Influence of Different Growth Conditions on Saponarin, Water-Soluble Vitamins, and Mineral Content of Barley Sprouts Cultivated in Chamber System

Abstract

Barley sprouts contain various secondary metabolites such as polyphenol, policosanol, and γ-aminobutyric acid (GABA). In particular, saponarin, which accounts for about 72% of polyphenols, is well known for antioxidant, anti-inflammatory, and liver function protection effects. Saponarin is greatly affected by environmental conditions such as light, temperature, and moisture. However, there is a lack of studies about the effect of the microclimatic environment on saponarin content in barley sprouts. This study was conducted to evaluate the influence of daily temperature range, light intensity, and light period on saponarin, water-soluble vitamins, and minerals content in barley sprouts. Seeds of Hordeum vulgare L. were sown on a plastic box and cultivated in growth chambers with different conditions by adjusting daily temperature range (DT, 0 → 10°C), light intensity (LI, 120 → 180 µmol m-2 s-1), and light period (LP, day 12 hours → day 18 hours). The plants were harvested when the leaf length reach 15 cm. The fresh weight was not significantly different between each treatment, yet the growth period was highest in barley sprouts cultivated with DT. Saponarin content was higher in DT, LI and LP than control, and highest saponarin content in DT. In contrast, vitamin C content was highest in control and lowest in DT. Similarly, vitamin B1 and B5 content showed the highest in control. Changes in light and temperature elevated saponarin content in barley sprouts, especially daily temperature range showed a dramatic increase. However, the change in daily temperature range affects an increase in growth period and a decrease in vitamin C content. In conclusion, daily temperature range is the predominant environmental factor to produce saponarin-enriched barley sprouts.Different response of saponarin and vitamin C in barley sprouts to change in daily temperature range.