Water Retention Improvement in Frozen Bullfrog Meat: Evaluating Basic Amino Acids as Clean-Label Phosphate Alternatives

The thigh meat of bullfrogs holds significant economic value, yet its supply in frozen form, due to seasonal availability and processing constraints, often results in a substantial decline in water holding capacity (WHC), thereby compromising meat quality. While traditional phosphate treatments effectively enhance WHC, they are increasingly scrutinized for potential health risks, fueling the demand for clean-label alternatives. This study explores the potential of the basic amino acids L-arginine (Arg) and L-lysine (Lys), which are GRAS-approved meat flavour precursors, as clean-label phosphate replacers in frozen bullfrog thigh meat. These amino acids were tested both individually and in combination with NaCl under controlled pH conditions. Compared with the negative control, 1% Arg + 1% Lys + 2% NaCl lowered centrifugal loss from 40.77% to 29.22% (P < 0.05), reaching a level comparable to the acidity regulator (WP) though slightly less effective than the 26.55% observed in the phosphates group. Structural analyses reveal that these amino acids modify the secondary structure of myofibrillar proteins, boosting their solubility and diminishing hydrophobicity. Thus, L-arginine and L-lysine emerge as highly promising, safe, and effective phosphate alternatives, poised to enhance the WHC of frozen bullfrog thigh meat while aligning with the growing consumer preference for clean-label declarations.