**3. Advanced nonthermal technologies**

Conventional thermal processing such as blanching and pasteurization can result in oxidation and other deleterious reactions that lower the levels of phytonutrients in processed foods [28–30]. For example, canned fruits and vegetables undergo retort processing temperatures in excess of 100°C to obtain commercial sterility. This can lead to significant losses in anthocyanin content, up to 70%, observed in the processing of strawberries into jam. Advanced nonthermal technologies are able to achieve preserving effects at sub-lethal temperatures (up to 40°C). These methods retain higher phytochemical content whilst minimally changing the sensorial properties of the food [29]. The stability of phytochemicals in thermally processed fruits and vegetables decreases exponentially with a linear increase in both the magnitude and duration of the heating process [30]. The use of nonthermal treatments at successfully lower temperatures and times provide real alternatives from traditional thermal processing through the production of additional health promoting-benefits and maintaining the desired *"fresh-like"* quality of foods for consumers [28, 29]. The present review will focus on the effects of the following novel technologies: pulsed electric field (PEF), high pressure processing (HPP), pulsed light (PL), cold plasma (CP) and ultrasound (US) on food quality and stability of phytochemicals particularly in fruit and vegetable products. These findings are reported below and summarized in **Table 1**.

(HBAs) and hydroxycinnamic acids (HCAs). Phenolic acids are seldom found in mangoes, berries, citrus fruits, red wine and plums. Their main benefits to human health are the preven-

Anthocyanins belong to the widespread group of plant constituents called flavonoids. In fruits and vegetables, they are responsible for the orange, red, purple and blue colors. Such dietary antioxidants aid in preventing neuronal diseases, heart diseases, cancer, diabetes and inflammation [23]. According to a study by Zhao et al. various commercial extracts of anthocyanin rich grapes, bilberry and chokeberry were prepared. When investigated for their chemopreventitive effects against colon cancer, it was found that all of the extracts inhibited the growth of HT-29 colon cancer cells [24]. In another study conducted by Wang and Mazza [25], the inhibitory effects of anthocyanins found in selected berries against nitric oxide (NO) were investigated. Since NO is associated with many chronic inflammatory diseases, the strong inhibition of anthocyanins on NO production indicated that anthocyanins can aid in

Phenolic acids are a major source of dietary phenolics belonging to the non-flavonoid group of phytochemicals. Two major groups are HBAs and HCAs as noted above [25]. HCAs are found in many conjugated forms, with p-coumaric, caffeic, ferulic and sinapic acids being the most common and in HBAs; p-hydroxybenzoic, vanillic, syringic and protocatechuic are the most common. Phenolic acids are often found in berries such as strawberries, raspberries and blackberries [26]. Studies conducted on caffeic acid have shown that phenolic acids possess

Conventional thermal processing such as blanching and pasteurization can result in oxidation and other deleterious reactions that lower the levels of phytonutrients in processed foods [28–30]. For example, canned fruits and vegetables undergo retort processing temperatures in excess of 100°C to obtain commercial sterility. This can lead to significant losses in anthocyanin content, up to 70%, observed in the processing of strawberries into jam. Advanced nonthermal technologies are able to achieve preserving effects at sub-lethal temperatures (up to 40°C). These methods retain higher phytochemical content whilst minimally changing the sensorial properties of the food [29]. The stability of phytochemicals in thermally processed fruits and vegetables decreases exponentially with a linear increase in both the magnitude and duration of the heating process [30]. The use of nonthermal treatments at successfully lower temperatures and times provide real alternatives from traditional thermal processing through the production of additional health promoting-benefits and maintaining the desired *"fresh-like"* quality of foods for consumers [28, 29]. The present review will focus on the effects

the ability to inhibit antitumor activity against colon carcinogenesis [27].

tion of stroke, cancer and coronary heart diseases [22].

192 Phytochemicals - Source of Antioxidants and Role in Disease Prevention

the prevention of chronic inflammatory diseases [25].

**3. Advanced nonthermal technologies**

*2.2.1. Anthocyanins*

*2.2.2. Phenolic acids*



**3.1. Pulsed electric field (PEF)**

Adapted from Toepfl et al. [32].

Pulsed electric field (PEF) involves the direct application of short, high current voltage pulses that create an intense electric field, applied to a food matrix placed between two electrodes [31]. PEF has been used as an alternative nonthermal treatment in the pasteurization of liquid or pumpable foods. Fruit juices, milk, smoothies, yogurt, sauces, wine, and soup-based products contain large amounts of water and dipolar molecules making them more conductive for passage of electrical currents compared to solid type foods. The PEF system discharges a high voltage pulse uniformly throughout the food in a treatment chamber (see **Figure 1a**) [29, 32]. Typical field strengths varies from 0.1 to 80 kV/cm with the time duration of the pulse cycles ranging from *μs* to *ms* depending on the application of PEF. The mechanism of PEF is best explained using the *"electroporation"* model in which the strong electric fields generated induce either reversible or irreversible (depending on electric field intensity) perforation of the cytoplasmic membrane promoting cell leakage (see **Figure 1b**) [31]. This effect has shown inactivation of microorganisms and food spoilage enzymes, thereby enhancing food safety, quality and phytochemical yield and extraction.

An Evaluation of the Impact of Novel Processing Technologies on the Phytochemical…

http://dx.doi.org/10.5772/intechopen.77730

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Kumar et al. on investigating the effect of PEF on carotenoids, microbial stability and different physicochemical changes on ready-to-drink (RTD) mango nectar, noted a high retention of carotene content (94.2%) and minimal changes in total soluble solids (TSS), pH acidity and color [33]. In a separate study [34], a higher retention of volatile monoterpene compounds, in particular (Z)-Ocimene, in mango nectar pasteurized at 96°C for 300 and 600 s was observed. Sensory scores conducted also found PEF samples to be insignificantly different from control samples owing to retention in volatile components and reduction in nonenzymatic 5-hydroxy methyl furfural (HMF) brown compounds. As cited in Buckow et al. several studies surveyed the effects of PEF on orange juice treated at ≤68°C, resulted in maintenance of vitamin C, carotenoid, polyphenol, and volatile aroma compounds compared to thermal pasteurization

**Figure 1.** (a) Configuration of treatment chambers for continuous PEF processing: (i) parallel plate, (ii) coaxial, and (iii) co-linear; and (b) effects of exposure of biological cells at different electric field strengths and applications in food.

PEF is capable of extracting compounds such as pigments, antioxidants and flavors through the ability of the electric fields to induce cell membrane breakdown in plant tissue, increasing the

(95°C for 30 s) both after processing and refrigerated storage [35].

**Table 1.** Impact of nonthermal processes on food quality and phytochemical compounds.
