Chemical composition and rheological behaviour of pectins from unconventional sources.

FISSORE E. N.; BASANTA M. F.; NIETO CALVACHE J. E.; ROJAS, A.M.; GERSCHENSON L. N.

Pectin: Chemical Properties, Uses and Health Benefits.

Nova Science Publishers, Inc.

Lugar: Hauppauge , NY ; Año: 2014; p. 187 - 202

Pectins are soluble dietary fibres that constitute a family of complex polysaccharides present in the primary cell wall and middle lamella of plants. The major sources of commercial pectins are citrus peel and apple pomace. Most pectin is produced by the extraction of the raw material with hot aqueous mineral acid at pH~2. In the food industry, pectins are used as gelling agents, thickeners, and stabilizers. New applications are constantly developing and their use as emulsifiers is one of the latest new-comes. Utilization of by-products of the fruit and vegetable industrialization as source of pectins may contribute to the efficiency of the processes and also to the sustainability of the environment. In the present work, pectins were extracted through different procedures from three unconventional sources and were characterized in their chemical composition and rheological behaviour. Beetroot pectin isolated through cellulase digestion and alkaline pretreatment, presented 54 % (w/w) of uronic acids (UA) and showed low degree of methylation (DM) and acetylation. The aqueous solution of this pectin presented low viscosity and pseudoplastic behaviour in flow. Gels were formed by addition of Ca2+. On the other hand, butternut pectin, isolated through cellulase digestion, also presented 54% (w/w) of UA and a high DM, and in the presence of high sugar concentrations and at low pH, produced viscous solutions with pseudoplastic behaviour. Pectins were also obtained from Japanese plums with water at different temperatures. Those extracted at room temperature contained 56% (w/w) of UA and low DM as well as pseudoplastic behaviour in water. Pectin fraction extracted with boiling water contained 50% of UA and showed high DM. Although the later procedure increased considerably the yield, the extracted pectin showed significant lower apparent viscosity in water, in spite of its high molecular weight. The isolating procedures assayed permitted the extraction of pectin enriched fractions from non conventional sources with interesting yields and diverse rheological characteristics.