Prevention of the accumulation of Alicyclobacillus in apple concentrate by restricting the continuous process running time

Abstract

To study the accumulation of vegetative cells and endospores of Alicyclobacillus, as well as viable aerobic counts during the continuous production of apple juice concentrate. Apples were processed for a continuous process running time of 108 h (processing rate 1·8-2·0 t h(-1) ) without clean-in-place (CIP) procedures in-between different batches. Samples from single-strength apple juice, concentrate after evaporation (± 30°Brix), the final product (concentrate pasteurized at 102-104°C for 90 s) and condensate water (by-product of the juice concentration process) were collected every 12 h. From 12 to 84 h of processing, vegetative Alicyclobacillus counts in single-strength apple juice increased significantly (P < 0·05) from 1 to 3·15 log(10) CFU ml(-1). Accumulation patterns of vegetative cells in apple concentrate and the final product were similar from 24 to 84 h of processing, with the respective counts increasing from 0·13 to 1·63 and 0·01 to 1·69 log(10) CFU ml(-1). The highest Alicyclobacillus endospore counts in single-strength juice, concentrate and the final product was at 84 h of processing with 1·32, 1·59 and 1·64 log(10) CFU ml(-1), respectively. Alicyclobacillus vegetative cells and endospores accumulate in fruit concentrates during a continuous process running time of 108 h. In conjunction with good manufacturing practices, fruit concentrate manufactures can minimize Alicyclobacillus accumulation in fruit concentrates by limiting the continuous process running time between clean-ups to under 84 h.