Under normal atmosphere packing conditions, a within a sealed container starts to spoil, several by-products and they accumulate inside. Therefore, theoretically it is possible to detect spoilage by detecting one or more of these by products. Production of heat, acidity, pressure, and carbon is commonly observed as by-products in food Ideally, a spoilage detector should be use able as different food products as possible, without requiring different detectors for each different type of food material As the small amounts of heat evolve during deterioration process, heat detection is not likely to be practical. And also, pH of the various food varies widely and therefore impractical. Pressure detection is also impractical.