Cacao pod husks as a source of low-methoxyl, highly acetylated pectins able to gel in acidic media

• Published in: International journal of biological macromolecules Vol. 101; pp. 146 - 152
• Main Authors: Vriesmann, Lúcia Cristina, de Oliveira Petkowicz, Carmen Lúcia
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-08-2017
• Subjects: Acetylation; Cacao - chemistry; Cacao pod husks; Gels; High acetyl; Hydrogen-Ion Concentration; LM pectins; Pectins - chemistry; Pectins - isolation & purification; Rheology; Solubility; Theobroma cacao; Cacao pod husks; LM pectins; Rheology; High acetyl; Theobroma cacao
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2017.03.082

•Cacao pod husk was used to extract high yield pectins with aqueous HNO3.•A highly acetylated LM pectin (NA-HYP) was obtained.•Rheological properties of NA-HYP were investigated.•NA-HYP was compared to BW (extracted with boiling water).•Gelation was observed (pH<3.0 and high [sucrose]), despite the presence of acetyl groups.
Cacao pod husks, the main by-product from cocoa production, have been investigated for pectin isolation. In the present study, the rheological properties of two low-methoxyl (LM) pectins isolated from cacao pod husks using different extraction conditions were evaluated. One pectin was obtained from optimized conditions employing aqueous nitric acid as an extractant, and the other one was extracted with boiling water. Pectin gels (0.99% galacturonic acid equivalent, w/w) were prepared at pH 2.5–3.0 in the presence of 60% sucrose (w/w) and subjected to rheological analysis. Dynamic oscillatory experiments at 25°C indicated that better gels were obtained at the lowest pH (2.5). Steady shear measurements revealed a shear-thinning behavior. The apparent viscosities of the samples increased as pH decreased. Gelation with calcium ions was not observed for either of the highly acetylated LM pectins analyzed. The rheological analysis results showed that despite their high acetyl content, LM pectins extracted by different methods from cacao pod husks were able to form gels at low pH under reduced water activity, suggesting a possible application in acidic products.