Improvement of nutritional value and bioactivity of ricegrass as affected of priming induced by fish protein hydrolysate

Abstract

Background: Wheatgrass (Triticum aestivum L.) is consumed worldwide and has been used for health benefits and as functional food or nutraceuticals. While ricegrass (Oryza sativa L.) is still not well documented, which is also in the grass family (Poaceae) as wheatgrass. Also, similar to wheatgrass, ricegrass is produced with aged around 8-10 d. Moreover, priming is a process for enhancing seed vigour properties and improving bioactive compounds. Utilization of fish protein hydrolysate (FPH) for liquid fertilizer is more interesting in order to increase the nutritional value and bioactive compounds as well as antioxidant activity of many plants. Objective: To investigate the nutritional value and bioactivity of ricegrass affected by the priming process of fish protein hydrolysate. Methods: The Chainat 1 rice seeds were soaked with FPH at 0, 5, 10, 15 and 20 ppm at a ratio of rice seed to FPH as 1:5 and grown for 7 d, thereafter, the ricegrass seed vigour properties, nutritional value and bioactive compounds such as chlorophyll, carotenoids, total phenolic and phytic acid were determined. The ricegrass was extracted with water at a ratio 1:2 (ricegrass:water), then homogenized and centrifuged at 10000xg for 20 min. Then the supernatant was brought to freeze dry. The freeze-dried powder was dissolved in distilled water and brought to measure total phenolic content by Folin-Ciocalteu method. Antioxidant activities were determined by 3 assays as ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl hydrazyl radical (DPPH) and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid radical (ABTS) methods. Results: The results showed that FPH at 10 ppm significantly improved (p<0.05) seed vigour properties including germination percentage, germination rate, height and fresh weight and nutritional values such as ash, protein, fat and carbohydrate. In addition, bioactive compounds including chlorophyll a and b, total chlorophyll and carotenoid content in ricegrass primed with 10 ppm FPH were higher than control. Phytic acid content in ricegrass primed with FPH at 5 and 10 ppm but not 15 and 20 ppm was lower than control. The ricegrass primed with FPH at 10 ppm yielded highest total phenolic content. Though ABTS activity was not highest in rice primed with FPH at 10 ppm, DPPH and FRAP assays were highest. Conclusion: The seed vigour property, nutritional value, bioactive compounds and antioxidant activity of ricegrass primed with FPH was significantly improved. The appropriate content of FPH for priming ricegrass was 10 ppm because it demonstrated improvement in seed vigour, nutritional value and bioactive compounds including chlorophyll, carotenoid, total phenolic content and antioxidant activity determined as FRAP, DPPH and ABTS and reduced the anti-nutrient compounds as phytic acid.