title: Antimicrobial properties of nisin after glycation with lactose, maltodextrin and dextran and the thyme oil emulsions prepared thereof.
abstract: To clarify the reported conflicting antimicrobial activities of nisin after glycation, nisin was glycated with lactose, maltodextrin, and dextran at 70 °C and 50% relative humidity for 1-24 h. Nisin before and after glycation was studied for the first time to prepare thyme oil emulsions. The activity of glycated nisin and the thyme oil emulsions was tested in both tryptic soy broth (TSB) and 2% reduced fat milk. Results showed that nisin glycated with a smaller saccharide for a longer duration had a higher degree of glycation and the reduced number of positive charges lowered its antibacterial activity. The emulsified thyme oil had an additive effect with either glycated or native nisin against Listeria monocytogenes Scott A and Bacillus subtilis in TSB and 2% reduced fat milk. However, emulsions were less effective against L. monocytogenes Scott A in milk than same units of native nisin and same concentration of free thyme oil, likely due to the reduced availability of thymol and carvacrol, the main components of thyme oil. These results showed that glycation of nisin cannot broaden its antimicrobial activity and nisin is not a good compound to prepare emulsions of essential oils.
authors.affiliation: Department of Food Science and Technology, University of Tennessee, Knoxville, United States.
authors.forename: Huaiqiong
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Food Science and Technology, University of Tennessee, Knoxville, United States.
authors.forename: P Michael
authors.initials: PM
authors.lastname: Davidson
authors.affiliation: Department of Food Science and Technology, University of Tennessee, Knoxville, United States. Electronic address: qzhong@utk.edu.
authors.forename: Qixin
authors.initials: Q
authors.lastname: Zhong
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology* / Q000592:standards; D003911:Dextrans / Q000378:metabolism*; D004655:Emulsions / Q000494:pharmacology; D005516:Food Microbiology; D007785:Lactose / Q000378:metabolism*; D008089:Listeria monocytogenes / Q000187:drug effects; D008892:Milk / Q000382:microbiology; D009561:Nisin / Q000378:metabolism / Q000494:pharmacology; D009822:Oils, Volatile / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D046930:Thymus Plant / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D003911:Dextrans; D004655:Emulsions; D009822:Oils, Volatile; D011134:Polysaccharides; D009561:Nisin; C008315:maltodextrin; D007785:Lactose
keywords: Antibacterial activity; Emulsion; Glycation; Nisin; Thyme oil