New possibilities for quality control of aseptic packages: Microbiological spoilage and seal defect detection using headspace indicators

Aseptic packages containing sausage gravy or tomato soup were studied with respect to microbiological spoilage and package integrity. Seal defects were made experimentally as well as bacterial inoculations (Bacillus cereus, Clostridium perfringens, Lactobacillus plantarum). Oxygen influx, carbon dioxide production and bacterial growth were monitored during the follow-up period at 4°C and 30°. The packages contained microstrips with oxygen- and pH-indicators, and the colour changes of these indicators were measured non-destructively through the packages by a Minolta Chroma detector. The results indicated that the growth of the bacteria in the food packs studied can be monitored by pH-indicators in the head-space. Likewise, the influx of oxygen due to a seal defect can be detected by an oxygen indicator in the head-space. The incubation conditions were very critical for opt. results, meaning that spoilage should be monitored at higher temp. (30°) and seal defects at lower temp. (4°).