**6. Conclusion**

cosides which were secondary metabolites showed various biological activities and act in plant defense mechanisms. Flavonoids usually occur as glycosides and aglycones in plant tissue which have significant antioxidant properties and antimicrobial and insect‐repel‐ lent properties as well [15]. Flavonoids and their antimicrobial effect are useful as a food preservative to extend the shelf life and safety of foods. Flavonoids play important roles in biological activities, including antiallergenic, antiviral and antifungal effects [23]. It is also present in various common fruits and vegetables (apples, grapes, lemons, tomatoes, onions, lettuce and broccoli). The following flavonoids are antifungal agents in plants: iso‐ flavonoids, flavans flavanones. However, the antifungal activity of flavonoid compounds plays an important role between plant‐microorganism and host plant's defensive systems [8]. Saponin and flavonoids are found in fruits and vegetables and in general they form a soapy lather after extracted from parts of plants [5]. Mandalari et al. [24] reported that Bergamot fruit extract which is rich in flavonoid has an effective on the yeast *Saccharomyces* 

180 Superfood and Functional Food - An Overview of Their Processing and Utilization

Okwu et al. [25] also showed that the antifungal activity of both citrus species and grape has an important effect against *Fusarium oxysporum* (**Table 1**). Thiosulfinates come from hydrolysis products of garlic and onion. They have a strong potential of producing antimi‐ crobial effects against pathogenic microorganisms [5]. Broccoli, Brussels' sprouts, cabbage mustard and horseradish have glucosinolates that also have a wide range of antibacterial effects. Moreover, olive leaves (*Olea europaea*) are rich in phenolic compounds, with dem‐ onstrated strong antimicrobial effects and can be potentially used in food processing [5]. Al‐Zoreky [29] reported that phenolics and flavonoids present in pomegranate fruit peels demonstrated strong antimicrobial activity against some food pathogen microorganisms. In addition, *Psidium guajava* has phenolic, flavonoid, carotenoid, terpenoid and triterpenes that demonstrated strong antimicrobial activity [30]. Salas et al. [31] reported that flavonoids extracted from citrus species, not only naringin, hesperidin and neohesperidin but also enzy‐ matically modified derivatives of these compounds, have strong antifungal activity [31]. The limonoid compounds have important antibacterial and antiviral activity as shown in **Table 1** [1]. Vikram et al. [32] reported that seeds of grapefruits have significant inhibitory effect on pathogenic *Escherichia coli* O157:H7. Black raspberry and Chardonnay seed extracts have also antibacterial activity to inhibiting growth of some food pathogen microorganisms [33]. Tehranifar et al. [26] reported that high percentage of phenolic content in the peel and seed of pomegranate fruit has high antifungal activity especially on postharvest fungi (*Penicillium italicum*, *Rhizopus stolonifer* and *Botrytis cinerea*). Another study showed that berry extracts exhibit selective inhibitory properties against intestinal bacteria [1]. Recently, antifungal activity has been found in all tissue types of strawberry fruit due to the phenolic compounds

*cerevisiae* (**Table 1**).

that inhibit the growth of fungi [23].

**5. Other beneficial properties of plant phytochemicals**

In the last decade, the results of many research have shown the positive effects of phytochemicals in human health. There is a strong correlation of antioxidant consumption In a conclusion, potentially a great number of phytochemicals including some of the vitamins, flavonoids, terpenoids, carotenoids, phenolics, phytoestrogens, minerals and antioxidants in plant materials are used as alternative preservative agents for controlling postharvest physi‐ ological disorders or microbial pathogen injuries of both fresh fruit and vegetables in the food industry. Many publications have focused on the potential protective nature of these natural phytochemical compounds against fungal and bacterial attacks. Moreover, these natural com‐ pounds have become interesting candidates not only for plant protection but also human and animal health protection from fungal and bacterial diseases because of their lower toxicity or absence of toxicity.
