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M. PARISH, Citrus Research & Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850

Until recent years, sporeforming bacteria were not implicated in spoilage of fruit juices. Historically, sporeforming bacteria commonly isolated from thermally processed juices were typically members of the genus Bacillus and were incapable of germination and outgrowth at pH levels commonly associated with most fruit juices. In 1984, our understanding of the relationship between juice and sporeforming bacteria began to change with the first report of spoilage by a sporeformer in apple juice. Other juice spoilage events have been reported in the ensuing years. Spoilage is limited to shelf-stable juices or juice-containing beverages and is characterized by a disagreeable off-flavor and lack of carbon dioxide production.

The genus responsible for this spoilage was designated Alicyclobacillus in the early 1990s and has been the subject of much research in recent years. Alicyclobacilli are wide-spread in nature, survive typical pasteurization and thermal concentration environments, and are thermo-acidophilic with a preference for growth at high temperatures and low pH. In citrus processing plants, these bacteria have found a niche in the condensate water recovery system associated with thermal evaporators used to produce concentrated juices. They are also found on the surfaces of fruit entering the plant.

The significance of finding alicyclobacilli in juice concentrates is not well established since many isolated strains appear not to grow in inoculated citrus juices; however, strains capable of growth can produce significant losses.