TY - JOUR
T1 - Pilot plant scale extraction of alginates from Macrocystis pyrifera 4. Conversion of alginic acid to sodium alginate, drying and milling
AU - Hernández-Carmona, Gustavo
AU - McHugh, Dennis J.
AU - Arvizu-Higuera, Dora Luz
AU - Rodríguez-Montesinos, Y. Elizabeth
N1 - Funding Information:
We acknowledge the Program of United Nations for Development (PNUD) of the Food & Agriculture Organization of United Nations (FAO), the Instituto Politécnico Nacional (CICIMAR-IPN), and the Sec-retaría del Medio Ambiente, Recursos Naturales y Pesca (SEMARNAP) for the financial support to construct the pilot plant for alginate production. Many thanks to the technicians Jorge Castro-Guereña, and Rafael Morales-Mendoza, who helped with the experimental work at pilot plant level. Gustavo Hernández and Elizabeth-Rodríguez thank the Comisión para el Fomento de Actividades Académicas del Instituto Politécnico Nacional (COFAA-IPN) for the scholarship salary for working exclusively for the IPN. Gustavo Hernández, Dora Luz Arvizu and Elizabeth-Rodríguez thank the IPN for the scholarship salary received by the program Estímulo al Desempeño de la Investigación (EDI-IPN).
PY - 2002/12
Y1 - 2002/12
N2 - The last three steps of the alginate production process were studied: conversion of alginic acid to sodium alginate, drying, and milling. Three methods were used to follow the conversion reaction: measuring the pH (a) in the ethanol-water liquid of the reaction mixture, (b) after dissolving a sample of the fiber taken from the reaction mixture, (c) after dissolving the dried sodium alginate obtained from the reaction. To obtain a neutral dried sodium alginate, in the first method the pH should be adjusted to 9, and in the second the pH should be adjusted to 8. The best method to control the reaction was to dissolve a sample of the fiber and adjust the pH to 8. The best proportion to reach the critical point, where pH just begins to rise, was 0.25 parts of sodium carbonate to 1 part of alginate in the initial dry algae. A pH above 7 may produce a break down of the molecule, reducing significantly the viscosity of the final alginate. Four different temperatures were used to dry the alginate: 50, 60, 70, and 80°C. Drying time to reach 12% moisture ranged from 1.5 h at 80°C to 3 h at 50 °C. The best drying temperature was 60°C for 2.5 h. The effect of drying temperature on alginate viscosity was dependent on the alginate type. Low and medium viscosity alginates were not significantly affected, but alginate with high viscosity was reduced by 40 to 54% using the temperature range of 60 to 80°C. A fixed hammer mill was used to reduce the particle size of the dried sodium alginate. Particle size measurements showed that after a first milling the product contained 76% large particles (20-60 mesh) and 24% fine particles (80-120 mesh). After a third milling the product still contained 42.9% large particles. No significant effect was found on alginate viscosity because of the milling steps.
AB - The last three steps of the alginate production process were studied: conversion of alginic acid to sodium alginate, drying, and milling. Three methods were used to follow the conversion reaction: measuring the pH (a) in the ethanol-water liquid of the reaction mixture, (b) after dissolving a sample of the fiber taken from the reaction mixture, (c) after dissolving the dried sodium alginate obtained from the reaction. To obtain a neutral dried sodium alginate, in the first method the pH should be adjusted to 9, and in the second the pH should be adjusted to 8. The best method to control the reaction was to dissolve a sample of the fiber and adjust the pH to 8. The best proportion to reach the critical point, where pH just begins to rise, was 0.25 parts of sodium carbonate to 1 part of alginate in the initial dry algae. A pH above 7 may produce a break down of the molecule, reducing significantly the viscosity of the final alginate. Four different temperatures were used to dry the alginate: 50, 60, 70, and 80°C. Drying time to reach 12% moisture ranged from 1.5 h at 80°C to 3 h at 50 °C. The best drying temperature was 60°C for 2.5 h. The effect of drying temperature on alginate viscosity was dependent on the alginate type. Low and medium viscosity alginates were not significantly affected, but alginate with high viscosity was reduced by 40 to 54% using the temperature range of 60 to 80°C. A fixed hammer mill was used to reduce the particle size of the dried sodium alginate. Particle size measurements showed that after a first milling the product contained 76% large particles (20-60 mesh) and 24% fine particles (80-120 mesh). After a third milling the product still contained 42.9% large particles. No significant effect was found on alginate viscosity because of the milling steps.
KW - Alginate
KW - Alginic acid
KW - Conversion
KW - Drying
KW - Macrocystis pyrifera
KW - Milling
KW - Pilot plant process
KW - Sodium alginate
UR - http://www.scopus.com/inward/record.url?scp=0036922443&partnerID=8YFLogxK
U2 - 10.1023/A:1022372807813
DO - 10.1023/A:1022372807813
M3 - Artículo
SN - 0921-8971
VL - 14
SP - 445
EP - 451
JO - Journal of Applied Phycology
JF - Journal of Applied Phycology
IS - 6
ER -