Post-roast Moisture Process Improvement of Fish Sheet Production Process

Abstract

The primary concern of this thesis is moisture control of fish sheets produced in a Thai factory. The moisture control of fish sheets is important because these fish sheets are primary work-in-process products used in the factory, and the sheets’ post-roasting moisture is a key quality metric for fish sheets. The factory initially used ad-hoc subjective procedures to control moisture level. However, it is found that variation of fish sheets’ moisture at all stages of production remains high, making it a subject of process improvement in this thesis. The Cpk index of post-air-drying and post-roasting fish sheets, measured at the start of the project, are 0.19 and 0.04 respectively. This report will present and evaluate two process improvement methods implemented in the factory. The first method modifies ingredient mixing procedures such that the quantity of water in ingredient mixture are adjusted based on measured moistures of frozen minced fish which is the primary non-water ingredient in the mixture. To avoid subjective adjustment of control parameter values, the second improvement finds an optimised set of values for post-mixing processes’ parameters, using response surface generated with regression analysis on data collected in a design of experiments. After improvement, the post-air-drying Cpk index and the post-roasting Cpk index were improved to 0.75 and 0.46 respectively.