Relationship between the compounds causing scourable diffuse yellow and the yellowness of clean and greasy wool.

J.E. Wood and T.C. Reid

Department of Wool Science, P O Box 56, Lincoln University, Canterbury, New Zealand.

E-Mail:Reid@wronz.org.nz

Proceedings of the New Zealand Society of Animal Production. 1997, 57: 70-72

As part of a study of the chemistry of wool yellowing, a pilot survey was conducted to examine the frequency of occurrence of two yellow compounds previously isolated from the suint of a few yellow fleeces. The relationship between the amounts of these compounds present and the degree of discolouration was examined in clean and greasy wool from Merino (n = 48), Halfbred (n = 12), Corriedale (n = 26), Romney/Crossbred (n = 52), Cheviot (n = 10) and Perendale sheep (n = 8).

The numbers of samples analysed, the mean yellowness (tristimulus Y-Z) and the relative proportions of the two yellow compounds detected are given in Table 1. Because not all the data was obtained for all samples, the number of data points used in each analysis may vary from those in this table.

Of the 172 wool samples examined, one yellow compound was present in all of them, and a second yellow compound in 91%. There was little relationship between the amounts of these compounds and the yellowness of the greasy wool. Furthermore, there were no significant relationships between the amounts of either compound and the yellowness of the clean wool.

The results suggest that the coloured compounds isolated are universally distributed in the wool of New Zealand sheep and may be responsible, in part, for the degree of yellow discolouration in greasy wool. They would appear to have little, if any, impact on the colour of clean wool.

Keywords: NZSAPAB; wool; yellow; colour; chemistry; compounds.

Last Updated 12-09-1998