Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2000
Publication Date: 6/1/2000
Citation: Brushwood, D.E. 2000. Modification of the potassium ferricyanide reducing sugar test to determine total sugars from extracts of cotton. Journal of Cotton Science 4:202-209.
Interpretive Summary: When insect infestations in cotton fields are high, the cotton lint is contaminated with excretions that are very high in sugar content. Also, under certain conditions excessive sugars from the cotton plant itself can contaminate the lint. This contamination severly limits the efficiency in textile processing of the cotton unless there is strict control on the use of the affected bales. Therefore, tests for sugar contamination are necessary to identify the bales. One widely used test, the Perkins test, is insensitive to the presence of two important sugars, sucrose and melezitose. The Perkins test procedure was modified to include a pretreatment with mild acid that converts sucrose and melezitose to a slightly different chemical structure that can be detected by the Perkins test. This test can be used easily to screen large numbers of suspected bales. Textile users and cotton producers can use this low cost test in cotton marketing and utilization to demonstrate that bales are not contaminated and to identify potentially troublesome cottons. Since stickiness in processing can be a major problem in some crop years, this modification could result in increased confidence in marketing and improved processing efficiency.
Technical Abstract: The Perkins or potassium ferricyanide reducing sugar test that determines sugars on cotton lint has been a widely used and reliable procedure for over 25 years. It is simple and can be set up in any small space with minimal initial investment costs. Sucrose, a sugar found in non-insect and insect contaminated cottons, and melezitose found exclusively in aphid and whitefly infested cottons are traditionally non-reducing sugars. Both contribute to the overall stickiness potential of sugars on cotton. High sugar levels on cotton, whether insect or non-insect contaminated, can cause interruptions and sometimes extreme handling problems in all phases of textile processing. The necessity to know a fiber's potential to stick is beneficial in planning processing protocols. Adding a simple extra sample preparation step to the Perkins test converts the two above sugars to reducing states. Hence, the test will be enhanced in predicting the cotton stickiness potential. Examples of authentic sugar standards and sugar extracts from insect and non-insect contaminated cottons determined by the normal Perkins reducing sugar test and subsequent modified test are illustrated by instrumental analysis of individual sugars and actual differences in percentages of sugars determined. Correlations between the modified sugar test and a routine physical stickiness test are also determined.