为了得到低分子柑橘果胶的物理制备方法，本文研究了高压均质法和亚临界水法处理对柑橘果胶分子质量的影响规律，发现两者均可降低果胶分子质量，50 MPa、100 MPa和150 MPa下均质处理后的果胶重均分子质量分别为140 ku、130 ku和120 ku；105 ℃、120 ℃和135 ℃亚临界水处理后的果胶重均分子质量分别达到了50 ku、20 ku和10 ku；综合考虑产品分子质量、得率、品质等因素确定120 ℃亚临界水处理为制备低分子柑橘果胶的较佳方法。对比了120 ℃亚临界水改性前后果胶的基本性质，发现：低分子柑橘果胶的单糖组成变化不大；单糖（特别是半乳糖）含量有一定程度下降；半乳糖醛酸含量从改性前的74.23%升高到87.92%；酯化度从70.32%下降到62.47%；重金属含量略有上升，但仍在安全范围内。可见，120 ℃亚临界水处理是制备低分子果胶的较好方法。

To obtain the satisfied physical preparation of low molecular citrus pectin, effects of high pressure homogenization and subcritical water treatment on citrus pectin molecular weight were studied in this paper. The results showed that both of them reduced the pectin molecular weight. Average molecular weights of homogenized pectin were 140 ku, 130 ku and 120 ku under the pressure of 50 MPa, 100 MPa and 150 MPa respectively; while those of subcritical water treated samples were 50 ku, 20 ku and 10 ku under 105 ℃, 120 ℃ and 135 ℃ respectively. Taking a comprehensive consideration of molecular weight, yield and quality, subcritical water treatment at 120 ℃ was selected as a suitable method to produce low molecular citrus pectin. Compared with those properties of non-treated sample, monosaccharide composition of the treated citrus pectin changed little and their contents (especially for galactose) were decreased at a certain degree. The content of galacturonic acid was increased from 74.23% to 87.92%, while degree of esterification decreased from 70.32% to 62.47% in the citrus pectin after treated with subcritical water at 120 ℃. The content of heavy metal in the treated sample was increased slightly, but still within the safe range.

浙江省自然科学基金资助项目（Y3110524）；国家现代农业柑橘产业技术体系专项经费项目（MATS）；浙江省农业科学院国际合作项目（2009R15Y04E01）