## 3 Results and Discussion
### Chicken Nugget Shelf Life
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{**MESOF**} & \multicolumn{5}{c}{**MAL**} \\ \cline{3-6}  & & **PSY** & **LAB** & **ENTER** & **PSEUD** & **STAPH** \\ \hline CTRL\_1 & 1.804 \(\pm\) 0.299 d & 0.762 \(\pm\) 0.164 e & \textgreater{}13 & 1.8165 \(\pm\) 0.163 a & 1.151 \(\pm\) 0.207 c & \textgreater{}13 \\ CTRL\_2 & 2.650 \(\pm\) 0.210 d & 2.099 \(\pm\) 0.162 d & \textgreater{}13 & 2.2175 \(\pm\) 0.233 a & 1.730 \(\pm\) 0.171 c & \textgreater{}13 \\ SAMP\_1 & 7.156 \(\pm\) 0.349 c & 3.989 \(\pm\) 0.335 c & 10.331 \(\pm\) 0.481 b & \textgreater{}13 & 2.905 \(\pm\) 0.406 b & \textgreater{}13 \\ SAMP\_2 & 7.924 \(\pm\) 0.371 b & 6.780 \(\pm\) 0.211 b & 13.029 \(\pm\) 0.996 a & \textgreater{}13 & 6.584 \(\pm\) 0.225 a & \textgreater{}13 \\ SAMP\_3 & 8.578 \(\pm\) 0.470 b & 5.965 \(\pm\) 0.474 b & \textgreater{}13 & \textgreater{}13 & 3.927 \(\pm\) 0.698 b & \textgreater{}13 \\ SAMP\_4 & 9.978 \(\pm\) 0.541 a & 10.725 \(\pm\) 0.388 a & \textgreater{}13 & \textgreater{}13 & \textgreater{}13 & \textgreater{}13 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Data regarding the microbial acceptability limit (MAL) calculated from the fitting procedure of sensory experimental data of tested chicken nuggets samples. a synergistic way when combined with other active agents. In fact, data from literature confirm the effects of bioactive compounds and organic acids applied to a wide range of foods against different types of spoilage and foodborne pathogens [37]. Figure 3 reports cell counts of psychothrophic bacteria. Psychotrophic bacteria are the most prevalent bacteria on refrigerated chicken meat, and are the microorganisms of choice to detect the true microbial loads of chicken products [38]. As can be noted, very similar trends to mesophilic bacteria were found also for these spoilage microorganisms. In both control products the bacteria grew in little time, whereas a significant delay was observed for the other four samples. The data in Table 4 for psychothrophic bacteria confirm these trends and show evidence that the first control became unacceptable within the first day of storage. About 2 days are necessary for the second control where lactic acid was used to treat meat. When GPP was used, the time to reach the microbial threshold significantly increased up to about 4 days (\(p<0.05\)). The best combinations are represented by GPP combined with LA (about 7 days) or with both LA and PE (about 10 days). Literature findings about the effects of these antimicrobials on mesophilic bacteria also support this experimental evidence. [PERSON] et al. [39] compared nisin, sodium nitrite, and lactic acid on the prevalence and antibiotic resistance patterns of the _Listeria monocytogenes_ that is naturally present in poultry and preliminarily verified the effects of these agents on the levels of certain microorganisms that indicate hygiene quality (aerobic plate counts, psychotrophic microorganisms and enterobacteria). They found that, of the three additives studied, lactic acid showed the most effectiveness as an antimicrobial agent. Under the conditions tested, lactic acid alone was able to reduce levels of aerobic plate counts, psychotrophic microorganisms and enterobacteria when compared with the untreated samples. During the entire storage period, the _Staphylococcus_ spp. was not found in tested samples. For this reason, the experimental data were not fitted and, in the last column of Table 4, the MAL parameter was reported higher than 13 days, as a maximum monitoring time. Enterobacteriaceae were only found in both the control samples. This means that the use of single GPP or its combination with other agents was effective in preventing the enterobacteria proliferation. [PERSON] et al. [40] have also found that products  
Figure 3: Evolution of total psychotrophic bacteria in controls and treated meat samples during storage at 4 °C.