Shoulei Yan

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.

Acetic acid pretreatment improves the hardness of cooked potato slices

The effects of acetic acid pretreatment on the texture of cooked potato slices were investigated in this work. Potato slices were pretreated with acetic acid immersion (AAI), distilled water immersion (DWI), or no immersion (NI). Subsequently, the cell wall material of the pretreated samples was isolated and fractioned to evaluate changes in the monosaccharide content and molar mass (MM), and the hardness and microscopic structure of the potato slices in different pretreatments before and after cooking were determined. The results showed that the highest firmness was obtained with more intact structure of the cell wall for cooked potato slices with AAI pretreatment. Furthermore, the MM and sugar ratio demonstrated that the AAI pretreated potato slices contained a higher content of the small molecular polysaccharides of cell walls, especially in the hemicellulose fraction. This work may provide a reference for potato processing.

Cell wall CSF/WSF ratio value discriminates the cooked texture of lotus rhizome

ABSTRACT In order to find out the key factors to affect the texture variation and the formation mechanism of different cultivars lotus rhizomes after thermal processing, representative lotus rhizomes harvested in year round with 2 months interval, including Lulinhu, Miancheng, and Elian 5, were chosen to calculate the cause of thermal process texture. The texture (hardness), content of different fractions of alcohol insoluble residue (AIR), and microstructure of the cell wall components of the lotus rhizomes exhibited changes during processing. The changes of three pectin fractions in the three lotus rhizomes cultivars were compared by combining the effect of thermal treatment on the lotus rhizome AIR pectin content degree of esterification (DE) and analysing the texture and microstructure, the cell wall materials were found to be the crucial factor in this process. Another six cultivars lotus rhizomes have been employed to replicate the above mentioned results, the total data were used to calculate the chelator soluble fraction (CSF) to water soluble fraction (WSF) ratio value (0.25), which determines the texture of the lotus rhizomes after thermal-processing. The CSF/WSF ratio values (0.25) will give an index for the lotus rhizome processing food industry.