Blue-colored rice flour innovation: a study of the effect of rice type and butterfly pea flower concentration

Abstract

Commercial rice flour is usually white and odorless. The innovation of making rice flour by adding natural ingredients such as butterfly pea, which contains a flavonoid component, and pandan leaves, which contain the aromatic compound 2-acetyl-1-pyrroline (ACPY), can be used as an alternative way to produce more attractive blue-colored rice flour (BCRF) with pandan fragrance. This study investigated the effects of rice type (white and brown rice) and levels of butterfly pea flowers (1, 3, 5, 7, and 9%) added on the physical and chemical characteristics of BCRF, and organoleptic characteristics of kue talam (talam cake). The result showed that these two variables significantly affected the properties of BCRF. The addition of 9% butterfly pea flower to both types of rice was determined as the best treatment using the Multiple Attribute Zeleny method. Compared to the control treatment (rice flour without butterfly pea flower and pandan leaves), BCRF has higher moisture, ash, and protein content. At the same time, the total carbohydrate content (by difference) was lower. A general preference for BCRF in the form of talam cake was acceptable (3.73-4.55 out of 6.00). The stability of BCRF to temperature, pH, and light was tested using the interpretation of color change value (ΔE). The stability test result showed that the BCRF was relatively stable when stored at low or room temperature, but the color change was quite visible at 100℃. The color of flour was strongly influenced by pH; the color changed from red (pH 1-4) to blue when pH was increased (7–10). The color was relatively stable when stored in a dark room but tended to fade with more exposure to light. BCRF has better color stability when stored at low to room temperature, away from direct light, and with a neutral pH.