This study investigated the effect of manufacturing variables (including heating temperature) on the physicochemical properties of nanoemulsion delivery system (NDS) prepared with WPI/Inulin Maillard conjugate and to study how the physicochemical properties of NDS affected the bioaccessibility of lycopene. The functional properties of the WPI/Inulin Maillard conjugate were determined using the OPA method, interfacial tension, and EAI. The physicochemical and morphological properties of NDS were measured using Zetasizer and TEM, respectively. The bioaccessibility of lycopene in the WPI/Inulin Maillard conjugate based NDS was measured using a spectrophotometer. As the pH and heating temperature increased, the Maillard conjugation efficiency increased significantly (p<0.0001). The emulsifying properties of the WPI/Inulin Maillard conjugate were greater than those of WPI. A WPI/Inulin Maillard conjugate based NDS with a size of ~180 nm was observed in TEM images while the droplet size of the WPI/Inulin Maillard conjugate based NDS was smaller than that of the WPI based NDS. During in vitro digestion, no significant changes in the droplet size and PDI of NDS were observed in the mouth and stomach phases, whereas in the intestinal phase, the droplet size and PDI increased significantly (p<0.0001). Moreover, the bioaccessibility of lycopene in the WPI/Inulin Maillard conjugate based NDS significantly increased (p<0.0001), compared with that of the WPI based NDS. There was a significant (p<0.05) increase in the bioaccessibility of lycopene with a decrease in the interfacial tension and droplet size of NDS. In conclusion, WPI/Inulin Maillard conjugate based NDS can be used to enhance the bioaccessibility of lycopene.

Introduction
Materials and Methods
    1. Chemicals and materials
    2. Preparation of whey protein isolate (WPI)/Inulinconjugate
    3. Measurement of free amino groups of WPI/InulinMaillard conjugates
    4. Measurement of interfacial tension of WPI andWPI/Inulin Maillard conjugates
    5. Measurement of EAI of WPI and WPI/InulinMaillard conjugates
    6. Development of lycopene-loaded nanoemulsiondelivery system (NDS) prepared with WPI andWPI/Inulin Maillard conjugates
    7. Physical properties of WPI and WPI/InulinMaillard conjugate based NDS
    8. Morphological properties of WPI/Inulin Maillardconjugate based NDS
    9. In vitro digestion model
    10. Measurement of bioaccessibility of lycopeneencapsulated in WPI and WPI/Inulin Maillardconjugate based NDS
    11. Statistical analysis
Results and Discussion
    1. Free amino groups of WPI/Inulin Maillard conjugates
    2. Interfacial property and emulsifying activity indexof WPI/Inulin Maillard conjugate
    3. Physical and morphological properties of WPI/InulinMaillard conjugate based nanoemulsion deliverysystem
    4. The physical stability of WPI/Inulin Maillardconjugate based NDS during in vitro digestion
    5. Bioaccessibility of Lycopene encapsulated inWPI/Inulin Maillard conjugate based NDS
Acknowledgments
References

• Se Hee Lee(Graduate student, Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Korea)
• Yeon Woo Kim(Graduate student, Division of Applied Life Science, College of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Korea)
• Won Jae Lee(Professor, Division of Animal Bioscience and Integrated Biotechnology (Institute of Agriculture and Life Science), College of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Korea) Corresponding author