Original article: Gel properties of red tilapia surimi: effects of setting condition,fish freshness and frozen storage

This study aimed to determine effects of setting condition, fish freshness and storage time of frozen surimi on properties of red tilapia surimi gel. To investigate the effect of setting condition, a combination of eight setting temperatures (35–70 °C) and four setting times (30–120 min) was used. Maximum breaking force, deformation and gel strength were obtained after the gel had been set at 40 °C for 90 or 120 min. Setting at 65 °C resulted in the lowest obtained gel strength, because of proteolytic degradation of myosin heavy chain. Increasing storage time of raw fish material in ice caused a significant decrease in gel strength of the resultant surimi gel (P < 0.05). Gels produced from surimi kept in frozen storage for up to 9 months also exhibited reduced gel strength, with a concomitant increase in the expressible drip, with increasing storage time (P < 0.05).     

Drying of Osmosed Cantaloupe: Effect of Polyols on Drying and Water Mobility

Cantaloupe slices were sequentially immersed in 40 and 50 °Brix sucrose solutions for 24 h each. Partial replacement of the 50 °Brix sucrose solution with one of two polyhydric alcohols (sorbitol or glycerol) at 10 or 15% (w/v) was also performed along with a 0% (w/v) polyhydric alcohol treatment and a 10% (v/v) invert sugar partial replacement of the 50 °Brix solution as a control and a reference, respectively. Solids gain (SG) and water loss (WL) were determined up to 48 h later. Conversely, the treatment with 10 and 15% (w/v) sorbitol and the reference showed a significantly higher SG and a lower WL than the control (p < 0.05). The treatments with 10 and 15% (w/v) glycerol presented a significantly lower SG and higher WL than the control (p < 0.05). Increasing concentrations of polyol led to an increase in both the WL and the SG. The osmosed cantaloupe was then dried in a hot air dryer at 60°C, where the numerical drying rate was observed to be as follows: control > 10% sorbitol > 15% sorbitol > 10% glycerol > 15% glycerol > reference, but these differences at each moisture ratio were not significantly different (p > 0.05). Page's model showed a better goodness of fit with the experimental data for all treatments than did the Henderson and Pabis model. The addition of either of the two polyhydric alcohols resulted in a decreased longitudinal relaxation time (T ₁), as monitored using nuclear magnetic resonance (NMR), indicating the decreased mobility of water molecules. Among all treatments evaluated, the sensory analysis derived acceptance scores for the product treated with 10% (w/v) sorbitol were not significantly different from that of the reference (p > 0.05). This may due to the ability of invert sugar and polyols to act as a humectant.