Spent coffee grounds (SCGs) are currently considered abandoned landfill waste despite retaining valuable organic compounds, especially with a high protein content of 16.64 ± 0.13 g/g dried SCGs and a high oil content of 15.48 ± 0.17 g/g dried SCGs. As a result, SCGs could serve as a potential source of valuable ingredients. However, utilizing a single technical strategy of alternative green extractions was insufficient for extracting the target compounds and hydrolyzing proteins. This work aimed to optimize the operating parameters of enzyme-assisted extraction (EAE), microwave-assisted extraction (MAE), and subcritical water extraction (SWE) using a response surface methodology. The results showed that EAE, at a papain-to-substrate ratio (E/S) of 0.5 and a duration of 15 min, generated a %DH of 93.39% and provided a water soluble protein concentration (WSPC) in the range of 400 to 800 µg/mL. Moreover, MAE provided a maximum %DH of 9.72% at 600 watts and 10 min, while SWE produced a maximum %DH of 13.41% at 160 °C in 17.5 min. However, the WSPCs of MAE and SWE extracts were comparable at ~250 µg/mL. The combination MAE−SWE enhanced the %DH of hydrolysates by more than the combined SWE−MAE, SWE, and MAE. However, the effects of differential hydrolysis on bioactivity are not directly correlated with %DH. In this study, the highest antioxidant activity was found at an E/S of 0.5 and in 15 min for EAE, at 350 W and in 10 min for MAE, and at 160 °C and in 30 min for SWE. This work demonstrated that the valorization of SCGs not only reduces the amount of waste but also yields functional cosmeceutical and nutraceutical ingredients.

In recent years, plant-based foods have gained substantial momentum around the world. Egg yolk, a key ingredient, is commonly used as an emulsifier in most salad dressings. Aquafaba was employed as an egg substitute in the development of plant-based salad dressings. Additionally, carboxymethyl cellulose (CMC) was incorporated as a stabilizing agent to enhance the emulsion stability of the formulation. The results showed that the control salad dressing (made with egg yolk) and the plant-based salad dressing containing 0.2–0.3 wt% CMC were highly stable with an emulsion stability index (ESI) of more than 90%, and a z-potential of approximately ±30 mV. To develop a healthier, lower-calorie alternative, reduced-fat plant-based salad dressings were formulated by decreasing the oil content and substituting it with chickpea-derived aquafaba. The results demonstrated that the oil used in the formulation could be reduced from 60 wt% to 45 wt% without significantly affecting the ESI. The droplet diameter of the reduced-fat plant-based salad dressing containing 45 wt% oil was significantly smaller than that of the full-fat formulation with 60 wt% oil. Furthermore, Wolffia was incorporated into the formulation to develop a functional salad dressing with enhanced health benefits. Fortification with Wolffia significantly decreased the lightness, redness, ESI, and z-potential of the plant-based salad dressing. However, fortification with Wolffia did not significantly affect the yellowness of the plant-based salad dressing. The research findings could benefit further research efforts focused on the development of alternative health-promoting food products.