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

Aims: 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.

Methods And Results: 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.

Conclusions: Alicyclobacillus vegetative cells and endospores accumulate in fruit concentrates during a continuous process running time of 108 h.

Significance And Impact Of The Study: 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.