B.J. Skura

Modified Atmosphere Packaging of Blueberries: Microbiological Changes

Abstract Blueberries were stored at 4°C in sealed pouches consisting of plastic films of intermediate barrier (IB) and high barrier (HB) properties. Microbial counts, headspace composition, fruit pH and soluble solids were followed with storage time. The atmosphere within the fruit packages constructed from IB film remained aerobic (6% O 2 ) with a relatively low carbon dioxide level (4% CO 2 ). Microbial growth was affected by the oxygen limitation after six weeks storage, but this storage condition could not suppress mould spoilage of the berries. In the packages constructed from the HB film, an anaerobic atmosphere developed within two weeks, and anaerobic respiration raised the carbon dioxide level to 70%. No microbial spoilage was observed in blueberries packed in HB film, even after 12 weeks storage.

Gas Production From Melibiose, Raffinose and White Bean Extracts by Bacteria of Human Fecal Origin

Four organisms Peptostreptococcus productus, P. anaerobius, Bacteriodes fragilis ss. distasonis, and Clostridium perfringens all isolated from human feces, were examined for their ability to grow and produce gas from α-galactosides and fractions of white beans (Phaseolus vulgaris var. Seafarer). C. perfringens produced the most gas from substrates, with raffinose and a low molecular weight soluble enzymic digested bean extract promoting the most gas. Insoluble undigestible carbohydrates of bean origin produced lower, but significant, amounts of gas. Melibiose did not promote gas formation, suggesting that the fructose moiety present in raffinose was responsible for gas production.