RLF Immunocromatographic Devices for Wuantification of Aspergillis and Laccase in Grape Juice at Harvest Time
Over 850 grape juice samples (approx 10ml) were collected, by CWIAB inspectors from the test stand at Gallo Livingston, throughout the 2006 harvest. They were collected from every 10th load graded for rot. In addition, 123 juice samples were collected, by Gallo personnel, from juice prepared on the test stand from loads that were not being graded for rot but were suspected of containing a significant amount of rot. Samples were collected by Dr Molly Dewey and her research assistant twice a week and tested in five different ways at UC Davis. Samples were tested separately for levels Botrytis and Aspergillus antigens by Lateral Flow immunoassay Devices from two different companies, Central Science Lab, York, UK and Envirologix, Portland, Maine and for laccase by the deScenzo method and by the pilot CSL Lacccase Lateral Flow Devices..
As in 2005, only low levels of rot were found by visual handsort tests but, as expected, levels of rot determined by both the CSL and EnvirologixLateral Flow devices indicated that there was a significant level of Botrytis rot in a number of the 2006 samples particularly toward the end of the season. Results from tests for Aspergillus antigens were suspiciously high but this may, in part, be due to the overly high sensitivity of the new devices. Nevertheless, tests indicated that there was far more Aspergillus rot in 2006 than in previous years. Almost all juice samples with high levels of Aspergillus antigens had high levels of Botrytis. There was a reasonable level of agreement between the fieldbased Lateral Flow devices produced by Central Science labs and the labbased devices produced by Envirologix for quantification of Botrytis and Aspergillus rot. Batch to batch variation in the devices from Central Science Labs was a problem but this should be rectified once their new spin off company ?Foresite? is launched in January 2007. The new company will have the necessary equipment for the manufacture and automatic assembly of devices in large batches. Tests for laccase, by the DeScenzo high through put method, confirmed results from 2005, in that, correlation between levels of Botrytis and laccase was poor at low levels of Botrytis but greater at high levels of Botrytis. The prototype laccaseLateral Flow devices from CSL, gave promising results.