# Volatile Compounds, Sensory Profile and Phenolic Compounds in Fermented Rice Bran
###### Abstract  
Rice bran (RB), a by-product of the rice milling process, is a rich source of bioactive compounds. Current studies have suggested that fermentation can enhance the bioactivities of RB. This study is aimed to analyse the volatile compounds and sensory profile of fermented RB from two cultivars (Inpari 30 and Compo Ireng) that are well-known in Indonesia, as well as to measure total phenolic content (TPC) and antioxidant activity. Volatile compounds of fermented RB were analyzed using gas chromatography-mass spectrometry combined with headspace-solid phase microextraction. The optimum TPC and antioxidant activity were observed after 72 h fermentation of RB. The 55 volatile compounds were identified in fermented and non-fermented RB. They were classified into alcohols, aldehydes, acids, ketones, phenols, esters, benzene, terpen, furans, lactone, pyridines, pyrazines, and thiazoles. Volatile compounds were significantly different among the varieties. The sensory analysis showed that the panelists could differentiate sensory profiles (color, taste, flavor, and texture) between the samples. Fermentation can enhance the acceptance of RB. These studies may provide opportunities to promote the production of fermented RB as a functional ingredient with enhanced bioactivity for health promotion. e 22 May 2  
the outer layer of the rice grain. Pigments in the outer layers are responsible for the color of some rice cultivars which are referred to as pigmented cultivars. In Indonesia, pigmented rice is classified into black and red rice. Solid-state fermentation (SSF) using microorganisms and their enzymes is one of the beneficial strategies to increase bioactive compounds in plant foods [10]. SSF is effective at increasing TPC, antioxidant activity, and organic acid [11; 12; 13]. The activity of the enzyme \(\beta\)-glucosidase in fungi increases hydroxyl compounds that increase free phenolic compounds in RB [14]. Recently, our groups' studies have shown that SSF with _Rhizopus oligosporus_ can induce enzyme activity that could also lead to the release of phenolic compounds, higher antioxidant activity, blood pressure lowering activity in stroke-prone spontaneously hypertensive rats, anti-\(\alpha\)-amylase activity, and antiproliferative properties toward colon cancer in WiDr cell lines [15; 16; 17]. Volatile compounds are chemicals that play a key role in the formation of aromas in food products. The volatile compounds of RB have been reported by several investigators. They have used gas chromatography-mass spectrometry (GC-MS) to identify the compounds. The identified compounds of RB consist of alcohol, alkanes, ketones, and aldehydes [18; 19; 20]. Hexanal is a common compound in RB that may cause off-odor in RB because of enzyme activity during processing of RB [21; 22]. Another report has shown that volatile compounds of black RB consist of aldehyde, alcohol, alkenes, and ketone [21]. Current data shows that volatile compounds of fermented RB by different lactic acid bacteria were acids, aldehydes, esters, furan derivatives, ketones, alcohols, benzene and benzene derivatives, hydrocarbons, and terpenes [23]. Furthermore, when RB was fermented by _Lactobacillus paracaei_, it produced some volatile compounds, especially lactones, 2,3-butanedione, and 3-hydroxy-2-butanone, which are similar to a compound in dairy products (i.e., cheese, fermented milk, and butter). These can improve the sensory profile of rice-based probiotic functional foods [24; 25]. This is the first study to investigate the formation of volatile compounds in Indonesian fermented RB. The objective of this study was to analyze the profiles of volatile compounds of two cultivars of RB in Indonesia as well as TPC and antioxidant activity. Inpari 30 (IPR30) cultivar is one of the Cibergang cultivars (white rice) that is most widely consumed in Indonesia. Compo Ireng (CI) black rice is one of the local pigmented rice varieties in Indonesia and has a high content of phenolics, total flavonoids, and total anthocyanins [16].