Precautions for vacuum freeze-drying of larvae (yellow mealworms/black soldier flies, etc.)
1、 Pre processing: 70% determines success or failure
1. Live purification (emptying the intestines)
After harvesting, fast for 24-48 hours and only give water or wet wheat bran to allow the larvae to empty their intestinal contents
Purpose: To reduce the decay, odor, and bacteria caused by residual internal organs; The finished product has a purer taste
Caution: Directly freeze-drying with feces may result in a noticeable fishy odor in the finished product
2. Cleaning and disinfection
Rinse with warm water (25-30 ℃) 2-3 times to remove surface impurities
Soak in 0.5% -1% sodium hypochlorite or ozone water for a short period of time (3-5 minutes), then rinse thoroughly as residual chlorine can affect flavor and color
3. Killing (key, easily overlooked)
It must be killed before freeze-drying, otherwise the larvae will be stressed and emptied during the freeze-drying process, and even self dissolve after death
Method: Blanch in boiling water for 10-30 seconds (depending on specifications), or steam kill for 30 seconds
Standard: Body color turns white/slightly yellow, body straightened, no longer wriggling
Avoid: Blanching for too long, excessive denaturation of proteins, hardening of finished products, and poor rehydration
4. Degreasing (depending on the purpose)
The fat content of yellow mealworms can reach up to 30% -50%, and direct freeze-drying is highly prone to oxidation and rancidity
If making protein powder or storing products for a long time, it is recommended to first degrease (n-hexane or supercritical CO ₂)
If making a whole snack (pet food), fat can be retained, but antioxidants (vitamin E, rosemary extract) must be added and the packaging must be strictly protected from light
2、 Freeze drying process parameters
Stage parameters
Stage parameters
Pre freeze below -40 ℃, quick freeze until the center temperature is ≤ -40 ℃, and maintain for 2-4 hours
One drying (sublimation) plate temperature -20~-10 ℃, vacuum degree 10-30 Pa, time 20-30 hours
Secondary drying (analysis) plate temperature 30-40 ℃, vacuum degree<10 Pa, time 4-8 hours
Discharge moisture content ≤ 5% (recommended 3% -4%)
Key Reminder:
Pre freezing must be thorough. Vacuuming before the center temperature drops below the eutectic point can cause "eruption" (liquid boiling), resulting in collapse and deformation of the finished product
The board temperature should not be too high. The surface of larvae is thin, and if the temperature rises too quickly, they will "crust" and the internal water cannot be released, forming a false dry product with "dry outside and wet inside"
Loading capacity: single-layer flat, do not stack, material layer thickness ≤ 2cm
3、 Post processing and packaging
1. Packaging upon release from warehouse
Freeze dried products absorb moisture very quickly, and will regain moisture and clump after being exposed to air for more than 30 minutes
Suggest directly packaging in a dry room (relative humidity<30%)
2. Packaging requirements (for high fat)
Must avoid light: Aluminum foil composite bag, avoid transparent packaging
Must be isolated from oxygen: evacuate or fill with nitrogen, add deoxidizer
Suggest small packaging (10-50g) and use up as soon as possible after opening
3. Storage
Temperature ≤ 20 ℃, avoid light, relative humidity<60%
The shelf life can reach 12-24 months; If not degreased and packaged improperly, a halal smell will appear after 3-6 months
4、 Frequently Asked Questions Quick Search
Reasons for the problem and countermeasures
Reasons for the problem and countermeasures
Finished product collapse, incomplete pre freezing due to deformation, prolonged pre freezing due to high board temperature, and reduced board temperature
Excessive heating of external dryness and internal wetness, step heating of crust, and prolonged drying for one time
There is a fishy odor that has not been emptied from the intestines and has not been killed. Strengthen purification and sterilization processes
Hala flavor (rancid), fat oxidation, degreasing or adding antioxidants+light and oxygen blocking
Add citric acid for color protection during blackening, oxidation, browning, and sterilization to shorten exposure time

E-mail:

sales@syguanfeng.com

Tel: 
+86 15088506234
 

Address: 

South Industrial Park of Dongguan, Shangyu District, Shaoxing City,Zhejiang Province,China.