Stability of lycopene during spray drying of tomato pulp

Lycopene is the principal pigment found in tomatoes and is important not only because of the color it imparts but also because of the recognized health benefits associated with its presence. Degradation of lycopene not only affects the attractive color of the final products but also their nutritive value. The objectives of this study were to determine the retention of lycopene during spray drying of tomato pulp and study the effect of drying conditions on the lycopene content of tomato powder. Sixty-four different experiments were conducted keeping constant the feed rate, the feed temperature and the atomizer pressure, and varying the compressed air flow rate, the flow rate of drying air and the air inlet temperature. Tomato powders were analysed for lycopene content. Lycopene content varied from 1016.05 to 1181.30 μg/g total solids, whereas lycopene loss ranged between 8.07 and 20.93%. Analysis of experimental data yielded correlations between lycopene retention and the variable operating conditions. Lycopene loss increased with increases in air inlet temperature and in both drying and compressed air flow rate. Multiple regression analysis was used to develop a predictive equation for final lycopene retention during spray drying. The decrease in lycopene content reported here was due to an actual degradation of lycopene, rather than to a progressive conversion from the all-trans-lycopene to a less strongly colored, less intensely absorbing cis form.