Food-Grade Baking aluminum Foil for Cooking

In the application scenarios of baking appliances such as air fryers and ovens, द “material adaptability” आणि “process standardization” of food-grade baking foil directly determine its safety, टिकाऊपणा, आणि कामगिरी. Unlike ordinary kitchen aluminum foil, this specialized foil requires precise alloy composition design and strict production process control to meet core demands such as high-temperature resistance, repeated folding, and food contact. This article systematically breaks down its professional technical key points from four dimensions: material selection, full-process production technology, surface treatment technology, and compliance standards.

I. Core of Material: का निवडा 8011 अॅल्युमिनियम धातूंचे मिश्रण? — Alloy Composition and Performance Adaptability

The material selection of food-grade baking foil is not random; it needs to balance three core requirements: “high-temperature resistance, easy shaping, and low migration”. सध्या, the industry mainly adopts 8011 अॅल्युमिनियम धातूंचे मिश्रण, whose composition design and performance advantages are irreplaceable.

1. Composition Design of 8011 अॅल्युमिनियम धातूंचे मिश्रण (Core Logic of Precise Proportioning)

8011 aluminum alloy belongs to the Al-Fe-Si series alloy, and its composition range strictly complies with GB/T 3190-2020 Chemical Composition of Wrought Aluminum and Aluminum Alloys. The specific proportions and functions are as follows:

This composition design endows 8011 aluminum alloy with three key properties:

① Ductility is improved by 30% (compared with ordinary 1235 अॅल्युमिनियम धातूंचे मिश्रण), allowing it to be folded repeatedly 10 times without obvious cracks;

② The maximum high-temperature resistance reaches 230°C, adapting to short-term high-temperature conditions of 250°C in ovens;

③ Puncture resistance is increased by 25%, preventing sharp parts of ingredients (उदा., rib tips) from piercing the foil and causing oil leakage.

2. Material Differences from Ordinary Foil: Why Is 1235 Aluminum Alloy Unsuitable?

Ordinary kitchen अॅल्युमिनियम foil commonly available in the market mostly uses 1235 अॅल्युमिनियम धातूंचे मिश्रण (aluminum content ≥99.35%, iron ≤0.25%, silicon ≤0.10%), and its material properties have inherent contradictions with the needs of baking scenarios:

• Insufficient High-Temperature Resistance: 1235 aluminum alloy tends to soften and deform at temperatures above 200°C. तथापि, the normal operating temperature of air fryers is 160-200°C, and the baking temperature of ovens often reaches 200-220°C. Long-term use may easily cause the foil to melt and stick to ingredients;

• Weak Structural Strength: Low iron and silicon content leads to poor puncture resistance, with creases and cracks appearing after 3-5 folds, making it impossible to make “अ‍ॅल्युमिनियम फॉइल ट्रे” suitable for small-particle ingredients;

• High Migration Risk: The pure aluminum base material easily reacts with acidic ingredients (उदा., roasted lemons, marinated meat in vinegar), and the aluminum ion migration amount can reach 15-20mg/kg (far exceeding the food-grade standard of ≤10mg/kg), posing potential health risks with long-term use.

त्यामुळे, जीबी 4806.9-2016 National Food Safety Standard for Metal Materials and Products in Contact with Food clearly stipulates that aluminum foil used in baking appliances must adopt specialized alloys such as 8011, and ordinary alloys such as 1235 are prohibited.

II. Production Process Standards: 6 Key Stages from Aluminum Ingot to Finished Product

The production of food-grade baking foil requires full-process control including “smelting-casting and rolling-cold rolling-annealing-finish rolling-slitting”. Parameter deviations in each stage will affect the final product quality, and the industry must strictly comply with the process requirements of YS/T 431-2021 Aluminum and Aluminum Alloy Foils.

1. Stage 1: Aluminum Ingot Smelting and Composition Fine-Tuning — Laying the Foundation for Material Quality

• कच्चा माल निवड: Industrial pure aluminum ingots with a purity of ≥99.7% (complying with GB/T 1196-2017) are used to avoid the introduction of heavy metals such as lead and cadmium from raw materials;

• Smelting Process: Smelting is carried out in a graphite crucible at 720-750°C, and Fe-Si master alloy is added (to control iron and silicon content). त्याच वेळी, nitrogen is introduced for degassing (vacuum degree ≤0.05MPa) to remove hydrogen from the melt (hydrogen content ≤0.15mL/100g Al) and prevent pinholes in finished products;

• Composition Testing: Each furnace of melt must be tested by a direct-reading spectrometer to ensure that the contents of Al, फे, and Si are within the standard range of 8011 मिश्रधातू, and the content of impurity elements does not exceed the standard. Only qualified melts can enter the next stage.

2. Stage 2: Casting and Rolling into Coils — Preparing Rough Blanks

• Process Parameters: A two-roll casting and rolling mill is used, with a casting and rolling speed controlled at 600-800mm/min and a casting and rolling temperature maintained at 680-700°C. The aluminum melt is rolled into “cast-rolled coils” with a thickness of 6-8mm;

• गुणवत्ता नियंत्रण: The surface of cast-rolled coils must be free of oxide scale, cracks, and inclusions, with a thickness deviation of ≤±0.2mm. नाहीतर, uneven stress during subsequent cold rolling will lead to thickness fluctuations.

3. Stage 3: Cold Rolling Forming — Gradually Reducing Thickness to Target Value

Cold rolling is the core stage determining the thickness uniformity of aluminum foil. It requires 3-4 passes of cold rolling to gradually reduce the 6-8mm cast-rolled coils to 0.015-0.025mm (the mainstream thickness range of baking foil). The key control points are as follows:

• Reduction Ratio Allocation: The reduction ratio of the first pass is 40%-50% (reducing thickness from 8mm to 4-5mm), and the reduction ratio of subsequent passes is gradually reduced to 20%-30% to avoid foil cracking caused by excessively high single-pass reduction ratio;

• Rolling Speed: Adjusted according to thickness. For thin specifications (0.015-0.02मिमी), the rolling speed is controlled at 800-1000m/min; for thick specifications (0.02-0.025मिमी), it can be increased to 1200-1500m/min;

• Thickness Accuracy Control: An X-ray thickness gauge is used for real-time monitoring, and the thickness deviation per meter must be ≤±0.002mm to ensure uniform overall thickness of the foil. If the thickness deviation is too large, local uneven heat transfer will occur, leading to the problem of “some parts burnt and some undercooked” in ingredients.

4. Stage 4: Intermediate Annealing — Improving Ductility and Eliminating Internal Stress

कोल्ड रोलिंग दरम्यान, lattice distortion (internal stress) occurs inside the foil, resulting in decreased ductility and brittleness. Intermediate annealing is required to restore performance:

• Annealing Temperature and Time: In a continuous annealing furnace, the temperature is maintained at 380-420°C for 1.5-2h. Specific parameters are adjusted according to the number of cold rolling passes — the higher the cold rolling reduction ratio, the slightly higher the annealing temperature and the longer the time required;

• Protective Atmosphere: Nitrogen with a purity of ≥99.99% is introduced as a protective atmosphere to prevent surface oxidation of the foil and avoid the formation of oxide films affecting subsequent surface treatment;

• Performance Improvement Effect: After annealing, the elongation of the foil increases from ≤5% (after cold rolling) to ≥15%, and it can be bent 180° without cracks, meeting the shaping needs of “folding into trays and wrapping ingredients” in baking scenarios.

5. Stage 5: Finish Rolling and Surface Smoothness Control

Finish rolling is the final process of cold rolling, with the main goals of:

① Controlling the thickness accuracy to the final requirement (उदा., 0.02mm±0.001mm);

② Improving surface smoothness and reducing oil adhesion;

• Roll Requirements: The rolls of the finish rolling mill must undergo mirror polishing, with a surface roughness Ra ≤0.2μm to ensure a flat and scratch-free foil surface;

• Rolling Oil Selection: Food-grade rolling oil (complying with GB 4806.10-2024) is used. After rolling, hot air drying (temperature 120-140°C) + vacuum degreasing are performed to ensure the residual oil rate on the foil surface is ≤5mg/m² and prevent odor emission at high temperatures.

6. Stage 6: Slitting and Coiling — Adapting to Application Scenarios

According to the common usage needs of air fryers and ovens, the following must be controlled in the slitting stage:

• Width Specifications: The mainstream slitting widths are 300mm and 450mm (adapting to the size of commonly used household baking trays). For special scenarios, custom widths such as 200mm (for mini air fryers) and 600mm (for commercial ovens) are available;

• Coil Diameter Control: The diameter of household rolled aluminum foil is ≤150mm for easy placement in kitchen storage racks. Each roll has a length of 10m or 20m (calculated based on 50cm of single use, which can meet 20-40 वापरते);

• Edge Treatment: After slitting, “deburring” treatment is required, with the edge burr height ≤0.1mm to avoid hand scratches during use.

III. Surface Treatment Technology: पासून “Basic Protection” करण्यासाठी “Performance Upgrade”

The surface treatment of food-grade baking foil is not simple cleaning, but the formation of functional coatings through chemical conversion to improve corrosion resistance and reduce aluminum ion migration. The core technology is “chromium-free passivation”.

1. Core Process: Chromium-Free Passivation (Zirconium-Titanium-Based Treatment Agent)

Traditional aluminum foil often uses chromate passivation (containing Cr⁶+), which has good corrosion resistance but poses heavy metal residue risks. सध्या, the industry has fully adopted “zirconium-titanium-based chromium-free passivators”, complying with the restrictions on hazardous substances in EU Regulation EC No. 1907/2006 (REACH Regulation):

• Treatment Process: The finish-rolled aluminum foil is immersed in a passivator solution (concentration 2%-5%, pH 3.5-4.5) and reacted at 40-50°C for 30-60 seconds, then dried at 80-100°C;
• Coating Structure: A 5-8nm ZrO₂-TiO₂ composite oxide film is formed, closely adhering to the foil surface. Its functions include:

• ① Isolating air and moisture to prevent foil oxidation and discoloration;
• ② Preventing direct contact between acidic ingredients and the aluminum base material, reducing the aluminum ion migration amount from 3.2mg/kg (untreated) to below 1.5mg/kg;
• ③ Increasing surface tension to reduce oil adhesion and facilitate peeling during cleaning.

2. High-End Upgrade: Functional Surface Treatment (for Special Needs)

For commercial baking scenarios or high-end household needs, some products will be equipped with additional surface treatment technologies:

• Antibacterial Coating: A layer of nano-silver ions (concentration 0.1%-0.2%) is coated on the outer layer of the passivation film, with an antibacterial rate of ≥99.9% against Escherichia coli and Staphylococcus aureus, suitable for scenarios such as baby food supplementary food and medical baking;

• Non-Stick Coating: Food-grade silicone resin (complying with FDA 21 CFR Part 177.2600) is used, with a coating thickness of 1-2μm, solving the problem of high-sugar ingredients (उदा., crème brûlée) sticking to the foil after cooling;

• High-Temperature Resistant Coating: Ceramic particles (उदा., अल) are added to increase the maximum temperature resistance of the foil from 230°C to 260°C, adapting to the “self-cleaning mode” of ovens (some models have a self-cleaning temperature of up to 250°C).

IV. Compliance Standard System: “Safety Red Line” for Materials and Processes

The materials and processes of food-grade baking foil must meet both domestic and international standards to ensure full-chain compliance from production to use.

1. Domestic Core Standards (GB Series)

• Material Standards: GB/T 3190-2020 Chemical Composition of Wrought Aluminum and Aluminum Alloys (regulating the composition of 8011 मिश्रधातू), जीबी 4806.9-2016 National Food Safety Standard for Metal Materials and Products in Contact with Food (specifying aluminum ion migration amount ≤10mg/kg and heavy metal residue requirements);

• Process Standards: YS/T 431-2021 Aluminum and Aluminum Alloy Foils (clarifying process parameters and quality requirements for cold rolling, annealing, and slitting), GB/T 22638.6-2020 Test Methods for Aluminum Foil — Part 6: Surface Cleanliness (controlling surface residual oil rate and impurity content).

2. International Mainstream Standards (Adapting to Export and High-End Needs)

• EU Standards: Regulation (EU) नाही 10/2011 (Food Contact Materials Regulation), requiring aluminum ion migration amount ≤1mg/kg (soaked in 4% acetic acid for 24h) and prohibiting chromate passivation;

• US Standards: FDA 21 CFR Part 175.300 (Food Contact Metal Standards), specifying lead content ≤0.01% and arsenic content ≤0.003% in aluminum alloys;

• Testing Standards: आयएसओ 15330-2018 Aluminum and Aluminum Alloy Foils — Test Methods (unifying testing methods for thickness, ताणासंबंधीचा शक्ती, आणि गंज प्रतिकार).

3. Enterprise Internal Quality Control Standards (Higher Than National Standards)

Leading aluminum foil manufacturers (उदा., Miaojie, Kelinlai) will establish stricter internal control standards, जसे:

① Internal control of aluminum ion migration amount ≤5mg/kg (far lower than the national standard of 10mg/kg);

② Internal control of thickness deviation ≤±0.001mm (national standard is ±0.002mm);

③ 100% pinhole testing for each roll of foil (pinhole count ≤1 per m², national standard is ≤3 per m²) to ensure product stability.

व्ही. Common Misunderstandings About Materials and Processes: Avoiding “Fake Food-Grade” अॅल्युमिनियम फॉइल

Some low-priced aluminum foils on the market have problems such as “shoddy materials and cut corners in processes”. The following points should be used to identify them:

1. Misunderstanding 1: “Pure aluminum material is better” — Pure aluminum (1235 अॅल्युमिनियम धातूंचे मिश्रण) has poor high-temperature resistance and puncture resistance, making it unsuitable for baking. द “aluminum-iron-silicon” proportion of 8011 alloy is the optimal choice;

2. Misunderstanding 2: “Thicker is more durable” — For aluminum foil thicker than 0.025mm, the thermal conductivity will decrease by 15%-20%, leading to uneven heating of ingredients and increased folding difficulty. The optimal thickness for baking is 0.018-0.022mm;

3. Misunderstanding 3: “Passivation is unnecessary” — The surface of unpassivated foil is prone to oxidation, and the aluminum ion migration amount will exceed the standard after reacting with acidic ingredients. Products labeled “chromium-free passivation” must be selected.

निष्कर्ष: Materials and Processes Determine the “Professional Attributes” of Baking Foil

The core value of food-grade baking foil specialized for air fryers/ovens stems from the “precise composition design of 8011 अॅल्युमिनियम धातूंचे मिश्रण” आणि “strict control of the full production process” — from the composition fine-tuning of aluminum ingot smelting, to the performance optimization of cold rolling and annealing, and then to the safety protection of chromium-free passivation. Each stage must focus on the needs of “high-temperature resistance, easy shaping, and low migration”. Only products that meet material compliance, process standards, and surface treatment requirements can truly adapt to baking scenarios, ensuring food safety while improving user experience.