Heating-Aided pH Shifting Modifies Hemp Seed Protein Structure, Cross-Linking, and Emulsifying Properties

Area of Science:

• Food Science and Technology
• Protein Chemistry
• Biochemistry

Background:

• Hemp seed protein isolate (HPI) possesses inherent limitations in solubility and emulsifying capacity.
• Structural modification of proteins is crucial for enhancing their functional properties in food systems.
• Alkaline pH treatments can alter protein structure but risk forming undesirable byproducts like lysinoalanine (LAL).

Purpose of the Study:

• To investigate the structural modification of HPI using alkaline pH shift treatment at varying temperatures and times.
• To optimize treatment conditions to improve HPI solubility and emulsifying activity while minimizing LAL formation.
• To assess the impact of the treatment on protein aggregation, amino acid content, and emulsion stability.

Main Methods:

• HPI was subjected to alkaline pH 12 treatment at temperatures ranging from 20-80 °C for durations of 1, 5, and 60 minutes.
• Solubility, LAL content, amino acid composition (cysteine, lysine), and emulsifying activity were quantified.
• Protein structure was analyzed through observation of aggregate formation and emulsion stability studies.

Main Results:

• Solubility of HPI significantly increased with higher temperatures and longer holding times, reaching 97.5% at 80 °C for 60 min.
• Controlled mild treatment (60 °C for 5 min) limited LAL production (<100 mg/100 g protein) with minimal loss of cysteine and lysine.
• The mild pH shift-heating treatment improved emulsifying activity and resulted in emulsions with superior particle size stability during storage.

Conclusions:

• Alkaline pH shift treatment is an effective method for structurally modifying HPI to enhance its functional properties.
• Optimized mild treatment conditions allow for significant improvements in solubility and emulsification while controlling LAL formation.
• Modified HPI demonstrates potential for use in food applications requiring enhanced protein functionality and emulsion stability.