Optimisation of spray drying operating conditions of tomato slurry using response surface methodology

Tomato fruits and tomato-based products are one of the most consumed foods globally due to its high nutritional value. However tropical temperature is not conducive for the cultivation of tomatoes which leads to post harvest losses. The development of spray-dried tomato powder is therefore crucial to extend the value and usability of these perishable produces. The main objective of this study is to determine the optimum condition for spray drying in order to obtain spray-dried tomato powders with the highest product yield, lowest moisture content, and the best retention of red-orange colour content. This study presents the effectiveness of spray drying of different fruit juices, the effect of selected spray drying parameters on the tomato powder production and its optimisation. The studied factors were the inlet air temperature (oC), the concentration of different carrier agents (%, w/w), and the feed flow rate (g/min). Meanwhile the response variables were the moisture content, product yield, and the red-orange colour retention of tomato powder. Suitable articles related to the spray-dried fruit powders and tomato powders were taken for analysis and comparison. Based on the analysed trend, it was observed that the most significant factors were the inlet air temperature (oC), and the concentration of carrier agents, whilst feed flow rate showed less significant effects on the spray-dried tomato slurry. On the other hand, response surface methodology (RSM) was applied to show the interaction of multiple factors and to conduct an optimisation study for the spray drying condition for tomato powder. The optimum value of inlet air temperature and the concentration of carrier agents for spray-dried tomato pomace powders were found to be 123.20 degrees C and 9.40% w/w with the addition of gum Arabic (GA), 180.44 degrees C and 16.42% w/w with the addition of inulin, respectively. Meanwhile, the optimal value of inlet air temperature, feed flow rate, and atomization speed for the spray-dried tomato pulp powder was found to be 220 degrees C, 276 g/min, and 25000 rpm, respectively.