Food functionality of protein isolates extracted from Yellowfin Tuna (Thunnus albacares) roe using alkaline solubilization and acid precipitation process

摘要

Four types of roe protein isolates (RPIs) were prepared through the alkaline solubilization and acid precipitation (ASAP) process, and their functional properties and in vitro bioactivities were evaluated. Higher buffer capacity in pH‐shift range of 8–12 was found in RPI‐1 (pH 11/4.5), required average 94.5 mM NaOH than that of other RPIs to change the pH by 1 unit. All the samples of 1% dispersion (w/v) showed the lowest buffering capacity near the initial pH. The water‐holding capacities (WHC) of RPIs and casein as controls without pH‐shift were in range of 3.7–4.0 g/g protein, and there were no significant differences (p > 0.05). At pH 2 and 8–12 with pH‐shift, WHC and protein solubility of style="fixed-case">RPIs were significantly improved compared to those of controls. Foaming capacities of style="fixed-case">RPI‐1 and style="fixed-case">RPI‐3 were 141.9% and 128.1%, respectively, but those of style="fixed-case">RPI‐2 and style="fixed-case">RPI‐4 were not detected. The oil‐in‐water emulsifying activity index of style="fixed-case">RPI‐1 and style="fixed-case">RPI‐3 was 10.0 and 8.3 m²/g protein, which was not statistically different from casein (7.0 m²/g), but lower than that of hemoglobin (19.1 m²/g). Overall, style="fixed-case">RPIs, casein, and hemoglobin exhibited lower food functionality at style="fixed-case">pH 4–6 near isoelectric points. Through the style="fixed-case">pH‐shift treatment, the food functionalities of style="fixed-case">RPIs were improved over the controls, especially in the style="fixed-case">pH 2 and style="fixed-case">pH 8–12 ranges. style="fixed-case">RPI also showed in vitro antioxidant and antihypertensive activities. Therefore, it has been confirmed that style="fixed-case">RPI extracted from yellowfin tuna roe has high utility as a protein‐ or food‐functional‐enhancing material or protein substitute resource for noodles, confectionery, baking, and surimi‐based products.