**3. Rice bran as functional bran**

#### **3.1. Fermentation**

because consumers in developing and developed countries wish to maintain better health [1]. The concept of a "functional food" originated in the 1980s in Japan, from where it migrated to Europe and the United States [2]. In general, a functional food is a modified food that improves health and well‐being beyond the effects of the nutrients it contains. Generally, foods can be made functional foods by increasing the concentration of, adding, or improving the bioavaila‐ bility of particular components. Food is considered functional when it can be established that

Functional foods have recently emerged as convenient, inexpensive and promising candidates to prevent chronic health problems. Rice bran, a byproduct of the rice milling process, is derived from the outer layer of the rice grain; it contains a number of nutrients and biologically active compounds. Rice bran is often processed using stabilization, fractionation, enzymatic treatment, or fermentation. This treated rice bran is called functional bran. The identification of the bioactive components contained in rice bran has reinforced its status as a functional food. Experiments have revealed that enzyme‐treated or ethanol‐extracted rice bran (6% of the diet for 8 weeks) improves blood pressure (BP), the lipid profile and glucose metabolism. Further‐ more, adenosine supplementation (10 mg/kg body weight), an active component of functional bran, improved metabolic syndrome in stroke‐prone spontaneously hypertensive rats (SHRSPs) [4]. In addition, ferulic acid (FA) supplementation (9.5 mg/kg body weight), another active compound in functional bran (0.19 mg/100 g of rice bran), improves BP and the lipid profile [5]. Thus, the aim of this review was to analyze the evidence of rice bran as a functional

The composition of rice bran differs with the variety of rice, geographical conditions and processing methods. Rice bran, the outer layer of the rice grain, accounts for 8–10% of the total weight of the grain; however, it contains most of the nutrients: carbohydrates (34–62%), lipids (15–20%), protein (11–15%), crude fiber (7–11%) and ash (7–10%). In particular, rice lipids and bioactive components are concentrated in rice bran [6, 7]. Fatty acids such as palmitate (21– 26%), linoleate (31–33%) and oleate (37–42%) are predominant in rice bran. In addition, due to its high content of polyunsaturated fatty acids, rice bran is considered a healthy food [7, 8]. Significant quantities of bioactive compounds such as γ‐oryzanol, tocotrienol, tocopherol and α‐sitosterol as well as dietary fibers such as α‐glucan, pectin and gum have been found in rice bran [9, 10]. Specifically, γ‐oryzanol, the main antioxidant present in rice bran, has a 10‐times higher antioxidant activity than tocopherol, while tocotrienol has 40–60 times greater antiox‐ idant activity than tocopherol. However, the proportions of these phytochemicals vary with the type of rice cultivar [11]. In addition, rice bran contains 4‐hydroxy‐3‐methoxycinnamic acid

The health information website SelfNutritionData (http://nutritiondata.self.com) reports that one cup of crude rice bran provides 88 calories and that 28 g of rice bran contains 5.8 g of fat, 1.2 g of which is saturated and 4.2 g of healthy unsaturated fatty acids. According to Walter

it enhances body function or reduces the risk of diseases [3].

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

food as well as the global interest in rice bran.

**2. Compositional distinctiveness of rice bran**

(FA), which has photoprotective and antioxidative effects [12–14].

Owing to its disease‐preventing properties, rice bran is popular in the food industry. Interest‐ ingly, the antidiabetic and antidyslipidemic activities of rice bran have been reported in different animal model experiments [15–17]. Furthermore, the active components in processed rice bran promote health; indeed, the processing itself adds value to the rice bran [18, 19]. Such treated rice bran may protect against metabolic syndrome by attenuating hypertension, dyslipidemia and insulin resistance; it is a candidate functional food because it prevents oxidative stress in rat and mouse models [20–23]. To create a more applicable and functional bran, several fermentation processes have been used to enhance its nutritional value. Rice bran fermented using *Saccharomyces cerevisiae* has anti‐stress and anti‐fatigue effects. Furthermore, the polysaccharide extracts of rice bran fermented using *Lentinus edodes* showed an anti‐cancer effect and they prevented defective immune responses; the water extracts of the same fer‐ mented rice bran had an anti‐photoaging effect [24, 25]. Moreover, brown rice fermented using *Aspergillus oryzae* has a suppressive effect on dextran sulfate sodium‐induced ulcerative colitis and it inhibits inflammation‐mediated cell infiltration [26, 27]. Rice bran extract fermented using *Lactobacillus plantarum* improves functional recovery and reduces cognitive impairment after ischemic brain injury in a rat model [28, 29]. Fermentation using different microbes can increase the levels of bioactive compounds as well as the availability of functional food. For instance, fermentation using *Rhizopus oryzae* increases the protein content of rice bran (43%); it also increases the levels of phenolic compounds, which have high antioxidant activity, by breaking down lignin in the substrate cell wall [30].

#### **3.2. Compositional improvement as functional bran**

Rice bran is processed to inactivate lipases and other nutritional inhibitors such as field fungi, bacteria and insects, to reduce their toxicity without damage to the protein quality of rice bran. The rice bran must be stabilized using suitable techniques while bran layers are removed from the endosperm during milling. Specifically, to achieve proper stabilization, each individual bran particle must have the same moisture content, depending on the time and temperature. Furthermore, to inactivate the enzymes in the rice bran that are responsible for rancidity, different stabilization methods are used. Among these, microwave energy offers an alternative energy source for stabilization [30–32]. Next, stabilization fractionation is performed. This is an important step in industrial processing; it involves the conversion of rice bran into various parts that contain more desirable than undesirable components. Subsequently, the different fractions are centrifuged to separate the insoluble fiber fraction—called rice bran fiber—from the aqueous dispersible fraction—called rice bran soluble. The mixture of both insoluble and soluble extracts is called rice bran balance. Using different technologies, the bran is fully stabilized and the oil is removed. The resultant food‐grade, defatted rice bran is temporarily stored in food grade silos until it can be used in edible applications. Bleaching of the edible oil typically leaves minor flavor and odor compounds that must be removed by steam distillation before the oil is used. Steam distillation is the final step in the processing of edible oil, whereby any off‐flavor and residual free fatty acids left in the oil are removed.

We produced two types of rice bran fraction: Driselase® fraction (DF) and ethanol fraction (EF). To process the rice bran, 500 g bran was agitated in 1.0 L of 70% ethanol for 2 h; this yielded two fractions: the solid and filtered fractions. The DF was derived from the solid fraction. Driselase® is a commercial plant cell wall‐degrading enzyme mixture containing cellulase, xylanase and laminarinase; however, it is esterase free. The solid fraction of rice bran was dried at room temperature and then suspended in 10 mM acetate buffer (500 mL) containing Driselase (0.2 mg/L) from *Basidiomycetes* spp. The bran was treated in this manner overnight at 37°C; the suspension was then filtered and finally lyophilized. As a result, Driselase‐treated rice bran had increased quantities of bioactive components that improve glucose and lipid metabolism in the SHRSPs—a genetic animal model of metabolic syndrome [33, 34].
