Influence of Pretreatments and Different Drying Methods on Color Parameters and Lycopene Content of Dried Tomato

1 Namik Kemal University, Department of Agricultural Machinery, Vocational School of Hayrabolu, 59400, Tekirdag, Turkey
2 Namik Kemal University, Department of Agricultural Machinery, Agricultural Faculty, 59030, Tekirdag, Turkey
3 Namik Kemal University, Department of Food Technology, Vocational School of Technical Sciences, 59030, Tekirdag, Turkey


HASTURK SAHIN, F., T. AKTAS, H. ORAK and P. ULGER, 2011. Influence of pretreatments and different drying methods on color parameters and lycopene content of dried tomato. Bulg. J. Agric. Sci., 17: 867-881

The effects of drying methods namely hot air drying (at 65, 75 and 85ºC drying temperatures and 1.5 and 2.5 m/s air velocity), vacuum drying, freeze drying and sun drying; and pretreatments namely dipping into 1% ascorbic acid + 1 % citric acid (EPSA) and dipping into 2 % sodium metabisulfite (EPSM) after 2% ethyl oleat + 4% potassium carbonate solution application on lycopene retention and color properties of dried tomato samples were investigated. Lycopene content values were determined by HPLC method and color parameters (L*a*b* and yellowness index) were measured directly a Hunter Lab chromatometer. a * / b *, b * L * / a *ΔL *, Δa*, Δb*, ΔC *, ΔE * values were calculated by using measured color characteristics. Effects of drying methods, pretreatments and interactions of pretreatments and drying methods on the lycopene values and color parameters were found significant as statistically. Maximum lycopene content was determined in freeze dried tomatoes and sun dried tomatoes followed these samples. Especially EPSA pretreatment increased the lycopene amount of dry tomato at the high temperature drying applications. In respect of color parameters, EPSM pretreatments the better results of L*, a* and b* values.

Key words: tomato, drying, lycopene, color, pretreatment
Abbreviations: AD - Hot air drying; VD - Vacuum drying; FD - Freze drying; SD - Sun drying; NPT - Nonpretreated; EPSA - 2% ethyl oleat + 4% potassium carbonate + 1% ascorbic acid + 1% citric acid; EPSM - 2% ethyl oleat + 4% potassium carbonate + 2% sodium metabisulfite; fw - fresh weight; dm - dry matter; fr - flow rate

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