Variations in bran carotenoid levels within and between rice subgroups

Area of Science:

• Agricultural Science
• Food Science
• Nutritional Science

Background:

• Rice (Oryza sativa L.) is a staple food globally, providing essential nutrients.
• Carotenoids, potent antioxidants, are present in rice bran, but varietal differences are poorly understood.
• Rice bran's nutritional profile, particularly its carotenoid content, is crucial for human health.

Purpose of the Study:

• To investigate and compare carotenoid levels across all five rice subgroups.
• To identify specific rice varieties with higher carotenoid content in their bran.
• To explore the potential for breeding enhanced rice varieties.

Main Methods:

• Utilized a rapid, non-destructive fluorescence quenching method for carotenoid measurement.
• Confirmed carotenoid identification and quantification using high-performance liquid chromatography (HPLC) after solvent extraction.
• Analyzed carotenoid stability over a 10-year storage period.

Main Results:

• Carotenoid levels in rice bran remained stable over 10 years.
• Significant varietal differences in bran carotenoid content were observed among the five rice subgroups.
• Tropical japonica rice, widely consumed in the US, exhibited the lowest carotenoid levels, while temperate japonicas showed the highest.
• Lutein was identified as the predominant carotenoid in rice bran.

Conclusions:

• Rice bran carotenoid content varies substantially by varietal subgroup.
• Temperate japonica rice possesses higher carotenoid levels, indicating potential for enhanced nutritional value.
• These findings provide a basis for selecting or breeding rice varieties with improved antioxidant capacity and nutritional benefits.