Measurement of changes of pungency-related compounds in pepper under cooking and development of stabilization method

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In this study, efficient extraction method and selective detection for pungent compound capsaicin and nonpungent compound capsiate in pepper were investigated. Then, the stability of capsiate during cooking was tested. Further, we tried to develop processing method for stable capsiate supply.On pungent capsaicin, we studied the extraction and determination method by using a curry roux because it contains various capsaicin-like compounds and is thought to be most difficult sample for capsaicin determination. By adding 10-volume of acetone to the sample and standing for a day capsaicin could be recovered quantitatively. For detection with HPLC, UV, fluorescence, and amperometric electrochemical detection were tested. HPLC with fluorescence detector and gradient elution of methanol gave the best result. By using this, capsaicin content in curry roux could be measured. And, simultaneous analysis of another pungent principle piperine in black or white pepper was tested. By changing the excitation and emission wavelength for fluorescence detector, both piperine and capsaicin could be analyzed at once. Capsaicin and piperine contents in commercially available curry roux were measured.Enzymatically synthesized vanillyl nonanoate (VN) was used as a model compound for capsiate. Stability of VN in aqueous and oil system was tested. Under strong acidic condition and in oil, VN was considerably stable. VN was stable in dressings, mayonnaise or chocolate and the half-lives of VN were longer than 1 year at room temperature.