Investigation of changes of aroma profile during storage of lemonades with different acidity levels

The aroma components and their changes in foods are important factors that directly affect sensory properties and affect consumer choice and shelf life of the product. The amounts of aroma components in foods generally range from nanograms to milligrams per liter and their amounts and formations can change due to various factors. These factors are; temperature, storage time, bacterial activities, the product's own characteristics and applied technological processes. In this study, it was aimed to evaluate the changes in the quality parameters and flavour profile depending on the storage time and temperature of lemonade samples at different acidity levels. For this purpose, lemonade samples prepared at 3 different acid levels (5,6, 5,8, 6,0 g/L) were stored at 2 different temperatures (25 ° C and 45 ° C) for 2 months and total soluble solid (TSS), titratable acidity, color (L*, a*, b*) and aroma component (d-limonene, linalool, terpinen-4-ol, α-terpineol) analyzes were performed in weekly periods.The aroma components were extracted by headspace solid phase microextraction (HS/SPME), identified by gas chromatography mass spectrometry (GC-MS), and their concentrations were calculated by the internal standard (Cinnamaldehyde) method. SPSS statistical package program was used for statistical analysis of changes in lemonade samples at different storage temperatures. It was found that The amount of SÇKM increased by 3% in storage at 25 ° C and 7% in storage at 45 ° C; titration acidity increased by 1.5-2.5% in storage at 25 ° C and 3.4-4.4% in storage at 45 ° C; there are significant changes in color parameters (L *, a *, b *) ; d-limonene compound decreased by 42-48% in storage at 25 ° C and 95-97% in storage at 45° C; Linalool compound decreased 23-51% in 25 ° C storage and decreased to undetectable level after 2 weeks in 45 ° C storage; Terpinen-4-ol compound increased by 27-118% in storage at 25 ° C and 47-62% in storage at 45 ° C; α-terpineol compound increased by 62-78% in 25 ° C storage and decreased after 150-160% increase in 45 ° C storage. These changes were found statistically significant and the change is due to the degradation of d-limonene and linalool compounds with time terpinen-4-ol and α-terpineol. The changes of aroma components in storage at 25 ° C are acceptable compared to storage at 45 ° C. Regardless of the product process, the thermal factors it is exposed to under storage and transport conditions affect the aroma composition and causing off-flavour compounds to form, it negatively affects the consumer's perception of safe food and reduces their preferability. Accordingly, it is important that storage and transport conditions are optimal and stable throughout the shelf life of the products. Keywords: Lemonade, flavour, storage, d-limonene, terpinen-4-ol.