Objectives
The specific objectives of the study included:
1) the development of a prototype wet-dehulling system for degummed solin seed;
2) exploration of aqueous extraction of oil from dehulled solin seed;
3) evaluation of the use of azeotropic/aqueous isopropanol for mucilage precipitation, oil
extraction and the preparation of protein concentrates;
4) compositional and physicochemical (i.e., functional) analysis of alkali-extracted, acid-washed and aqueous-alcohol washed concentrates; and,
5) determination of the effects of azeotropic isopropanol extraction of oil and acid and aqueous alcohol washing of solin meal on the levels of toxic/antinutritional factors in solin meals and protein products.
Project Description
The wet-dehulling technology developed for Linola™ 947 varied in its effectiveness when applied to other solin/linseed lines and cultivars. This would reflect the fact that the technology was optimized specifically for Linola™ 947 and that different lines/cultivars may differ in structure in ways relevant to the wet-dehulling process. Further studies on improving the efficiency of wet-dehulling of Linola™ 947 and on determining the optimal wet-dehulling conditions for other lines/cultivars are recommended.
The solin hull fraction derived by wet-dehulling of Linola™ 947 was similar or superior in functionality to manually derived solin hull (testa), wheat bran and pea hull, and inferior to solin protein concentrates and soy flours. The superior emulsification and foaming properties of solin hull, compared to solin testa, wheat bran and pea hull, no doubt reflected contamination of the solin hull fraction with mucilage and protein. The inferiority of the solin hull fraction, compared to the solin protein concentrates and soy flour, reflected the much lower concentration of protein in the solin hull fraction.
Processing of solin seed/meals reduced the levels of most of the antinutritive factors assayed to low levels. Phytic acid, however,.was concentrated in degummed, dehulled solin seed and in solin meals and solin protein products. However, the levels of phytic acid present do not appear to be of concern. In light of the solubility of the lignan precursors (secoisolariciresinol, etc.) in linseed in aqueous alcohol, a portion of the lignan content in linseed/solin would be expected to be co-extracted with oil by azeotropic isopropanol, and a larger proportion during the preparation of protein concentrates by aqueous alcohol washing.
Solin hull was effectively incorporated into fibre-enriched cookie and muffin formulations. Incorporation of linseed hull resulted in less acceptable colour and flavour, to the extent that the use of linseed hull in such products is not recommended. The effect of incorporating solin hull into a white-bread formula was generally similar to that of incorporating an equivalent amount of wheat bran. Solin hull had a less deleterious effect on crumb brightness and increased dough water absorption to a lesser extent.
Addition of solin mucilage improved the loaf volume of both white and whole-wheat bread in proportion to its concentration in the formulation. This observation warrants further investigation, as most reports on the addition of carbohydrate gums to bread systems note reductions in loaf volume at all levels of incorporation. Future research should include development of a whole-wheat bread baking procedure yielding loaves with superior volume and height, with and without the addition of mucilage.
