Subcritical water extraction (SWE) is an eco-friendly new extraction technology because it does not contain harmful organic solvent and has high extraction efficiency in a short time compared with conventional extraction methods. Blueberries (Vaccinium corymbosum) are widely known as superfood due to rich source of anthocyanin (malvidin-3-o-galgctoside) and antioxidant activity. In this study, optimal extraction condition of SWE from blueberries was determined and compared with the conventional extraction methods. SWE was carried out using a Dionex Accelerated Solvent Extractor (ASE, Model 350) under conditions of temperatures (110, 130, 150 and 170°C) and times (1, 3, 5 and 10 min). Total anthocyanin of SWE extracts was compared with hot water (60°C, 1 h) extract and pressed juice extract. The total anthocyanin content was determined by pH differential method. Considering both the extraction time and temperature conditions, the highest content of total anthocyanin content was 0.455 mg/g FW Vaccinium corymbosum at 130°C for 3 min. At high temperature and long extraction time, the anthocyanin in the blueberries will undergo thermal degradation due to low stability of anthocyanin at extreme condition. Besides, maximum yield of anthocyanin from blueberries using SWE was about 1.2 and 3.8 times more higher than hot water extract and pressed juice extract, respectively. Therefore, SWE is faster and more efficient method to extract anthocyanin from blueberries than conventional extraction methods. This study shows a possibility of SWE applied to food processing industry.

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.