Indication of the growth of Cl. perfringens in aseptically packed sausage and meat ball gravy by headspace indicators: Part 2

Growth characteristics of Clostridium perfringens were measured in sausage and meat ball gravy during the preincubation period at 30°C for 14 d. Clostridia were inoculated either directly into the gravy or the particle (meat ball, sausage). The food packs were sealed into plastic bags containing different headspace gas constituents (20% oxygen + 80% nitrogen or 100% nitrogen). The growth of clostridia was checked every 2 d by cultivation and measuring the headspace O₂ and CO₂. The headspace composition was also determined by powder-based redox indicators. Clostridia did not grow in air-flushed sausage gravy or sausages whereas it grew well in both air and nitrogen-flushed meat ball gravy. There was no difference in the outcome of growth if clostridia were inoculated into particles of meat or gravy. Both the redox indicators tested could detect the growth of clostridia in air and nitrogen packages. The colour parameters of the redox indicators selected for the detection are described.