Microencapsulation of Lactobacillus plantarum by avocado seed- type 3 resistant starch and okara protein isolate

• The conjugation between type-3 resistant avocado starch and okara was established. • The conjugated powder was thermal-chemically altered. • Suitable ratio of starch and protein was chosen for spray drying. • The encapsulated probiotic was stable in gastrointestinal conditions. • The encapsulated probiotic was heat-resistant and stable during storage time. Probiotics provide significant health benefits, but their viability is often compromised by environmental conditions during storage and digestion, such as temperature, moisture, oxygen exposure, acidic pH, digestive enzymes, and bile salts. To enhance probiotic stability, this study explored the microencapsulation of probiotics using complexes formed from resistant starch (RS3) extracted from avocado seeds and okara protein isolate (OPI), which underwent the Maillard reaction. The addition of RS3 altered the secondary structure of OPI and increased its thermal resilience. An optimal ratio of RS3 to OPI was identified. At this ratio, the microcapsules had under 5 % of moisture content which was suitable for long-term storage at 25 °C and 4 °C for up to 8 weeks. This compact structure provided better protection for over 80 % of probiotics at the inlet temperatures and around 99.77 % under simulated gastrointestinal conditions, demonstrating superior characteristics compared to other studies. Additionally, the use of okara protein as a plant-based alternative to animal-derived proteins eliminated allergen concerns, making the encapsulation system suitable for a wider range of consumers. The findings suggested that these naturally derived, biodegradable complexes offered a promising encapsulation material for improving probiotic stability and targeted delivery in functional food and pharmaceutical applications. This study contributed to the advancement of sustainable and effective probiotic encapsulation techniques.