Milk powder is an important foodstuff and ingredient that is produced on large scale (over 20 million tonnes per annum). Milk powders are widely used in food-processing industries, such as bakeries, ice-cream factories, and the manufacture of chocolate or for reconstituting. However, the powder quality in storage may be decreased by some changes, such as stickiness, caking, degradation, and nonenzymatic browning. The major reason for production of milk powders is to prolong their shelf-life and to facilitate storage and handling. The surface composition of milk powders may be changed during storage, deteriorating many powder properties that exist at the interface between particles and environments (e.g. flowability, wettability, oxidative stability). Sensor based on biopolymer has been fabricated. Biopolymer is used as a sensing material to detect degradation of milk powder. The electrical result shows that voltage increases as the number of exposure day of milk powder in open air increases. This is due to the production of volatile gas compound such as aldehyde (hexanal) and ketone upon oxidation process in milk powder when it is exposed to atmosphere. The sensor shows good performance in term of sensitivity, stability, response time, recovery and repeatability.