Effect Of High Hydrostatic Pressure On Structure And Functional Properties Of High Methoxyl Pectin And Its Gel

Pectin is a kind of high molecular carbohydrate widely found in the cell wall of green plants,which is the main component that affects the key functional properties such as rheology and cloud stability of fruit and vegetable products.High hydrostatic pressure(HHP)treatment is a new non-thermal sterilization method for fruit and vegetable products.At the same time of sterilization,HHP causes the multilevel structure of pectin to change,thereby affecting the physical and chemical properties and functional properties of fruit and vegetable products.In this paper,high methoxyl apple pectin(HMP)was used as the research object,and HHP treatment was carried out on its solution and gel system respectively.The effect of HHP on HMP multilevel structure and its solution and gel properties was investigated,aiming at elucidating the influence rule and action mechanism of HHP.The main research contents and results are as follows:After treatment of 5%HMP solution at 0.1,200,400 and 600 MPa for 30 min,it was found that the primary structure of HMP molecules in the solution remained unchanged,while the HMP molecular chain was more extended at high pressure;Appropriate pressure had obvious thickening and stabilizing effect on HMP solution,while excessive pressure would cause excessive aggregation between HMP molecules,resulting in a more uneven molecular weight distribution of HMP and a decrease in the stability of its solution.After treatment of HMP gel(2%HMP+50%sucrose+48%water)at different pressures(<600 MPa)for 30 min,it was found for the first time that the HMP gel could be converted into a sol at the pressure above a certain threshold(200～220 MPa),showing a certain fluidity,and the gel state was restored within a period of time after pressure relief;HHP had a significant effect on the steady-state properties of HMP gels,of which 200 MPa was the optimum pressure for HMP cross-linking,and the mechanical performance indexes and water holding capacity of HMP gel treated at 400 MPa were signifi cantly improved;by utilizing the melting phenomenon of HMP gel at high pressure,the embedding of vitamin C at normal temperature could be achieved,and its biological activity is well preserved.Molecular dynamics simulation results indicated that HHP mainly affects the strength of hydrogen bond and hydrophobic interaction between HMP molecules by affecting the volume of the system and the distribution of water and sucrose molecules around the HMP molecule,thereby regulating the properties of HMP solution and gel.