Drying methods affect physicochemical and functional properties of quinoa protein isolate

Area of Science:

• Food Science
• Protein Chemistry
• Biomaterials Science

Background:

• Quinoa protein isolate (QPI) has excellent amino acid profiles, making it a promising food ingredient.
• Understanding how processing affects QPI functionality is crucial for its application.
• Drying methods are key in determining protein isolate characteristics.

Purpose of the Study:

• To investigate the impact of freeze-drying, spray-drying, and vacuum-drying on QPI's functional and physicochemical properties.
• To analyze changes in morphology, amino acid composition, protein structure, and thermal stability.
• To correlate these changes with specific functional attributes like emulsification and solubility.

Main Methods:

• Quinoa protein isolate was subjected to three drying methods: freeze-drying, spray-drying, and vacuum-drying.
• Properties analyzed included: morphology, amino acid profile, SDS-PAGE, sulfhydryl/disulfide content, secondary structure (FTIR), surface hydrophobicity, thermal stability (DSC), emulsification, oil binding, water absorption, and solubility.
• Gel properties (elastic and viscous modulus) were evaluated for 8% gels.

Main Results:

• Freeze-dried QPI showed superior emulsification capacity/stability and oil binding capacity, linked to higher surface hydrophobicity.
• Spray-dried QPI exhibited the highest solubility and water absorption capacity at pH 7.
• Freeze-dried QPI formed gels with higher elastic and viscous modulus; it also had the highest denaturation temperature but lowest enthalpy, suggesting more random coil structures.

Conclusions:

• Drying methods significantly alter the functional and physicochemical properties of quinoa protein isolate.
• Freeze-drying and spray-drying yield distinct QPI characteristics beneficial for specific food applications.
• This study provides valuable data for optimizing QPI production and expanding its use as a functional food ingredient.