Aroma retention in evaporated and freeze-dried strawberry pastes
Stability of volatile aroma compounds in different foods has been of increasing interest because of its relationship with the quality and acceptability of foods, but it is difficult to control. In this work aroma (fruity esters) of strawberry pastes were investigated by GC-MS. Loss of aroma compounds especially due to high temperature treatments is a well-known problem in food industry, since absence of aroma compounds causes considerable decrease in the quality. Strawberry pastes are very complex mixture. For the purpose of this research strawberry pastes were prepared by evaporation and freeze-drying, so that those two processes could be compared. Samples were also prepared with and without addition of artificial strawberry aroma. To improve aroma quality of evaporated and freeze-dried strawberry pastes, sucrose (3, 5 and 10%) was replaced by addition of the same concentration of trehalose. Results showed that freeze-drying was more effective than evaporation in aroma retention of strawberry pastes, but it had higher impact on samples without addition of artificial aroma. Increase wasn’t proportional with trehalose concentration. The highest concentration of trehalose i.e. 10% didn’t have the highest impact on aroma retention. Addition of 3 and 5% of trehalose had better effect on aroma retention in both evaporated and freeze-dried samples with and without addition of artificial aroma. Influence of trehalose addition on individual selected fruity esters was also investigated. The same trend is noticed as in overall amount of fruity esters.