Studies in Wool Yellowing

Abstract

Wool fabric has been analyzed for amino acids after severe yellowing caused by irradiation with various sources of ultraviolet and visible light. Tyrosine and tryptophan were partly destroyed by all forms of radiation examined. In addition sunlight on the dry fabric caused partial destruction of histidine, serine, threonine, proline, methionine, isoleucine, leucine, phenylalanine, and cystine and increased the content of ammonia, cysteic acid and cysteine—the last three compounds arising from other amino acids. The Xenotest apparatus magnified these changes and also destroyed some lysine and glutamic acid. Sunlight acting on wet fabric partly destroyed histidine, the 254-m μ lamp acting on dry fabric partly destroyed cystine, and sunlamp irradiation of dry fabric partly destroyed proline, methionine, leucine, phenylalanine, and cystine, that is, in addition to tyrosine and tryptophan. No correlation exists between destruction of any particular amino acid and the final yellowness when the various methods of irradiation are compared.