Revel, G. deCapela, Ana BelaHogg, T.2011-09-132011-09-131994REVEL, G. de ; CAPELA, Ana Bela ; HOGG, T. - A pre-spoilage marker for bacterial activity in fortified wine, conversion of L-malic acid to L-lactic acid. Letters in Applied Microbiology. ISSN1472-765X. Vol. 18, n.º 6 (1994), p. 329–332http://hdl.handle.net/10400.14/5483Sixty-one different fortified wines, from the Douro valley, inoculated with Lactobacillus hilgardii previously isolated from a spoiled fortified wine, were sampled progressively for 280 d. Samples were analysed for volatile acidity (acetic acid) and frozen for subsequent analysis where appropriate. After 280 d, 7/61 wines showed increases in volatile acidity of >0.5 g l-1 and were considered spoiled. Retrospective analysis of frozen samples of spoilage-positive wines showed that all had apparently undergone a malolactic conversion before the onset of heterolactic activity (acetate production). It is suggested that the monitoring of L-lactic acid might be a method of detecting activity of spoilage lactobacilli before the onset of spoilage.engjournal article10.1111/j.1472-765X.1994.tb00881.x0028264213A1994NR40000007