Effect of manufacturing processes and storage on aroma compounds and sensory properties of yoghurt
Citation
Moineau-Jean, A., Raymond, Y., Sabik, H., Graveline, N., Champagne, C.P., Roy, D., LaPointe, G. (2020). Effect of manufacturing processes and storage on aroma compounds and sensory properties of yoghurt. International Dairy Journal, [online] 105 http://dx.doi.org/10.1016/j.idairyj.2020.104662
Plain language summary
Greek-style yogurts having 10% protein can be manufactured by many processes, but the two most popular are 1) concentration of a traditional yogurt by centrifugation or filtration, and 2) fermentation of a concentrated milk. The goal of this study was to examine if aromas and sensory properties of the yogurts are different when manufactured by the two processes using the same milk. A traditional 4% protein yogurt served as the “Control” as well as the base for the CCF product. The aroma or yogurt is very complex and 34 volatile compounds were followed in the three yogurts. Four groups of compounds were identified: 1) seven aromas were not present in milk, but were only detected in the yogurt, 2) six aromas were found in milk and in yogurts at the same concentrations, 3) twelve compounds increased in concentration following fermentation or storage and 4) nine aromas showed lower concentrations in the fermented products than in the initial milk. These data show that the fermentation has a strong effect of the aromas in milk: in some instances the yogurt cultures produce some aromas, while in other cases they actually remove some aromas naturally present in milk. When a statistical analysis limited to the compounds produced by the cultures, it was found that volatiles increased on the average by 27% during storage. There was no effect of manufacturing process on the overall levels of the 34 aromas during storage. However, the manufacturing process affected the acidity perception and smoothness of the uogurts. The products that were made by fermentation of a concentrated milk were perceived as being more acid, and were less smooth, than those manufactured by concentrating a traditional yogurt. These data show how manufacturing processes affect the flavor or yogurts. This is useful information to companies which are in the process of selecting technologies for the development of innovative yogurt products. These data are also useful to Canadian consumers because it provides one explanation on why there are such differences in flavours between Greek-style yogurt brands.
Abstract
The goal of this study was to examine how yoghurt manufacturing processes influence the synthesis of aromas and to examine links with sensory properties. A traditional product with 4% protein (control) and two Greek-style yoghurts with 10% protein were made using curd centrifugation or milk ultrafiltration. Of 32 potentially aromatic compounds, six were detected only in yoghurt, six showed no changes between milk and yoghurt, 12 increased following fermentation or storage, and eight showed lower concentrations in yoghurt than in the initial milk. For the six compounds that appeared only after fermentation and the 12 others with higher levels in yoghurt than in milk, volatiles were found to increase by 27% on average during storage. The Greek-style yoghurts had higher “perception of acidity” and lower “smoothness” than did the control. Positive or negative correlations between “typical yoghurt flavour” and 12 volatiles were found.