The availability of sophisticated instrumental techniques for adulteration detection in milk is a distant dream for rural areas in India. To address this constraint, a simple chromatographic paper‐based test strip for the detection of urea in milk is developed. The said strip was prepared by dipping a chromatographic paper for 10 min in an admixture of a supernatant (coarse ground soybean powder soaked overnight in water) and an acid‐base indicator. The strip utilizes the urease naturally present in soybean for the production of ammonia from urea which consequently raises the pH enabling the change in color of the strip. The limit of detection of urea by developed strip is 0.07%. The response time of the strip ranges from 3 to 5 min. The strip was found to be stable for 6 months when stored at ambient temperature with reproducible results. Novelty impact statement A simple, low cost and sensitive strip based test for detection of urea in milk is developed. The strip works on the principle of use of natural urease present in soybean slurry. The limit of detection observed in the test for urea detection in milk is 0.07%.

Effect of sterilization of milk and its subsequent storage on performance of qualitative tests used for detection of adulterants in the milk was studied. Some of the most prevalent adulterants viz. detergent, urea, ammonium salt, maltodextrin, starch, glucose, sucrose, gelatin, formaldehyde, hydrogen peroxide, and neutralizers were tested. Control and adulterated samples of milk were sterilized at 121ºC for 15 min. The samples of sterilized milk were stored at 35 ± 2ºC. The respective qualitative tests were performed for detection of adulterants on 0th, 15th, 45th, and 75th day of the storage. The performance of the qualitative tests varied depending on length of storage period for which samples were stored and chemical nature of the target adulterant spiked in the milk. Practical applications Adulteration of milk is serious food safety issue in developing countries. Chemical qualitative tests are one of the most affordable and convenient means for detection of adulteration, particularly in such countries. However some processing treatments like sterilization affect these qualitative tests significantly. Moreover, limited information is available related to effect of such processing treatment on test performance. Hence, evaluation of the effect of such treatment on qualitative test for detection of adulterant in milk is essential.

No abstract