Nanotechnology plays a major role in the food sector through the quality food production ends with advanced processing, packaging, and long-term storage, provided enormous growth in food industry through enhancement in food quality by improving its flavour and texture. In recent world, impurities are increasing in different food products. So by synthesizing various nanosensors, which can differentiate the toxicity based on different parameters. Food science means the science of food which includes food components, their behaviour under different environmental conditions, process of harvesting, milling, exposure to heat, cold, acid, alkalis etc. Today, the field of food science has progressed from basic physical, chemical and biological reactions that take place during processing to the fields of biotechnology, food engineering, packaging and its effect on the consumer. There are many parameters, which can affect the environmental life decisively. Nature is minimising the hazards, while human beings are maximising them. Environmental contamination has changed the lifestyle of the people in many ways all around the world. This chapter explains the brief introduction of various poisonous materials and their effects. It explains the brief introduction and history of food science including nutrition and digestions of food. It also describes the different properties of food. The chapter is also mentioning the detection of different hazardous/poisonous materials by metal oxide based nanosensors with inherent literature survey.