freezing; D006358:Hot Temperature; D008084:Lipoxygenase / Q000378:metabolism; D009584:Nitrogen / Q000008:administration & dosage; D009812:Odorants / Q000032:analysis*; D019697:Onions / Q000737:chemistry* / Q000201:enzymology; D010100:Oxygen / Q000008:administration & dosage
chemical_list: D003577:Cytochrome P-450 Enzyme System; D008084:Lipoxygenase; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase; D009584:Nitrogen; D010100:Oxygen