EXISTENCE AND DEVELOPMENT OF NATURAL MICROBIAL-POPULATIONS IN WOODEN STORAGE VATS USED FOR ALCOHOLIC CIDER MATURATION

Wooden maturation vats, traditionally used in the fruit-based alcoholi c beverage industry, are gradually being superseded by vessels constru cted from sterilizable materials, such as stainless steer. However, it is shown that the surfaces of existing vats, even after cleaning, pos sess a unique, individual microbial profile. One 10,000-gallon oak vat was studied over a nine-week maturation period, and the changing micr obial profile within the fermented cider was recorded. Microbial colon ization of wood was also examined by suspending cubes of unused oak in the cider vat and visualized using scanning electron microscopy. A va riety of microorganisms progressively colonized the porous structure o f wood, which once established, would appear to persist throughout emp tying, cleaning, and refilling cycles.