Quality-aware robotic frying of fragile sheet intermediates using a dual-slot gripper

This study investigates the development and validation of a robotic dual-slot frying gripper designed for fragile sheet-based intermediates, exemplified by laver bugak. Conventional frying processes often rely on artisanal dexterity, leading to inconsistent outcomes, whereas the proposed system represents a quality-oriented robotic strategy that integrates food engineering principles with robotic compliance, perception, and control. As a result of the proposed gripper design, the system incorporated a dual-layer mesh structure, compliant hinges, silicone padding, and hook-shaped retainers, all synchronized with robotic trajectory planning to minimize adhesion, fracture, and deformation during frying. Direct comparative trials confirmed that this design markedly reduced adhesion (42%→7%), fracture (28%→2%), and slippage (9%→0%) relative to manual frying. Furthermore, experimental results demonstrated that the optimal frying time differed depending on operation mode-8 s for single mode and 11 s for dual mode-conditions that maximized puffing and brightness while avoiding overprocessing. These optimal times were identified through a comprehensive evaluation of post-frying quality attributes, including optical, moisture-related, dimensional, mechanical-acoustic, and chemical indices. Analysis of physicochemical quality metrics further revealed that the dual mode exhibited greater structural consistency and higher quality uniformity compared to the single mode, while most other quality traits showed no significant differences between modes. Importantly, dual mode maintained comparable quality to single mode even when frying time was extended to 11 s, indicating that both product quality and productivity can be secured simultaneously. Beyond these quality outcomes, a key performance indicator (KPI) framework demonstrated that dual-slot operation achieved approximately 3.15 times higher throughput than single-slot operation, while preserving sensory and physicochemical properties. These results confirm a robust linkage between gripper design, post-frying quality uniformity, and production efficiency. In conclusion, this work goes beyond automation aimed solely at productivity, showing that a robotic design centered on quality uniformity can serve as a foundation for autonomous food manufacturing systems that jointly optimize both quality and efficiency. The proposed framework provides a transferable methodological basis for extending robotic frying technologies to a wider range of fragile, semi-finished food products.