การทำไมโครแคปซูลของสารสกัดจากมะกรูดโดยการทำแห้งแบบพ่นฝอยสำหรับต้านจุลินทรีย์ในผลิตภัณฑ์ปลาสดบด / วรัญญา ปานเกตุ = Microencapsulation of kaffir lime extract using spray drying for antimicrobial in fresh fish paste product
This research is aimed to study a suitable condition to encapsulate Kaffir lime oil using spray drying to use as antimicrobial substances in food products. In the first part, Kaffir lime oil components and its antimicrobial activity was determined. The results showed that the main components in Kaffir lime oil were β-pinene and limonene. Minimum Inhibitory Concentration (MIC) values of Kaffir lime oil was in the range of 0.4 to 0.7 % w/w and clear zone of inhibition was in the range of 9.53-23.73 mm. Vibrio cholerae was sensitive to Kaffir lime oil more than Escherichia coli, Staphylococcusaureus, Salmonella Typhimurium and Pseudomonas fluorescens, respectively. In the second part, microencapsulation of Kaffir lime oil was produced by spray drying using 2 coating materials namely Konjac glucomannan (KGM) and Konjac glucomannan mixed with Gum arabic (KGM-GA). The results showed that KGM-GA showed ability to retain %total oil, %inner oil and amount of active compounds such as terpinene-4-ol and α-terpineol more than using just KGM alone. The suitable condition of spray drying was studied at different air inlet temperatures (160, 180 and 200 °C). The results showed that spray drying at air inlet temperature of 180 °C yielded the highest %total oil, %inner oil and its ability to inhibit bacteria better than other conditions. In the third part, Microencapsules of Kaffir lime oil (0.8 and 1 % w/w) were mixed with fresh fish paste and stored at 4±1°C. The results showed that they could extend the shelf life of fish paste more than 6 days over the control but not exceed 9 days. In addition, physical, chemical and microbiological properties of fish paste mixed with Kaffir lime oil microcapsules were not significantly different (p>0.05). However, they were different from control significantly (p≤0.05). In the final part, changes of the Kaffir lime oil microencapsules during storage were studied at 35, 45 and 55 °C for 3 months. Kaffir lime oil that extracted from the microcapsules could inhibit the bacteria Pseudomonas fluorescens for 14 days, Salmonella Typhimurium for 21 days, Staphylococcus aureus for 79 days and Escherichia coli for 94 days during storage at 35 °C. Furthermore, it still had ability to inhibit Vibrio cholerae during 3 months at 3 storage temperatures. For L* value of the powder decrease, while b* value increased significantly (p≤0.05).