Quantification of blends of black gram and rice using pentosan as an indicator

Instant mixes for traditional foods, based on blends of rice and black gram flours, are widely available in the Indian subcontinent. However, no analytical methods are as yet reported to determine the blend composition. This work attempts to utilise differences in the pentosan content of rice (0.16%) and black gram (7.41%) as parameters to quantify the blend composition, using a modified bromate/bromide method. The validity of the method was confirmed by using model blends of rice and black gram flours. Analysis of market brands of such mixes using the method revealed that the premixes for idli, dosa, medu vada and papad flours contained black gram, ranging from 24.5 to 31.0, 28.0 to 31.35, 71.0 to 74.5 and 69.0 to 80.0%, respectively.