Study on the Processing and Flavor Enhancement Technique of Edible Polygonatum cyrtonema Rhizomes

Objective  During the period of processing of Polygonatum cyrtonema Hua rhizomes, the addition of ginger and black bean juice enhances the flavor and quality of rhizomes, reducing the number of steaming and drying cycles and lowering overall costs.

Methods  A three-factor completely randomized block design experiment was conducted: different processing equipments (A), different concentrations of ginger and black bean juice (B), and different numbers of steaming (or drying/sun-drying) cycles (C). Factor A had two levels: A₁ (modern equipment) and A₂ (traditional equipment). Factor B had two concentration levels: B₁ (2.5%) and B₂ (5.0%). Factor C included seven levels: C₀ (control, 0 cycles) to C₆ (7 cycles). This experiment was designed with three groups: modern processing equipment, traditional processing equipment, and a control, each of which measured the content of seven functional components (extractives, polysaccharides, reducing sugars, total saponins, total phenolics, total flavonoids, and crude protein) in the rhizomes. Evaluations were based on rhizome quality value, product sensory attributes and taste.

Results  On the whole, rhizomes processed with modern equipment (A₁) exhibited higher quality than those processed with traditional equipment (A₂). Rhizomes treated with 5.0% ginger and black bean juice concentration (B₂) showed superior quality compared to those treated with 2.5% concentration (B₁). In the number of processing cycles, rhizome quality ranked in descending order: 6 cycles (C₆) > 5 cycles (C₅) > 4 cycles (C₄) > 3 cycles (C₃) > 2 cycles (C₂) > 1 cycle (C₁) > 0 cycles (C₀). The quality of rhizomes processed for 6 times was 2.34 times higher than that of unprocessed rhizomes (C₀). The quality of rhizomes processed by the four primary method combinations were as follows: A₁B₂C > A₂B₂C > A₂B₁C > A₁B₁C. Compared to the last, the quality of the first three methods increased by 14.84%, 5.06%, and 4.78%, respectively. A₁B₂C₆ was the optimal treatment among the 28 experimental combinations.

Conclusion The optimal processing for improving the flavor and quality of fresh P. cyrtonema rhizomes comprises three steps: peeling the fresh rhizomes, steaming and drying in modern equipment for six cycles, during which the rhizomes are immersed five times in the concentration of 5.0% ginger and black bean juice.