# Is Prolonged Ageing a Necessity for Improving the Quality of Sous-Vide Cooked Beef?
## 3 Results and Discussion
### The Influence of Ageing on Sous-Vide Cooked Beef
Prolonged ageing up to 14 and 21 days increased proteolysis extent, whereas conducting heating at a relatively low temperature (60 \({}^{\circ}\)C) for a long time (4 h) resulted in the limited denaturation of myofibrillar and connective tissue proteins as well as the weakening of connective tissue via collagen solubilisation [50]. The results of the sensory analysis are shown in Table 5. In general, the sensory scores of the beef steaks aged at different times fell within acceptable ranges. The duration of ageing exhibited negligible impact on both the aroma and taste intensity of the meat, as evidenced by comparable scores across all treatments, with consistently high values. The high scores noted in this study for aroma and taste indicate that all sous-vide cooked products showed an intensive meat flavour. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Attribute**} & \multicolumn{3}{c}{**Ageing Time (days)**} & \multirow{2}{*}{**Significance**} \\ \cline{2-2} \cline{4-4}  & **4** & **14** & & **21** \\ \hline Cooking loss (\%) & 22.0 \(\pm\) 0.8 & 24.0 \(\pm\) 1.0 & 23.8 \(\pm\) 0.9 & NS \\ WBSF (N) & 48.1 \({}^{\text{a}}\)\(\pm\) 1.8 & 30.0 \({}^{\text{b}}\)\(\pm\) 1.2 & 22.9 \({}^{\text{c}}\)\(\pm\) 0.8 & *** \\ Hardness-1 (N) & 80.0 \({}^{\text{a}}\)\(\pm\) 5.0 & 63.0 \({}^{\text{b}}\)\(\pm\) 3.0 & 51.0 \({}^{\text{b}}\)\(\pm\) 3.0 & * \\ Hardness-2 (N) & 68.0 \({}^{\text{a}}\)\(\pm\) 4.0 & 52.9 \({}^{\text{b}}\)\(\pm\) 2.6 & 43.7 \({}^{\text{b}}\)\(\pm\) 2.4 & * \\ Springiness (mm) & 2.03 \({}^{\text{a}}\)\(\pm\) 0.05 & 1.96 \({}^{\text{ab}}\)\(\pm\) 0.05 & 1.80 \({}^{\text{b}}\)\(\pm\) 0.04 & * \\ Adhesiveness (N\(\cdot\)mm) & \(-\)2.32 \(\pm\) 0.04 & \(-\)2.36 \(\pm\) 0.08 & \(-\)2.37 \(\pm\) 0.06 & NS \\ Cohesiveness (-) & 2.49 \(\pm\) 0.06 & 2.41 \(\pm\) 0.03 & 2.48 \(\pm\) 0.06 & NS \\ Chewiness (N\(\cdot\)mm) & 408 \({}^{\text{a}}\)\(\pm\) 28 & 299 \({}^{\text{b}}\)\(\pm\) 18 & 231 \({}^{\text{b}}\)\(\pm\) 21 & * \\ \hline \hline \end{tabular}  
* Data are presented as the mean \(\pm\) standard error of the mean (SEM). \({}^{\text{a,b}}\) mean values in the same rows with different letters differ significantly at \(p<0.05\); NS—non-significant differences (\(p>0.05\)), \({}^{\text{*}}\) differences significant at \(p<0.05\); *** differences significant at \(p<0.001\).  
\end{table} 
Table 4: The effect of wet ageing on cooking loss and texture of sous-vide cooked _longissimus lumborum_ steaks. Generally, the flavour characteristics of cooked meat are associated with volatile compounds, which are created during meat heating as a result of Maillard reactions and the thermal degradation of lipids. When cooking proceeds at a low temperature (as used in the present study, 60 \({}^{\circ}\)C), the Maillard reaction and thiamine degradation products do not play a significant role in shaping the flavour of meat [12]. In contrast, volatile compounds derived from fatty acid degradation, such as linear saturated aldehydes (from butanal to nonanal), unsaturated aldehydes, a ketones, furans and furanones, are detected in sous-vide meat, which indicates their role in shaping the flavour of sous-vide meat [12]. The changes in lipids proceed in both high and moderate (or low) temperatures as a result of thermal lipid degradation and lipid autoxidation, respectively [12]. Lipid oxidation is noted during ageing, even if it proceeds in vacuum packages [51]. As it might be assumed from the results of the present study, ageing which was conducted in vacuum packages up to 21 days did not change the fatty acid composition to the extent that could reflect the flavour profile of sous-vide cooked beef determined by the sensory panel. No significant differences were recorded in the juiciness scores of the samples, which corresponds with the lack of differences in cooking loss. Sous-vide products obtained from beef aged for 14 days and 21 days were more tender than those aged for 4 days (\(p<0.05\)), but no differences were noted between the 14 d and 21 d aged samples.