Validation of the Vitamin B6 Profile (Pyridoxine, Pyridoxal, and Pyridoxamine) Analysis in Rice Consumed in Korea: Effects of Cooking and Variety

Rice, a widely consumed grain, contains various forms of vitamin B6, including pyridoxine (PN), pyridoxal (PL), and pyridoxamine (PM). However, limited information exists on their content and distribution in rice. This study analyzed the vitamin B6 profile and retention of different rice varieties consumed in Korea, using sonication-assisted acid extraction and HPLC-FLD. Retention rates were calculated based on B6 content before and after cooking. Five rice varieties were selected: Baromi2 (brown rice), Annammi, Chucheong (white rice), New breed white Baromi2, and New breed brown Baromi2. Vitamin B6 content ranged from 142.92 μg/100 g (Baromi2) to 35.89 μg/100 g (Chucheong). After cooking, Annammi showed the highest retention (109.4%), with pyridoxamine retaining 116.4%. Baromi2 had the lowest retention (34.5%), with pyridoxal at 22.1%. The analytical method demonstrated excellent accuracy (recovery rate 100.0-103.4%), precision (RSDr < 3.0%, RSDR < 6.7%), and linearity (R2 > 0.9998). The detection limits and quantification limits for the vitamin B6 vitamers ranged from 0.040 to 0.070 μg/100 g and 0.103 to 0.187 μg/100 g, respectively. The results showed significant variations in vitamin B6 profiles and individual retention rates across rice varieties, highlighting the need for more comprehensive data on B6 levels. Analyzing the pyridoxal, pyridoxamine, and pyridoxine provides a more complete understanding of the B6 profile of rice, enhancing nutritional evaluations and precision nutrition.