## 3 Results and Discussion
### Volatile Compounds
Investigations into the effect of water on volatile Maillard reaction products showed that both quantitative and qualitative changes occurred in the volatile profile of a meat flavor model system with different moisture levels [42]. The maximum amount of volatiles was observed at an a\({}_{\text{w}}\) of 0.72. The kind of major volatiles also differed: higher amounts of both DMDS and DMTS were present in the high-water system (\(p<0.05\)). Thus, it may be that the presence of pro-oxidant metal ions from the beef in the cooking juices favored the further reactions of methanethiol from the Strecker degradation of methionine. In our research, no effect of the type of heat treatment on the content of 2- and 3-Methyl butanal was observed (\(p>0.05\)). Hexanal, pentanal, and 2-pentylfuran are derived from lipid oxidation reactions. Consideration was given to whether their higher levels in the stewed meat could be from the oil used for frying. These compounds are characteristic of the breakdown of linoleic acid [43]. Oleic acid is the main fatty acid in olive oil and accounts for 55-83% of the total fatty acid content but variable amounts of linoleic acid (3-21%) and linoleic acid (<1%) may also be present [44], and these latter are more subject to lipid oxidation than oleic acid. The analysis of the heated frying oil alone gave some hexanal but at very much lower levels than those obtained from the meat samples. Octanal and nonanal, which are the characteristic products of the oxidation of oleic acid [43] were unaffected by the cooking method, suggesting that this was not the primary cause of the observed differences. All the observed n-alehydes are the products of the thermal degradation of linoleic acid but pentanal and hexanal may also be derived from arachidonic acid [43]. It is possible that the greater comminution of the stewed meat allows a greater breakdown of the very long chain fatty acids in the phospholipids. The increases in some Maillard and lipid oxidation products suggest that stewing provides an environment conducive to both certain oxidation reactions and the facilitation of subsequent chemical transformations. This may be influenced not only by the greater access of oxygen to the surface of the stewed meat during browning, but also by the presence of free radical intermediates from the heated oil, contact with aqueous pro-oxidants, anti-oxidants, or other components from the meat and vegetables, and the role of water and extended time in facilitating further reactions of the primary volatile products. Further study of each stage of the cooking process would be needed to elucidate the mechanisms concerned. Similar results have been reported by other researchers. [PERSON] et al. investigated the volatile compounds and consumer palatability scores for four beef muscles (_Longissimus humporum, Psoas major, Semimembranosus_, and _Glutetus medius_) and five USDA quality grades (Prime, Upper 2/3 Choice, Low Choice, Select, and Standard), demonstrating that these measures of meat quality did not have a direct impact on consumer ratings or volatile compounds. However, significant interactions between muscle type and quality were identified, along with differences in ratings and volatile compounds among muscles.