In the framework of searching for new pectin sources to partially compensate for domestic and regional demands, the peel (albedo) of the “non-comestible” fruit of Poncirus trifoliata was investigated using a relatively simple experimental design for optimization, in which only the variable was the extraction pH (1.0, 1.5, and 2.0) on the basis of our previous studies on diverse pectin sources. The results showed that the yield of pectin (7.4%-19.8%) was strongly influenced by the extraction pH when the other parameters, namely the solid to liquid extractant (S/L) ratio, temperature (T °C), and time (t) were fixed to 1:25 (w/v), 75°C, and 90 min, respectively. Likewise, the galacturonic acid content (GalA: 61.4%-79.2%), total neutral sugar content (TNS: 9.1%-22.5%), degree of branching (3.5%-13.9%), homogalacturonan (HG) to rhamnogalacturonan-I (RG-I) ratio (2.2-5.6), degree of methylesterification (DM: 54-77), viscosity average molecular weight (Mν: 57-82), and gelling capacity (GC: 124-158) were all affected by the extraction pH. The optimum pH for producing pectin with good yield, quality characteristics (GalA > 65%, DM > 60, Mν > 80 kDa), and gelling capacity (GC > 150), from the peel of P. trifoliata fruit, was found to be pH 1.5.
 Yapo, B.M. (2011) Rhamnogalacturonan-I: A structurally puzzling and functionally versatile polysaccharide from plant cell walls and mucilages. Polymer Reviews, 51, 391-413.
 Schols, H.A. and Voragen, A.G.J. (1996) Complex pectins: Structure elucidation using enzymes. In: Visser, J. and Voragen A.G.J., Eds., Pectins and Pectinases, Progress in Biotechnology, Elsevier Science, Amsterdam, 3-19.
 Vincken, J.P., Schols, H.A., Oomen R.J.F.J., McCann, M.C., Ulvskov, P., Voragen, A.G.J. and Visser, R.G.F. (2003) If homogalacturonan were a side chain of rhamnogalaturonan I. Implications for cell wall architecture. Plant Physioliogy, 132, 1781-1789.
 Yapo, B.M. (2011) Pectic substances: From simple pectic polysaccharides to complex pectins—A new hypothetical model. Carbohydrate Polymers, 86, 373-385.
 May, C.D. (1990) Industrial pectins: Sources, production and applications. Carbohydrate. Polymers, 12, 79-99.
 Voragen, A.G.J., Pilnik, W., Thibault, J.-F., Axelos, M.A.V. and Renard, C.M.G.C. (1995) Pectins. In: Stephen, A.M., Ed., Food polysaccharides and Their Applications, Marcel Dekker, New York, 287-339.
 Yapo B.M. and Koffi K.L. (2013) Utilisation of model pectins reveals the effect of demethylated block size frequency on calcium gel formation. Carbohydrate Polymers, 92, 1-10.
 Yapo, B.M. (2010) Improvement of the compositional quality of monocot pectin extracts contaminated with glucuronic acid-containing components using a step-wise purification procedure. Food and Bioproducts Processing, 88, 283-290. http://dx.doi.org/10.1016/j.fbp.2009.07.001
 Turecek, P.L., Buxbaum, E. and Pittner, F. (1989) Quantitative determination of pectic substances as an example of a rhamnopolysaccharide assay. Journal of Biochemical and Biophysical Methods, 19, 215-222.
 M’sakni N.H., Majdoub, H., Roudesli, S., Picton, L., Le Cerf, D., Rihouey, C. and Morvan, C. (2006) Composition, structure and solution properties of polysaccharides extracted from leaves of Mesembryanthenum crystallinum. European Polymer Journal, 42, 786-795.
 Yapo, B.M. and Koffi, K. L. (2006) Yellow passion fruit rind—A potential source of low-methoxyl pectin. Journal of Agriculture and Food Chemistry, 54, 2738-2744.
 Yapo, B.M. (2009) Biochemical characteristics and gelling capacity of pectin from yellow passion fruit rind as affected by acid extractant nature. Journal of Agriculture and Food Chemistry, 57, 1572-1578.
 McComb, E.A. and McCready, R. M. (1957). Determination of acetyl in pectin and in acetylated carbohydrate polymers. Analytical Chemistry, 29, 819-821.
 Yapo, B.M. (2009) Pineapple and banana pectins comprise fewer homogalacturonan building blocks with a smaller degree of polymerization as compared with yellow passion fruit and lemon pectins: Implication for gelling properties. Biomacromolecules, 10, 717-721.
 Canteri-Schemin, M.H., Fertonani, H.C.R., Waszczynskyj, N. and Wosiacki, G. (2005) Extraction of pectin from apple pomace. Brazilian Archives of Biology and Technology, 48, 259-266.
 Garna, H., Mabon, N., Nott, K., Wathelet, B. and Paquot, M. (2006) Kinetic of the hydrolysis of pectin galacturonic acid chains and quantification by ionic chromatography. Food Chemistry, 96, 477-484.
 Yapo, B.M., Robert, C., Etienne, I., Wathelet, B. and Paquot, M. (2007) Effect of extraction conditions on the yield, purity and surface properties of sugar beet pulp pectin extracts. Food Chemistry, 100, 1356-1364.