Corn arabinoxylan biopolymers as materials for biodegradable films for food packaging

• Autor(a) principal: Weng, Verónica Lee
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/109081
• topic: Corn Fiber; Arabinoxylan; Diafiltration; Biopolymer discoloration; Arabinoxylan Films; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Corn fiber is a by-product of the starch industry, currently used as animal feed. It contains in its composition arabinoxylan, with film-forming properties, thus this material has a great interest in being valorized. Arabinoxylan was extracted with an alkaline solution and centrifuged. The resulting extract was purified with an ultrafiltration membrane hollow-fiber unit, in a continuous diafiltration process, at two different Reynolds number at the feed side (129 and 267), under controlled temperature and permeate flux conditions. At the final diavolume of 10, rejections were higher at Reynolds number 267, (91±2)% of NaCl equivalents, NaCleq, and (97±1)% of ferulic acid equivalents, FAeq, than at Reynolds number 129, where rejections were (87±3)% and (95±1)% of NaCleq and of FAeq, respectively. At both Reynolds numbers, the removal of small compounds was similar (97.0±0.3)% in NaCleq and (91±1)% in FAeq, meaning that the final extracts had a similar quality. The discoloration of the purified extract was then evaluated with activated charcoal and hydrogen peroxide treatments, in which only the latter resulted in a lighter colored solution. Various formulations were applied to the decolorized extract: glycerol was used as a plasticizer and different non-hazardous diacids (succinic, malonic and citric acids) were used as cross-linkers. The resulting films were characterized in terms of their antioxidant properties, solubility in water and mechanical properties. It was found that a decolorized film formulated with glycerol and citric acid had a lower antioxidant activity (0.053±0.001)μmol Trolox/mg film than a pure arabinoxylan film (0.091±0.002)μmol Trolox/mg film. Films were still very soluble in water, with the minimum solubility being around 70%. The decolorized film with glycerol and citric acid showed the highest tension of perforation (1.28±0.14)MPa and deformation (6.4±1.7)%.