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S. CHAISERI, Dept. of Food Science and Technology, Faculty of Agro-Industry, Kasetsart Univ., 50 Paholyothin Road, Chatuchak, Bangkok, 10900, Thailand and V. Cheetangdee.

Pandan leaves are commonly used to flavor desserts in Southeast Asia. There has been many attempts to process pandan leaves to preserve its aroma. Processed pandan leaves, however, have mild pandan aroma with an off-flavor. Process conditions, therefore, play an important role in formation of volatile compounds. The objective of this study was to investigate the effect of temperature, pH, and heating time on aroma impact compounds in pandan leaves. In this experiment, pandan leaves were heated at 80, 100, and 120° C for 5, 10, and 20 min. at pH 4.5, 7.0, and 8.0. Volatile compounds were extracted using dichloromethane and analyzed by gas chromatography-mass spectrometry. Aroma impact compounds were identified by gas chromatography-olfactometry. The samples were classified into under processed, well processed, and over processed samples. The under-processed samples, having green-note, were those heated under pH 4.5 at 80° C for 5 to 10 min. or 100° C for 5 min. The well-processed samples had clean pandan aroma that produced when heating the leaves at 80° C for 10 min. at pH 7.0 or 5-10 minutes at pH 8.0. Heating at 100° C could produce strong pandan aroma in 10 minutes at pH 4.5 and 5 to 10 min. at pH 7.0 and 8.0. Heating longer than 20 minutes at 80 to 120° C resulted in over-processed samples that had weak pandan aroma with cooked leaf and tobacco notes. Key aroma compound for pandan aroma was 2-acetyl-1-pyrroline (log₃FD=9). The under-processed samples had trans-2-heptenal (green, log₃FD=7) and the over-processed samples had 3-methyl-2(5H)-furanone (medicinal-like, sweet, log₃FD=4) and ß-damascenone (tobacco with burnt, log3FD=3) as their key aroma compounds. Minor key aroma compounds (log₃FD=1-2) were 4-ethylguaiacol (tobacco, green) and 3 unknowns. From this study, it was clear that heating at 100° C gave more flexibility in processing time and pH to produce 2-acetyl-1-pyrroline without formations of off-flavor compounds.

Session 83, Food Chemistry: Antioxidant and bioactive agents
2:30 PM - 5:30 PM, Tuesday PM Room 393

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana