Studies On The Differences And Influencing Factors Of Cell Wall Components Of Lotus Rhizomes In Crispy And Mealy Texture

Mealy and crispy lotus rhizomes were used as raw materials in this work. Fristly, the texture, the activity of pectin methyl esterase and the cell wall composition of the lotus rhizome of mealy and crispy properties were determined to compare the difference between them. Furthermore, the influences of preheating and/or calcium pre-treatment on thermal texture degradation were investigated to identify the factors that cause differences in texture. Finally, lotus rhizomes of mealy and crispy properties harvested in the same harvest period were studied to explore the variation of cell wall composition. The results are as follows:(1) The activity of pectin methyl esterase, content of alcohol-insoluble residue and pectin (water-soluble fraction-WSF; cyclohexanediaminetetraacetic acid(CDTA)-soluble fraction-CSF; NaCO3-soluble fraction-NSF) and cellulose of mealy lotus root were significantly higher than that of crisp lotus root. Hemi-cellulose Hemicellulose content was significantly lower than that of the crispy lotus rhizome, The pectin in mealy and crispy lotus rhizome are low methyl-pectin, but the degree of esterification of the mealy lotus rhizome is lower than that of the crisp lotus rhizome. There were the same type of monosaccharide between Mealy and crispy lotus rhizomes, but the content of arabinose in WSF and CSF from mealy lotus rhizome is lower than that of the crispy lotus rhizome.(2) In this paper five pre-treatments were selected(①No pre-treatment;②40℃blanching30min;③90℃blanching5min;④0.5%CaCl2soaking1h;⑤40℃blanching30min before0.5%CaCl2soaking1h), the results indicated that all the pre-treatment had little effect on the texture of crispy lotus rhizome compared that with no pre-treatment, but suitable temperature and a certain concentration of calcium ion treatment can effectively improve the texture of mealy lotus rhizomes. Heating at40℃for30min followed by0.5%CaCl2solution soaking processing of lotus rhizome improved the relative hardness, and kept the cell wall integrity after thermal processing, minimized increasing the content of the water-soluble pectin, chelating high pectin content, reduced the extent of losses of alkali-soluble pectin and chelate-arabinose pectin the and increase the proportion of galactose. indicating that pectin branched reduce losses. (3) In each growth cycle, the hardness, pectin methylesterase(PME) activity and the content of AIR in crispy lotus rhizomes were significantly higher than mealy lotus rhizomes. The hardness of crispy lotus rhizomes rhizomes in November and in January for mealy lotus rhizomes.The content of alcohol insoluble residue(AIR) unchanged from crispy lotus rhizomes in growth period, while mealy lotus rhizomes the content of AIR was significantly increased in November, The content of WSF were slightly increased, and CSF were reduced in all lotus rhizomes. In September the content of CSF from mealy lotus rhizomes was significantly higher than crispy lotus. NSF had no difference.In the harvest period, galacturonic acid content of WSF and CSF did not change significantly, a slight rise of NSF for the two lotus. At the same harvest period, brittle lotus root was significantly higher than farinose lotus, but NSF still no difference.The degree of esterification of the two lotus root was maintained at a relatively stable level, but at the same harvest period, brittle lotus degree of esterification was significantly higher than farinose lotus. In addition to the arabinose content of farinose lotus is less than the brittle lotus, the other was no evident regularity.