High-pressure processing of Porphyra sp.: A sustainable approach for enhanced protein and phycobiliprotein extraction and nutritional quality

High-pressure processing (HPP), a non-thermal technology, has gained attention in the food industry for its environmental sustainability and versatility in preservation and extraction. This study aimed to optimize HPP conditions to enhance the extraction of proteins and phycobiliproteins (PBP) from red algae (Porphyra sp.), highlighting their potential as sustainable bioresources. A Box-Behnken design was employed to optimize three key factors: pressure (100–600 MPa), time (10–30 min), and pH (4–10). The optimal conditions for maximizing nitrogen recovery and PBP content were 600 MPa, 28 min, and pH 7.8. Under these conditions, nitrogen recovery and PBP content reached 31 % and 1.57 g/100 g, respectively. Scanning electron microscopy (SEM) revealed that HPP-induced cell disruption led to significantly higher nitrogen recovery (31 %) compared to the alkaline method (27 %). The denaturation temperature of protein extracted using HPP was similar to that of untreated Porphyra sp. (151–154 °C) but significantly higher than that of alkaline-extracted protein (138 °C). Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that HPP reduced protein denaturation compared to the alkaline method, preserving the amide I (∼1650 cm−1) and II (∼1550 cm−1) peaks characteristic of Porphyra sp. Nutritionally, HPP improved protein digestibility, increased the essential amino acid content of threonine, and enhanced both the amino acid score and the protein digestibility-corrected amino acid score (PDCAAS). These findings suggest that HPP is a promising green technology for producing cost-effective alternative proteins with superior functional and nutritional properties. Moreover, it promotes the sustainable utilization of marine resources, aligning with both environmental and economic goals.