Black pepper (piper nigrium L.) is a spice commonly used but has a problem with microbial control, so it needs non-thermal decontamination method for product quality of dried foods. Intense pulsed light (IPL) technology is a non-thermal method for superficial decontamination of foods to inactivate pathogenic microorganisms by using high peak power and short duration pulses of a broad-spectrum (170-2600 nm) using a xenon lamp. The objective of this study was to reduce total number of bacteria in ground black pepper effectively by combined treatments of IPL and immobilized TiO2 photocatalyst. Self-designed cyclone type of pilot-scaled IPL device (> 5 kg/h) was used, which makes samples to flow cyclonically in a vacuum space longer time rather than moving vertically. Using this device alone, without TiO2 coated, 0.3-0.6 log reductions were achieved under a total energy fluence of 14.85 J/cm2 (DC voltage; 1200, 1800, and 2400 V, pulse duty; 0.5, 2.1, and 3.0 ms, treatment time; 60, 120, 180, 240, and 300 s, frequency; 2 Hz). Subsequently, TiO2-coated quartz plates with different layers between light source and samples were installed to observe the effect of photocatalyst and the efficiency of decontamination was improved slightly. However to increase the effect of the photocatalyst, several factors (TiO2 particle size, TiO2 film thickness and transparency, adhesiveness between quartz and photocatalyst, etc.) need to be concerned additionally. Nevertheless, the application of IPL treatment combined with TiO2 photocatalyst offers a potential of effective non-thermal decontamination method for dealing with powder foods in food 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.

Citrus fruit is important source of flavonoids, mainly flavanones which are narirutin and hesperidin. Those citrus flavonoids have been found to have health-related properties including antioxidant, anticancer, and anti-inflammatory. The main purpose of this study was to verify that the extraction of narirutin and hesperidin from Citrus peel can be more effective by combining pulsed electric field (PEF) pre-treatment and subcritical water extraction (SWE). Citrus unshiu peels were treated with PEF under conditions of electric field strength (3 kV/cm) and times (1 and 2 min). Subsequent SWE was conducted by using a Dionex Accelerated Solvent Extractor (ASE, Model 350) at extraction temperature 170°C for 10 min. The total flavonoids content was measured by using the aluminum chloride colorimetric method and the antioxidant capacity was analyzed by the Ferric reducing antioxidant power (FRAP) assay using spectrophotometer. The concentrations of narirutin and hesperidin were increased as PEF pre-treatment time increased. The highest concentrations of narirutin and hesperidin were 13.41 mg narirutin/g dry citrus peel and 141.16 mg hesperidin/g dry citrus peel at PEF pre-treatment condition of 3 kV/cm and 2 min. The total flavonoids contents of the extracts increased 105.2% and 123.1% for citrus peel PEF treated at 1 and 2 min, respectively. In addition, compared to the untreated sample, PEF pre-treatments of 1 and 2 min increased the antioxidant capacity of the extracts 109.2% and 160.8%, respectively. Therefore, the results demonstrate the potential of PEF pre-treatment to improve the SWE of flavonoids from citrus unshiu peel.