Effect Of Primary Salty Components In Aqueous Extract From Cuttlefish Bone On The Gel Properties Of Myosin From Grass Carp (Ctenopharyngodon Idella)

Salt, being as a common salty flavoring, has the important physiological regulation effect. It can adjust the water-salt metabolism and osmotic balance between cells and blood. Epidemiological surveys show that a large number of salt intake is closely related to the incidence of hypertension and long-term high sodium diet can increase blood pressure. Reducing the amount of salt in food processing has become a major concern for researchers since the 1980s. Comprehensive studies on many aspects of salt substitution, including salt partial substitution, inorganic salt substitute and effect of salt substitute on food quality, were conducted abroad, whereas related investigations of salt substitute in China started relatively later, and researches in this area were conducted only in the past few years. How to reduce the amount of salt while maintaining saltiness was a major problem in this area all over the world. The objectives of the present study were to develop a salt substitute which contained low sodium and had strong saltiness, discuss the interaction between salty components, and study the effect of salt substitute on the processing properties of myosin. The contents and results were as follows:1. Analysis of salty components in the aqueous extracts of flora and faunaThe aqueous extracts of clamshell, cuttlefish bone, kelp, seaweed, oyster shell, inula flower, semen cassiae, sanna leaf and arabia cowry shell were analyzed for salty components. The saltiness of aqueous extracts and sodium chloride were compared in the experiment. Results showed that only clamshell and cuttlefish bone aqueous extracts tasted significant saltiness among the 9 aqueous extracts. The type and quantity of amino acid in cuttlefish bone aqueous extract were much more than those in clamshell aqueous extract, as same as the content of sodium and potassium (P< 0.05). The sodium content of cuttlefish bone aqueous extract was 73% of that of NaCl at the same level of saltiness. The saltiness evaluations of different concentrations of cuttlefish bone extract solutions and NaCl solutions showed that the saltiness between cuttlefish bone extract and NaCl at the same concentrations was similar.2. Study on the interaction among primary salty componentsThe effect of potassium chloride, L-histine and L-lysine on saltiness of sodium chloride at a certain range of concentration was researched. The results showed that 20mg/ml KCl inhibited the saltiness of 2-24mg/ml NaCl and had additive effect on the saltiness of 24～44mg/ml NaCl. The 60mg/ml L-His increased the saltiness of NaCl. The 55mg/ml L-Lys suppressed the saltiness of 2-24mg/ml NaCl and increased the saltiness of 40-44mg/ml NaCl, while it had additive effect on the saltiness of 28-36mg/ml NaCl.3. Development of low-sodium saltBased on the results of the second chapter and third chapter, bionics principles, the formula uniform design was used to determine the formulation of salt substitute through sensory evaluation for saltiness, off-flavor and salty persistent. The sensory evaluation results were further verified by electronic tongue for saltiness among samples, optimization and NaCl, which was at the same concentration as optimization. Finally, the formulation of the salt substitute was determined as follows:the contents of NaCl, sodium gluconate, KC1, KOH, L-histine and L-lysine were 42.8%,3.5%,45.2%,0,1.5% and 7.0%, respectively. The sodium content in the salt subitute was 56.3%less than that in a NaCl solution of the same degree of saltiness.4. Study on the effect of low-sodium salt on the gel properties of myosin from grass carp and the development of low-sodium salt in surimi productEffect of salt substitute at different concentrations on the secondary structures and gel properties of myosin from grass carp was investigated, and low-sodium surimi product was further developed. Results showed that salt substitute addition significantly increased the a-helix content (P< 0.05), while the content of β-turn, β-sheet and random coil decreased when salt substitute was added. There was a significant transformantion in the protein secondary structure, which had a good effect on the hydrophobicity and solubility of myosin. The gel strength, springiness, water-holding capability and hardness of myosin gel with salt substitute were increased. No matter partial or complete salt substitute used, the sodium contents of surimi products were significantly decreased at the same time the potassium contents were increased (P< 0.05). There was no significant difference in whiteness between treatment with salt and salt substitute (P> 0.05). The surimi product with 50% salt substitute had good sensory quality and the sodium content was 33.52%less than that of surimi product with 100% NaCl, while the potassium content was 20.72% more than that of 100% NaCl surimi product.