Effect of strong alkaline solutions on yield and characteristics of Pacific white shrimp (Litopenaeus vannamei)

Effects of sodium hydroxide (NaOH) and potassium hydroxide (KOH) solutions with different concentrations on yield and characteristics of Pacific white shrimps (Litopenaeus vannamei) meat were studied. Peeled and deveined shrimps were soaked in both solutions having concentrations of 0.125, 0.25, 0.50 and 0.75% (w/v) in the presence of 2.5% NaCl. The increases in weight gain and cooking yield were observed with increasing concentration of both solutions (P < 0.05). The coincidental decrease in cooking loss was noticeable. pH of soaked shrimp muscle (6.84-9.44) increased as the concentrations of alkaline solutions increased (P < 0.05). When protein patterns of soaking solutions were determined, higher degradation of proteins was found as the concentration of both solutions increased. Although the treatment of shrimp with 0.75% NaOH + 2.5% NaCl showed the highest cooking yield, it resulted in the increased a^* value, the decreased shear force and lower likeness score for all attributes. Generally, shrimps treated with mixed phosphates or sodium bicarbonate possessed the superior characteristics to those with alkaline treatments.