Hydrolysis, with subcritical water and Co2, of the starch and cellulose gifts in the residue of supercritical extration of ginger (Zingiber officinale Roscoe): production of oligossacarids

Author(s)

Silvania Regina Mendes Moreschi

• Document type: Doctoral Thesis
• Press: Campinas, SP. , gráficos, ilustrações, tabelas.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos
• Defense date: 2004-05-11

Examining board members

Maria Angela de Almeida Meireles Petenate; João Alexandre Ferreira da Rocha Pereira; Luiz Antonio Viotto; Silvio Roberto Andrietta; Carlos Eduardo Vaz Rossell; Francisco Maugeri Filho; Antonio José de Almeida Meirelles

• Advisor: Maria Angela de Almeida Meireles Petenate
• Field of knowledge: Agronomical Sciences - Food Science and Technology
• Indexed in: Base Acervus-UNICAMP
• Location: Universidade Estadual de Campinas. Biblioteca Central Cesar Lattes; T/UNICAMP; M816h; Universidade Estadual de Campinas. Biblioteca da Faculdade de Engenharia de Alimentos; T/UNICAMP; M816h

Abstract

Cellulose and starch contained in aromatic-plant residues, which had been subjected to supercritical CO2 extraction, were hydrolyzed with subcritical water and CO2 to obtain oligosacharides. Cellulose and starch are not soluble in supercritical CO2; therefore, they remained in the solid matrix after the supercritical extraction. The extraction step acted as a pre-treatment step for hydrolysis because the pressure affected the solid matrix by relaxing the starch granule resulting, thus, increasing the rate of hydrolysis. Ginger (Zingiber officinale Roscoe) bagasse containing about 50% of starch was hydrolyzed in a semicontinuo reactor in the temperature range of 132 - 200°C and pressure range of 80 ¿ 220 bar. The reactor was filled with a mixture of ginger bagasse and water (3:7). The CO2 was used to pressurize the system. To withdraw the products from the reactor a CO2 flow rate of 7.48 × 10-5 kg s-1 was used. The hydrolysis yield was evaluated with respect to the amount of reducing sugars formed. The hydrolysis assays were done for a constant reaction time of 15 min to search for the condition of temperature and pressure that maximized the hydrolysis degree and the yield. The results were analyzed by the surface response methodology. The hydrolysis kinetics tests were performed at 150 bar and at 176, 188, and 200 °C. The kinetics tests were done keeping constant the ratio between ginger bagasse and water, as well as the CO2 flow rate; the following reaction times were evalueted: 1, 5, 7, 9, 11 and 15 min. The highest hydrolysis degree (97.1% at 15 min) and the highest yield (18.1% at 11 min) were stablished for 200 °C. Different oligosaccharide mixtures with different molecular mass distributions were obtained, depending on the temperature and on the reaction time. The ginger bagasse hydrolysis was treated as a heterogeneous reaction with a first-order global chemical kinetic, with respect to the starch concentration; resulting in an activation energy of 185.1 kJ mol-1 and a preexponential factor of 5.8 × 1017s-1. Hydrolysis of fresh ginger and turmeric (Curcuma longa Linneu), dried ginger, dried turmeric, and sugar-cane bagasse were performed at the best conditions established for ginger bagasse (150 bar, 200 °C and 11 min) (AU)

• FAPESP's process: 99/12868-6 - Study of the use of supercritical water for the hydrolysis of starch and cellulose: production of sucrose substitutes with low caloric level
• Grantee: Silvânia Regina Mendes Moreschi
• Support Opportunities: Scholarships in Brazil - Doctorate