부산대학교 도서관

Objective: To investigate changes in vitamin C (V.C) content during heating in the cook-freeze system compared with the traditional cook-serve method.Methods: Samples were 7 food items (potatoes and vegetables group). Samples were chopped in a food processor and divided for different cooking processes: soaking in water, freezing, and heating (steaming and boiling in water). The fraction of V.C remaining was measured by high-performance liquid chromatography (HPLC) after derivatization with 2,4-dinitrophenylhydrazine. Water used for boiling was also analyzed by HPLC.Results: With V.C content in fresh samples set as 100%, mean V.C content was 23.7 ± 6.0% after soaking in water and 94.7±3.5% after freezing fresh samples for 1 week. In steamed samples, mean V.C content was 69.7 ± 17.8% after steaming heating), 62.9 ± 15.8% after steaming and freezing, and 53.7 ± 18.0% after reheating. In boiled samples, mean V.C content was 56.7 ± 17.7% after boiling (heating), 52.2 ± 17.2% after boiling and freezing, and 45.7 ± 20.8% after reheating. Mean V.C content in sliced potato samples was 99.9 ± 1.6% after steaming and 84.5 ± 1.8% after boiling.Conclusion: Due to preparation in a food processor, V.C loss was larger in soaked samples than in heated samples. Loss was minor in frozen fresh samples. V.C loss was less after reheating than after heating, but a large loss was observed in the heating process of the cook-freeze system compared with the traditional cook-serve method. V.C content remained low in boiled samples, even after accounting for V.C in water used for boiling.