Determination of growth characteristics and lipolytic and proteolytic activities of Penicillium strains isolated from Argentinean salami

The growth of Penicillium spp. on the surface of meat-based dry fermented sausages provides them with a protective effect against some undesirable microorganisms. Penicillium also acts as an antioxidant, minimizes the risk of excessive drying, and it is responsible for flavor development due to the decomposition of proteins, free fatty acids and lactic acid. With the aim of developing starter cultures, important physiological properties such as growth and proteolytic and lipolytic activities were evaluated on 13 mold strains belonging to the genera Penicillium. These strains were isolated from Argentinean dry fermented meat sausages named “salami”. The selection was based on color, mycellium appearance and growth characteristics. The most important factors of the drying process of salami, such as temperature (14 and 25 °C), water activity ( a w) (0.90, 0.95 and 1.00) and presence of 2.5% sodium chloride (NaCl), were analyzed. Although all strains analyzed were able to grow under the different conditions evaluated, they showed different growth velocity ( K=mm/day) in response to temperature, a w and presence of NaCl in the media. All strains showed both proteolytic and lipolytic activities under the studied factors of the drying process. Nevertheless, differences in inter-species and even intra-species were found. The addition of NaCl gave a stimulant effect to the proteolytic activity at 25 °C, but the response at 14 °C was variable. The same variability was observed in the presence of salt, both at 25 and 14 °C, when the lipolytic activity was assayed. According to our results, detailed assays of the physiological capacities of indigenous strains proposed as starter cultures are required.