Pre- and Postharvest Strategies to Enhance Bioactive Constituents of Fruits and Vegetables

摘要

In addition to vitamins, minerals, and dietary fibre, fruits and vegetables provide a whole range of non-nutrient constituents that have been suggested to be responsible for the health benefits associated with their consumption. Different strategies for increasing the health-promoting properties of fruits and vegetables have been explored. Successful examples of breeding and selection challenge for new cultivars have been described. An important strategy for growers to maximize specific phytochemicals is that the plants should be grown in open environments rather than in greenhouses. Solar radiation affects the production of phytochemicals involved in plant defence responses. Greenhouse grown plants have lower levels of phytonutrients due to the combined effects of higher temperatures and lower light intensities. To date, agricultural practice recommendations have been established primarily for productivity goals, but not as a way to increase the phytonutrients. However, agricultural practices including type and rate of fertilization, irrigation and time of harvest can also be managed to enhance the content of bioactive compounds. It is difficult to draw definitive conclusions from data that prove more benefits to the organic vs. conventional agricultural practices. High doses of organic fertilizers can promote plant growth and decrease the content of bioactive compounds. Management of water frequency is critical for the yield and postharvest quality. Different beneficial phytochemicals tend to reach optimal levels around harvest maturity stage. Some flexibility exists for growers to harvest within a window of opportunity, but it seems evident that immature and over mature vegetables will contain lower concentrations of some important phytochemicals. Baby and multi leaves are excellent raw materials with high content of bioactive compounds. The effect of fresh-cut processing can increase the content of bioactive compounds which can be preserved under optimum storage conditions.