Influence of pandan leaf extract and fortificants addition and cooling duration to cooking quality, preference level, and glycemic index of brown parboiled rice fortified with chromium and magnesium

Abstract

The number of diabetics in Indonesia continues to increase. Therefore it is necessary to provide rice as a staple food that has a low glycemic index. It was also reported that diabetics had deficiencies of chromium and magnesium. Brown rice and parboiled rice are known to be low in the glycemic index, although it seems less preferred by consumers. Pandan leaf extract is known as an ingredient for strengthening flavor, and cooling is believed to be able to increase resistant starch and reduce the glycemic index. This study aimed to evaluate the effect of the addition of pandan leaf extract (PE) and fortificants in parboiling steps and cooling duration on cooking quality, preference level, and glycemic index of brown parboiled rice which was fortified with Cr and Mg. This study was carried out in a completely randomized design with two treatment factors. The first factor was the method to add PE and fortificants, namely: (1) addition of PE, Cr and Mg at the soaking (65 °C); (2) addition of Cr and Mg at soaking of 65 °C and adding pandan extract at boiling of 100 °C; (3) addition of PE, Cr, and Mg at soaking (65 °C) and followed by the addition of PE at boiling 100° C, and (4) addition of PE, Cr, and Mg at boiling (100 °C). The second factor was the cooling duration of 2 °C for 0, 12, 24, 36 hours. The method to add PE and fortificants and cooling time affects the cooking quality (water uptake ratio, elongation, and solid loss), but does not affect cooking time, and alkali spreading value. The addition of PE and fortificants (PE + Cr + Mg -65 °C, & PE-100 °C) for 36 hours of cooling time resulted in brown parboiled rice with a glycemic index of 40.39 (< 55 = low) and was slightly favored by panelists. The rice produced has cooking time of 43 minutes, alkali spreading value of 2, water uptake ratio of 3.10 g/g, elongation 1.21 mm/mm, and solid loss of 1.87 g/100 g.