NMR Analysis of Lipid Oxidation in Flaxseed Oil-in-Water Emulsions.

The formation of linolenic (Ln) and linoleic (L) acyl oxidation products during storage of flaxseed oil (FO)-in-water emulsions was monitored using proton nuclear magnetic resonance (1H NMR) spectroscopy, as well as chemical analytical methods and gas chromatography. Emulsions containing 10% FO and 1% Tween 60 were prepared by homogenization and then stored at 37 °C in the dark for 21 days under accelerated oxidation conditions (500 µmol ferrous sulfate). The induction time of the emulsions, after which rapid lipid oxidation was first observed, was 5-7 days, as shown by increases in peroxide values and hydroperoxide concentrations determined by NMR spectroscopy. Analysis of the hexanal and propanal concentrations during storage by HS-SPME-GC indicated that the oxidation of Ln and L acyls in the emulsions occurred simultaneously. The oxidation products originating from the Ln and L acyls were monitored using 1H NMR spectroscopy throughout the oxidation process. These results also showed that the Ln and L acyls oxidized simultaneously, and isomers of hydroperoxy-cyclic hydroperoxides (HCPs), Z,E-conjugated dienic hydroperoxides (ZECDHPs), and E,E-conjugated dienic hydroperoxides (EECDHPs) were the major primary oxidation products. Aldehydes were observed after 7 days, which was taken to be the start of the propagation stage, with the formation of a significant amount of oxygenated α, ß-unsaturated aldehydes (OαßUAs). Based on the concentrations of hydroperoxides originating from the Ln and L acyls, our results suggested that the loss rate of L acyls was parallel to that of Ln acyls. This result was consistent with Ln acyls adopting a tighter packing at the oil-water interface in the emulsions than L acyls. This hypothesis was supported by the NMR relaxation time data. A good correlation between the isomer concentrations of ZECDHPs and HCPs in Ln acyls and between ZECDHPs and EECDHPs in L acyls was shown, with the mole ratios between them being 1.2 and 1.1, respectively. Droplet size and microstructure analyses showed that droplet aggregation occurred from 11 days onwards, which was attributed to polar oxidation products located at the oil droplet surfaces promoting coalescence. Zeta-potential measurements indicated that the droplets became more negative during storage, which was attributed to the accumulation of anionic reaction products at the droplet surfaces.

Analysis of iodine nutritional status of high-risk population in coastal salt-producing areas and coastal nonsalt-producing areas in Xiamen city of Fujian province / 中国地方病学杂志

Objective To assess the iodine nutritional status of special target population in coastal saltproducing areas and coastal non-salt-producing areas in Xiamen city,and to provide a basis for take appropriate measures for prevention of iodine deficiency disorders.Methods The Xiang-An salt-producing areas and the JiMei non-salt-producing areas were chosen as research spots in 2009.One sample of produced water and 2 samples of tap water were collected to test iodine level; 600 children aged 8 to 10 were selected and thyroid palpation was performed,besides,the urine sample and household salt sample were also collected for iodine determination.Sixty pregnant women,breasffeeding women,and 0 - 2 year old infants were recruited,respectively,and urine samples and household salt samples were collected to perform the determination of iodine level.Results The iodine levels in drinking water of Xiang-An district and Ji-Mei district were 3.23 and 6.05 mg/L,respectively.The consumption rates of edible qualified iodinated salt were 84.4％ (438/519) and 98.3％ (392/399),respectively.The goiter rates of children aged 8 - 10 were 3.03％(19/628) and 0.67％(4/600),respectively.The medians of urinary iodine were 202.80 and 238.40 μg/L,respectively.The proportions of urinary iodine level ＜ 50 μg/L were 3.5％ (14/405) and 1.0％(2/202),respectively.The medians of urinary iodine of the pregnant women were 120.55 and 153.35 μg/L,respectively,and the proportions of urinary iodine level ＜ 150 μg/L were 62.1％ (46/74) and 46.8％ (29/62),respectively.The medians of urinary iodine in three trimester were 173.10,144.75 and 101.90 μg/L,respectively,early trimester of pregnancy ＞ second trimester and third trimester (Z =6.151,3.052,all P ＜ 0.05),second trimester ＞ third trimester (Z =2.016,P ＜ 0.05 ).The medians of urinary iodine of the breastfeeding women were 131.20 and 104.35 μg/L,respectively.The proportions of urinary iodine level ＜ 100 μg/L were 35.3％ (24/68) and 46.7％(28/60),respectively.The medians of urinary iodine of the infants were 81.95 and 80.20 μg/L,respectively,the proportions of urinary iodine level ＜ 100 μg/L were 59.7％(37/62) and 61.6％(40/65),respectively,＜ 50 μg/L were 32.3％ (20/62) and 30.8％ (20/65),respectively.Conclusions The levels of iodine nutrition in pregnant women,breastfeeding women,and 0 - 2 year old infants from Xiang-An district and Ji-Mei district in Xiamen city are still below the desired level of iodine nutrition,and the infants and pregnant women in coastal salt-producing areas are poor in iodine nutrition,we should pay close attention.We should strengthen market supervision on iodized salt,carried out iodine nutrition monitoring on pregnant women,breasffeeding women,and infants,and disseminate knowledge of iodine nutrition among high-risk population should be carried out immediately.