Vacuum impregnation pretreatment with maltose syrup to improve the quality of frozen lotus root

The objective of this study was to investigate the effect of vacuum impregnation (VI) with maltose syrup on the quality characteristics, thermo-physical and sensory properties of frozen lotus root slices. The results showed the addition of maltose syrup significantly affected the glass transition behaviour of lotus root matrix. VI increased the process efficiency for attaining desired frozen lotus root product characteristics. The optimal VI conditions obtained by response surface methodology were as follows: maltose syrup, 10.99%, vacuum level, 0.04 MPa and treatment time 60 min. Under the optimal VI conditions, the desired crispiness quality of frozen lotus root (1267.54 g, Hunter L* value, 84.51, ascorbic acid, 27.06%) was achieved. The sensory and SEM microstructural analyses confirmed the positive effect of VI with maltose syrup on the storage quality of frozen lotus root slices. The results of kinetic study showed a significant improvement in ascorbic acid stability.