Changes in physicochemical properties related to the texture of lotus rhizomes subjected to heat blanching and calcium immersion

Pretreatments such as low temperature blanching and/or calcium soaking affect the cooked texture of vegetal food. In the work, lotus rhizomes (Nelumbo nucifera Gaertn.) were pretreated using the following 4 treatments, blanching at 40°C, blanching at 90°C, soaking in 0.5% CaCl2, and blanching at 40°C followed by immersion in 0.5% CaCl2. Subsequently, the cell wall material of pretreated samples was isolated and fractioned to identify changes in the degree of esterification (DE) and monosaccharide content of each section, and the texture of the lotus rhizomes in different pre-treatments was determined after thermal processing with different time. The results showed that the greatest hardness was obtained after blanching at 40°C in CaCl2, possibly attributing to the formation of a pectate calcium network, which maintains the integrity of cell walls. Furthermore, the content of galactose, rhamnose and arabinose decreased due to the breakage of sugar backbones and subsequent damage to cell walls. Our results may provide a reference for lotus rhizome processing.