Currently, domestic seaweed production is about 800,000 tons per year, which is the largest seaweed production in the world after China and Japan. However, most seaweeds (Pyropia ssp, Undaria pinnatifida, Saccharina japonica, etc) are consumed in the form of dried products or hot water extracts, and there are many difficulties in developing various products due to difficulties in the manufacturing process. Through the pulsed electric field treatment device, the extraction efficiency can be expected to increase compared to the convectional hot water extraction. Pulsed electric field technology is a non-heating treatment technology in which high-voltage electric energy is processed into cells in the form of pulses, affecting the potential difference of cell membranes, and performing collapse or perforation treatment. In this study, components such as protein and carbohydrate content were extracted by treating Saccharina japonica with PEF, and compared with the hot water extraction method, As a result of experiment at voltages of 0.7 and 1.5㎸ and pulse duration of 5㎲, the crude protein content increased by up to 42% and the sugar content increased by up to 30% compare to the hot water extraction. Higher efficiency results can be expected through optimization of several parameters that may affect the extraction process.

High voltage impulse(HVI) has been gained attention as an alternate technique controlling CaCO3 scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on Ca2+ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to 60°C, the Ca2+ concentration decreased, indicating that the aqueous Ca2+ precipitated to CaCO3. The Ca2+ concentration decreased up to 81% under the condition of 15kV and 60°C. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and 60°C condition was evaluated to 66☓10-3 L/(mmol·hr), which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to 60°C) was much greater than at lower temperature region(20 to 40°C), which implies temperature is more important parameter than voltage for reducing Ca2+ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to CaCO3, particularly much faster at higher temperature.

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.

The effects of pulsed electric field (PEF) treatments on tenderization of beef were investigated. The beef was prepared by using the eye of round. PEF treatment of beef was performed using a newly manufactured movable batch chamber. The PEF treatment was conducted with electric field strength of 0.5~2.0 kV/cm using a fixed pulse width of 30 μs and frequency of 20 Hz. There was no significant change in appearance of PEF treated beef. The cutting force [N] of the sample was greatly reduced as the field strength of the PEF was stronger. The cutting force of beef treated with PEF at 2.0 kV / cm was 41.18 ± 3.28 N and the control was 57.25 ± 4.16 N. In the texture profile analysis, hardness and chewiness weakened as the field strength increased (p <0.05). There was no difference in springiness, cohesiveness, resilience before and after PEF treatment (p <0.05).

비열 처리 기술인 고전압 펄스 전기장(pulsed electric field, PEF)을 이용하여 당근 주스 내 토착 미생물의 억제와 처 리 전후의 품질 보존 효과를 연구하였다. 당근 주스의 PEF 시스템 내 주입 온도는 25℃와 40℃였고, 전기장 세기와 처리 시간은 각각 14 kV/cm, 170-198 μs와 13 kV/cm, 113-127 μs로 설정하였다. 처리 후 주스의 품온은 65℃를 넘지 않았다. 토착 미생물 저해율은 25℃의 주입 온도에서 3.9 ± 0.4-5.5 ± 0.9 log CFU/mL이었고, 40℃에서는 5.9 ± 0.6-6.6 ± 0.4 log CFU/mL이었다. 온도 상승과 미생물 저해율을 고려한 최적 조건은 주입 온도 25℃ 조건에서 14 kV/cm-198 μs, 주입 온도 40℃ 조건에서 13 kV/cm-127 μs로 결정하였다. 결정된 최적 조건으로 PEF 처리한 결과 당근 주스 내 베타 카로틴, 비타민 C, 항산화능, 색도, 갈변도, 당도, 그리고 pH는 처리 전후로 유의적 차이가 없었다(P>0.05). 또한, 주입 온도 증가에 따른 품질 특성의 변화를 보이지 않았고, 짧은 처리 시간으로 효과적인 살균이 가능함을 알 수 있었다. 본 연구를 통해 PEF 기술은 당근 주스의 품질 특성 변화를 최소화하면서 미생물 안전성을 증대시켜, 당근 주스의 살 균에 적합한 가공 기술임을 확인할 수 있었다.

회분식 고전압 펄스 전기장 처리에 의한 막걸리의 비가열 살균 공정 적용의 가능성을 알아보았다. 막걸리의 초기 균수는 약 2×108 CFU/mL로 전기장의 세기와 처리시간이 증가할수록 사멸율은 증가하여, 30 kV/cm, 256 pulse 처리하였을 경우 약 2 log 정도의 사멸율을 나타내었다. 고전압 펄스 전기장과 열을 병합처리하였을 경우 50oC에서 20 kV/cm, 256 pulse 처리를 한 후 8 log의 높은 사멸율을 나타내었으며, 알코올 농도를 달리하였을 경우 알코올 농도가 높아질수록 높은 사멸율을 나타내어 12%의 알코올 농도에서 4.8 log의 사멸율을 보였다. 고전압 펄스 전기장 처리한 막걸리를 4oC와 30oC에서 4주간 저장하였을 경우 무처리막걸리에 비하여 4oC에서는 pH, 산도, 미생물의 수에 변화가 거의 없었으며, 30oC에서도 적정산도나 미생물의 증가가 일정 수준이하로 억제되어 막걸리의 비가열 살균 공정으로서의 가능성을 보였다.

Apple juices were sterilized by continuous pulsed electric field (PEF) treatments of pulse width of 25 μs at electric field intensity of 20.0 kV/cm, and with the varied pulse frequencies of 35 Hz (40 kJ/L), 55 Hz (70 kJ/L), 72 Hz (100 kJ/L) and 85 Hz (130 kJ/L). The PEF treatments of apple juice reduced the microbial counts from 5.3 log CFU/mL of initial state to 3.0 log CFU/mL after PEF treatment at energy density of 130 kJ/L. Also yeast and fungi after PEF treatments were reduced from 5.3 log CFU/mL to 3.0 log CFU/mL and Escherichia coli were from 5.3 log CFU/mL of initial state to 4.7 log CFU/mL to <101 CFU/mL. The soluble solids and free sugars did not significantly differ (p<0.05) depending on conditions of PEF treatment. The total phenolic contents and antioxidant activity such as the DPPH and ferric reducing antioxidant power (FRAP) by PEF treatments were significantly partly reduced, but the PEF-reduced value came in smaller uantities than the heat treatment at 65℃. The iterative PEF treatments with pulse width of 25 μs and pulse frequency of 85 Hz at electric field intensity of 20.0 kV/cm showed limited in microbial reduction. Also, total phenolic contents and antioxidant activity such as DPPH and FRAP, significantly decreased depending on treatment numbers of PEF (p<0.05).

The effects of pretreatment by pulsed electric fields (PEFs) on the juice expression characteristics of the Malus pumila fruit were investigated. Fresh fruits were divided into quarters, were produced on a laboratory scale (100 g apples per lot) by pretreatment with electric fields at two different field intensities (1, 2 kV/cm; n=50, 100, 200, and 400 pulses), and were then pressed at room temperature. Relative to the control samples, the juice yield increased with increasing field intensities. The total phenolics and antioxidant activity were higher in the juice from the PEF-treated fruit than in the juice from the untreated fruit. There was no significant difference in soluble-solid and reducing sugar contents between the PEF-treated and untreated fruits. These results suggest that PEF pretreatment may be useful for increasing the juice yield, total phenolics, and antioxidant activity of the Malus pumila fruit.

천연 식용 색소원으로서 최근 주목받고 있는 자색 고구마로부터의 색소 추출에 대한고전압펄스전기장의 영향을 조사하였다. 자색 고구마 색소는 일정한 주파수와 처리시간 하에서 전기장의 세기를 변화시켜 추출하였을 경우 전기장의 크기가 증가함에 따라 색소의 추출량도 점차 많아지고 있음을 나타내었으며 최적 전압은 35kV/cm임을 알 수 있었다. 동일한 전기장의 세기와 처리시간을 주고 주파수만을 변화시키면서 추출을 했을 경우 낮은 주파수에서 500Hz까지는