Enzymatic purification of Balangu seed (Lallemantia royleana) gum and evaluation of its functional and antioxidant properties

Proteins and polysaccharides are common compounds in many food formulations. They are responsible for some food characteristic, such as texture and controlled release of flavor. They can modify phase stability in colloidal food systems. These biopolymers play an important role in structuration and stabilization of food through their gelling, thickening and surface activity properties. The products of this reaction are new materials that have different functional properties in comparison with reactants. The aim of this study was to investigate the structural, functional and antioxidant properties of protein-free balangu seed (Lallemantia royleana) gum.

Balangu seeds were purchased from a local market in Bojnord. Protein-free Balangu was achieved by protease hydrolysis (by proteinase enzyme K). To inactivate the enzyme, ethanol added at ratio of 3 to 1 on the system and kept for 6 h. Then, polysaccharide was separated and resolubilized in water and the resultant solution was centrifuged at 15,000 × g for 15 min and the supernatant was named as protein-free fraction. The samples were dried in an air forced oven at 38 ̊C. To evaluate the functional properties of the gum, different parameters such as surface tension (using a Wilhelmy plate technique with a platinum-iridum plate), emulsifying properties (particle size distribution in emulsion, light microscopy, emulsion stability in storage period and emulsion stability test centrifuges) and foaming properties (foaming capacity and foaming stability). Moreover, the antioxidant activity balangu gum and protein-free balangu were measured by two methods, DPPH free radical scavenging and FRAP assay. Butylated Hydroxy Toluene (BHT) was used as positive control for comparison. A completely randomized design was used for statistical analysis. The data was statically analyzed by Analysis of Variance (ANOVA) and Duncan Multiple Range Test. The P level of

The results showed that a decrease in protein content of balangu seed gum by protease enzyme led to significant reduction in surface activity and weakened emulsion and foam stabilization properties of balangu seed gum, which presents the importance of protein in emulsifying and foaming properties of balangu seed. Antioxidant activity of the gum and protein-free fraction in the both methods were less than standard BHT. Protein-free fraction had the lowest protein content which caused a sharp reduction in its antioxidant activity compared to the primary gum.

The functional properties revealed that the balangu seed can be well used as an emulsifier and foam stabilizer.