[Standard Process] Export-Quality Sweet Potato Drying: Secrets to Retaining Color & Chewiness with Daxwell Heat-Pump Dryer

Elevating the "Food for Longevity" into a High-Value Export Product

Sweet potatoes, abundant in protein, starch, amino acids, and minerals, have long been praised as a "food for longevity." According to the Harvard T.H. Chan School of Public Health, sweet potatoes are an excellent source of Beta-carotene (a precursor to Vitamin A), which helps boost the immune system and eye health. However, selling fresh sweet potatoes often involves transportation difficulties, preservation challenges, and low economic value.

Deep processing into soft-dried or dried sweet potatoes is the only way to increase value and target export markets. But how do you dry them while maintaining their vibrant yellow/orange color, natural chewy sweetness, and precious nutritional content? The answer lies in applying the correct standard drying process with the Daxwell Heat-Pump Dryer technology.

1. Why Dry Sweet Potatoes with Heat-Pump Technology?

• Nutrient Preservation: Scientific studies in Food Research International have shown that high temperatures (above 70°C) rapidly destroy Vitamin C and antioxidants in sweet potatoes. Heat-Pump drying technology operates in a low-temperature range (30-60°C), helping to retain maximum nutritional value.
• Color & Texture Retention: Low-temperature drying helps keep the natural yellow/orange color by preventing carotene degradation. The dried product remains naturally chewy and sweet, without becoming dark, burnt, or hard like when dried with wood/coal kilns.

2. Crucial Pre-Processing Steps (Before Drying)

To achieve a beautiful final product, the preparation stage is decisive:

1. Wash & Parboil (Steam): Sweet potatoes need to be parboiled or steamed until just cooked (not mushy). This step gelatinizes the starch, creating the characteristic chewiness and preserving the beautiful color.
2. Cool & Slice: Let the potatoes cool completely before slicing. This ensures flat, smooth slices that don't crumble. Slice thickness must be uniform to ensure even drying times.
3. Traying: Arrange the slices evenly on the INOX trays of the Daxwell dryer, ensuring spacing for hot air to circulate over all surfaces.

3. Setting Up the 5-Stage Drying Process on the Daxwell Machine (The Core Secret)

This section demonstrates the power of the Smart PLC & HMI controller on the Daxwell dryer. Instead of setting a single fixed temperature, we program an automatic optimized 5-stage cycle:

• Stage 1 (Start-up - 1 to 2 hours): Raise temperature to 30°C, then gradually to 40°C. Purpose: Slow surface moisture removal to avoid "thermal shock" causing hard crusts.
• Stage 2 (Acceleration - 2 hours): Increase temperature to 55°C. This is the main moisture removal phase, increasing drying speed.
• Stage 3 (Deep Drying - 2 hours): Increase temperature to 65°C to draw moisture from deep within the potato slice core.
• Stage 4 (Finishing - 1 hour): Increase temperature to 70°C. This stage helps sterilize and bring humidity down to a safe preservation level.
• Stage 5 (Cooling): Turn off heat, let the machine run the fan to cool the product slowly before unloading.

Total time: Approximately 8 hours. Drying temperature is strictly controlled not to exceed 70°C to protect quality.

4. Infographic: Comparison of Drying Methods Efficiency

5. Advantages of the Daxwell Dryer in This Process

• Precise Control: The HMI touchscreen allows setting exactly every degree Celsius and minute for all 5 drying stages, ensuring absolute consistency between batches.
• Energy Savings: Heat-Pump technology significantly reduces electricity costs for the 8-hour drying process, optimizing profits.
• Even Airflow: DeAir's industrial fan system ensures temperature and airflow are distributed evenly to every tray, eliminating the need for manual tray rotation.

6. Frequently Asked Questions (FAQ)