Raw Material Inspection → Thawing & Cleaning → Trimming & Cutting → Blanching & Color Protection → Dewatering & Draining → Pre-dusting → Low-temperature Batter Mixing → Automatic Batter Coating → Two-stage Continuous Frying → Vibrating Oil Draining → Air Cooling → Quick Freezing → Metal Detection → Weighing & Packaging → Low-temperature Cold Storage
1. Raw Material Inspection & Thawing
Raw materials include white shrimp, fish fillet, pumpkin, eggplant, shiitake mushroom, green beans and other vegetables & seafood. Adopt slow thawing at 0～4°C, avoid normal temperature thawing to keep moisture and complete shape. Reject damaged, blackened and deteriorated raw materials by visual sorting.
2. Pretreatment & Trimming
For shrimp: Remove head and shell, keep tail → cut back and remove shrimp line → make shallow cuts on abdomen to prevent curling → shape and straighten. For vegetables: Cleaning & peeling → slice or cut into strips with thickness 3～5mm. Drain water by vibrating conveyor, ensure no obvious surface moisture.
3. Vegetable Blanching & Color Protection
Blanch in hot water at 90～95°C for 10～30 seconds. Immediately cool down in ice water for color protection, bacteriostasis and fiber softening. Centrifugal dewatering to control surface moisture, prevent batter falling off and excessive oil absorption.
4. Pre-dusting
Formula: Low-gluten flour + corn starch + leavening agent in proper proportion. Adopt drum flour coating machine. Function: Improve batter adhesion, prevent batter peeling during frying with thin dust coating only.
5. Industrial Tempura Batter Mixing
Main ingredients: Low-gluten flour, tapioca starch, leavening agent, salt, sugar and ice water. Key process points:
- Mix with ice water under low temperature ≤10°C in whole process.
- Stir at low speed for short time, keep small flour lumps without over-stirring, ensure crispy and fluffy crust after frying.
- Keep batter at constant temperature, replenish in time to avoid gluten formation and fermentation.
6. Automatic Batter Coating
Adopt immersion batter coating machine; raw materials pass through batter tank at constant speed. Vibrating sieve removes redundant batter after discharging to ensure uniform coating thickness.
7. Two-stage Continuous Frying (Core Process)
First Stage: Shape Setting
Oil temperature: 130～150°C Time: 60～90 seconds Function: Rapid batter shaping, no collapse and less oil soaking.
Second Stage: Cooking & Crisping
Oil temperature: 170～185°C Time: 40～60 seconds Function: Golden color and crispy crust; core temperature reach above 75°C for sterilization and full cooking. Equipment: Full automatic mesh belt continuous frying machine with constant temperature control and automatic oil filtering.
8. Oil Draining & Cooling
Remove surface excess oil via vibrating mesh belt after frying. Forced air cooling to normal temperature to avoid crust softening and sticking caused by residual heat.
9. Quick Freezing
Tunnel freezer at -35～-40°C. Freezing time: 25～40 minutes. Require product core temperature drop below -18°C to lock crisp taste and prevent water regaining & deterioration.
10. Detection, Packaging & Warehousing
Pass metal detector for foreign object inspection. Automatic weighing, bag/box sealing. Finished products stored in constant temperature cold storage at -18°C away from light.
Key Control Points
- Strict low temperature control for raw materials, batter and production environment to control bacteria.
- Raw materials must be fully drained; excessive moisture causes batter peeling and high oil absorption.
- Avoid over-stirring batter to prevent gluten and hard crust.
- Two-stage frying is essential for keeping long-term crispness of industrial tempura.
- Fast quick freezing is required to lock flavor and crispness for shelf life.