B li Research theme 4 - Phytochemicals in the food supply chains

Introduction A large variety of phytochemicals (phyto = "plant" in Greek) are present in virtually all fruits, vegetables, legumes, and grains and are therefore easy for people to include them in their diet. Some phytochemicals are responsible for the typical color or sensorial properties in fruits and vegetables. Moreover, they are intensively studied for their protective or disease preventive properties. Major groups of phytochemicals are polyphenols, carotenoids, and glucosinolates. Many epidemiological studies have shown significant associations of diets rich in fruit and vegetables and reduced risk of certain cancers as well as several other chronic diseases like cardiovascular diseases and diabetes type 2 and obesity. To some extent these associations are ascribed to health promoting properties of various phytochemical actions like antioxidant, hormonal, enzyme stimulation, and antibacterial. The concentration and composition of the phytochemicals in different plants, but also within a plant (e.g. in the seeds, roots or leaves), can vary greatly and also changes during plant development. Furthermore, various factors in the supply chain of vegetables including breeding, cultivation, storage and processing affect the intake and bioavailability of phytochemicals. Glucosinolates A specific group of phytochemicals called glucosinolates occur in representatives of the Brassicaceae family and are of particular importance in vegetables such as cabbage, Brussels sprouts, broccoli, cauliflower. Glucosinolates are claimed to be the active components responsible for many of the physiological effects proposed for Brassica vegetables in different types of studies, including in vitro, animal, human and epidemiological studies. Processing is one of the major factors affecting changes of glucosinolate content along the production and supply chain. Also domestic cooking methods influence the glucosinolate levels in various ways. Processing changes the glucosinolate content through several mechanisms. Each processing method involves specific conditions, which lead to various degrees of impact of the different mechanisms on the glucosinolate content. Using the underlying mechanisms that are critical for a processing or cooking method can be a valuable approach to understand the changes in glucosinolate profiles.