Effect of microwave-vacuum drying on the physicochemical properties of a functional tomato snack bar

<p>Abstract</p> <p>BACKGROUND</p> <p>Tomato is one of the indispensable ingredients of the Mediterranean diet. Reformulation of traditional Mediterranean products to increase the adherence of the consumers is getting popular. In this study, a tomato snack bar enriched with olive powder and pea protein was developed by using microwave-vacuum drying. Formulations also included the tomato powder (TP) and low methoxylated pectin (LMP) as a structuring agent.</p> <p>RESULTS</p> <p>The moisture content (MC) of the microwave-vacuum-dried samples varied in the range 13.6%-19.8% and water activity (<em>a</em>_w) values were ~0.6. The LMP and TP concentration affected the color of microwave-vacuum-dried samples. However, the color mainly changed in conventionally dried samples due to browning. In microwave-vacuum-dried samples, lycopene content decreased with increasing LMP, but increased with increasing TP. Textural properties of microwave-vacuum-dried snack bars increased with increasing LMP and TP.</p> <p>CONCLUSION</p> <p>Both texture and FTIR spectroscopy results indicated that there was a network formation due to the contribution of protein and pectin; however, the type of interaction was highly dependent on the drying mechanism. NMR relaxometry data showed that microwave-vacuum-dried samples had a more uniform water distribution. Besides its time and energy efficiency, microwave-vacuum drying improved the color and textural properties of tomato snack bars compared to conventionally dried ones.</p>