Using the high temperature resistant pH electrode to auxiliarily study the sugar beet pectin extraction under different extraction conditions

Abstract

A full two-level factorial experiment design was employed to investigate the effects of temperature (75 and 85 °C), time (2 and 3 h) and initial pH(1.5 and 2.0) on the molecular composition of sugar beet pectin extracted by citric acid. And the high temperature resistant pH electrode was used to monitor the pH variation during pectin extraction. The results showed that the pH of pectin extraction solution was not constant during pectin extraction, and the pH of extraction solution fluctuated more widely at 85 °C than at 75 °C. In the experiment design, the initial pH was the most significant factor on pectin composition such as arabinose, total neutral sugars, and degree of acetylation, while the temperature became the most important factor for yield, galacturonic acid, rhamnose, galactose, and weight-average molar mass. The degree of methoxylation was significantly affected by extraction time. It was observed that the emulsifying properties of the extracted pectin samples were significantly affected by the extraction conditions. All the results revealed that 1.) the pH value of extraction solution is directly related to the yield and the degradation of the extracted pectin during sugar beet pectin extraction, 2.) the extraction temperature could significantly affect the pH fluctuation of extraction liquid, 3.) the most significant effect factor for a given pectin composition is dominated by the pH fluctuation of the extracting liquid and acid stability of this discussional pectin composition, 4.) beet pectin extracted by citric acid is an effective emulsifier.