Oats (Avena satica L.) are an important source of dietary fiber mainly composed of β-glucans, which is reported to be effective in lowering of cholesterol and decreasing the risk of heart attack. Subcritical water extraction (SWE) is a new and promising method for the extraction of β-glucan due to its polarity-selectivity, efficiency of recovery, time-efficiency, and lower cost. In this study, efficiencies of the SWE were investigated for the extraction of β-glucan from oat flour. The conditions for maximizing the extraction efficiency were determined by varying temperature (110-190°C), pH of solvent (pH 3.0-10.6), static time (5-20 min) and particle size of oat flour. The amount of β-glucan was determined with a ‘Mixed-linkage β-glucan’ assay kit (Megazyme International Ltd.), according to McCleary and Codd (1991). The overall results showed that the concentration of β-glucan was highest under the following conditions: extraction temperature of 200°C, pH value of 4.0, static time of 10 min, and particle size of 425-850 μm. The extraction yield under the optimum condition was 6.98±1.17 g/100 g oat flour, which was over two-fold higher than that obtained using hot water extraction method (60°C, 3 h). Therefore, SWE is a feasible alternative for extracting soluble dietary fiber (β-glucan) from oat flour.

Oat! It entices us with its awesome components such as β-glucan and unsaturated fatty acid. This study was performed to investigate the changes of flour size distribution, pH, moisture content, Hunter color value, polyphenol, protein, flavonoid, lipid rancidity, β-glucan content and sensory evaluation of covered and naked oat flour that heated at 80, 120, 160 and 200℃. It was roasted for 5min to begin with, followed by complete cool, and for 10min at the second time. There was some difference in flour size distribution before and after of roasting. With increasing temperature, oat was more broken finely. For the Hunter b value representing the blackish color of the surface, after oats went through a roasting process, one went through until 160℃ showed same color statistically. Moisture content declined more as the roasting temperature became higher. As for pH, its range of variation was small from 6.2 to 6.6. While a polyphenol was on the reduction, protein was on the rise by the increase of temperature. In total, a flavonoid was declined at 80℃ but increased from 120 until 200℃ compared to control. A MAD (malonaldehyde) related with lipid acidification was statistically identical until 160℃ and sharply risen at 200℃. Roasting conditions had significant effect on β-glucan content. A covered oat’s β-glucan was declined as opposite to naked oat’s β-glucan with temperature being increased. Variation in sensory evaluation such as color, taste, smell and preference was observed. There is no statistically significant difference in specimens heated at 160℃ and 200℃ of covered and naked oat in sensory evaluation(p<5%). All things considered including MDA, β-glucan content and sensory evaluation, a optimum temperature for roasting oat to develop processed goods was verified as about 160℃.

This study was performed to investigate the physicochemical properties of raw and roasted oats for the production of processed goods. Changes in particle size, pH, moisture content, Hunter b value, polyphenols, proteins, flavonoids, lipid rancidity, β-glucan content and sensory evaluation were compared between raw and roasted hulled oats (HO) and de-hulled oats (DO) after heating treatment at 0, 80, 120, 160 and 200°C. HO was more finely crushed than DO. The Hunter b value of HO was lower than that of DO, which increased sharply at 200°C. The pH range was from 6.2 to 6.6, with an average value of 6.4. In contrast to the protein contents of the two oat types, polyphenol content showed gradual decrease as roasting temperature increased. A comparison of the flavonoid content of HO with DO, indicated difference in the increase of flavonoids with increasing temperature. The protein content of HO was observed to be higher than that of DO. Furthermore, the protein level was slightly increased with increasing temperature. Malonidialdehyde (MDA) content was statistically identical from 0°C to 160°C, but then increased sharply at 200°C. As expected, the β-glucan content of HO was higher than that of DO. The β-glucan content of HO was decreased at 80°C, but increased from 120°C to 200°C. In contrast, the β-glucan of DO increased constantly compared to the control. Variations in sensory characteristics such as color, taste, smell and overall preference were observed. There were statistically significant difference among the sensory characteristics of the two oat types heated at 0°C and 120°C and at 160°C and 200°C (p<0.05). Our collective results, including those for particle size, MDA, protein, β-glucan content and sensory evaluation, indicated that HO would be more useful in the development of processed goods than DO, and that an optimum temperature for roasting oats is approximately 160°C for 15 min. Moreover, our results indicate that suitable roasting temperatures and cultivars are necessary to produce high-quality processed oat goods.

Oat flour was purchased and investigated for quality characteristics of oat bread. Antioxidant and flour pasting properties of oat flour, and water content, weight, volume, Hunter color value, texture of bread were measured. DPPH radical scavenging capacity (%) of oat extract was 68.49%. Pasting temperature of oat flour ranged between 66.60~circC and 70.93~circC . Flour pasting properties of sample added with 10 and 30% oat flour was shown similar results compared with wheat flour. Final viscosity of sample was increased by adding concentration of oat flour (up to 311.65 RVA). Water content (%) of bread was shown increasing trend by adding oat flour. Weight of bread loaf with 100% oat flour was shown higher score than other samples. Volume of loaf by adding oat flour of 10, 30, and 50 % ratio was 550, 450, and 388 mL, respectively. The Hunter color L* values of bread by adding oat flour was dark compared with wheat bread. Color value of bread added 10% oat flour was similar results with L* values of bread with wheat flour. The bread added with 20 and 30% oat flours had the higher hardness, gumminess, and chewiness compared with other samples. Cohesiveness of the bread with wheat flour showed higher than that of bread added with oat flour and increased by storage period. The growth of total viable cell was inhibited depending on the concentration of oat flour during storage.