Evaluation of technical feasibility of dry fractionation as a method to obtain novel protein foods from quinoa
- Authors
- Idrovo Guzm?n, Mar?a Elisa
- Format
- MasterThesis
- Status
- publishedVersion
- Description
Quinoa has remarkable nutritional properties because of its protein content and amino acid balance, which give this grain a great potential for food applications. This work aimed to explore and compare different fractionation technologies to separate and exploit the benefits from individual components or enriched fractions of quinoa. Understanding the grain structure and its behavior under different processing conditions sheds new light on the optimal conditions to rationally develop a more efficient fractionation process. The major anatomical parts of quinoa grain are: (1) the pericarp, a thin layer that covers the grain, (2) the perisperm, the main storage tissue composed mostly of starch granules, and (3) the embryo (radicle and cotyledons), a yellowish ring-like structure, surrounding the perisperm and that, unlike other grains, represents 30% of the seed?s volume. The protein content in the full quinoa meal, pericarp, perisperm and embryo was found to be 16.84%, 10.56%, 42.91% and 3.16% respectively. The main quinoa components (fiber, starch, oil and protein) were easily separated in an alkaline medium, obtaining a protein concentrate of 77.36% purity with a yield of 43.41% with respect to the initial flour. However, the extreme pH used caused protein denaturation and starch damage, as verified by DSC. Furthermore, this process involved the use of large amounts of water and considerable energy to dry the final products. For dry fractionation, quinoa was pin-milled at two different speeds and temperatures. The milling temperature showed a big influence on the particle size of the resulting meals. Freezing of the grains in liquid nitrogen just before milling resulted in considerably smaller particles than milling at room temperature. However, independent of the particle size distribution of the flour, milling resulted into a product were the particle sizes of the protein and starch fractions largely overlapped. Nevertheless, the fractions could be further purified successfully in a dry process. Applying electrostatic separation on meals with a typical protein content of 14%, protein enriched fractions of up to 27.57% and protein depleted fractions down to 5.85% could be obtained. Coarseness in the flour showed a positive effect on the electrostatic separation. The fracture properties of quinoa seed were evaluated by a compression method, finding that a force of 30N applied over a displacement of only 200 ?m were sufficient to separate the cotyledon from the rest of the seed without damaging of the structure. Based on that observation quinoa seed was roller-milled and sieved into three different fractions. The coarse fraction contained mainly pericarp (hulls) and fragments of perisperm, the medium fraction was composed mostly of cotyledons, and the finer fraction contained smaller starch particles. These preliminary results showed that by breaking the grain under controlled conditions making use of its structure, a mild and efficient fractionation process could be develop that keeps the native functionalities of quinoa intact.
El presente estudio identifica la factibilidad de obtener alimentos novedosos de alto contenido de prote?na de quinoa, extra?da aplicando un fraccionamiento en seco. Comienza con un estudio profundo acerca de la estructura del grano de quinoa a nivel microsc?pico; seguido por ensayos de molienda del grano para obtener diferentes harinas en las cuales es posible realizar un fraccionamiento de la prote?na. Por ?ltimo se eval?a cual es el m?todo ?ptimo que se deber?a aplicar al grano para lograr los resultados esperados.
- Publication Year
- 2014
- Language
- eng
- Topic
- INGENIER?A DE PROCESOS
QUINOA
PROTE?NAS
FRACCIONAMIENTO EN SECO
- Repository
- Repositorio SENESCYT
- Rights
- openAccess
- License