Modelling and Optimization of the Processing of a Healthy Snack Bar Made of Grape and Tomato Pomaces

A snack made of 36% by byproducts of grape and tomato pomaces was developed, also including other ingredients, such as oats, chia, quinoa, honey and peanut butter. The recipe was defined as tasty and healthy by a focus group. The snack was produced by using forced air at three different drying temperatures (50 °C, 60 °C and 70 °C). The Newton, Page, Henderson and Pabis, and Midilli-Kucuk models fit the drying curves well. The average values for the Newton's model drying constants were k₅₀ = 2.71 × 10^-1 ± 3 × 10^-3 min^-1, k₆₀ = 2.76 10^-1 ± 4 × 10^-3 min^-1 and k₇₀ = 3.91 × 10^-1 ± 8 × 10^-3 min^-1 at 50 °C, 60 °C and 70 °C, respectively. The product's quality was assessed in terms of storage with respect to water activity and texture (hardness, springiness, cohesiveness, chewiness and resilience). There were no differences among the three tested processing temperatures in terms of their influence the final product's quality. As there were no significant differences between initial and final water activity and texture attributes at any temperature and they were mainly unaltered during storage, the snack bar was considered stable during this period. This new snack, which includes byproducts from the food industry, reduces food waste and contributes to a circular economic model, simultaneously presenting environmental and economic advantages.