Research On The Preparation And Characteristics Of Low-ester Pectin

The low-methoxyl pectin is a good food stabilizer,gelling agent and thickener.Under the condition of sugar or sugar free,it can form gelatin with excellent properties.It is mainly used in foods with low sugar,low energy and low sweetness,just in line with modern people’s consumption concept.The low-methoxyl pectin has unique medicinal value,so it is increasingly favored by consumers and has broad market prospects.With the improvement of people’s quality of life,the demand for low-methoxyl pectin will also increase dramatically.Pectin produced in China is mainly high-fat pectin extracted from natural plant tissues.The low-methoxyl pectin is limited by production technology,It is not really put into production.It mainly depends on foreign imports,and its price is quite expensive.If we can make full use of the abundant high-methoxyl pectin resources in China and make more exquisite research on pectin demethylating process,it will bring enormous social and economic benefits.In this research,commercial apple high-methoxyl pectin was used as raw material to produce low-methoxyl pectin by acid deesterification under appropriate pH,temperature and time conditions.The effects of pH,temperature and time on the process of the low-methoxyl pectin by acid demethylating and the effects of the yield,methoxyl content and viscosity were discussed.The viscosity and gel strength of the low-methoxyl prepared by this method were analyzed,and the effects of various factors on viscosity and gel strength were explored,providing solid data support for producing high quality low-methoxyl pectin,and providing theoretical basis for the application of low-methoxyl pectin in industry.Through the study of this subject,the following conclusions can be drawn:1.High-ester pectin can be deesterified by acid method to produce low-ester pectin.The major factor influencing the yield,methoxyl content and viscosity of low-ester pectin is pH,while the minor factor is time.Optimum technological conditions for time t was set at 12 h,pH was set at 1.1,temperature was set at 50℃。2、The viscosity of the low-methoxyl pectin solution increases with the increase of solution concentration and sucrose concentration,and increases obviously when solution concentration is more than 1%.With the increase of temperature,it decreases almost linearly,and the change tends to be gentle after temperature is higher than 30℃.The viscosity of the low-methoxyl pectin solution increases first and then decreases with the increase of Ca²⁺concentration in solution,and Ca²⁺concentration reached at 30mg/g in solution.The viscosity of the low-methoxyl pectin reached the maximum;The viscosity of the low-methoxyl pectin decreased with the increase of pH value of solution,but the change trend was not obvious.Among these factors,the concentration of the low-methoxyl pectin solution,temperature,sucrose concentration and Ca²⁺concentration have greater influence on the viscosity of the low-methoxyl pectin,while the pH of the solution has less effect on its viscosity.3、The gel strength of the low-methoxyl pectin solution increased with the increase of its concentration,and its change trend was very similar to that of its viscosity.The pH value of the low-methoxyl pectin solution,the concentration of sucrose and the concentration of Ca²⁺had first increased and then decreased.When the solution pH value was 4.0,the concentration of sucrose in the solution was 30%,and the concentration of Ca²⁺in solution was 30mg/g,the gel strength reached the maximum under the corresponding conditions.The gel strength of the low-methoxyl pectin solution was higher than that of high temperature at low temperature.At the same temperature,the gel strength increased first and then decreased with the increase of storage time,and the gel strength reached the maximum at 48h.These factors affect the gel strength of the low-methoxyl pectin solution,The concentration of Ca²⁺in solution is the biggest factor affecting the gel strength of the low-methoxyl pectin,and sucrose concentration is the least significant.