Effects of Temperature, Light and Storage Time on the Microflora of Vacuum- or Nitrogen-Packed Frankfurters

Frankfurters were vacuum- or nitrogen- packaged and stored at -4, 0, 3 and 7°C for 49 d under light or dark display conditions. Effects of temperature, light and storage duration on microflora in vacuum- and nitrogen-packed sausages were then examined. Differences in number of lactobacilli, psychrotrophic and anaerobic bacteria in vacuum- or nitrogen-packed samples were not statistically significant during storage tests. Lactobacillus development was slightly higher in nitrogen gas compared to vacuum packages, but was also not significantly different. The effectiveness of nitrogen packaging on yeast and mold inhibition was significant, particularly at higher temperatures (3 and 7°C). Nitrogen gas packaging thus offers little advantage over vacuum to promote lactobacillus development, but it is particularly effective against growth of mold and yeast. Initially, the dominant flora of both package samples consisted of Pseudomonas and Microbacterium sp. but Lactobacillus sp. became the predominant psychrotrophs (85.2-96.3%) after 49 d of storage, regardless of different treatments. Temperature was the most important factor which influenced growth of the microflora on frankfurters; freezing temperatures of -4 and 0°C were an effective insurance against development of spoilage microflora in frankfurters for up to 49 d, regardless of packaging atmosphere. With an initial level of 10 to 10³ coliforms per gram, there was no significant change in the number of coliforms during storage. Light had no important influence on microbial growth in frankfurters, irrespective of packaging atmosphere.