TECHNOLOGICAL CHARACTERIZATION OF PECTIN EXTRACTED WITH SODIUM CITRATE

TECHNOLOGICAL CHARACTERIZATION OF PECTIN EXTRACTED WITH SODIUM CITRATE AND NITRIC ACID FROM SUNFLOWER HEADS N. Muñoz-Almagro 1, P. J. Wilde 2, F. Rico-Rodríguez 3, M. Villamiel 1, A. Montilla 1 1. Instituto de Investigación en Ciencias de la Alimentación CIAL (CSIC-UAM). C/ Nicolás Cabrera 9, Universidad Autónoma de Madrid, 28049 Madrid, España 2. Quadram Institute Bioscience, Norwich Research Park, Norwich NR 4 7 UA, UK 3. Departamento de Ingeniería Química y Ambiental, Facultad de Ingeniería. Universidad Nacional de Colombia, Cr 30 Nº 45 -03, Bogotá D. C. , Colombia Currently, a wide variety of food products requires INTRODUCTION OBJECTIVE the presence of pectin in its formulation due to the To compare the gelling and emulsifying properties. However, rheological and commercial high methoxyl pectins need at least emulsifying 50% of sucrose to form gels. In 2015, the World properties of Health Organization recommended reducing the sunflower daily intake of free sugar to less than 10% of total pectins caloric intake to reduce the risk of extracted with noncommunicable diseases. In this sense, the sodium citrate sunflower pectin is able to make gels in presence and nitric acid. of calcium ions and limited amount of sugar, although the firmness of the gel can vary MATERIAL AND METHODS depending on extraction method. Mw: 464 k. Da Gal. A: 85. 4 % DM: 36. 8 % Neutral sugars: 9. 4% 2 pectins Mw: 89 k. Da Gal. A: 88. 3 % DM: 40. 1 % Neutral sugars: 4. 1% 1. Emulsifying properties • • • Preparation of emulsions (O/W 9: 1 v/v) Determination of droplet-size distribution Light microscope Coulter LS 13 320 Laser Diffraction Particle Sizer SP-SC Extracted with sodium citrate SP-NA Extracted with nitric acid RESULTS 1. EMULSIFYING PROPERTIES A B Figure 1. Micrographs (10 x) of the O/W emulsions (1%) prepared with pectins obtained using different extractant A, sodium citrate (SP-SC) 2. Rheological properties • • • [Ca 2+]: 0, 25, 50, 75 mg/g pectin p. H 3. 0 Sucrose content: 0, 10, 20 and 40% 25 ºC AR 2000 rheometer Cone 60 mm diameter and 0º angle 2. GELLING PROPERTIES A B C D E F B, nitric acid (SP-NA) AR 2000 Rheometer ØThe emulsion formed with SP-NA (Figure 1 B) showed larger droplet size than that formed with SP-SC (Figure 1 A) (D 3, 2, 22. 7 µm vs 7. 6 µm, respectively), indicating a lower stability of emulsion. ØThe effect of calcium (Figure 2 A-D) and sucrose concentrations (Figure 2 E-H) was studied in gels formed with SP-SC and SP-NA. The strength of gels is reflected by the storage (G´) and loss (G´´) modulus. When G´ > G´´, the pectin solution forms gel. ü Pectin solutions did not give rise to gel when Ca 2+ ≤ 50 mg/g (Figure 2 A-C) while 75 mg/g adequate amount to form the gel, (Figure 2 D). ü The addition of sucrose improved the firmness of all formed gels as compared to control with only Ca 2+. G ü For SP-SC (Figure 2 G-H), the strongest gels were reached by addition of 20 and 40% of sucrose, without significant differences (p>0. 05) between them, being the former preferred from a health point of view. CONCLUSIONS Figure 2. Study of strength of sunflower pectin gels obtained using sodium citrate (SC) and nitric acid (NA) (p. H 3. 5, pectin concentration 1%). Influence [Ca 2+] concentration. (A) 0, (B) 25, (C) 50, (D) 75 mg/g. Influence sucrose concentration at 75 mg Ca 2+, (E) 10%, (F) 20%, (G) 40%. G´ > G´´ gel Pectin extracted with sodium citrate showed a better ability to form emulsions and gels than pectin recovered with nitric acid, requiring the half of amount of sucrose to give similar gel. Therefore, this pectin could be healthier. References: [1] Adetunji, L. R. , Adekunle, A. , Orsat, V. , Raghavan, V. Food Hydrocoll 62, pp. 239 -250. ; [2] Han, W. , Meng, Y. , Hu, C. , Dong, G. , Qu, Y. , Deng, H. , Guo, Y. Food Hydrocoll 66, pp. 37 -48. Acknowledgements: This work has been funded by MINECO of Spain (Project AGL 2014 -53445 -R)