Frozen durian This is a process of rapidly cooling durian segments or whole fruit to below -18°C (-0.4°F) to completely inhibit the activity of microorganisms and enzymes, preserving the cellular structure and characteristic flavor for up to 24 months of storage. This is a mandatory process for all durian processing plants exporting to the Chinese, EU, and Korean markets.
This article presents a complete process for freezing durian according to industrial standards, including common freezing methods (IQF, blast freezers, contact freezers, liquid nitrogen), temperature and time parameters for each stage, and criteria for selecting equipment suitable for the factory's scale. Tan Long has over 20 years of experience designing and installing refrigeration systems for the tropical fruit processing industry, including numerous cold storage and IQF production line projects specifically for durian in the Mekong Delta region.
What is durian freezing?
Frozen durian This is a technique for ultra-fast freezing pre-processed durian products so that the temperature at the core of the durian segments reaches -18°C or lower in the shortest possible time. In food technology, the "speed" factor plays a decisive role in the quality of the product. If the freezing process is slow, the water inside the cells will crystallize into large ice crystals, breaking down the cell walls, leading to the durian segments becoming mushy and watery after thawing. Conversely, the rapid freezing process creates ultra-fine ice crystals, preserving the structure of the durian flesh, its natural color, and its characteristic flavor.
In the industrial refrigeration industry, this process is typically divided into two main operating modes:
- Batch freezing: Use the system air blast freezer or contact freezers. This method is suitable for processing facilities with a capacity of 1 ton to 20 tons of product per shift, ensuring flexibility in operation.
- Continuous freezing: Utilizing IQF (Individual Quick Freezing) conveyor technology, this is the optimal solution for export factories with a large capacity of 500 kg/hour or more, optimizing productivity and ensuring stringent quality standards. cold storage Frozen durian.
Why is freezing durian the best preservation solution currently available?
Naturally ripened durian can only maintain its best quality for about 2 to 4 days at room temperature (28 to 32 degrees Celsius). Even when stored in a cold environment at 4 degrees Celsius, the shelf life only lasts about 7 days. However, with the application of technology... frozen durian By adhering to technical standards of freezing at -18°C and storing in a cold storage system with high temperature stability, durian can maintain its commercial quality for up to 24 months. This process fully meets the stringent Codex Alimentarius CXS 52-1981 standard for quick-frozen foods globally.
Currently, no other preservation method can simultaneously meet the three core requirements of the export market: preserving the distinctive flavor, meeting international food safety standards, and allowing for long-haul sea transport. That is why this solution... frozen durian Modern IQF conveyor systems account for over 801 TP3T of Vietnam's total durian export value to China. To achieve this efficiency, investment in the production process is crucial. cold storage design Technical standards are a key factor in helping businesses optimize the agricultural value chain.
Standard industrial-grade durian freezing process
To achieve the best product quality for the export market, the standard process at processing plants is divided into five consecutive stages, requiring strict control over technical variables.
Phase 1: Harvesting and receiving raw materials
Durian used for processing must be fully physiologically ripe, with a Brix level of 28 to 35, and no ripening agents are used. Upon receipt, the factory checks the surface moisture of the peel, the color of the thorns, and the characteristic aroma. The temperature of the raw materials entering the factory must not exceed 35°C (95°F). This is an important note in the process. frozen durian If the fruit has naturally cracked open for more than 4 hours at room temperature, the oxidation level of the durian pulp will increase, affecting its color, and it should be discarded.
Phase 2: Separating and processing the segments.
Durian is separated into segments manually or semi-automatically. After separation, the durian flesh is sorted by color (cream yellow, dark yellow), weight (100–200 g/segment), and surface integrity. All food contact surfaces must be made of 304 stainless steel and disinfected with a chlorine-based disinfectant solution at a concentration of 50–100 ppm before each production shift. The temperature in the segment separation room is maintained between 15 and 18°C (59–64°F) to limit microbial growth during processing.
Phase 3: Preliminary Packaging
Depending on capacity and customer requirements, durian segments are arranged according to the appropriate refrigeration method:
- With the IQF conveyor system, durian segments are placed directly onto the mesh conveyor belt.
- With the method used contact freezer, The durian segments are arranged on flat metal trays to optimize heat transfer.
- With a blast freezer, products can be vacuum-packed before being frozen.
Stage 4: Rapid freezing
This is the crucial stage that determines the success of the process. frozen durian. The freezing chamber temperature is maintained between -35°C and -40°C (-31°F to -40°F). The time required for the core temperature of the product to reach -18°C (-0.4°F) depends on the method and batch size, typically ranging from 30 minutes (IQF) to 4 hours (large batch air-cooled freezer). Control standard: Randomly measure the core temperature of 5% products per batch; the result must reach -18°C (-0.4°F) before transferring to storage.
Phase 5: Storage and Shipping
The product after the cycle is complete. frozen durian The durian will be immediately transferred to cold storage at -18°C to -20°C (-0.4°F to -4°F). The storage temperature will not fluctuate by more than ±1°C throughout the storage period. Frozen durian stored at the correct temperature maintains its commercial quality for up to 24 months. During shipment, the cold chain remains uninterrupted from the warehouse to the refrigerated container to the receiving point.
Comparing methods for freezing durian
The factory selects the freezing method based on three factors: production capacity (kg/hour or tons/shift), required output product quality, and initial investment budget and operating costs. The table below compares the four most common methods currently used in durian processing factories.
| Method | Room temperature | Freezing Retention Time | Typical power | Key advantages | Suitable for scale |
|---|---|---|---|---|---|
| IQF conveyor | -35°C to -40°C | 20–40 minutes | 500 kg–5,000 kg/hour | The product is packaged in individual segments, with consistent and uniform quality. | Large factory, exporting |
| Air Blast Tunnel Freezers | -35°C to -40°C | 2–6 hours/batch | 500 kg–10 tons/batch | Lower investment costs compared to IQF, product flexibility. | Medium-sized factory |
| Contact freezer | -35°C to -40°C | 1–3 hours/batch | 100 kg–2 tons/batch | Fast speed, space-saving. | Small to medium scale |
| Liquid nitrogen (LN₂) | -80°C to -100°C | 5–15 minutes | 100 kg–500 kg/hour | Fastest freezing method, best preservation of cell structure. | High-end, high-value products |
Note: Liquid nitrogen technology uses N₂ in liquid form (-196°C / -321°F) as the working fluid. The actual temperature inside the freezing chamber is maintained between -80°C and -100°C (-112°F and -148°F), not -196°C. This is a common misconception in many technical documents.
Durian freezing equipment: How to choose the right one for your factory.
Equipment selection frozen durian This depends directly on the target production capacity, investment budget, and export market orientation of the enterprise. Below are the optimal technological solutions designed by Tan Long specifically for the durian industry:
- IQF conveyor This is the standard choice for large-scale export factories with a capacity of 500 kg/hour or more. The system mesh belt IQF freezer Tan Long's conveyor belt is suitable for durian segments because the mesh belt allows cold air to flow directly from below, ensuring uniform freezing speed across the entire surface of the product. The durian segments exit the conveyor belt completely separated, not sticking together, making it convenient for automatic quantitative packaging.
- Air Blast Tunnel Freezers Suitable for factories with a capacity of 2 to 10 tons/shift, or factories processing various products other than durian. Tan Long's blast freezer is designed in a modular format, allowing for capacity expansion when demand increases without replacing the entire system.
- Contact freezer Suitable for whole durian segments packed in flat trays. The contact freezer uses direct cold transfer through metal contact surfaces, resulting in faster freezing speeds than conventional blast freezers of the same capacity, and lower power consumption (approximately 20–30L/TP3T).
In addition to freezing equipment, the cold storage facility for post-freezing preservation needs to maintain a stable temperature of -18°C to -20°C, have an automatic defrosting system, and temperature control via a remote control. PLC control cabinet.
Properly frozen durian: Quality control criteria
Durian product after undergoing the process frozen durian A product is only considered to meet commercial quality standards when it fully satisfies the following five stringent criteria (verified after natural thawing at 4°C for approximately 8 hours):
- Color: Durian flesh must retain its characteristic creamy yellow to dark yellow color, and absolutely must not show any discoloration to gray or brown due to oxidation.
- The structure of durian rice: The durian segments should not be mushy. When checking by gently pressing with a finger, the surface should be elastic and not leave a deep indentation.
- Drip loss rate: Minimize liquid leakage after thawing. The standard drip loss rate must be below 5% by weight. This is the result of applying IQF conveyor belt technology for ultra-fast freezing, preventing the formation of large ice crystals.
- Flavor: It retains the intense, characteristic aroma equivalent to freshly peeled durian.
- Standard temperature: The core temperature of the product must be maintained at a stable level of -18°C throughout the storage period in the cold storage system.
In cases where the product is mushy, loses its aroma, or has a water loss rate exceeding 5%, refrigeration engineers need to re-check three core factors: the quality of the raw materials (overcooked), and the system capacity. frozen durian It's not fast enough, or the storage temperature in the cold storage fluctuates erratically. To completely resolve this, an upgrade is necessary. refrigeration compressor And the control system is the optimal solution for businesses.
Technical considerations when operating a durian freezing system.
Through the implementation of numerous real-world projects, Tan Long's engineering team has identified key technical aspects that directly impact system performance. frozen durian as follows:
- Control the phenomenon of condensation on the evaporator coil: Durian is characterized by its high fat content (approximately 5g per 100g of flesh) and very high moisture content. These two biological characteristics affect the digestive system. industrial refrigeration The processing unit is more prone to frost buildup compared to conventional seafood or vegetable processing. To maintain efficient heat exchange, businesses need to set up automatic defrost cycles 2 to 3 times per shift and perform a check of the cooling unit's condition at the end of each shift.
- Odor management and storage area planning: To prevent the distinctive smell of durian from spreading to other food products, the best solution is to designate a designated area. frozen durian and a completely independent cold storage system. In the case of using a shared warehouse, products must be absolutely hermetically sealed using vacuum packaging technology before being stored.
- Refrigeration compressor redundancy standard (N+1): Refrigeration compressor system serving the process frozen durian The system needs to be designed according to the N+1 redundancy standard. This means that if one compressor fails unexpectedly, the remaining compressors will still be able to maintain a safe temperature until the problem is resolved. This is a minimum technical requirement for export processing plants, because even a single refrigeration interruption lasting more than 4 hours can alter the quality and damage the entire high-value shipment in storage.
Durian freezing system solutions from Tan Long
Tan Long proudly stands as a pioneering provider of solutions. frozen durian We offer a complete package, from site survey and capacity consultation to cold storage design and full installation. With a team of engineers possessing over 20 years of practical experience in the industrial refrigeration industry, we have successfully implemented numerous processing systems for fruit, seafood, and frozen food factories nationwide.
Each project frozen durian At Tan Long, equipment is personalized based on the specific needs of each business: from production capacity in tons per day and floor space characteristics to target export standards. Based on these variables, Tan Long will propose the most optimal equipment solution: from high-tech IQF conveyor systems for large factories to standard blast freezers and cold storage facilities for medium and small-scale establishments.
Hopefully, this detailed information about the process and equipment will be helpful. frozen durian The above information will help customers gain a clearer understanding to optimize their agricultural product value chain. If you are looking for a reputable company to design and install a professional freezing system, please contact Tan Long immediately for technical advice and detailed pricing.
Contact information:
- Headquarters: 86 Dong Den Street, Ward 14, Tan Binh District, Ho Chi Minh City, Vietnam.
- Working hours: Monday to Saturday (8:00 AM to 5:30 PM).
- Consulting hotline: (+84) 933357058 – Mr. Thinh
- E-mail: info@tanlongvn.com.
Frequently Asked Questions about Freezing Durian
Why does durian need to be frozen?
Because durian ripens very quickly and can only be consumed within a short time after being separated, freezing allows for longer preservation, export to distant markets, and year-round sales instead of just during the season.
What methods are used to freeze durian?
Rapid freezing is a mandatory requirement to maintain the segment structure. Depending on the scale and type of product—loose segments, whole fruit, or tray packaging—choose a blast freezer, IQF conveyor freezer, or contact freezer.
Why is it necessary to freeze durian quickly?
Because slow freezing creates large ice crystals that break down the segment structure, the product becomes mushy, watery, and loses its characteristic texture after thawing—something that export markets do not accept.
What requirements must frozen durian for export meet?
Meeting the food safety and quarantine requirements of the importing country, an uninterrupted cold chain from the factory to the destination market, with records documenting temperature and traceability.
What refrigeration equipment is needed for a durian processing facility?
The pre-processing area has temperature control, a rapid freezing system, a cold storage facility for finished products, and a central refrigeration system that provides cooling for the entire production line.
Does Tan Long have a freezing system for durian?
Yes. Tan Long designs and constructs freezing systems and cold storage facilities for agricultural product processing plants exporting their products, selecting configurations based on product type and actual production capacity.
Related pages
- What is flake ice? Applications of flake ice in real life
- What is IQF? How to use and maintain the IQF system
- What is freezing? Advantages and classifications of freezing machines.
- What is soft freezing technology? Benefits and process | Tan Long
- IQF freezer conveyor
Engineer Nguyen Toan Thinh (Technical Director)
With over 18 years of practical experience in directing, consulting, designing, and constructing heavy industrial refrigeration systems, ASRS automated warehouses, and IQF freezing systems across more than 29 major national projects.
