# Effects of Pretreatment on the Volatile Composition, Amino Acid, and Fatty Acid Content of Oat Bran
###### Abstract  
Pretreatment improves the edible quality of oat bran and prolongs the shelf life, whereas the effect of pretreatments (i.e., steaming(S-OB), microwawing(M-OB), and hot-air drying(HA-OB)) on the flavor characteristics of oat bran is unknown. This study identified volatile composition using HS-SPME/GC-MS and an electronic nose of oat bran. The amino acid compositions were determined by a High-Speed automatic amino acid analyzer and the fatty acids were determined by gas chromatography. The results showed that steaming and microwaving pretreatments enhanced the nutty notes of oat bran. Sixty-four volatile compounds in four oat brans were identified. OB exhibited higher aroma-active compounds, followed by S-OB, and M-OB, and the HA-OB had the lowest aroma-active compounds. Hexanal, nonanal, (E)-2-octenal,1-octen-3-ol, 2-ethylhexan-1-ol, and 2-pentylfuran were the key volatile compositions in oat bran. The aldehyde content decreased and the esters and ketones increased in steamed oat bran. Microwaving and hot air drying increased the aldehyde content and decreased the ester and alcohol content. Steamed oat bran had the lowest levels of total amino acids (33.54 g/100 g) and bitter taste amino acids (5.66 g/100 g). However, steaming caused a significant reduction in saturated fatty acid content (18.56%) and an increase in unsaturated fatty acid content (79.60%) of oat bran (\(p<0.05\)). Hot air drying did not result in an improvement in aroma. The results indicated that steaming was an effective drying method to improve the flavor quality of oat bran. oat bran; volatile composition; amino acid; fatty acid Article  
[PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Effects of Pretreatment on the Volatile Composition, Amino Acid, and Fatty Acid Content of Oat Bran
puffing, and hot air drying [10]. Steam processing of oats inactivated enzymes and produced the unique oat flavor [11]. [PERSON] et al. observed remarkable differences in the flavor of oats after dry heat (hot air baking and infrared baking) and wet heat treatments (atmospheric pressure cooking, high-pressure cooking, microwaving). Compared to wet heat treatment, dry heat treatment improves the flavors of oats [12]. [PERSON] found that the types of volatile composition in Sino-Australian oat rice increased after steaming, and alkanes and aldehydes were the main flavor components of cooked oat groats [13]. Microwave heating has been used successfully as extraction support [14] to inactivate unwanted enzymatic activities such as the decomposition of \(\beta\)-glucan [15] or the decomposition of fat [16]. [PERSON] found that microwave heating of oatmeal for 3 min had the highest starch content and lowest GI, and it was the meal with highest carbohydrate equilibrium [17]. The preliminary results showed that the three pretreatment methods of steaming, microwaving, and oven heating improve antioxidant activity [18] and storage stability of the oat bran [19]. However, there are few technology applications for oat bran production and flavor enhancement. The focus of flavor research is to determine the relationship between key volatile compounds and their sensory properties. A particular challenge in the study of the volatile composition of oats is the low and characteristic content of active flavor volatiles; thus, it lacks the sensitivity of the instrumental limit of detection required for identification [20]. Solid-phase microextraction (SPME) is a commonly used technique for the separation of volatile compounds that increases the sensitivity of dynamic headspace [21]. The use of SPME in oat analysis was first reported by [PERSON] et al., as a comprehensive comparison of volatiles produced in the intermediate stages of processing from raw and de-grained oats to flaked oats [22]. The flavor of oats is mainly formed during the kinds of processing treatments, and the precursors and enzymes of natural oats are helpful in the formation of flavor. The aroma of processed oats is a complex combination of heat-related volatile aromas.