Probing the physicochemical and sensorial properties of pasteurized milk via nanoparticles

The present study was conducted to evaluate the effects of storage time and temperature on physicochemical and sensory properties and to measure the spoilage of pasteurized fluid milk stored at different temperatures via nanoparticles on pasteurized fluid milk. The mean values for pH of milk samples decreased (from 6.81 to 6, 5.46, and 4.37), acidity increased (10%, 21%, and 35%), fat contents decreased (13%, 24%, and 32%), protein contents decreased (7%, 18%, and 24%), lactose contents decreased (5%, 7%, and 12%), and total free fatty acids increased (14%, 19%, and 27%) respectively at 4°C, 7°C, and 10°C. Similarly, the score of sensory parameters like aroma, taste, and overall acceptability decreased 16%, 23%, and 45%; 31%, 43%, and 52%; and 33%, 42%, and 53% respectively in linear pattern along with increasing the time and temperature. The L* values were non-significantly changed or decreased with mean values of 64.82 ± 0.08 to 64.13 ± 0.07 at 4°C and significantly with 64.81 ± 0.03 to 63.87 ± 0.07 and 64.77 ± 0.02 to 61.43 ± 0.05 at 7°C and 10°C respectively at 0-19th day of milk storage. During storage, the pasteurized milk stored at all temperatures 4°C, 7°C, and 10°C showed that a* value non-significantly decreased from 48.69 ± 0.18 to 48.63 ± 0.18, 48.74 ± 0.14 to 48.57 ± 0.11, and 48.68 ± 0.18 to 47.97 ± 0.07 respectively. Values of b* decreased non-significantly at 4°C and 7°C with the values of −17.56 ± 0.23 to −18.58 and −17.54 ± 0.25 to −19.85 ± 0.85 but significantly decreased at 10°C from −17.56 ± 0.23 to −43.22 ± 0.11. The results suggested that pasteurized milk can be kept for 17-19 days at 4°C but this shelf life drastically reduced at 7°C and 10°C. Color of nanoparticles was significantly changed from pink to dark blue from 14th day of storage onwards to the end at 10°C. Conclusively, nanoparticles can be used for the rapid and at the post-spoilage measurement of pasteurized milk.