Lemon oil is very unstable and deteriorates rapidly during storage at low pHs. The key flavor compound in lemon oil, citral, degrades by a series of cyclization and oxidation reactions to form potent odorants which provide off-flavors. Degradation of citral and/or formation of potent odor compounds can be used as indicators to assess the quality of lemon oil-containing beverages during storage. The storage stability of lemon oil treated to remove citral has not been reported. This investigation was conducted to compare the stabilities of citral-containing and citralless lemon emulsions (EC and ECL) and beverages (BC and BCL) during storage at different temperatures by both gas chromatographic and sensory analyses.
Materials and Methods
Control lemon oil and a citraless oil (produced using a proprietary process by Robertet SA, Grasse, France) were provided by Robertet Flavors Inc. of South Plainfield, New Jersey. These two lemon oils were used to prepare flavor emulsion concentrates (EC = an emulsion which contains citral, and ECL = an emulsion which is citralless), Then each of these lemon oil emulsions was used to formulate two types of lemon-flavored still beverages, one with a pH of 3.3 (coded BC3.3 and BCL3.3) and the other with a pH of 2.7 (coded BC2.7 and BCL2.7). The higher pH was obtained by adding a lemon juice concentrate (54.5°B from Robertet Flavors Inc.). The codes used in this article to identify these materials are summarized in Table 1. The formulations used for preparing the lemon flavor emulsions and lemon beverages are listed in Table I.
Methods: Analysis of Systems With Lemon Oil
The prepared lemon oil emulsions and lemon beverages were stored at 4, 25, 35 and 45°C, and samples were removed at appropriate time intervals (every 4 days @4°C, 24 hrs @25°C, 16 hrs @35°C and 8 hrs @45°C) for analysis.