Response surface optimization of culture conditions for improving lutein content in NaCl‐stressed germinated corn kernels

Abstract

Germination conditions strongly influence the content of phytochemical compounds of corn kernels. In this study, we optimized NaCl concentration, germination time, and temperature for maximizing the content of lutein. The effects of NaCl concentration (X1: 150–450 mmol/L), germination time (X2: 2–4 d), and germination temperature (X3: 20–30°C) on the recovery of lutein content (Y) of germinated corn kernels were investigated and the culture conditions were optimized using a Box–Behenken design (BBD). Results showed that the optimized conditions were 283 mmol/L of NaCl, 3.14 days of germination time, and 26.5°C of germination temperature. The predicted lutein content could be as high as 11.77 μg/g DW, which is 20.95% higher than control and 1.91 times that of non-germinated corn kernels. The quadratic polynomial model showed high coefficients of determination, demonstrating their adequacy to explain the variations in experimental data. The germinated corn under optimized conditions may become promising health-promoting foods. Practical applications Yellow corn kernels contain significant amounts of lutein, zeaxanthin, and other carotenoids and has become increasingly popular as a snack or vegetable. Germination process represents an inexpensive technology to improve nutritional and nutraceutical value of cereal grains. Exogenous NaCl induced the increase in the carotenoid content in the germinated corn kernels. This study was designed to detect optimal germination conditions including NaCl concentration, germination time, and temperature to obtain the highest yields of carotenoids. The germinated corn kernels can be used directly as a functional vegetable. Also, it is used as the raw materials with improved nutritional and nutraceutical value for food processing, such as corn flour, which can be applied in series of products, including noodles, steamed bread, biscuits, etc.