草酸法提取柠檬果胶工艺优化及品质评价

Optimization and quality evaluation of extracting lemon pectin by oxalic acid

目的:提高柠檬果胶的得率及凝胶性能。方法:采用草酸法从柠檬皮渣中提取果胶,通过单因素试验和正交试验,筛选出提取柠檬果胶的最适料液比、pH、提取温度及提取时间,并对所提取柠檬果胶的纯度和酯化度、流变学特性进行分析,对比所提取的柠檬果胶与市售高酯果胶1(HMP-1)、高酯果胶2(HMP-2)的凝胶性能差异。结果:当料液比为1∶20 (g/mL),pH为2.2、提取温度为95℃、提取时间为75 min时,果胶粗提物得率为22.83%(总半乳糖醛酸含量为76.06%,酯化度75.94%)。采用该法提取的果胶黏度高于两种市售高酯果胶、钙敏性介于HMP-1与HMP-2之间、温敏性与HMP-2相似,钙离子环境下可在76.55℃时发生溶胶—凝胶转变。结论:草酸法提取的柠檬果胶拥有良好的流变性能和凝胶性能,具备作为酸性乳饮料中稳定剂的潜力。

Objective: This study aimed to improve the yield and gelling property of lemon pectin. Methods: Oxalic acid was used to extract pectin from lemon residue. The factors of optimal ratio of solid-liquid, pH, extraction temperature and extraction time were optimized through single factor experiments and orthogonal experiments. The purity, degree of esterification and rheological properties of the extracted lemon pectin were analyzed. The differences of gelling property between the extracted lemon pectin and two kinds of commercial high methoxyl pectins(HMP-1, HMP-2) were compared. Results: The results showed that the yield of pectin extract was 22.83%, with total galacturonic acid of 76.06% and degree of esterification of 75.94%, when the ratio of solid-liquid was 1∶20(g/mL), extracting pectin at pH 2.2 and 95 ℃ for 75 min. The viscosity of the extracted lemon pectin was higher than HMP-1 and HMP-2. The calcium sensitivity was between HMP-1 and HMP-2, and the temperature sensitivity was similar to HMP-2. The sol-gel transformation of the extracted lemon pectin was found at 76.55 ℃ in the calcium ion environment. Conclusion: Lemon pectin extracted by oxalic acid has good rheological and gel properties, and can be potentially used as a stabilizer in acidic milk drinks.