Improvement of functional properties of Chlorella-inulin conjugates via Maillard reaction

Abstract

Functionalities of proteins for the formulation of protein-fortified products are crucial, impacting the use of protein from sustainable sources such as algae. Glycation (the initial step of the Maillard browning reaction) is a standout modification technique explored to improve the functions of the protein in the food matrices. In this study, Chlorella powder was conjugated with inulin using a wet glycation method. It is a quick, scalable and easy method for improving the functionality of food proteins. In this study, conjugation was performed for three different Chlorella to inulin molar ratios (S1:1, S3:1 and S5:1). The solution of each molar ratio was heated at 90°C for 30 min under alkaline state (9.0 pH). Characterisation was conducted employing OPA assay, browning intensity and FTIR spectroscopy techniques. The results suggested glycation achieved the highest for the Chlorella-inulin ratio of 1:1. Glycation extent influenced the solubility of this conjugate significantly (P < 0.05) under an acidic medium. Other functional properties including hydration, moisture uptake, oil-binding and emulsifying activity were also significantly (P < 0.05) enhanced compared to unmodified Chlorella powder. Chlorella conjugate with molar ratio 1:1 also displayed higher antioxidant properties suggesting glycation's role in improving Chlorella powder free radical scavenging capabilities (1.25-fold increase) and reducing power (2.24-fold increase). The total scavenging activity and total reducing power of S1:1 were 2.526 × 10⁻³ and 1.872 × 10⁻³ mg mL⁻¹ mg⁻¹(Trolox Eq.), respectively. The results provide an understanding of different functionalities for glycated conjugates promising utilisation in the food and beverage industry.