Robotic-automated vs. manual deep-frying of laver snack (Kimbugak): quality and uniformity comparison

This study compared robotic-automated and manual deep-frying of laver snack (Kimbugak) at 175 °C over short times (2–23 s) using an integrated robotic system (sorting, gripping, frying, cooling) to ensure consistent motion. Under the tested conditions, 8 s was optimal for both robotic and manual frying, achieving sufficient expansion while avoiding excessive browning, deformation, and texture deterioration; beyond 8 s, quality metrics showed no further improvement. Visual and color development exhibited a rapid early phase followed by a plateau: the white pixel ratio and L* indices, which indicate the degree of frying of the glutinous rice batter, increased to 74.67 and 48.18 in manually fried samples and to 48.18 and 46.40 in robot-fried samples by 8 s, with no significant changes afterward. Physical properties differed between methods: manual frying caused greater structural shrinkage, edge curling, and a larger increase in height, while robotic frying maintained a more uniform shape. Over time, width and length decreased while height increased; average height was 1.50 for robotic frying compared to 2.03 for manual frying. In the 8–20 s range, robotic samples showed higher average texture metrics (hardness 76.39 N vs 15.46 N; stiffness 20.61 N vs 8.43 N; crispness 3.82 vs 1.18), and acoustic analysis revealed more fracture events but lower maximum amplitudes at several time points. Chemical indices stayed within regulatory limits: the acid value averaged 0.41 ± 0.12 mg KOH/g, with no effects from time or method. The peroxide value decreased after frying and changed little afterward. Antioxidant activities increased slightly over time, with no differences between methods. At 8 s, coefficient-of-variation analysis showed lower variability in 15 out of 25 attributes for robotic frying—especially in color—indicating more uniform heat and mass transfer. Overall, robotic-automated deep-frying consistently produced Kimbugak of high quality while clarifying the relationships between process, structure, and quality, supporting a quality-focused approach toward autonomous food production.