Sunflower proteins : overview of their physicochemical, structural and functional properties
González-Pérez, S. ; Vereijken, J.M. - \ 2007
Journal of the Science of Food and Agriculture 87 (2007)12. - ISSN 0022-5142 - p. 2173 - 2191.
helianthus-annuus l - seed storage proteins - low-molecular-weight - reduced soy glycinin - chlorogenic acid - foaming properties - ionic-strength - defatted sunflower - globulin fraction - oilseed proteins
There is increasing worldwide demand for proteins of both animal and plant origin. However, animal proteins are expensive in terms of both market price and environmental impact. Among alternative plant proteins, sunflower seeds are particularly interesting in view of their widespread availability in areas where soy is not or only sparsely produced. Compared with other sources of vegetable proteins, sunflower seeds have been reported to have a low content of antinutritional factors. Although the absence of these factors is important, the functionality of the protein preparations will mainly determine their applicability. This review provides detailed information about sunflower seed composition and processing, including processes to remove phenolic compounds from meals. The main part of the review concerns the structure and functionality of the two major protein fractions, helianthinin and 2S albumins. Regarding functionality, emphasis is on solubility, thermal behaviour and surface activity. Protein structure and functionality are discussed as a function of extrinsic factors such as pH, ionic strength, temperature and the presence of other seed components, particularly chlorogenic acid. In addition, sunflower proteins are compared from a structural and functional point of view with other plant proteins, particularly soy proteins.
Emulsion properties of sunflower (Helianthus annuus) proteins
Gonzalez-Perez, S. ; Koningsveld, G.A. van; Vereijken, J.M. ; Merck, K.B. ; Gruppen, H. ; Voragen, A.G.J. - \ 2005
Journal of Agricultural and Food Chemistry 53 (2005)6. - ISSN 0021-8561 - p. 2261 - 2267.
seed storage proteins - functional-properties - physicochemical properties - emulsifying properties - charge heterogeneity - globulin fraction - chlorogenic acid - soy proteins - albumin - meal
Emulsions were made with sunflower protein isolate (SI), helianthinin, and sunflower albumins (SFAs). Emulsion formation and stabilization were studied as a function of pH and ionic strength and after heat treatment of the proteins. The emulsions were characterized with respect to average droplet size, surface excess, and the occurrence of coalescence and/or droplet aggregation. Sunflower proteins were shown to form stable emulsions, with the exception of SFAs at neutral and alkaline pH values. Droplet aggregation occurred in emulsions made with SI, helianthinin, and SFAs. Droplet aggregation and subsequent coalescence of emulsions made with SFAs could be prevented at pH 3. Calcium was found to cause droplet aggregation of emulsions made with helianthinin, at neutral and alkaline pH values. Treatments that increase conformational flexibility of the protein molecule improved the emulsion properties of sunflower proteins.
Conformational states of sunflower (Helianthus annuus) Helianthinin: Effect of heat and pH.
Gonzalez-Perez, S. ; Vereijken, J.M. ; Merck, K.B. ; Koningsveld, G.A. van; Gruppen, H. ; Voragen, A.G.J. - \ 2004
Journal of Agricultural and Food Chemistry 52 (2004)22. - ISSN 0021-8561 - p. 6770 - 6778.
differential scanning calorimetry - seed storage proteins - physicochemical properties - circular-dichroism - globulin fraction - ionic-strength - charge heterogeneity - molecular-structure - 11-s globulins - soy glycinin
The structure and solubility of helianthinin, the most abundant protein of sunflower seeds, was investigated as a function of pH and temperature. Dissociation of the 11S form (hexamer) into the 7S form (trimer) gradually increased with increasing pH from 5.8 to 9.0. High ionic strength (I = 250 mM) stabilizes the 11S form at pH > 7.0. Heating and low pH resulted in dissociation into the monomeric constituents (2-3S). Next, the 7S and 11S forms of helianthinin were isolated and shown to differ in their secondary and tertiary structure, and to have denaturation temperatures (Td) of 65 and 90 C, respectively. Furthermore, the existence of two populations of the monomeric form of helianthinin with denaturation temperatures of 65 and 90 C was described. This leads to the hypothesis that helianthinin can adopt two different conformational states: one with Td = 65 C and a second with Td = 90 C.