Gelatin addition improves the nutrient retention, texture and mass transfer of fish balls without altering their nanostructure during boiling

- Exponential and linear models were more suitable to study fish ball mass transfer.
- Added gelatin increased the mass transfer coefficient of fish balls during boiling.
- Added gelatin decreased the hardness and chewiness of fish balls.
- The added gelatin did not affect the nanostructure of fish balls.
- The added gelatin decreased nutrient loss during boiling.

The effect of fish gelatin addition on mass transfer, nutrient loss, texture and nanostructure of fish balls was investigated. Mass transfer models were built and the root-mean-square-errors were 0.1432, 0.3178 and 0.1000 for exponential, power-law and linear models, respectively. After gelatin addition, the mass transfer coefficient/model parameter and moisture content increased, and the hardness and chewiness of fish balls decreased. Myofibrils were imaged using atomic force microscope (AFM). The length of the myofibrils was greater than 15 μm before and after boiling for 10 min; however, they decreased to around 14 and 11 μm after 20 and 30 min boiling, indicating degradation of myofibrils. Meanwhile, there was no significant difference among different groups, suggesting that the added gelatin did not affect the nanostructure of the fish balls. Furthermore, increasing gelatin addition resulted in fewer water-soluble proteins and peptides in the boiling water. The results suggest that added gelatin increased the mass transfer coefficient/model parameter by increasing the moisture content and decreasing the nutrient loss. It also improved the texture by decreasing the hardness and chewiness, and did not affect the nanostructure of fish ball myofibrils.