Non-thermal plasma (NTP) treatment of Trigonella foenum-graecum L. seeds stimulates the sprout growth and the production of nutraceutical compounds

Abstract

Abstract The possibility to stimulate the production of some nutraceutical properties of fenugreek sprouts by non-thermal plasma (NTP) processing of the seeds in different conditions was studied. Seeds were treated in direct plasma and direct plasma with a cover, to keep the reactive species near the place where the seeds were. Moreover, the effect of seed pre-soaking was investigated. The outcome of plasma processing was analyzed on the seeds by micro-imagining their surface after treatments, determining the water contact angle, and studying the germination potential. Biometric and biochemical measurements were performed on the resulting sprouts to determine their length, weight, concentrations of photosynthetic pigments, polyphenols, flavonoids, and total protein, with Pearson correlation analysis of the results. We found that it is possible to stimulate the germination of the sprouts, especially for the pre-soaked seeds, and also the growth of the sprouts by about 50%. The concentrations of chlorophyll pigments increased mostly for pre-soaked seeds when exposed to direct plasma without cover more than in with-cover treatments. Direct plasma treatment for 30 s of dry seeds led to a flavonoid concentration triple compared to one of untreated seeds. For polyphenols and antioxidant activity, with cover treatment proved to be better, with an increase, especially for 90 s treatment with cover of the pre-soaked seeds. All the results indicate the possibility of tuning the nutraceutical properties of fenugreek sprouts by NTP treatment.