Effect of DC motor rpm variation on working capacity and thickness uniformily of local Lampung plantain (Musa sp.) fruit leather

Pengaruh variasi rpm motor DC terhadap kapasitas kerja dan keseragaman ketebalan fruit leather pisang jantan (Musa sp.) lokal Lampung

Abstract

ABSTRACT

A DC motor-driven fruit leather spreading machine was designed and fabricated to support small-scale processed banana production. Rotational speed (RPM) is a critical operating parameter that directly influences the spreading rate and thickness uniformity of fruit puree; however, its effect has not been systematically investigated. This study aimed to evaluate the effect of DC motor rotational speed on thickness precision, machine working capacity, and the physical quality of fruit leather produced from local Lampung plantain (Musa sp.). The experiment employed a Completely Randomized Design (CRD) with a single factor consisting of three rotational speeds: 8, 10, and 12 RPM, each replicated three times using 200 g of banana puree per replication. The results showed that rotational speed had no significant effect on fruit leather thickness (F = 1.25; p = 0.35) or thickness coefficient of variation (CV) (F = 0.001; p = 0.999). All machine treatments produced lower thickness variation (CV = 11.59–11.88%) than the manual spreading method (CV = 17.12%), indicating that mechanization consistently improved product uniformity. In contrast, rotational speed had a highly significant effect on machine working capacity (F = 38.27; p = 0.0004). The working capacities at 8 RPM (2.956 cm² s⁻¹) and 10 RPM (2.176 cm² s⁻¹) were 49.7% and 10.2% higher, respectively, than that of the manual method (1.974 cm² s⁻¹), whereas the capacity at 12 RPM (1.742 cm² s⁻¹) was lower than the manual method. All treatments differed significantly according to the Least Significant Difference (LSD) test at the 5% significance level (LSD = 0.344 cm² s⁻¹). The best physical quality was obtained at 8 and 10 RPM, where no air bubbles were observed, while the 12 RPM treatment produced air bubbles in all replications. Considering the balance between thickness uniformity, working capacity, and physical quality, a rotational speed of 10 RPM is recommended as the optimum operating parameter for small and medium-scale fruit leather production.