Literature sources indicate that the level of phytochemicals is dependent on several pre- and post-harvest stages of the fruit and vegetable Production chain. In order to retain the nutraceutical and pharmacological properties of phytochemicals in processed fruit and vegetable products, the food processor must optimise relevant processing steps in order to restrict the loss of phytochemicals. The objective of this review was to critically analyse and discuss the factors influencing the level of major phytochemicals in selected berries and vegetables belonging to Brassica, Compositae (lettuce), Apiaceae (carrots and parsnip) and Allium (onions) families, during both pre- and post-harvest processing stages throughout the production chain. Specific fruit and vegetables were selected due to increased interest in these products, which are readily available in Europe, commonly consumed and recognised as containing high phytochemical levels.