Identification and quantification of hay‐like off‐flavor in basil samples after various processing

Abstract

The food industry is becoming increasingly interested in aromatic herbs and spices. Most herbs and spices are marketed in dry form to extend shelf life. Hence, drying is the most widely used treatment. Nevertheless, severe aroma changes occur during the drying processing or even the sample pretreatment processing before drying, one of representative which is to create hay-like off-flavor and further to reduce quality of the final products. The typical hay-like off-flavor is often present in dried spinach, parsley samples and even soybean oil. Fresh and dried basil leaves are popularly used in cooking. Many studies concerning the volatile composition of basil leaves have been carried out. However, no study regarding hay-like off-aroma of dried basil samples in identification and quantification has been reported. The aim of our research is to understand the formation of hay-like off-flavor, which may contribute to the industrial processed basil. In our study, we found that the hay-like offflavor was present in both frozen-thawed (3 h at room temperature) and dried basil samples, revealed by a trained panel (n = 10). By application of stir bar sportive extraction in combination of gas chromatograph-mass spectrometer-olfactory, the haylike odorant 3-methyl-2,4-nonanedione was identified in both types of basil samples by comparison of odor impression, retention indices on two columns of different polarity (DB-WAXms and DB-5MS) and selected mass ions with those of authentic standard. In addition, the quantitative change of the hay-like odorant was monitored under the sample preparation process by means of sensory evaluation and instrumental aroma analysis.