# _Oncom_: A Nutritive Functional Fermented Food Made from Food Process Solid Residue
## 6 A Potential Functional Food? Health-Promoting Properties of _Oncom_
### Antioxidant Activity of Oncom  
Free radicals are highly reactive, unstable chemical compounds with one or more unpaired electrons that can cause harm to cell components [119; 120]. Proper enzymatic activity or natural antioxidants are the body's defence systems against the harmful effects of free radicals [119]. However, an imbalance will develop if the number of free radicals outweighs the number of antioxidants [10]. An imbalance between oxidants and antioxidants in the body results in oxidative stress, leading to cell death and chronic diseases, including cardiovascular disease, cancer, immune deficiency disease, and ageing [10]. Dietary factors with oxidants and antioxidants are responsible for altering the operating system and improving the host's antioxidant defence system [10]. The fermentation process significantly enhances antioxidants levels in _oncom_[4; 25; 121], a fermented product typically produced with moulds like _Neurosposa intermedia_, which not only ferment the substrate but also improve its nutritional and bioactive qualities [98; 122]. This fermentation promotes the breakdown of complex carbohydrates and proteins, releasing phenolic compounds, carotenoids, and isoflaves known antioxidants [4]. Total phenol, flavonoids, and antioxidant activity all rise directly to the lengthening of the fermentation process [10]. Most bioactive compounds with antioxidant activity are aromatic polyphenol compounds, including flavonoids and isoflaves [13; 119; 123]. These compounds can delay oxidation and protect biological systems from oxidation processes, preventing the oxidative deterioration of lipids and preserving food quality [13]. The mechanisms underlying the antioxidant activity of these compounds can be attributed to their chemical structures, which typically include electron-donating groups that enhance their radical scavenging capabilities [124]. The antioxidant and anti-cancer properties of red _oncom_'s flavonoid concentration were reported by [PERSON] et al. [120] and [PERSON] et al. [71] using F-CRS (Folin-Ciocalteu reaction substance) and ABTS (2,2\({}^{\prime}\)-azino-bis 3 (ethylbenzothazoline-6-sulfonic acid)) radical scavenging activities to quantify total phenolics and determine the antioxidant activity of SSF with _A. oryzae_ and _N. intermedia_. The fermentation with _A. oryzae_ and _N. intermedia_ increased the level of F-CRS in the material, resulting in higher accumulation of phenolic compounds and increased antiradical activity. The antioxidant activity of flavonoids in red _oncom_ can be attributed to their chemical structure, which typically includes hydroxyl groups that can donate electrons to free radicals, stabilizing them and preventing cellular damage [82; 125]. The presence of these compounds not only contributes to the health benefits of red _oncom_ but also enhances its potential as a functional food in cancer prevention strategies. For instance, flavonoids have been shown to inhibit the proliferation of cancer cells and induce apoptosis, thereby exerting protective effects against tumour development [126; 127]. Moreover, the relationship between the antioxidant properties of red _oncom_ and its anti-cancer effects can be further understood through the lens of the mechanisms by which flavonoids exert their activity. Research indicates that flavonoids can modulate various signalling pathways involved in cell growth and apoptosis, including the inhibition of nuclear factor kappa B (NF-\(\kappa\)B) and the activation of p53, a tumour suppressor gene [122; 128]. These interactions suggest that the consumption of red _oncom_ may not only provide antioxidant benefits but also contribute to the regulation of cellular processes that are critical in cancer prevention. In addition to their direct effects on cancer cells, flavonoids in red _oncom_ may also enhance the body's overall antioxidant defence system.