Snacks account for nearly a quarter (22%) of total energy intake among adults in the US with more than 90% of them eating one or more snacks on any given day (ref) therefore they make an excellent delivery vehicle for functional ingredients. Watermelon rind, which comprises 40% of the fruit's total weight, is typically discarded despite containing valuable bioactive compounds including L-citrulline (CIT), polyphenols, and dietary fiber (Romdhane et al., 2016). CIT has demonstrated potential to increase muscle mass, function, and athletic performance (Jourdan et al., 2015). Upcycling these agricultural byproducts offers dual benefits of enhanced sustainability and economic competitiveness (Jin et al., 2018). An extruded puff snack was formulated with 0,10,15 and 20% watermelon rind, 20% pea protein (due to the high demand for high protein snacks) and cornmeal (Fig 1). It was hypothesized that increased inclusion of watermelon rind (due to fiber content) would increase hardness of puffed snack and nutrient delivery. Dried watermelon rind, pea protein, and cornmeal were blended prior to twin-screw extrusion processing at temperatures ranging from 30°C to 150°C across zones 1–8, with screw speed of 600 rpm and moisture content of 20%. HPLC and UV Spectrophotometry were used to quantify CIT and total polyphenols respectively. Hardness was determined using Instron texture analysis.

Results demonstrated significant changes with watermelon rind addition: CIT content increased 2.3-fold (from 14.4 mg/g at 10% to 33.2 mg/g at 20% watermelon rind), total polyphenol levels increased 49 % and hardness increased by 76 %.

These experiments demonstrate that a functional snack can be manufactured utilizing food waste (watermelon rind) that can yield a sustainable, bioactive-rich functional food rich in polyphenols, protein and CIT. Future studies are planned to utilize the watermelon rind puff in a human clinical study