Effect of Oil Type and Chitosan Concentration in Alginate-Based Microcapsules on the Survivability of Lactobacillus Acidophilus and Antioxidant Properties During Simulated Gastrointestinal Digestion

Tan, Li Ying (2026) Effect of Oil Type and Chitosan Concentration in Alginate-Based Microcapsules on the Survivability of Lactobacillus Acidophilus and Antioxidant Properties During Simulated Gastrointestinal Digestion. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Microencapsulation is widely used to improve the stability and functionality of probiotics during processing and gastrointestinal digestion; however, its effectiveness depends on formulation factors such as coating materials and emulsification conditions. This study aimed to evaluate the effects of chitosan concentration (0, 0.4%, 0.8% w/v) and oil type (sunflower oil and red palm oil) on the encapsulation efficiency, bead size, survival rate, and antioxidant activity (DPPH and ABTS) of Lactobacillus acidophilus encapsulated in calcium-alginate beads prepared via emulsification. In addition, the survival rate and antioxidant activity were determined before and after exposure to simulated gastrointestinal digestion (SGID) conditions. Results showed that the highest encapsulation efficiency (82.22 ± 0.50%) and largest bead size (395 ± 59.86 μm) were obtained in sunflower oil beads coated with 0.8% (w/v) chitosan. Under simulated gastrointestinal digestion conditions, free cells showed 0% survival, whereas encapsulated cells exhibited significantly higher survival (p < 0.05), with the highest survival rate in red palm oil beads coated with 0.4% (w/v) chitosan, 97.19 ± 0.56% at 60 minutes and 96.88 ± 0.54% at 120 minutes in simulated gastric juice, while red palm oil beads coated with 0.8% (w/v) chitosan has a survival rate of 82.88 ± 0.08% under simulated intestinal conditions. Antioxidant activity (DPPH and ABTS) increased significantly during digestion with sunflower oil beads coated with 0.8% (w/v) chitosan, showing the highest DPPH (12.15 ± 0.89%) and ABTS (34.4 ± 1.59%) activity at the intestinal stage. Overall, chitosan concentration and oil type significantly affect the performance of encapsulated beads, while beads coated with 0.8% (w/v) chitosan and emulsified with sunflower oil as the oil phase were identified as the possible optimal formulation due to their enhanced antioxidant activity and balanced encapsulation efficiency performance.