Influence of processing conditions on the physical properties, retention rate, and antimicrobial activity of cinnamaldehyde loaded in gelatin/pectin complex coacervates

To enhance the release characteristics and antimicrobial properties of cinnamaldehyde microcapsules based on gelatin and pectin coacervates, microcapsules were prepared using different emulsification and stirring speeds. The physical properties, encapsulation efficiency, and retention rate were investigated. The in vitro antimicrobial activity and application in frozen and defrosted minced lean beef meat preservation were explored. Microcapsules generated at high emulsification (13,000 rpm) and stirring speed (400 rpm) showed an average particle size of 14.6 μm and encapsulation efficiency of 78.7% with a low retention rate (62.5 at 6 °C and 50.7 at 37 °C) during storage. However, samples produced at low emulsification and stirring speeds exhibited particle sizes and encapsulation efficiencies of 44.5 μm and 77.9 μm; 85.2% and 92.1%, respectively. Samples with large particle sizes have shown a high retention rate during storage (70.2 and 78.9% at 6 °C, 64.9 and 56.8% at 40 °C). The minimum inhibitory concentration (MIC) of cinnamaldehyde microcapsules ranged from 2–4 mg/mL of total microcapsules. Microcapsules stored at 6 °C and 37 °C for 9 days inhibited the growth of Staphylococcus aureus during in vitro experiments. The application of microcapsules in frozen and defrosted minced lean beef meat decreased the CFU/g from 7.8 in control samples to 7, 6.5, and 5.2 during storage. Additionally, cinnamaldehyde microcapsules delayed the color and pH change during nine days storage at 6 °C. The sensory properties of frozen and defrosted minced lean beef meat were enhanced using cinnamaldehyde microcapsules during storage. This study suggests that emulsification and stirring speed can be tailored to generate microcapsules prepared by complex coacervation with excellent release characteristics and antimicrobial activities for food application. Graphical abstract