Impact of Electron Beam Irradiation on the Bioactive Principles of Seeds of Coastal Sand Dune Wild Legumes (Canavalia spp.).

BACKGROUND: Recent patents reveal that vegetable ingredients have several applications in novel food formulations. Many so-called antinutritional components (e.g. tannins, saponins, lectins and protease inhibitors) have nutraceutical as well as pharmaceutical significance. Seeds of two wild legumes of the genus Canavalia inhabitants of the coastal sand dunes of Southwest India are known for a variety of bioactive principles (e.g. phenolics, tannins, canavanine, concanavalin and phytohemagglutinins). OBJECTIVE: This study evaluates the impact of Electron Beam (EB) irradiation on the bioactive components of seeds of two coastal sand dune wild legumes Canavalia cathartica and C. maritima. METHODS: The dry seeds of C. cathartica and C. maritima were EB irradiated with different doses (2.5, 5, 10 and 15 kGy) to follow changes in six bioactive principles (total phenolics, orthodihydric phenols, tannins, canavanine, trypsin inhibitors and phytohemagglutinins) in comparison to control seeds. One-way ANOVA was employed to follow the variation in bioactive components of seeds in control and different doses of irradiation. RESULTS: Seeds of both legumes were devoid of orthodihydric phenols and trypsin inhibitors. In C. cathartica, the total phenolics showed significant dose-dependent increase up to 5 kGy and decreased thereafter. Tannin content was not altered up to 10 kGy followed by significant decrease at 15 kGy. There was no significant change in canavanine content and the phytohemagglutinin activity against human erythrocytes was not altered. Seeds of C. maritima did not show significant changes in total phenolics as well as tannin contents. The content of canavanine showed significant dose-dependent increase up to 5 kGy followed by significant decrease. There was no variation in phytohemagglutinin activity against erythrocytes A, B and O, while against AB, the activity decreased at 2.5 kGy and further decrease was constant at higher doses. CONCLUSION: The EB irradiation doses employed have selectively altered the bioactive principles of Canavalia seeds and such treatments may facilitate to maneuver desired medicinal, nutritional, functional and cooking properties. Besides selective changes in bioactive components the seeds have extended shelf life.

Impact of Electron-Beam Irradiation on Functional Attributes of Seeds of Two Coastal Wild Legume Landraces of Canavalia.

BACKGROUND: Vegetable proteins have widespread application in the food industry as functional ingredients in food formulations according to the recent patents. Requirement to develop less expensive protein-rich supplementary foods has resulted in shift of emphasis towards lesser known wild than popular legumes. OBJECTIVE: The aim of this study is to expose seeds of two coastal sand dune wild legumes of the Southwest India (Canavalia cathartica and C. maritima) to different doses of electron-beam (EB) irradiation to assess changes in functional attributes. METHOD: Intact dried seeds were exposed to EB irradiation (2.5, 5, 10, 15 kGy). Protein solubility, gelation concentration, water-absorption capacity, oil-absorption capacity, emulsion properties and foam properties of control and irradiated seeds were assessed by standard methods. RESULTS: Protein solubility of both seed flours attained the highest at 2.5 kGy, followed by gradual dosedependent decrease. The gelation concentration increased in C. cathartica only at 5 kGy, while it decreased in C. maritima at 2.5 kGy without further change at higher doses. The water-absorption capacity of C. maritima was significantly higher than C. cathartica in control sample, while at 15 kGy C. cathartica showed significantly higher absorption capacity than C. maritima. The oil-absorption capacity was significantly higher in C. maritima than C. cathartica in control as well as all doses of irradiation. Emulsion activity of C. maritima was slightly higher than C. cathartica in control and irradiated samples, while both seeds showed similar emulsion stability in control with significant increase in C. cathartica at 10 kGy and 15 kGy. The foam capacity in both seeds was similar up to 2.5 kGy followed by significant increase in C. maritima at 5 kGy and 10 kGy. The foam stability was significantly higher C. cathartica than C. maritima in control as well as in irradiated samples. The foam capacity was higher in C. maritima than C. cathartica in control and irradiated samples, which showed gradual time-dependent decrease in stability with higher stability at 8 hr in C. cathartica than C. maritima. CONCLUSION: Improved functional properties (protein solubility, emulsion stability and foam capacity) and decreased gelation concentration in seeds of C. maritima irradiated at 5 kGy is advantageous in the production of functional foods. Even though both species of Canavalia grew on the coastal sand dunes and their seeds were exposed to same doses of radiation, they differed in functional attributes confirm that it is species-specific. Canavalia seeds being rich in proteins, carbohydrates, essential amino acids, essential fatty acids and bioactive components, further studies on the impact of EB irradiation helps in optimization of nutraceutical potential as well as functional attributes for future applications.