Abstract

A combined treatment of high hydrostatic pressure and carbonation was used to inactivate pectinesterase (PE) and sterilize microorganisms in Valencia orange juice without major changes in its nutritive components. Quality characteristics of Valencia orange juice, such as microorganisms, PE activity, vitamin C content and color, were evaluated after it was treated with pressure, carbonation-and-pressure, and heat. Quality changes during storage at $4^{\circ}C$ and $30^{\circ}C$ after the treatments were also investigated. Pressurized orange juice (pressurized at 600 MPa for 10 min at $20^{\circ}C$) showed 7.0% residual PE activity, while the carbonated-and-pressurized orange juice (207 $kPa-CO_2$ gas pressure, pressurized at 600 MPa for 10 min at $20^{\circ}C$) showed 0%. Pressurization at 400 MPa or higher decreased the population of microorganisms in the orange juice to less than 10 CFU/mL. Carbonated-and-pressurized orange juice showed slight decrease in vitamin C content when stored at both $4^{\circ}C\;and\;30^{\circ}C$. While heat-treated ($90^{\circ}C$ for 60 sec) orange juice showed 75% decrease in vitamin C content when stored at $30^{\circ}C$. L value (lightness) and b value (yellowness) of carbonated-and-pressurized orange juice were higher than those of heat-treated orange juice when they were stored at $4^{\circ}C$ for 30 days.

오렌지쥬스 내 pectinesterase를 불활성화하기 위하여 열처리 ($90^{\circ}C$, 60 sec), 초고압처리 $(200{\sim}600\;MPa,\;5{\sim}15\;min)$, 그리고 carbonation $(138{\sim}207\;kPa-CO_2)$과 초고압을 병합처리 하였다. $207\;kPa-CO_2$ 조건으로 carbonation 한 후 600 MPa에서 10 min 동안 초고압처리한 오렌지쥬스는 pectinesterase가 완전히 불활성화되었고, 완전 멸균되었으며, 4% 미만의 비타민 C 파괴를 보였다. 설정된 최적 살균조건($207\;kPa-CO_2$로 carbonation 한 후 $20^{\circ}C$에서 600 MPa 압력으로 10 min 동안 초고압처리)으로 처리한 오렌지쥬스를 $4^{\circ}C$에서 저장하면서 pectinesterase 불활성화, 열처리, 그리고 초고압처리한 오렌지쥬스와 품질을 비교하였다. Carbonation과 초고압의 병합처리 된 오렌지 쥬스는 저장기간 동안 PE의 재활성화를 보이지 않았으며, 열처리에 상당하는 살균효과를 유지하였다. 비타민 C 함량은 $4^{\circ}C$ 저장의 경우 모든 처리방법에서 안정한 결과를 보였으나, $30^{\circ}C$ 저장의 경우 열처리한 시료에서 급격한 감소를 나타내었다. Carbonation과 초고압의 병합 처리는 오렌지 쥬스의 L값을 상승시켰으며 높은 b값을 유지하였다.

Keywords

• high hydrostatic pressure;
• carbonation;
• pectinesterase