Quick Freezing Technology Guide | IQF, CAS & Liquid Freezing: Principles and Quality Control

"Frozen, yet tasting freshly made"—quick freezing technology dramatically improves post-thaw quality by freezing food without destroying cell structures. It is the single most important technology determining the quality of frozen food OEM products.

Quick freezing is a technology that rapidly lowers food temperature below freezing point in a short time. It is the most fundamental and critical process affecting frozen food quality. The cause of quality degradation when freezing food is the speed at which it passes through the maximum ice crystal formation zone—the temperature range of -1 to -5°C. In this zone, water in the food transforms into ice crystals; if passage through this zone takes too long, large ice crystals grow and physically destroy cell walls and tissue structures.

With slow freezing (natural convection freezing in a household-type freezer at about -18°C), passing through the maximum ice crystal formation zone can take several hours to half a day or more. During this time, ice crystals grow to diameters of 50–100 μm or larger, puncturing and rupturing cell membranes. As a result, cellular fluid (drip) is released in large quantities upon thawing, significantly degrading food texture, flavor, and nutritional value. Drip loss of 5–10% in meat products is not uncommon.

Quick freezing, on the other hand, targets passing through the maximum ice crystal formation zone in 30 minutes or less. The ice crystals formed by rapid freezing are extremely fine—only a few μm to 10 μm in diameter—causing virtually no damage to cell structures. Post-thaw drip is reduced to 1/5 to 1/10 of slow-frozen levels, maintaining quality close to fresh product.

Definition and Standards for Freezing Rate

Freezing rate is generally evaluated as "the time required for the thermal center (the slowest-cooling point) of the food to drop from 0°C to -5°C." The International Institute of Refrigeration (IIR) also uses freezing front velocity (cm/hour)—the distance from the food surface to the thermal center divided by the time required for freezing. The benchmark for quick freezing is a freezing front velocity of 5–20 cm/hour, which is dozens of times faster than slow freezing (0.1–0.5 cm/hour).

Japan's Frozen Food Market and Technology Trends

According to the Japan Frozen Food Association, Japan's frozen food production volume reached approximately 1.6 million tons annually (2024), with a market size exceeding ¥1 trillion (approximately $6.6 billion USD). Market expansion is driven by growing at-home eating demand following the pandemic, increasing dual-income households, and quality improvements from advanced freezing technology. In particular, there is growing interest in professional frozen (professional-grade high-quality frozen foods), with an increase in high-value-added products utilizing CAS freezing and liquid nitrogen freezing. In frozen food OEM as well, product development that uses quick freezing technology as a differentiator—rather than merely for cost reduction—is becoming the mainstream approach.

Quick freezing encompasses multiple methods, and the optimal method is selected based on the food's shape, size, physical properties, production volume, and target quality. Below is a detailed explanation of each method's principles, characteristics, and applicable foods.

(a) Air Blast Freezing

This method blows cold air at -30 to -40°C directly onto food at wind speeds of 3–8 m/s. It is the most widely used method in the frozen food industry. Available in batch (tunnel or rack type) and continuous (belt conveyor) configurations—batch for small to medium lots, continuous for mass production. Equipment cost is relatively low with high versatility, but ensuring uniform wind speed and refrigerant temperature distribution is a challenge. Surface dehydration (freezer burn) is prone to occur, so packaging before freezing or glazing treatment is recommended. Freezing time depends on food thickness but is approximately 30–60 minutes for a hamburger patty (15 mm thick).

(b) IQF (Individual Quick Freezing)

IQF is a technology that freezes food items one piece at a time individually. It is essential for frozen vegetables, frozen fruits, peeled shrimp, frozen rice (free-flowing grains), and other foods that need to be individually removable. Representative equipment includes fluidized bed and belt-type systems. Fluidized bed systems blow cold air upward to suspend and agitate food while freezing—ideal for small items like green peas and corn. Belt-type systems move food on a vibrating conveyor while applying cold air from above and below—suitable for slightly larger items like shrimp and cut fruit. IQF's key feature is preventing clumping (adhesion between items), allowing consumers to remove only the amount they need.

(c) Contact Freezing (Plate Freezer)

This method sandwiches food between metal plates cooled to -35 to -40°C, using contact heat transfer to freeze. It is especially effective for flat foods (fish fillets, hamburger patties, sliced meats, gyoza trays) and freezes 2–3 times faster than air blast methods. Freezing efficiency depends on plate-to-product contact, so uniform product thickness is a prerequisite. In the seafood processing industry, this method is widely used for onboard freezing of fish, establishing it as a technology for preserving freshness immediately after catch.

(d) Liquid Nitrogen (LN₂) / CO₂ Freezing (Cryogenic Freezing)

This ultra-rapid freezing method sprays liquid nitrogen (boiling point -196°C) or liquefied carbon dioxide (-78°C) directly onto food. Freezing speed is extremely fast, passing through the maximum ice crystal formation zone in just a few minutes. Because ice crystals are ultra-fine, quality preservation is at the highest level. However, the running cost of liquid nitrogen is ¥50–150/kg (approximately $0.33–1.00 USD/kg), making it primarily used for high-value foods (sashimi-grade fish, foie gras, premium fruits) and new product prototyping/small-lot production. The equipment itself is compact with low initial investment, making it suitable for startups and test production.

(e) CAS Freezing (Cells Alive System)

CAS freezing is a technology developed in Japan that aims to achieve uniform and instantaneous freezing of the entire food item by applying weak magnetic fields or electromagnetic waves during rapid freezing to promote supercooling of water molecules. The developer, ABI Corporation, claims it can "freeze cells while keeping them alive," with application examples reported for sushi-grade fish, fruits, and wagashi (Japanese confections). While academic verification continues to be debated, commercially, more than 100 units are in operation in Japan, primarily among seafood processors and Japanese restaurant chains, earning market recognition for superior post-thaw quality. CAS equipment prices range from ¥5–30 million (approximately $33,000–200,000 USD), including add-on CAS units that can be retrofitted to existing air blast freezers.

Frozen food OEM requires an integrated quality management system from raw material receiving to shipping, not just the freezing process alone. Cold chain (low-temperature distribution system) maintenance and microbial control form the foundation of quality.

Product Temperature Monitoring and Freezing Curve Recording

The foundation of freezing process quality assurance is continuous monitoring of the food's core temperature (center temperature). By recording the freezing curve (time-temperature curve), you can objectively evaluate passage time through the maximum ice crystal formation zone, final temperature reached, and freezing uniformity. Core temperature is measured using T-type thermocouples or data logger-equipped temperature sensors inserted into the food. The final product temperature of -18°C or below is the international standard (Codex Alimentarius), and Japan's frozen food labeling standards also mandate "store at -18°C or below." Quick freezing completion is determined when the core temperature reaches -18°C or below.

Cold Chain Maintenance and Temperature Excursion Management

Frozen food quality is said to be "determined by the moment the temperature was highest." Maintaining an unbroken cold chain at -18°C or below at every stage from production to consumer is essential. Within OEM factories, freezer temperatures are automatically recorded 24 hours a day, with alert systems and corrective procedures pre-established for temperature excursions (e.g., rises above -15°C). TTI (Time-Temperature Indicator) labels are also increasingly applied to packaging to make temperature management during distribution visible. Freeze-thaw-refreeze cycles cause ice crystal regrowth and severely degrade quality, so management rules must strictly prohibit this.

Microbiological Control Standards

At -18°C or below, microbial growth in frozen food is halted but microorganisms are not killed. The pre-freezing contamination level is preserved as-is during frozen storage, making pre-freezing hygiene management critically important. The Japan Frozen Food Association's voluntary standards set general viable counts at 3,000,000/g or below and coliform group as negative for frozen foods to be consumed after heating; frozen foods for unheated consumption (frozen fruits, etc.) have stricter standards (general viable counts 100,000/g or below). OEM manufacturing requires a systematic HACCP-based management framework covering raw material incoming inspection, microbiological testing at CCPs (Critical Control Points) during processing, and final product sampling inspection.

Glazing Treatment and Oxidation Prevention

For frozen seafood products, glazing—coating a thin ice film (glaze) on the surface of frozen food—is widely practiced. The glaze blocks air from the food surface, preventing dehydration (sublimation) and oxidation during frozen storage. Glaze amount is typically 5–15% of product weight; excessive glazing raises issues with net weight labeling and requires proper control. For high-fat foods (mackerel, saury, pork belly), lipid oxidation progresses even during frozen storage, so vacuum packaging, high gas-barrier packaging materials, and antioxidants (vitamin E, rosemary extract, etc.) are effective for quality preservation.

Frozen food packaging is a technically demanding field requiring both physical durability under low-temperature conditions and barrier performance. Improper packaging material selection directly leads to quality problems such as freezer burn, odor migration, and package breakage.

Basic Performance Requirements for Packaging Materials

Frozen food packaging materials must simultaneously meet the following requirements: (1) Low-temperature resistance: Must remain flexible and not become brittle (brittle fracture) at -30°C or below. Polyethylene (PE) and nylon (ON) have excellent low-temperature resistance, but some polypropylene (PP) grades become brittle below -20°C, requiring caution. (2) Gas barrier properties: Ability to block oxygen transmission, suppressing lipid oxidation and freezer burn. EVOH layers or aluminum-deposited film are effective. (3) Moisture vapor barrier properties: Ability to prevent sublimation (moisture evaporation) from the food surface. (4) Seal strength: Heat seal portions must not delaminate at -18°C or below. LLDPE (linear low-density polyethylene) is widely used for sealant layers.

Vacuum Packaging and MAP (Modified Atmosphere Packaging)

Packaging methods for frozen food are selected based on product characteristics and shelf life requirements. Vacuum packaging closely conforms packaging to food and removes air, providing excellent oxidation prevention—suitable for long-term frozen storage (12–24 months) of meats and seafood. However, it is unsuitable for shape-sensitive foods (bread, cakes, fried foods). MAP (Modified Atmosphere Packaging) replaces the atmosphere inside the package with nitrogen or CO₂, suppressing oxidation while preserving food shape. It is used for frozen pizza, frozen bread, frozen bento, and other products where appearance matters. Target residual oxygen concentration is 1% or below, monitored inline with gas-flush filling machines and oxygen meters.

Representative Packaging Formats

• Pillow Packaging (Pillow Bag): The most versatile packaging format, used for a wide range of frozen foods including frozen gyoza, frozen udon, and frozen vegetables. High-speed filling capable at low cost. Standard film construction is ON/PE (nylon/polyethylene) two-layer; when oxygen barrier is needed, ON/EVOH/PE three-layer construction is adopted.
• Stand-Up Pouch: A self-standing pouch suited for products where retail display impact in frozen aisles matters, such as frozen fruits and frozen smoothie mixes. Adding a zipper provides reclosability, improving consumer convenience.
• Tray + Film Lid: Used for frozen bento, frozen gratin, frozen pizza, and other products heated directly in the microwave. Tray materials are typically PP (heat-resistant) or PET/CPET, requiring both microwave compatibility and freeze resistance. A steam vent hole in the film lid prevents bursting from internal pressure buildup during heating.
• Paper Box + Inner Bag: Used for frozen food gift products and premium lines. The outer box's printing conveys premium quality while the inner bag (aluminum-deposited film, etc.) provides barrier properties.

Labeling Legal Requirements

Under Japan's Food Labeling Act (Shokuhin Hyoji Ho), frozen food unified labeling must include "Storage method: Store at -18°C or below". Additionally, frozen foods requiring cooking must indicate "whether heated before freezing" and "necessity of heat cooking." For frozen food OEM, the labeling method for the client's (labeling responsible party's) name and address should also be confirmed in advance.

When selecting a frozen food OEM partner in Japan, the key to success is a comprehensive evaluation of the types and capacity of freezing equipment, cold chain infrastructure, and quality management standards. Below are the major considerations and cost estimates.

Freezing Equipment Checklist

• Freezing method and number of units: Whether they have air blast, IQF, contact, CAS, or other systems. Top priority is confirming that the method suited to your product is available.
• Daily processing capacity: Processing volume per day (tons/day). Small-scale OEMs handle 1–5 tons/day; medium to large handle 10–50 tons/day. Seasonal fluctuation and peak-period capacity headroom are also important.
• Cold storage capacity: Number of pallets and storage volume in -25°C or below cold storage. Whether the manufacturer can hold product inventory for a certain period significantly impacts logistics costs.
• Frozen logistics partners: Shipping infrastructure with refrigerated trucks and containers. Confirm whether nationwide delivery is possible and the status of logistics partner relationships.

Cost Estimates

The frozen food OEM cost structure breaks down into raw material costs, pre-processing costs, freezing costs, packaging costs, and storage costs. Freezing costs vary significantly by method:

• Air blast freezing: Processing fee ¥30–60/kg (approx. $0.20–0.40 USD/kg). Most economical, suited for mass processing.
• IQF freezing: Processing fee ¥50–100/kg (approx. $0.33–0.65 USD/kg). Requires more labor for individual freezing but yields higher-value products.
• Contact freezing: Processing fee ¥40–70/kg (approx. $0.26–0.46 USD/kg). Limited to flat products but enables high-speed freezing.
• Liquid nitrogen/CO₂ freezing: Processing fee ¥80–200/kg (approx. $0.53–1.30 USD/kg). High liquid nitrogen consumption cost limits this to premium products.
• CAS freezing: Processing fee ¥100–250/kg (approx. $0.65–1.65 USD/kg). Equipment lease and maintenance fees add to running costs.

Frozen storage fees are approximately ¥5,000–15,000/pallet/month (approx. $33–100 USD/pallet/month) for -25°C cold storage. Longer storage periods significantly impact total costs, making optimization of shipping cycles and storage volumes important.

Equipment Investment Reference

If investing in IQF equipment yourself, belt-type IQF freezers cost ¥30–100 million+ (approx. $200,000–660,000+ USD) and CAS freezing units cost ¥5–30 million (approx. $33,000–200,000 USD). The biggest advantage of choosing OEM outsourcing is avoiding these large capital investments.

Minimum Lots and Prototyping

Minimum lots for frozen food OEM are generally 300–1,000 kg. IQF products start from approximately 500 kg, while contact and air blast freezing can accommodate 300 kg or more with some manufacturers. Before full production, always conduct trial freezing to verify the freezing curve, measure post-thaw drip rate (target: 2% of weight or below), and perform sensory evaluation (texture, flavor, appearance). Trial freezing typically costs ¥50,000–200,000 (approx. $330–1,300 USD). Based on initial trial results, fine-tune freezing conditions, and confirm quality standards are met before transitioning to production—this is the foundation of quality assurance.

Quick freezing is the single most important technology determining frozen food quality. Here are the key decision points for OEM utilization.

When Quick Freezing Is a Good Fit

• Developing high-quality frozen foods
• Commercializing frozen prepared meals and bento
• Preserving freshness of seafood and meat products
• Launching frozen food for e-commerce

Key Points to Confirm with Your OEM Partner

• Freezing methods available (air blast, IQF, liquid freezing, etc.)
• Whether post-freezing quality evaluation (drip rate measurement) is conducted
• Cold storage warehouse capacity
• Frozen logistics (cold chain) arrangements
• Minimum lot sizes and processing fees by method

On our platform, you can search and compare OEM manufacturers in Japan that offer quick freezing capabilities. Start by finding manufacturers that can handle your needs and identify the right partner for your product concept.