Preparation Of Citrus Low Methoxyl Pectin Using Immobilized Enzyme And Studies On Its Property And Application

The method to prepare low methoxyl pectin using commercial high methoxyl citrus pectin by immobilized Aspergillus niger pectin esterase and the influencing factors on de-esterification were discussed in this paper to obtain the optimum conditions to prepare low methoxyl pectin. Next, the texture analyzer were used to be annlyze the liquid and gel texture of nature of low methoxyl pectin immobilized Aspergillus niger pectin esterase, getting the pectin's viscosity and gelation under different conditiongs, and more suitable conditions for the gel.At the same time the main physical and chemical characterisitics of pectin products were tested, and were compared with the relevant standards. Finally, the low-methoxy pectin prepared by immobilized enzyme were used in strawberry low sugar jam, and obtain the best conditions. The following is the related research content and results.(1)Prepared low methoxyl pectin by immobilized enzyme: Fixed with sodium alginate pectin esterase from Aspergillus niger with high-methoxy pectin on the goods processing solution, esterification degree of pectin, viscosity and product yield index, then make the single factor and orthogonal tests to affect the quality of the final product of pectin on the main factors, and get optimum conditions of immobilized low methoxyl pectin: Substrate of high-methoxy pectin concentration of 1.5%, skim the timing for the 7h, immobilized enzyme dosage of 10ml. The product yield of low ester pectin was 97.7%, degree of esterification was 29.8%, viscosity was 91.52mpa.s.(2)Analysis of effecting factors of low methoxyl pectin'soltion viscosity: the low methoxyl pectin made by the best method of removal ester were used to analyze various factors to effect soltion viscosity in different conditions,the result shows that viscosity of pectin fluid were proportional to the pectin concentration but reciprocal proportional to the temperature and pH. With the increase of sucrose content, low methoxyl pectin solution viscosity index also increased, meantime found that the pectin solution has become increasingly thick, gradually decreased mobility. When adding the calcium ion concentration in the 5-10mg / g, the low methoxyl pectin solution viscosity index rose slowly along; in the 10-40mg / g, the low methoxyl pectin solution viscosity index increased dramatically, their mobility decreased; when the calcium ion concentration in the 40mg / g, the viscosity of pectin solution peak indicators; continue to add calcium, pectin solution viscosity index did not continue to rise, but fell, pectin solution and layered honeycomb began phenomenon.(3)Analysis of effecting factors of low methoxyl pectin gel strength: breaking strength as the main indexes, make single factor test to affect the quality of the final product of pectin's gel quality on the main factors, and analyze the impact of various factors on the pectin gel conditions, to get the better gel conditions of low methoxyl pectin: sucrose content of 10-30%, pectin concentration of 1.0-1.3%, pH was 3.6-4.4, calcium content 20-45g/mg, the gelling temperature of 5℃, gel time was 24h.(4)Detection of low-methoxy pectin main physical and chemical indicators:the broken strength as the main indicators, determination of low-methoxy pectin loss on drying, ash, acid insoluble solids content, degree of esterification, galacturonic acid content, the results were: drying loss of moisture was 6.9%, ash content was 1.96%, acid insoluble solids content was 0.28%, degree of esterification was 29.8%, galacturonic acid content was 72.8%, These results are in line with standard indicators of pectin-related requirements(5)Study of making low sugar strawberry jam by low-methoxy pectin: according the single factor and orthogonal design, the sensory score of Low sugar strawberry jam as the main indexes, combined with the texture of the auxiliary apparatus for gel strength evaluation, get optimum conditions of low-sugar strawberry jam prepared by low methoxyl pectin:low-methoxy pectin content was 0.3%, CaCl2 content was 1.6mg/g, sugar content was 20%. This low sugar strawberry jam on the condition senses mark of 9.3, gelatinous of 7. 85g.