Interaction of chitosan gel at different pH conditions prepared with acetic acid as food acidulant in fish protein emulsion sausages

Chitosan gel with various concentrations (0.12-0.33 g) at different pH conditions (pH 3.8 to 5.2) was prepared in eleven combinations as per the Central Composite Design (CCD) for incorporation into fish (Pangasianodon hypophthalmus) mince formulated sausage. Emulsion stability, gel strength, and water holding capacity of the treatment combinations were considered for optimization of chitosan concentration and pH through Response Surface Methodology. Furthermore, the process parameters, i.e., pH (batter and sausage), cooking loss, purge loss, as well as textural and sensory properties, were evaluated for further validation of the findings. It was observed that the gel having 0.3 g of chitosan at a pH of 5 had the highest acceptability and was considered the best combination for desired properties. Increasing pH decreased the cooking loss and purge loss parameters of the sausages, signifying the role of pH in these parameters. However, the range of cooking loss and purge loss in all experimental groups was within an acceptable range. The hardness was increased at lower pH while the adhesiveness was influenced by the combined interactive effect of pH and chitosan concentration. On other hand cohesiveness had shown a direct relationship with pH while springiness did not varied much between the combinations. Sensory evaluation indicated equal acceptance among the panelists except for the sausages with lowest pH range. The study concludes an overall quality improvement in sausages in terms of functional, sensorial, and textural attributes, when the range of chitosan and pH is optimized scientifically before incorporation.