title: Elucidation of the role of different sources of phospholipids in meat aroma formation
Creators: name: Yeo, HuiQi
Publisher: name: University of Reading
Year: 2022

description: The characteristic aroma of cooked meat is generated from thermally induced reactions, principally the Maillard reaction and lipid oxidation, between non-volatile components of lean and adipose tissues during heating. Although meat aroma formation is a well-documented topic, the shift in consumer landscape towards vegan, vegetarian and flexitarian diets has presented an unprecedented challenge of creating meat aroma from plant-based alternatives. The search for potential vegan solutions has thus led to a renewed interest in authentic meat flavour profiles. Using Likens-Nickerson simultaneous distillation-extraction, aroma extracts from boiled beef and chicken were obtained for Gas Chromatography-Mass Spectrometry and Gas Chromatograhy-Olfactometry analyses. This technique offers the advantage of in-situ heating and extraction, which facilitates the mimicking of meat cooking in stocks and stews in a kitchen setting. Besides the Maillard reaction products, such as sulfides, thiols and mercaptoaldehydes, as well as lipid oxidation products, such as alkenals and alkadienals, families of thiazoles and thiazolines were also found to be important contributors to meat aroma. The identification of these odour-active compounds facilitated the investigation of the role of lipids in meat aroma formation. Chicken triglycerides and/or phospholipids were added individually or as a mixture (1:1 w/w) to a defatted chicken matrix and the aroma generated during heating was extracted as before. The results showed that the incorporation of chicken phospholipids significantly enhanced the production of some sulfur- and/or nitrogen�containing Maillard reaction products and most of the lipid-derived products. This was further emphasised in a kinetics experiment, which monitored the accumulation of lipid-derived volatiles over an extended heating duration. The experiment not only demonstrated the higher efficiency of phospholipids in generating lipid-derived products, but also their catalytic effect on the formation of key volatiles in systems containing triglycerides. With the aim of finding a suitable plant phospholipid for use in chicken aroma generation, sunflower and soy phospholipids were explored as plausible alternatives in comparison to the triglyceride counterparts using a defatted chicken matrix. Despite the higher saturated and polyunsaturated fatty acid content in chicken and plant lipids respectively, sunflower phospholipids are proposed to be a better choice as compared to the other lipids studied based on the volatile profile of the samples. This also suggests that fatty acid composition is not the only factor to consider in the substitution of animal lipids with plant lipids. In conclusion, not only are phospholipids more reactive than triglycerides in part due to their higher polyunsaturated fatty acid composition, but also play a catalytic role in the reactivity of the latter. In addition, sunflower phospholipids have the potential for use in the substitution of chicken lipids in plant-based meat products. These findings would be useful for food manufacturers who are keen on the creation and modification of process flavourings or those in search of animal lipid alternatives for application in plant-based meat products.