Microbiological evaluation of navy bean flour and its blend with retail ground beef

Sterile water suspensions of navy bean flour (NF) were used as a model medium on which the growth of eight microorganisms important for food hygiene and technology was evaluated. Almost all microorganisms grew better on model mediums with 10 and 15% of NF than on the nutrient broth (control). Retail ground beef with and without 5, 10 and 15% addition of NF was wrapped with plastic film and stored at 4°C. Aerobic plate count, psychrophiles, coliforms and yeasts and molds were assessed after 0, 3 and 6 days. Navy bean flour added to ground beef had a significant effect only on aerobic plate count. Growth of psychrophiles, coliforms, yeasts and molds was not affected by addition of NF. Microflora of retail ground beef-NF blends mainly consisted of Lactobacillus spp., while other genera of bacteria were found in smaller numbers. The pH of blends increased in proportion to the level of NF added and was significantly higher in comparison with retail ground beef alone, but decreased during storage due to the large amount of lactic acid bacteria.