Evaluation of qualitative and quantitative methods for detection of NaOH in milk

Subject Areas : Food Science and Technology

S. Ardalan ¹ , G. karim ² , R. pourahmad ³

1 - Graduate, Dep., Food Science and Technology, Varamin-pishva Branch, Islamic Azad University, Varamin, Iran
2 - Professor, Dep., Food Hygiene, Faculty of Veterinary Medicine, University of Tehran, Iran
3 - Associate Professor, Dep., Food Science and Technology, Varamin-pishva Branch, Islamic Azad University, Varamin, Iran

Received: 2016-04-18 Accepted : 2016-05-30 Published : 2017-05-22

Keywords: Milk, Adulteration, Electrical Conductivity, Measurement of caustic soda,

Abstract :

The aim of this study was to achieve a quick and simple quantitative and qualitative method to detect even the trace amount of added soda in raw milk, since the existing tests methods are not applied in practical and real terms. For this purpose, after determining the microbiological and chemical characteristics of the raw milk, the samples were divided into 4 groups. Each group was added by different values of lactic acid, and then different rates of soda were added to the samples. Tests for acidity, pH value, electrical conductivity, alcohol, ash and Rosalic acid were conducted. According to the results with increasing the amount of soda, the electrical conductivity and total ash were increased, however the acidity was decreased. No significant correlation was observed between the added soda and pH value. Alcohol test had the same results on all samples. Rosalic acid test was negative in all treatments. In the case of alkaline ash, in none of the samples the volume of hydrochloric acid consumed reached to 1.2 ml. It was concluded that Rosalic acid test did not work for the detection of soda in raw milk; in addition alkaline ash test did not specify the small amounts of soda. Among the various tests electrical conductivity assay was found to be credible and could be used to detect and quantify the added soda in raw milk.

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