Biochemical study the formation of key flavor precursors in various skeletal muscles post-mortem

生肉没有熟肉的香气，因为其特有的香气主要是在烹调过程中产生的。事实上，这些风味化合物是通过生肉在加热过程中存在的天然前体之间的化学反应产生的。在这些天然风味前体中，糖和磷酸糖，特别是五碳糖（戊糖）在通过美拉德反应产生熟肉的理想香气和风味方面起着重要作用。然而，导致肉中这些戊糖形成的生化途径尚不完全清楚。核糖是一种五碳糖，是肉中一种关键的风味前体，通过死后肌肉中ATP的分解而形成，这种公认的途径无法解释肉中所有戊糖的形成。例如，5-磷酸核酮糖、5-磷酸核酮糖、木糖已在各种肉类（鸡肉、牛肉和兔肉）中被发现，但它们的生化来源仍未得到解释。生化途径如戊糖磷酸途径可能参与其中，并且可能是肌肉和/或物种依赖的。此外，目前尚不清楚肉类调理如何影响关键风味前体浓度的形成和/或演变，以及这一步骤在多大程度上依赖于肌肉/物种。这项NSERC发现提案旨在采用化学和生化方法来阐明在死后选定的骨骼肌中产生关键风味前体（戊糖）的选定生化反应的作用。采用白肉（鸡胸肉和鸡腿肉）和加拿大流行的瘦肉红肉（野牛肉和麋鹿肉）进行比较研究，旨在首先阐明对肉类风味重要的选定生化反应的肌肉和/或物种依赖性，其次，研究肉类调理对每种肉类中关键风味前体的影响。模型系统将用于研究候选风味前体在选定肉类中的作用，以及它们对每种选定肌肉的特征香气和风味的贡献。这个研究项目将有助于了解肉中风味前体的形成，并最终有助于选择风味的遗传标记。

Raw meat has none of the aroma of cooked meat as the characteristic aroma is largely generated during cooking. In fact, the flavor compounds are generated via chemical reactions occurring between natural precursors present in raw meat during heating. Among these natural flavor precursors, sugars and sugar phosphates, and particularly five carbon sugars (pentoses) play a major role in generating the desirable aroma and flavor of cooked meat via the Maillard reaction. However, the biochemical pathways leading to the formation of these pentoses in meat are not fully understood. The accepted route for the formation of ribose, a five carbon sugar and a key flavor precursor in meat via the breakdown of ATP in muscle post-mortem, cannot explain the formation of all pentoses present in meat. For instance, ribulose-5-phosphate, ribose-5-phosphate, xylulose have been identified in various types of meat (chicken, beef and rabbit) while their biochemical origins remain unexplained. Biochemical pathways such as the pentose phosphate pathway may well be involved and could be muscle and/or species dependent. In addition, it is not clear how meat conditioning affects the formation and/or evolution of key flavor precursors' concentrations with time, and to what extent this step is muscle/species dependent. This NSERC discovery proposal aims to employ chemical and biochemical approaches to clarify the role of selected biochemical reactions in generating the key flavor precursors (pentoses) in selected skeletal muscles post-mortem. A comparative study using both white meat (chicken breast and leg) and popular Canadian lean red meats (bison and elk) is designed to elucidate firstly, the muscle and/or species dependency of the selected biochemical reactions important for meat flavor and secondly, to study the effect of meat conditioning on key flavor precursors in each type of meat. Model systems will be employed to investigate the role of candidate flavor precursors in selected meats and their contribution to the characteristic aroma and flavor of each selected muscle. This research program will help to understand the formation of flavor precursors in meat and will ultimately help with selection of genetic markers for flavor.