Production of Disposable Cups from Post-Consumer Cooked Rice: Formability and Use-Phase Performance for Circular Packaging Systems

Food waste and disposable beverage packaging represent coupled sustainability challenges, yet practical pathways that convert food residues into functional packaging products remain limited. This study investigates the feasibility of upcycling post-consumer cooked rice into disposable cup bodies and evaluates their formability and use-phase performance as decision-oriented metrics for circular packaging systems. Cup shells were formed under controlled moisture content, charge mass, and dielectric consolidation time, and assessed for manufacturing robustness, short-term hot-fill containment, water uptake, and grasp-related thermal safety at 100°C. A medium moisture range (46–55 % w.b.), charge mass of 16–19 g, and dielectric dwell of 4–5 min produced the highest formability, yielding continuous rims (≈83–92 %), low wall non-uniformity (Δδ ≤ 0.30 mm), and clean demolding. Optimized cups showed no leakage during 1–5 min hot-fill screening, with limited water uptake (≈0.9–1.2 % of dry mass for short-grain formulations). SEM observations revealed a heterogeneous porous morphology that became more structurally continuous after thermoforming, while FTIR spectra confirmed the characteristic polysaccharide functional groups of the gelatinized rice material. Effective thermal conductivity at 25°C ranged from 0.046 to 0.052 W m⁻¹ K⁻¹, approximately 28–36 % lower than single-wall paper cups and comparable to paperboard. During hot-fill tests, rice-based cups exhibited outer-surface temperatures about 2–3°C lower and retained liquid temperatures 3–9°C higher over 5–20 min relative to paper references. The results provide pre-LCA, use-relevant performance evidence for defining functional substitution scenarios and the system boundaries required for subsequent comparative life-cycle assessment. The findings indicate that waste-derived cooked rice can be processed into functional disposable cups with performance suitable for short-term hot-beverage service, supporting resource-recovery strategies within circular packaging systems.