Development of beetroot extract-based rapid chromogenic test to ascertain the proper pasteurization of milk

Abstract

Pasteurization is a standard method to prolong the shelf life of milk by preventing the growth of spoilage and pathogenic microorganisms. Alkaline Phosphatase (ALP) activity tests (qualitative and quantitative) are recommended and widely used methods to ascertain the proper pasteurization of milk. However, the traditional methods are time-consuming. Therefore, those methods are difficult in field testing conditions, especially in rural-based dairy industries. In the present study, a simple, quick, safe, and economical chromogenic test protocol based on the ALP activity was developed to ascertain the proper pasteurization of milk. The chromogenic dye was prepared from the water extract of beetroot. Under selected assay conditions, the raw milk turns yellow-orange whereas pasteurized milk remains bright pink; which can be visualized by naked human eyes within two minutes. The developed assay is extremely useful in rural areas of our country where modern instrument facilities are rarely available. The activity of ALP was also evaluated in raw and heat-treated milk using Front-face Fluorescence Spectrophotometer (excitement and emission mode) followed by PCA.