Healthy Promoting Properties and Thermal Processing
The Dietary Guidelines for Americans (2015) recommend that adults consume at least 2.5 cups of vegetables and 2 cups of fruits daily (Based on 2000 kcal/day diet) as they provide many health benefits including prevention of chronic diseases such as coronary heart disease, cancer, diabetes. The health promoting effects of fruits and vegetables have been attributed to their essential nutrients and nonessential phytochemical composition. Available data suggests that the U.S. population consumes approximately half the recommended intake of fruits and vegetables. The delicate tissues and high moisture content of fresh fruits and vegetables make them highly perishable, limiting their availability throughout the year, in addition to competition from alternative delivery forms such as beverage.
Fruit and vegetable based beverages are often thermally processed (pasteurized) more than once, subjecting them to thermal abuse. In general, in the production of beverages, they are pasteurized after extraction and again after blending or ingredient addition prior to packaging. Thermal processing uses a combination of temperature and time to achieve a desired reduction in the number of microorganisms in a beverage as required by the food safety regulation. Depending on the intensity of the heat and time of the application, thermal processing can provide mild or severe heat treatments. Recognizing the health promoting benefits of fruit and vegetable beverages, it is important to understand the chemical changes that occur during thermal processing and how they may impact the biological activity of health promoting properties. The effect of heat treatment can vary depending on the nutrients, matrix and other chemicals present in the beverage. It is widely believed that thermal processing can have adverse effects on health prompting properties such as phytochemicals. An example of this is that degradation of heat-sensitive bioactive phytochemicals such as pelogonidin-3-glucoside in strawberry beverage in response to high temperature short term (72°C/20 s) processing. However, thermal processing can have beneficial effects too as seen in certain phytochemicals improving their bio accessibility or modifying chemical structures to enhance absorption. Thermally stable bioactive phytochemicals, such as lycopene present in tomato based beverages, is a prime example of a product that is favorably affected by the thermal process.
Thermal processes that ensure beverage product safety and acceptable shelf life will continue to be predominant. However, consumers, government and health care professionals have become increasingly aware of the impact of the thermal processing on health prompting properties in fruit and vegetable based beverages. Hence, the industry should pay attention to understand the effects of thermal processing on the health promoting properties such as phytochemicals of fruit and vegetable based beverages, including the relevance of these effects in humans.