Latex quantification in homogenate and purified latex samples from various plant species using near infrared reflectance spectroscopy

Parthenium argentatum (guayule) is under commercial development as a source of hypoallergenic latex, which is suitable for the manufacture of latex medical devices safe for use by people suffering from Type I latex protein allergy. Improving agronomic practices, post-harvest shrub handling, and optimizing latex extraction and purification protocols during bioprocessing are hampered by the relatively cumbersome latex quantification methods currently employed. Current methods require several hours before analytical results can be obtained. The object of our study was to develop and test a near infrared (NIR) spectroscopic method for rapid quantification of latex in both wet and dried P. argentatum homogenate and purified latex samples. The procedure was tested on latex samples from Ficus elastica (Indian rubber tree), Helianthus annuus (sunflower), Hevea brasiliensis (Brazilian or para rubber tree) and Taraxacum kok-saghyz (Russian dandelion). P. argentatum latex could be accurately quantified, over a wide concentration range of 0 to 25 mg/ml. The correlations between the measured rubber content and the rubber content predicted by NIR were 0.96 and 0.91 for dry and wet samples, respectively. The presence of homogenate components unrelated to the latex fraction did not perturb the correlations obtained. Similar predictive models could be used to measure the rubber content in F elastica, H. annuus, H. brasilensis and T kok-saghyz. (C) 2003 Published by Elsevier B.V.