The bacterial genera Lactobacillus and Pediococcus are regarded as spoilage organisms in winemaking. Changes in winemaking practices have led to increased incidence of wine spoilage post fermentation by these bacteria. The recent trend to longer hang time for flavor development in grapes, coupled with higher juice pH values and reduced concentrations of sulfur dioxide, have exposed wine to increased spoilage by these bacteria. Our program has focused on raising specific antibodies to these bacteria, attaching a fluorescent dye to the antibody and identifying these bacteria from other material in the cell. We have made significant progress in purifying the antibodies to reduce cross reactions with other bacteria.
We have, however, encountered some unexpected problems with regard to both progress of achieving the research objectives and project personnel. The adsorption process reported last year to reduce cross reactions has proved fairly satisfactory, but we have observed batch to batch variations, i.e. different antisera bleeds from different chickens respond differently to the adsorption process. This has slowed progress as the process has to be refined each time to meet the changes in the antisera. The eggs that were a potentially rich source of antibodies were lost when the cold box deep freeze could not withstand the 113oF temperatures Fresno endured last summer with the result that the eggs spoiled. A graduate student, Tiffany Otto, had been using re-constituted juice concentrate and observed some discrepancies in antibody attachment. It has been hypothesized that this interference could be caused by polymerized phenolics adhering to the cell surface and interfering with the antibody-antigen binding process. This was unexpected since the problem had not been encountered when using an Oenococcus oeni specific antibody in Chardonnay fermentations. This problem is being addressed using fresh juice.