Content area
Full Text
Eur Food Res Technol (2012) 235:507515 DOI 10.1007/s00217-012-1780-1
ORIGINAL PAPER
Polar lipid fraction from oat (Avena sativa): characterization and use as an o/w emulsier
Mika Kaimainen Suvi Ahvenainen Mirka Kaariste
Eila Jarvenpaa Martti Kaasalainen Mikko Salomaki
Jarno Salonen Rainer Huopalahti
Received: 15 March 2012 / Revised: 29 June 2012 / Accepted: 2 July 2012 / Published online: 18 July 2012 Springer-Verlag 2012
Abstract Oat seeds have an oil content of up to 13 %, of which up to 34 % can be polar lipids (glycolipids and phospholipids). Because of their amphiphilic structure, these polar lipids are potential emulsiers. In this study, polar lipid fraction from oat produced by a supercritical uid extraction process was fractionated into different polar lipid classes by HPLC and the lipid classes in subfractions were identied by comparing retention times with reference compounds and performing co-injections. The oat polar lipid fraction contained monogalactosyldiacylglycerol, digalactosyldiacylglycerol, steryl glycoside, and phosphatidyl choline, and also possibly phosphatidyl inositol. The polar lipid fraction was also used as an emulsier to produce oil-in-water emulsions with different amounts of emulsier and oil, and the stability and other properties of emulsions were studied. Emulsions were formed quite easily, but they
were prone to rapid creaming even after a couple of days of storage at ambient conditions. Droplet size and droplet size distribution of the emulsions seemed to be slightly smaller with smaller amount of oil and larger amount of emulsier. Generally, the droplet size of the emulsions was in the range of 0.24 lm, and with the largest amount of oil (5 %, w/v)
up to 10 lm. The upper phase of creamed emulsions contained slightly larger droplets, up to 30 lm, while the lower phase retained smaller droplets. Microscopic investigation revealed that the increase in droplet size of the upper phase was mainly due to aggregation, which implies that these emulsions may be stable against coalescence to some extent.
Keywords Oat Avena sativa Polar lipids Emulsier
Emulsion Emulsion stability
Abbreviations
BF3 Boron triuoride
DGDG DigalactosyldiacylglycerolDLS Dynamic light scatteringELSD Electronic light scattering detector FAME Fatty acid methyl esterGC Gas chromatographyHPLC High-performance liquid chromatography MGDG MonogalactosyldiacylglycerolLD (Fraunhofer) laser diffractiono/w Oil-in-water (emulsion)
PC Phosphatidyl cholinePE Phosphatidyl ethanolaminePG Phosphatidyl glycerolPI Phosphatidyl inositolPS Phosphatidyl serineSG Steryl glucosidew/o Water-in-oil (emulsion)
M. Kaimainen (&) S....