Milk contamination is a widespread problem, especially in low and middle-income countries where milk is often diluted with water to meet demand and increase profits. In order to make the diluted milk look and taste like normal milk, additives like starch, urea, and sugar are added to help restore the milk’s appearance. Dilution of milk with water changes fat content, which is an important quality indicator. Screening milk for additives is an expensive process requiring instrumentation and trained personnel. We are developing a spot test to measure fat content on paper. Milk Yellow (MY), a fat-soluble dye developed by researchers from the National University of Singapore, emits fluorescence as a function of milk fat content. MY is hydrophobic and aggregates in aqueous solutions. However, if milk fat globules are present, the MY dye can disaggregate and dissolve in the fat globules, at which point it becomes a strong fluorescent emitter. MY is able to differentiate nonfat, 2% and full fat milk on paper. Current studies are working on enhancing the stability of MY on paper and developing an internal fluorescent standard. Rhodamine 6G (R6G) will be used as an internal standard. I have demonstrated that R6G is stable on paper and has similar fluorescence intensity than MY. R6G’s fluorescence can be compared to the fluorescence of the sample and the fat percentage of the milk can be deduced. Future directions will focus on a portable fluorescence device able to measure fluorescence intensity which will be needed in order to successfully implement this paper analytical device.

Determining milkfat content on a paper-based analytical device

255th National Meeting (2018)

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