Effect of Multi-Pin Cold Plasma Treatment On the Growth Parameters and Nutritional Quality of Fenugreek Microgreens

Abstract

Microgreens, the young seedlings of vegetables, legumes, cereals and herbs, are gaining global attention as nutrient-dense functional foods due to their rich bioactive compounds and rapid cultivation cycle. This study evaluated the effects of multipin atmospheric cold plasma (CP) treatment a novel, sustainable, non-thermal technology on fenugreek (Trigonella foenumgraecum L.) seeds to enhance seed germination, growth, and nutritional quality. Seeds were exposed to CP for different durations: control (CP₀, 0 seconds), 30 seconds (CP₁), 60 seconds (CP₂), 90 seconds (CP₃) and 120 seconds (CP₄). Moderate exposure at 60 seconds (CP₂) significantly improved germination percentage to 80%, compared to 60% in CP₀ and CP₁, with a slight decrease at 90 seconds (CP₃) and 120 seconds (CP₄) to 70% and 60%, respectively. Similarly, germination and vigour indices were highest in CP₂, indicating improved seedling establishment. Photosynthetic pigments, including chlorophyll a, chlorophyll b, and total chlorophyll, increased notably in CP₂, reflecting enhanced photosynthetic efficiency, while the pigment stability declined with prolonged exposures (CP₃ and CP4). Antioxidant activity, assessed using the DPPH radical scavenging assay, peaked at 31.18% in CP₂. A similar pattern was followed in the case of TPC (58.75 mg GAE/g dry weight in CP₂). Both antioxidant activity and phenolic content decreased in CP₃ and CP4, likely due to phenolic degradation caused by extended plasma exposure. Overall, these results demonstrate that 60 seconds of cold plasma treatment optimally enhances germination, vigour, chlorophyll biosynthesis, and antioxidant potential of fenugreek microgreens, while excessive exposure has detrimental effects on seed physiology and nutritional quality. This study highlights atmospheric cold plasma as a promising green technology to improve the functional quality of microgreens, supporting their application as future foods to promote sustainable nutrition and health benefits.