The answer is, it all depends—on the type of produce, the type of processing, and which nutrients. In general, fresh produce picked at peak maturity offers the highest amount of vitamins and minerals and tastes the best, but soon after harvest these nutrients degrade. It can take 1-2 weeks for produce to be transported from farms to supermarkets and then purchased by the consumer. Several more days may pass before you actually eat it. Part of the nutrient losses occur with moisture loss if water-rich produce sits at room temperature. Estimates show that at room temperature, fresh peas lose about 50% of vitamin C in one week, and fresh spinach can lose 100% of the vitamin in less than 4 days. (1) quicker cooking times and reduced contact with water.