To the top

Page Manager: Webmaster
Last update: 9/11/2012 3:13 PM

Tell a friend about this page
Print version

Loss of redness (a*) as a… - University of Gothenburg, Sweden Till startsida
Sitemap
To content Read more about how we use cookies on gu.se

Loss of redness (a*) as a method to measure hemoglobin-mediated lipid oxidation in washed cod mince

Journal article
Authors Daniel Wetterskog
Ingrid Undeland
Published in Journal of Agricultural and Food Chemistry
Volume 52
Issue 24
Pages 7214-7221
ISSN 0021-8561
Publication year 2004
Published at Institute of Anatomy and Cell Biology
Pages 7214-7221
Language en
Links dx.doi.org/10.1021/jf0307907
Keywords Redness; a*; lipid oxidation; cod; hemoglobin; TBARS; Hb
Subject categories Biological Sciences, Agricultural Science, Forestry and Fisheries

Abstract

Instrumental measurement of redness loss (decrease in a* value) was evaluated as a tool to follow hemoglobin (Hb)-mediated lipid oxidation in fish muscle. Two washed cod mince model systems were used (prepared at pH 6.5 and 5.5), both fortified with 15 μmol/kg of trout Hb and adjusted to pH 6.5 and 81% moisture. The rate of oxidation was varied through pH alterations (pH 6.1 and 6.9) and addition of an antioxidative cod muscle press juice. During ice storage, TBARS, painty odor, and a* values were followed. In all “oxidizing” samples, a* values correlated well with TBARS and painty odor development; r = −0.95 and −0.77, respectively. In press juice containing samples, the correlation was lower (0.55 for a* vs TBARS) because there was a slight a* value decrease even in the absence of measurable lipid oxidation. a* values distinguished between “oxidizing” and stable samples within 1 day, before any lipid oxidation products could be chemically detected. It was confirmed in an aqueous phosphate buffer model system that the redness loss corresponded to a buildup of brownish met-Hb at the expense of oxy- and deoxy-Hb. The a* value data were best used as a lipid oxidation index by calculating the rate of decrease (k value) in the “initial phase” of the redness loss (before accumulation of lipid oxidation products) or in the “differentiation phase” (during the exponential raise in TBARS/painty odor). Calibration to lipid oxidation products must, however, be made for each specific sample type. Washing method, pH, Hb-type, etc., all affected both k values and absolute a* readings. Small yellowness (b*) increases also occurred along with a* value losses, possibly the result of polymerized Schiff bases.

Page Manager: Webmaster|Last update: 9/11/2012
Share:

The University of Gothenburg uses cookies to provide you with the best possible user experience. By continuing on this website, you approve of our use of cookies.  What are cookies?