Quality Evaluation and Mathematical Modelling Approach to Estimate the Growth Parameters of Total Viable Count in Sausages with Different Casings

The growth kinetics for the total viable count (TVC) in sausages with modified hog casings (treated by surfactant solutions and slush salt with lactic acid), natural hog casings and sheep casings as a function of the storage time (up to 50 days) were studied for the first time. The growth of TVC was fitted by the Baranyi model, and the maximum specific growth rate, lag time and initial and final cell populations were estimated via DMFit. The coefficient of determination of the Baranyi model reached 0.94, 0.77 and 0.86 for sausages stuffed in modified hog casings (MHC), control hog casings (CHC) and natural sheep casings (NSC), respectively. The experimental data for the initial populations were 4.69 +/- 0.10 log cfu/g for MHC, 4.79 +/- 0.10 log cfu/g for CHC and 3.74 +/- 0.14 log cfu/g for NSC, whilst the predicted initial cell populations for MHC, CHC and NSC were 4.81 +/- 0.20 log cfu/g, 5.19 +/- 0.53 log cfu/g and 3.74 +/- 0.54 log cfu/g, respectively. Their shelf lives can also be predicted. The results show that the average pH value of MHC samples (6.96 +/- 0.01) was significantly lower than that of CHC (7.09 +/- 0.01) and NSC (7.05 +/- 0.02) samples at day 50 (p < 0.05). Sausages with CHC possessed a significant higher water holding capacity (99.48 +/- 0.14%) at d 29 than those with MHC (97.40 +/- 0.46%) and NSC (98.55 +/- 0.17%) (p < 0.05). On the last day, the average moisture content for samples with NSC (38.30 +/- 3.23%) was significantly higher than that for those with MHC (29.38 +/- 2.52%) and CHC (29.15 +/- 1.16%) (p < 0.05).