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

Abstract

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 log10 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 log10 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 log10 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.

Spoilage by Alicyclobacillus Bacteria in Juice and Beverage Products: Chemical, Physical, and Combined Control Methods

“…Juice and beverage products are not easily contaminated by microbes due to their low pH (usually <5.0, in some products even <4.0), but there are still several kinds of microbes that can survive this acid environment and cause spoilage, including some aerobes such as Bacillus coagulans and Bacillus megaterium (causing flat‐sour type spoilage), some anaerobic spore‐forming bacteria such as Clostridium butyricum and Clostridium pasteurianum (producing gas and butyric odors) (Silva and Gibbs ), some lactic acid bacteria such as Lactobacillus brevis and Leuconostoc mesenteroides (causing vinegary, buttermilk off‐odors) and some heat‐resistant mycelial fungi such as Byssochlamys nivea and Talaromyces flavus (Steyn and others ). Nevertheless, a large‐scale apple juice spoilage incident in 1982 in Germany made people realize that besides the microbes mentioned above, a new type of aerobic spore‐forming bacterium can also spoil juice and beverage products (flat‐sour spoilage and generating medicinal, antiseptic offensive off‐odor).…”