A comparative study on functional properties of beet and citrus pectins in food systems

Abstract

Pectin is used in a number of foods as a gelling agent, thickener, texturizer, emulsifier and stabilizer. Sugar-beet pulp, the residue left from sugar extraction, is a rich source of pectin. It was the purpose of this study to optimize the extraction of pectin from sugar-beet pulp and to improve the functional properties of this pectin for more potential uses. To extract pectin, pressed beet pulp was dried and powdered. Beet pectin was then extracted under various conditions (pH 1 and 1.5, temperatures of 80 and 90 °C and extraction periods of 1–4 h). The highest yield (22.4%) was obtained at 90 °C after 4 h at pH 1. Chemical components of the extracted pectin and that of commercial citrus pectin were determined and compared. Also, the beet pectin was used in certain foods and its functional properties compared with those of the commercial citrus pectin. The effects of ammonium persulfate and high pH levels on viscosity and gelling properties were investigated. Finally, the effects of the beet pectin and the commercial citrus pectin on the flavour of certain foods were evaluated. The results indicate that the extracted beet pulp pectin can be used in certain foods such as Ketchup tomato sauce as a thickener or as an agent increasing the viscosity; however, it does not have the ability to form firm gels in food, as compared with commercial citrus pectin.