Optimization of Composite Coating Film for Optimal Color Protection Process of Scraped Ginger by Response Surface Methodology

Objective: The effect of three coating agents, namely chitosan, sodium alginate, and carrageenan, on the color protection and preservation of peeled ginger was investigated to screen the best combination of color protection coating for scraped ginger to inhibit the browning of scraped ginger during processing. Methods: Based on a single-factor test, three color protectors, namely chitosan, sodium alginate, and carrageenan, were selected as independent variables and the browning degree was used as the response value, and the Box-Behnken central combination experiment and response surface analysis were used to investigate the effects of the interaction of independent variables on the browning of scraped ginger. The optimum composite color protection coating process for the inhibition of browning of peeled ginger was determined. Results: The optimum formulation of the composite coating agent was 1.399% chitosan, 1.783% sodium alginate and 1.311% carrageenan. The browning of scraped ginger stored for 15 days under this color protection condition was 0.232, which was close to the response surface prediction (2.230). The measured curcumin content was 1.62%, total flavonoid content was 1.83%, total phenolic content 53.88 μg/g, weight loss 0.89% and DPPH free radical scavenging capacity 442.21 μg Trolox/g, all had significantly different compared with the control (P<0.05). Conclusion: The combination of three coating agents, chitosan, sodium alginate and carrageenan, produced a composite coating film with good color protection, which not only inhibits browning and water loss in ginger to a certain extent, but also preserves the nutritional quality of scraped ginger during storage.