Role of Ionic Strength in Biochemical Properties of Soluble Fish Proteins Isolated From Cryoprotected Pacific Whiting Mince

Abstract

Biochemical characteristics of Pacific whiting muscle proteins extracted at acidic, neutral and alkaline conditions were investigated as affected by various ionic strength levels. The protein solubility at pH 4 declined, as NaCl was added up to 200 mM, due to protein aggregation through hydrophobic interactions. In contrast, at pH 7 and 10, solubility increased as NaCl was added up to 400 mM after which it remained constant. Changes in total SH content and Sowere highly related to the different molecular weight distributions of the soluble proteins. At pH 4, myosin heavy chain (MHC) was soluble as evidenced by the presence of MHC in the soluble fraction, even though degraded molecules were shown at IS 10–100 mM, and became completely insoluble at IS ≥ 150 mM. At pH 10, the density of the MHC band gradually increased as IS increased and the formation of high MW polymers was observed at IS ≥ 150 mM.

Comparative Study of Washing Treatments and Alkali Extraction on Gelation Characteristics of Striped Catfish (Pangasius hypophthalmus) Muscle Protein

“…Addition of NaCl had no effect on total SH content ( P > 0.05). This was in agreement with Thawornchinsombut and Park (2005) who reported that total SH content of alkali‐treated surimi of uncooked samples were not affected by addition of 10 to 400 mM NaCl.…”

Characteristics of Sarcoplasmic Proteins and Their Interaction With Myofibrillar Proteins

“…Several studies have reported a similar phenomenon (Feng 2000; Mireles Dewitt et al. 2002; Thawornchinsombut and Park 2004).…”

EFFECT OF NaCl ON GELATION CHARACTERISTICS OF ACID- AND ALKALI-TREATED PACIFIC WHITING FISH PROTEIN ISOLATES

“…This might have contributed more available hydrophobic patches on the protein molecules for the probe to bind. Moreover, the greater ability of PW muscle proteins to bind ANS at neutral and alkaline conditions could be promoted by salt ions (Thawornchinsombut and Park 2004, 2005). Electrostatic interactions possibly strengthen the hydrophobic interactions between ANS and proteins (Haskard and Li‐Chan 1998).…”

“…2000). Previous studies in our lab also demonstrated that pH and ionic strength play an important role on PW muscle proteins including protein solubility, biochemical properties and molecular distribution of proteins using sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) (Thawornchinsombut and Park 2004, 2005). However, few studies have employed both pH and ionic strength changes with the FPI prepared using the pH‐shift method.…”