Implementation of statistical quality control (SQC) as a defective quality product control of Chinese tofu

Abstract

Tofu is a plant-based food product made in small industries, with a lack of quality control in the production process, so the amounts of the defective product are relatively high. This research aims to identify the causes of the defective product, analyze the application of Statistical Quality Control (SQC) methods, determine actions to minimize defective products, and how to improve product quality. The research method used is data collection followed by data processing using seven tools of SQC consist of check sheet, histogram, Pareto diagram, p - control chart, and fishbone chart. The results of Chinese tofu product quality obtained size, dirt, and crack defects with the numbers recorded on the check sheet sequentially are 33, 58, and 60 units. The percentage of Chinese tofu defects analyzed using the Pareto diagram was 39.74% for crack, 38.41% for dirt, and 21.85% for size defects. Factors that caused defects are shown in the fishbone chart: humans, machines, raw materials, environment, and methods. P – control chart indicates central line (CL) that is 0.260; upper control limit (UCL) is 0.554, and the lower control limit (LCL) is -0.334. Thus, this research can conclude that the production process of Chinese tofu is in control because no variation lies outside the control area. The main factor causing defects in Chinese tofu is the inaccuracy of workers. One of the steps to minimize defects is to implement a Standard Operating Procedure (SOP).