Optimization of a new coating agar gel formulation using D‐optimal mixture design and study its effects on fresh‐cut apple slices along with cold storage

Abstract

The current work aimed to produce coating agar gel suitable for decoration purposes and investigate its ability to preserve quality characteristics of apple slices along with cold storage. Preliminary experiments followed by D‐optimal mixture design were performed to study the effect of agar (X1), glucose syrup (X2), and sucrose (X3) on the storage moduli (G′), loss moduli (G″), and complex viscosities (η*) of produced gels. The results indicate that the full cubic model adequately fitted the responses variances. The interaction regression coefficients indicate that either glucose syrup and agar (X1X2) or sucrose and agar (X1X3) were antagonistically interacted; however, glucose syrup, sucrose, and agar (X1X2X3) were synergistically interacted. The optimal formula was obtained at 1% agar, 35.40% glucose syrup and 32.80% sucrose. Coating apple slices with optimally formulated gel significantly (p < .05) reduced their weight loss and maintained their firmness along the storage period. On the other hand, coated slices exhibited high browning indexes. Practical applications A new coating agar gel suitable for enhancing the appearance and shine of bakery products was developed. D‐optimal mixture design was used to assess the individual and interactive effects of agar, glucose syrup and sucrose on the rheological properties of the studied gel formulas. Implementing the optimally formulated gel to coat apple slices decreased weight loss percentage and preserve the firmness of the coated slices along the storage period.