Calcium-based pH-shift processing for production of low sodium pea protein isolates - Impact on yields, composition, properties and life-cycle impacts.

This study investigated calcium hydroxide (Ca(OH)₂) as an alternative alkalising agent to sodium hydroxide (NaOH) in pH-shift extraction of pea protein isolates (PPIs) to reduce sodium (Na) content and assess impacts on composition, techno-functionality, and environmental performance. Four extraction routes were evaluated, and blended Ca(OH)₂:NaOH neutralisation systems. Replacing NaOH with Ca(OH)₂ eliminated Na incorporation and increased calcium content while maintaining high protein contents (85-88%), although slight reductions in protein yield occurred. Neutralisation base choice had the largest impact on mineral content. Phytate and phytate:mineral ratios remained unfavourable across treatments, indicating limited mineral bioavailability. Calcium-rich isolates exhibited substantially reduced solubility and water-holding capacity and formed firm, aggregated gels, whereas Na-rich isolates produced weaker, more uniform networks. Blended neutralisation allowed intermediate functionality with lowered Na. Life-cycle assessment showed that chemical choice contributed minimally to overall environmental impacts. Ca(OH)₂ thus enables production of low-Na PPIs with tuneable functional properties for targeted food applications.