Abstract

Red amaranth sprouts are rich in nutrients and bioactive compounds that promote health-promoting properties. These sprouts are suitable for home growing or commercial production for use in fresh salads. In this study, red amaranth seeds were pretreated with limonene nanoemulsions at concentrations ranging from 5 to 20 μL/mL to improve germination and enhance functionality. At 5 μL/mL, limonene had no negative effect on germination, with sprouts averaging 3.3 cm in length and a 96% germination rate. Higher concentrations reduced germination significantly. Microscopy showed that limonene at 5 μL/mL was absorbed and moved to stems and leaves, forming a thin surface film and encouraging vascular growth. This led to a deep red coloration, with anthocyanin content of 57.1 ΔA/100 g and an a* value of 1.29, higher than the control. Sprouts also increased phenolics at 53.7 mg GAE and flavonoids to 16.2 mg QE/100 g, along with strong antioxidant activity. Nutritional content supported the growth of beneficial probiotics, including Lactobacillus plantarum, L. acidophilus, and Bifidobacterium longum. Antibacterial activity was more effective against Gram-positive bacteria. This simple seed-soaking method provides a novel approach to producing bioactive-rich, high-quality sprouts that resist microbial contamination, support probiotic growth, and can be sustainably applied in industry using limonene from citrus peels.