Greater Gel Strength Research Articles

Vessel Volume, Gelling Agent, and Basal Salts Affect pH and Gel Strength of Autoclave Tissue Culture Media

Effects of autoclaving volume, gelling agent (Bactoagar, Gel-gro, Phytagar), and basal salts [Murashige and Skoog (MS); Woody Plant Medium (WPM); Gamborg B5 (GB)] on gel strength and pH of tissue culture media were tested. Gel strength was significantly affected by gelling agent and basal medium. MS media were generally softer than comparable WPM or GB media. As the vessel volume during autoclaving decreased, gel strength significantly decreased with Phytagar and Bactoagar gelling agents; Gel-gro had greater gel strength at the intermediate volume of medium autoclave. In all cases, autoclaving resulted in a pH decrease of 0.2 to 0.5 pH units. Lower pH values were associated with softer gels. The type of gelling agent did not greatly affect the postautoclave pH; mean values among gelling agents were within 0.05 pH units. Postautoclave pH of MS medium was lower than that of WPM or GB. This study verifies the need to observe uniform sterilization protocols to maintain consistency in the chemical and physical properties of media.

高圧によるスケトウダラすり身のゲル化と筋原線維タンパク質の変化

Frozen surimi of Alaska pollack was ground with 2.5% NaCl and treated by a high hydrostatic pressure. Strong gel was formed from the salted paste by treatment at 2.0-4.0kbar at 0°C for 10min. The gel by 3.0kbar pressure treatment had the greatest gel strength. The high pressure-induced gel was different from the heat-induced gel in its property. It had greater gel strength and is more transparent in the appearance compared with the heat-induced gel. The high pressure-induced gel had a small amount of myosin heavy chain and concomitantly a large amount of high molecular weight components. Furthermore, it also had a large amount of Cl component which was not solubilized with SDS-urea-mercaptoethanol medium, whereas the heat-induced gel had no such component. These findings suggest that gel-formation by a high pressure depend largely on the cross-linking of myosin heavy chain. These results indicated that gelation of meat paste induced by a high pressure may be advantageous to processing of a new type fabricated food from fish meat.

Simultaneous heating, forming and extruding of surimi-based products

The United States market for imitation seafood products made from surimi has grown significantly over the past eight years. To continue growth new processing technology is needed. A continuous forming and heat setting extrusion process would greatly increase the market for surimi-based products. The objective of this study was to gain information to be used to predict the effects of heat and flow rate on surimi-based products. Unheated surimi-based products showed Bingham-plastic-like behavior. Assuming unsteady-state conduction, it was shown that radial heat transfer could be predicted to within ±20%. The flow of heated surimi-based products was affected by replacing salt with certain phosphate blends. Texture, as measured by stress and strain at the breaking point of cooked surimi-based products, shows that the heated flow process used in this investigation produced products with greater gel strength than material not subjected to heated flow before cooking.