Comparative Study Between Conventional Preservatives and Methylene Blue on Chemical and Bacteriological Composition of Raw Milk.

The objectives of this study were to compare conventional preservatives used in milk analysis, including potassium dichromate and bronopol with a non-toxic and biodegradable preservative such as methylene blue, to verify their effectiveness and limitations of use. This was achieved by comparing their effects on raw milk composition at different storage temperatures. The best performing preservative doses were 0.1, 0.036 and 0.01% for potassium dichromate, bronopol, and methylene blue respectively. Raw milk composition was significantly affected (p < 0.05) during the storage period at 25°C for all tested preservatives. However, at 4°C, potassium dichromate and bronopol preservatives maintained stable milk composition during 10 days of storage, whereas methylene blue maintained stable milk composition for three days. Methylene blue can be considered as an environmentally friendly and safe alternative for short-term preservation of refrigerated raw milk samples. [ABSTRACT FROM AUTHOR]