Effect of salt and smoke on the microbiological quality of cold-smoked salmon during storage at 5 degrees C as estimated by the factorial design method

The simultaneous effect of salt and smoke on the natural flora of cold-smok ed salmon was studied during 5 weeks of vacuum storage at 5 degrees C. The quadratic polynomial, as a function of factors, was used to express total v iable count (TVC), total lactic acid bacteria, lactobacilli numerated on Ro gosa agar, H2S-producing bacteria, and yeasts at different sampling times. TVC and total lactic acid bacteria were mainly inhibited by the salt concen tration (5% wt/wt) in the meat and to a lesser extent by the phenol content . Inhibition was linearly proportional to salt: and smoke content (the high er the concentration, the greater the inhibition). No synergistic effect on inhibition was observed between the two factors. In our working conditions , the TVC French standard (<10(6) CFU g(-1)) was maintained during 4 weeks of storage at 5 degrees C, with a minimum concentration of 2.4% (wt/wt) of salt in meat and smoking treatment corresponding to 0.6 mg 100 g(-1) of phe nol. When the salt level was higher than 3%, the TVC standard was maintaine d, regardless of phenol level. A negative interaction between the two facto rs was found for H2S-producing bacteria and a positive one for yeasts.