This chapter provides introduction to the current sources of food waste from agricultural production and to identify some of the most important classes of bioactive compounds found in the food waste. It focuses on different groups as a function of the number of phenol rings and on the structural elements that bind these rings together. In addition, the use of non-usable food products commonly seen as the leftover of the primary food production, can also prove a significant source of bioactive compounds and as such, potentially reduce the burden on the primary food product itself. In 2011, the Food and Agriculture Organisation (FAO) identified that every year one-third of the world's food produced for human consumption is wasted. Bioactive compounds have aroused significant interest in the recent past, predominately due to their antioxidant properties, which suppress and inhibit the production of common free radicals, such as superoxide anion and hydroxyl radical.