From Waste to Functional Snack: Drying Kinetics, Neural Network Modeling, and Utilization of Tomato Pomace in Cracker...

This study investigates the sustainable valorization of tomato pomace (TP), a significant industrial by-product, by processing it into a tomato pomace powder (TPP) and utilizing it in cracker formulations to support the circular economy. TP was dried using convective oven drying (CO; 50°C, 60°C, 70°C) and microwave (MW; 240, 400 W) methods. The drying kinetics were analyzed using theoretical and semi-empirical models; the Dincer and Dost model provided the most accurate description of moisture diffusion. The Biot number values, falling within the range of 0.1-100, indicated a mixed regime where both internal and external resistances were present; however, the external convective resistance was identified as the more effective and governing factor. Artificial Neural Network modeling exhibited higher predictive performance compared to the Weibull distribution model under the specific experimental conditions tested in this study. Regarding bioactive retention, a trade-off was observed: while microwave drying at 400 W maximized the retention of Total Phenolic Compounds and antioxidant activity with the highest energy efficiency, CO drying at 70°C was identified as the optimal method for bakery applications due to superior preservation of carotenoids (lycopene and β-carotene) and color stability. Crucially, no 5-Hydroxymethylfurfural was detected in the dried samples. The optimized TPP was incorporated into crackers at 10%, 20%, and 30% levels. This incorporation transformed the crackers into a functional food by introducing significant amounts of lycopene and β-carotene-compounds absent in the control-while notably increasing Total Phenolic Compounds and antioxidant activity. ATR-FTIR analysis confirmed physical modification of the matrix and reduced water activity (aw). Although 30% substitution maximized bioactivity, Principal Component Analysis and sensory data identified 10% and 20% substitution levels as the optimum formulations, offering the best balance between functional enrichment and acceptability of sensory acceptability by the panelists.