This study developed a Ganoderma lucidum soybean fermentation liquor-based lactic acid beverage, and used Six Sigma to improve Ganoderma lucidum soybean fermentation. It also applied the Analytic Hierarchy Process (AHP) integrated with Data Envelopment Analysis (DEA) to determine important factors (including inoculum size, dissolved oxygen, temperature) having major influence on process parameters. The obtained parameter range was used as reference for control factor levels for the Taguchi method. The Taguchi method was used to analyze the contribution degrees of various control parameters of the process, and the optimal control parameter combination with the most polysaccharide target values was obtained. The results of which are inoculum size 7%, dissolved oxygen 70%, and temperature 31 °C. With the same fixed factors, the Ganoderma lucidum polysaccharide output is 2.59–4.56 g/kg before the process improvement, and the output is 4.58–4.93 g/kg after improvement. This study took Ganoderma lucidum polysaccharide as an example for isoflavone and SOD (superoxide dismutase) as quality characteristics for multi-quality process capability analysis. The process capabilities of individual quality characteristics were identified upon experimentation, two quality characteristics are C pk = 1.53, meaning that the process capability of these two quality characteristics is sufficient to achieve the 6-sigma level.
