**2.1. Carotenoids**

the Food and Agriculture Organization (FAO), the United States Department of Agriculture (USDA) and the European Food Safety Authority (EFSA) have recommended the consumption of fruits and vegetables to lower the risk of cardiovascular diseases and cancer due to their high content of micronutrients and fibers [3]. Thus, the main contributor to the protective effect of fruits and vegetables against chronic diseases are largely due to their phytochemical content.

190 Phytochemicals - Source of Antioxidants and Role in Disease Prevention

Phytochemicals are nonnutrient, biologically active compounds and are commonly found in vegetables, fruits, grains and other crop plants. The major groups of phytochemicals based on their chemical structure are polyphenols, terpenoids, sulfur compounds, and alkaloids [4]. In the fight against diseases, phytochemicals act as antioxidant, antibacterial, antifungals, antivirals, anti-inflammatory and cholesterol reducing agents [5]. Studies have shown that polyphenols found in potatoes have the ability to inhibit the enzymes responsible for Alzheimer's disease [6]. Consumption of blueberries containing high levels of phenolic acids, flavonols, anthocyanins and proanthocyanidins were associated with the prevention of degenerative

In developed countries, approximately 75% of all deaths are due to non–communicable diseases (NCDs) related to an unbalanced diet [8]. Developing countries are also overburdened due to over and under nutrition [8]. Associated with an increasing demand for fresh cut fruits and vegetables in developed countries, developing countries are now following suit due to an increased level of education and awareness for healthy food amongst consumers [3, 7]. The need for nutritious, ready to eat convenience foods has thus given rise to minimally processed fruits and vegetables (MPVFs) [7, 9], which are mildly processed such that they possess "fresh-like" attributes [9]. Some key attributes that ensure the marketability of MPVFs are the maintenance of nutritional value especially phytochemical content, flavor, color, texture,

Some methods used to minimally process fruits and vegetables, negatively affect its phytochemical content and thus, the consumer does not benefit from the desired health benefits. Thermal processing allows for a longer shelf life by reducing microbial load and inhibiting enzymes that leads to deterioration, but it also decreases the level of phytochemicals in the fruits and vegetables [7, 10, 11]. Thus, this has prompted food scientists and researchers to find new ways to process fruits and vegetables without compromising the nutritional content and quality. Novel, nonthermal processing such as pulsed electric field (PEF), pulsed light (PL), ultra sound (US), high pressure processing (HPP) and cold plasma (CP) techniques have been promising in maintaining the integrity of phytochemicals and the nutritional quality of fruits and vegetables, inclusive of minimally processed ones [10]. Such technologies have the potential to be adapted in developing countries. This chapter will explore the use of nonthermal processing technologies and their effects on key phytochemicals such as carotenoids, flavonoids and phenolic acids in several fruits and vegetables with a focus on health benefits.

Scientific evidence has shown that phytochemicals are highly beneficial in lowering the risk of several noncommunicable diseases [10]. They are known to have the ability to treat diseases

and chronic diseases [7].

appearance and shelf life.

**2. Sources of phytochemicals and functions**

Carotenoids are the red, yellow and orange color plant pigments of fruits and vegetables. To date approximately 600 types of carotenoids have been identified. They are mostly present as fat soluble, colored pigments in plants [12]. They can be separated into two groups; carotenes and xanthophylls. The two primary forms of carotenoids are β-carotene and α-carotene [12]. Other essential carotenoids include zeaxanthin, lutein and lycopene. The health benefits of carotenoids are due mainly to their antioxidant effects and physiological functions as provitamins. However, post-harvest technologies and processing greatly affect the composition and bioavailability of carotenoids in fruits and vegetables. Fruits and vegetables such as papaya, mangoes, carrots, sweet potatoes, pumpkin and cantaloupes are rich in β-carotene, whilst tomatoes, pink grapefruits, and watermelons contains high levels of lycopene [10]. In a study by Leoung and Oey, it was found that the highest content of carotenoids was found in red peppers followed by carrots, apricots, plums and peaches, whilst cherries contained the lowest amount of carotenoids [13].

Since carotenoids are a precursor of vitamin A, they have been found to decrease the incidence of diseases such as cancer of the lungs, pancreas and gastrointestinal tracts, cardiovascular diseases and eye-related diseases [14]. According to Toniolo et al., a case-control study conducted in New York between the years 1985–1994, showed that the carotenoids lutein, zeaxanthin, lycopene, α carotene and β carotene were responsible for decreasing the risk of breast cancer [15]. In another study by Giovannucci, it was observed that a decrease in prostate cancer was associated with a consumption of tomatoes due to their high lycopene content [16]. With respect to cardiovascular diseases, studies showed that the blood plasma of patients suffering with coronary artery disease, contained lower levels of zeaxanthin, lycopene, β carotene and α carotene [17]. This is in agreement with a study conducted by Knekt et al. who showed that a higher intake of β carotene and several carotenoids, led to a lower risk of major coronary heart diseases [18].
