Investigation of storage stability and usage as food additive of aroma capsules obtained by using different encapsulation methods

Flavors, one of the component that comprised of the taste of foods, play a very important role in determining consumers' interest in food. For this reason, all kinds of aroma substances are added to different food groups to increase the attractiveness of foods. Nevertheless, sensitive to the environmental conditions such as oxygen, temperature and light, aroma compounds lose their activity during processing or storage period. In order to minimize these restrictions during their usage, it is aimed to increase the stability of the aromas by encapsulation treatments. For this purpose, strawberry, banana and watermelon aromas were encapsulated by spray drying, freeze drying, coacervation and alginate beads. The production conditions of the aroma capsules by different methods were optimized for each method as well as some method-specific parameters. The aroma capsules obtained under optimum conditions were stored for 60 days at 2 different temperatures (4 and 25 °C). Aroma, particle size, solubility, bulk density and morphological structure analyses were performed on the aroma capsules at the 15th, 30th and 60th days with the beginning of storage. In addition, the glassy transition temperatures and structural analyzes by scanning electron microscopy were performed of the aroma capsules produced under optimum conditions, and sensory taste states were determined after processing to model foods (chocolate and cake). According to the Design Expert Package Program with mixture design for strawberry aroma, optimum points of spray drying conditions, which provides minimum aroma release, maximum aroma gain, drying yield and solubility, were determined as air inlet temperature was 190 ° C, maltodextrin (MD) concentration was 15.30%; modified starch (Ms) concentration was 1.83%and arabic gam (AG) concentration was 12.87%. In addition, 1%β-cyclodextrin (β-SD) should be in optimum conditions. The shape factor (SF), sphericity values (KD) and aroma gain values of microcapsules were used in response to the encapsulation of banana flavor for alginate bead method. According to the results where SF value is maximum, KD is minimum and aroma gain is maximum, alginate concentration is 1.32%; calcium concentration 1.0%; dropping rate 100 mL/min; The dripping height was 4.4 cm, the stirring speed of the calcium solution was 650 d/dk and the dripping direction was horizontal determined as the optimal processing conditions. According to the values where the maximum release of aroma gain is minimum, polymer concentration 5%, enzyme amount 20 UA and 24 hours processing time were found as optimum conditions for encapsulation of watermelon aroma by coacervation method. The Tg values of the aroma capsules produced under the optimum conditions of each encapsulation method were calculated by DCS method, Tg values of spray-dried, alginate beads, coaservation and freze-dried capsules were between 132.53-163.69 °C, 64.66-80.16 °C, 115.81-123.11 °C and 172.04-180.21 °C, respectively. In chocolate and cake samples produced with strawberry, banana and watermelon microcapsules, the flavors were felt more than those produced by liquid flavors in commercial form. In chocolate samples, the most popular products were the aroma capsules obtained by spray drying and alginate beads, whereas in the cake samples, aroma capsules were generally produced by spray and freeze drying methods. Storage stability studies have shown that commercial aroma of strawberry, banana and watermelon has decreased by at least 80%of the total area of the aroma components in the first 30 days of storage, and this reduction has been achieved by> 95 at the end of 60 days. The encapsulation process was found to significantly reduce the aroma release, and the storage stability characteristics of each aroma were found to be different from each other. In addition, the loss of aroma from capsules obtained by all encapsulation methods was more frequent at high temperatures. It was concluded that the particle size of strawberry, banana and watermelon microcapsules obtained by spray drying, freeze drying and coacervation methods increased due to moisture absorption with increasing storage time and this increase was higher in high temperature storage conditions. In addition, it has been observed that the bulk density decreases with increasing particle size depending on the storage time of the microcapsules. The results of the research showed that the applied methods significantly reduced the loss of aroma.