title: The effect of various antioxidants on the degradation of O/W microemulsions containing esterified astaxanthins from Haematococcus pluvialis.
abstract: Esterified astaxanthins are used as functional nutraceuticals and pigments in many food products. Unfortunately, the utilization is currently limited due to their chemical instability and poor water-solubility. In this study, esterified astaxanthins were quantified and purified from Haematococcus pluvialis using a novel and precise approach. By HPLC-(+)APCI-MS/MS, twenty esterified astaxanthin molecular species were identified, of which classified into eight monoester forms (approximately 85%, w/w) and twelve diester forms (approximately 15%, w/w), depending on the number of fatty acids that bind thereto. The MS data showed that the predominant fatty acids in astaxanthin esters of H. pluvialis are usually a long chain fatty acid with 16~18 carbon atoms, such as C18:1, C18:2, C18:3, C18:4, C16:0, C16:1. The purity of the esterified astaxanthins was determined to be 96.8±1.2% after purification. A well water-dispersible microemulsion was fabricated using high purity esterified astaxanthins, ethyl butyrate, Tween 80 and ethanol; and that emulsion exhibited a mean particle radius around 60 nm. The chemical degradation of esterified astaxanthins was monitored under accelerated stress storage conditions. After storage for 20 days, the results indicated that the degradation of esterified astaxanthins was effectively slowed by the addition of antioxidants to the microemulsions. By investigating the dependence of the chemical degradation of the esterified astaxanthins in O/W microemulsions on the concentration of the additives, it was concluded that the effectiveness of the additives at inhibiting the degradation of the esterified astaxanthins decreased in the following order: EDTA > ascorbic acid > vitamin E acetate. The utilization of antioxidants in combination was less effective than using them individually. These results provide information for designing effective delivery systems, thereby delaying the chemical degradation of esterified astaxanthins in foods, beverages and other commercial products during long-term storage.
authors.affiliation: College of Food Science and Engineering, Ocean University of China.
authors.forename: Qingxin
authors.initials: Q
authors.lastname: Zhou
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Shu
authors.initials: S
authors.lastname: Yang
authors.forename: Yong
authors.initials: Y
authors.lastname: Xue
authors.forename: Ting
authors.initials: T
authors.lastname: Zhang
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Wang
authors.forename: Changhu
authors.initials: C
authors.lastname: Xue
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D000460:Chlorophyta / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D019587:Dietary Supplements; D004355:Drug Stability; D004655:Emulsions; D004951:Esterification; D005505:Food Coloring Agents; D061353:Food Storage; D009821:Oils; D012995:Solubility; D053719:Tandem Mass Spectrometry; D013997:Time Factors; D014867:Water; D024341:Xanthophylls / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000975:Antioxidants; D004655:Emulsions; D005505:Food Coloring Agents; D009821:Oils; D024341:Xanthophylls; D014867:Water; C005948:astaxanthine