Due to its “resource recycling” លក្ខណៈ, recycled aluminum foil is increasingly used in food aseptic packaging—particularly for croissants and baked goods. ខាងក្នុងអាយ័តនិ 2024, this recycled material accounted for 38% of the global market for aseptic croissant packaging aluminum foil (ប្រភព: International Aluminium Institute).

Its raw materials mostly come from waste batches of this specialized សន្លឹកអាលុយមីញ៉ូម. For aseptic croissant storage, the foil requires an extremely low surface microbial load (≤1 CFU/cm²).

ទោះយ៉ាងណាក៏ដោយ, during recycling, the foil easily absorbs croissant oil. This oil is a complex mixture: “saturated fatty acids (palmitic acid, 35%-45%), unsaturated fatty acids (oleic acid, 25%-30%), and emulsifiers (monoglycerides, 0.5%-2%)”.

គួរកត់សំគាល់, industry research reveals that approximately 22% of enterprises producing this recycled foil struggle with excessive croissant oil residue (>50mg / m²). This far exceeds the 10mg/m² limit for aseptic croissant packaging aluminum foil.

The excess residue often stems from improper cleaning parameters—such as insufficient alkali concentration or overly short cleaning time.

Such residues not only reduce the purity of the recycled material but also damage its “aseptic barrier”. This threatens subsequent croissant packaging safety through “migration contamination” និង “ការលូតលាស់អតិសុខុមប្រាណ”. An in-depth analysis from the perspective of aseptic packaging material science is therefore essential.

ECO-B. Component Characteristics of Croissant Oil and Its Residue Mechanism on the Recycled Foil

Aseptic croissant packaging aluminum foil must satisfy both “ទ្រព្យសម្បត្តិរបាំង” និង “aseptic property”. Croissant oil residues directly compromise these two traits, and its residue mechanism differs from that of ordinary aluminum foil.

(ក) Core Components and Physicochemical Properties of Croissant Oil (Relevance to Aseptic Packaging)

Component Category	Representative Substance	ជួរមាតិកា	Key Physicochemical Properties	Relevance to the Aseptic Packaging Foil
Saturated Fatty Acids	Palmitic Acid, Stearic Acid	35%-45%	Melting point 50-60℃, semi-solid at room temperature, easy to solidify	Solidified oil film covers the foil surface, hindering subsequent sterilization
Unsaturated Fatty Acids	Oleic Acid, Linoleic Acid	25%-30%	Contains double bonds, easy to oxidize into aldehydes and acids	Oxidation products may react with the foil’s passivation layer, damaging barrier property
Emulsifiers	Monoglycerides, Sucrose Esters	0.5%-2%	Easily adsorbs on metal surfaces, enhancing oil adhesion	Makes oil harder to clean, increasing microbial growth risk in aseptic packaging
Antioxidants	BHA, TBHQ	50-100មីលីក្រាម / គីឡូក្រាម	Contains benzene ring structure, potential migration risk	Migration to croissants violates food safety requirements for aseptic packaging

Each component in croissant oil plays a role in worsening residue issues. ឧទាហរណ៍, emulsifiers strengthen oil-foil bonding, while antioxidants introduce potential migration risks.

(ខ) Residue Mechanism of Croissant Oil on the Recycled Aseptic Foil

After crushing, រលាយ, និងរមៀល, the raw material (waste aseptic croissant packaging aluminum foil) exhibits a “double-layer adsorption” pattern of oil residue.

ជាក់លាក់, micropore adsorption residue poses a unique risk for aseptic packaging. To boost barrier performance, this specialized aluminum foil forms a dense microporous structure (pore size 0.1-0.5μm) កំឡុងពេលរមៀល.

Small croissant oil molecules (ឧ។, methyl palmitate, 0.5-0.8nm in diameter) penetrate these pores, forming an “intra-pore oil film”.

Nitrogen adsorption experiments (BET) show that residual oil reduces the foil’s specific surface area from 1.2m²/g to 0.8m²/g. This blocks pores and triples oxygen transmission rate, eliminating the aseptic packaging’s barrier function.

បន្ថែម, chemical adsorption residue damages the aseptic barrier. Oleic acid in croissant oil reacts with Al₂O₃ on the foil surface to form aluminum oleate (អាល់(C₁₈H₃₂O₂)₃).

X-ray Photoelectron Spectroscopy (XPS) confirms that the binding energy of Al 2p in residual areas shifts from 74.5eV to 73.8eV—proof of chemical bonding.

This chemically bound oil resists conventional water washing. It also forms a “nutrient layer” on the foil surface, creating conditions for microbial growth and directly undermining the aseptic state of the packaging material.

ECO-C. Mechanism of Croissant Oil Residue Reducing the Purity of the Recycled Aseptic Foil

Aseptic croissant packaging aluminum foil has stricter purity requirements than standard foil: ≥99.5% for food grade and ≥99.7% for aseptic grade. Oil residues lower purity through two key pathways: “component contamination” និង “structural damage”.

(ក) Chemical Purity Reduction Caused by External Impurity Introduction

នៅលើដៃមួយ។, carbon enrichment harms aseptic stability. Palmitic acid (C₁₆H₃₂O₂) in the oil carbonizes during rolling heating (120-150℃), generating free carbon.

Carbon-sulfur analyzer tests show that for recycled foil with 50mg/m² residue, surface carbon content rises from 0.05% ទៅ 0.25%. This exceeds the 0.1% limit for aseptic grade.

At 100mg/m² residue, carbon diffuses 0.5-1μm into the foil. This drops purity from 99.7% ទៅ 99.4%, failing to meet GB/T 25198 Aluminum and Aluminum Alloy Plates for Pressure Vessels standards for aseptic packaging.

ម៉្យាងទៀត, excessive oxygen damages the barrier layer. Hydroxyl and carboxyl groups in the oil react with Al₂O₃, thickening the oxide layer from 5-10nm to 15-20nm.

Oxygen-nitrogen analyzer data shows oxygen content increases from 0.12% ទៅ 0.35%. This reduces the foil’s ductility—elongation falls from 15% ទៅ 10%.

Cracks form during foil shaping, destroying the aseptic barrier.

(ខ) Physical Purity Reduction Caused by Microstructural Damage

The aseptic packaging foil relies on a uniform microstructure to maintain sterility—something oil residues disrupt.

ឧទាហរណ៍, monoglycerides in the oil adsorb at grain boundaries during annealing (300-350℃). This hinders grain growth.

Metallographic observations reveal that normal foil has a consistent 20-30μm grain size. Residue-contaminated foil, ដោយភាពផ្ទុយគ្នា។, shows uneven 5-40μm grains.

Fine-grain areas easily accumulate microorganisms, leading to incomplete sterilization.

លើសពីនេះទៀត, free carbon from oil carbonization accumulates at grain boundaries. This forms a 0.2-0.5μm thick carbon-enriched layer (observed via TEM).

With grain-boundary carbon content reaching 0.5%-1.0%, the foil’s intergranular cracking rate during stamping rises from 3% ទៅ 15%. This prevents the formation of a complete aseptic packaging structure.

ECO-D. Multi-Dimensional Threats of Croissant Oil Residue to Aseptic Croissant Packaging Safety

Beyond purity issues, oil residues pose severe risks to the core goals of aseptic croissant packaging: “maintaining an aseptic environment” និង “ធានាសុវត្ថិភាពសុវត្ថិភាពម្ហូបអាហារ”. These threats manifest in three key ways.

(ក) Aseptic Barrier Failure (Unique to Aseptic Packaging)

The foil achieves aseptic storage through “physical barrier + surface sterility”, and residues damage both.

តីមយយ, microbial growth breaches sterility. Foil with 50mg/m² oil residue, stored at 25℃ and 70% humidity for 7 ថៃ, shows 10² CFU/cm² of Escherichia coli. This far exceeds the ≤1 CFU/cm² aseptic standard.

When used for croissant packaging, microorganisms multiply rapidly. This increases deterioration rates from 0.1% ទៅ 8% within the typical 7-day shelf life.

ទីពីរ, reduced sterilization penetration exacerbates the issue. The oil film blocks the foil surface, cutting ultraviolet sterilization penetration (a common aseptic packaging process) ពី 90% ទៅ 50%.

Unsterilized areas show 20% microbial residue. This violates GB/T 31402 Microbial Limit for Packaging Materials and Products.

(ខ) Food Contact Migration Risks (Exacerbated in Aseptic Settings)

Oil residues also cause harmful substances to migrate into croissants.

ឧទាហរណ៍, oleic acid oxidizes into malondialdehyde during storage. Migration amounts reach 0.3-0.8mg/dm²—exceeding the 0.5mg/dm² limit in GB 31604.1.

Malondialdehyde reacts with croissant proteins, compromising food safety.

គួរកត់សំគាល់, the foil’s damaged passivation layer leads to excessive aluminum leaching. This is a bigger concern for aseptic packaging due to long-term food contact.

In acidic croissants (ឧ។, those with lemon), aluminum leaching hits 0.2mg/dm². This is double the 0.1mg/dm² limit in GB 4806.3, posing long-term health risks.

(c) Packaging Integrity Damage (Shortening Aseptic Shelf Life)

Aseptic packaging requires an intact barrier, but oil residues accelerate foil corrosion.

Electrochemical workstation tests show residue-contaminated foil has a corrosion current density of 1.5×10⁻⁶ A/cm². This is three times that of clean foil.

A 0.01mm thick foil perforates within 6 នៃរេប្យនៈ. This cuts croissant shelf life from 7 ថ្ងៃទៅ 3 ថៃ.

ដោយភាពផ្ទុយគ្នា។, Cl⁻ in the oil (from croissant salt) and fatty acids form pitting pits (1-5μm diameter, observed via SEM).

This increases oxygen transmission rate from 1cm³/(មការ៉េ · 24 ម៉ោង · 0.1 MPa) to 5cm³/(មការ៉េ · 24 ម៉ោង · 0.1 MPa). Croissant oxidation deterioration rises by 40%.

អេកូ-អ៊ី. Optimized Cleaning Process for Croissant Oil Residue on Recycled Aseptic Foil

To address these issues, a cleaning process tailored to the unique needs of aseptic croissant packaging must balance “oil removal” និង “aseptic maintenance”. The optimized workflow is as follows.

(ក) ការព្យាបាលមុន។: Balancing Degreasing and Aseptic Preparation

ជាបឋម, hot air pre-degreasing is conducted in an aseptic workshop. Waste aseptic foil is heated in a hot air furnace (120-150℃, 2m/s air velocity) for 10-15min.

This step removes 60%-70% of surface oil, preventing contamination of the aseptic environment.

ជាបន្តបន្ទាប់, ultrasonic rough cleaning uses aseptic deionized water as the medium. Low-frequency ultrasound (20kHz, 500វ) operates for 5-8min.

Its cavitation effect removes 30% of micropore oil without introducing external microorganisms.

(ខ) Main Cleaning: Chemical Degreasing + Aseptic Enhancement

Process Parameter	តម្លៃដែលបានធ្វើឱ្យប្រសើរ (for Aseptic Packaging)	យន្តការ	Effect Verification (Aseptic Foil)
Cleaner Type	5%-8% ណាអូ + 0.1% Aseptic Agent	Strong alkali decomposes aluminum soap; aseptic agent inhibits microorganisms	Aluminum soap decomposition ≥95%; post-cleaning microorganisms ≤1 CFU/cm²
Cleaning Temperature	60-70℃ (Aseptic Constant Temperature)	Improves reaction rate; avoids microbial growth from temperature fluctuations	Efficiency doubles vs. សីតុណ្ហភាពបន្ទប់; no microbial contamination
Cleaning Time	15-20នាទី	Thoroughly removes grain boundary residues	Oil residue drops from 50mg/m² to 15mg/m²
Stirring Speed	300r/min (Aseptic Stirring)	Enhances convection; prevents re-adsorption	Residue falls by another 3mg/m², meeting aseptic limits

These parameters ensure deep oil removal while preserving the foil’s aseptic state. ឧទាហរណ៍, the added aseptic agent prevents microbial growth during cleaning.

(c) ការព្យាបាលក្រោយ: Aseptic Drying + Sterilization Verification

ចាតីបហ្ចប់, aseptic hot air drying occurs in a furnace (80-90℃, dew point ≤-40℃) for 10min. This keeps moisture ≤0.1%, avoiding microbial growth.

បន្ទាប់មក, ultraviolet sterilization + residue detection is performed. 254nm UV light irradiates for 30s to eliminate any remaining microorganisms.

Near-Infrared Spectroscopy (NIRS) detects oil residue via its 1720nm characteristic peak. This ensures residue ≤10mg/m² and microorganisms ≤1 CFU/cm²—meeting all requirements for aseptic croissant packaging aluminum foil.

ECO-F. ករណីឧស្សាហកម្ម: Optimized Process in Practice

Real-world application of this process confirms its effectiveness. A enterprise producing 50,000 tons of recycled aseptic croissant packaging aluminum foil annually faced three major issues in 2023 due to oil residue.

តីមយយ, foil purity only reached 99.3%—below the 99.7% aseptic grade requirement. ទីពីរ, 8% of customer complaints stemmed from excessive aluminum leaching. ទីបី, ការចម្លងរោគអតិសុខុមប្រាណដែលបណ្តាលមកពី 1 លានស៊ីអិនស៊ីក្នុងការខាតបង់ត្រឡប់មកវិញនៃការវិលត្រឡប់មកវិញ.

បន្ទាប់ពីអនុវត្តដំណើរការសំអាតដែលត្រូវបានធ្វើឱ្យប្រសើរឡើង, ភាពបរិសុទ្ធនិង asepticity មានភាពប្រសើរឡើង: មាតិកាកាបូនបានធ្លាក់ចុះ 0.08%, អុកស៊ីសែនទៅ 0.15%, និងភាពបរិសុទ្ធមានស្ថេរភាពនៅ 99.7% ជាមួយអតិសុខុមប្រាណ≤1 cfu / ស។ ម ./.

សូចនាករសុវត្ថិភាពបានពង្រឹង: ការលេចធ្លាយអាលុយមីញ៉ូមបានធ្លាក់ចុះដល់ 0.08mg / DM², ការខ្សោះជីវជាតិនៃក្រេឌីតបានធ្លាក់ចុះ 0.5%, ហើយពាក្យបណ្តឹងបានបញ្ឈប់ទាំងស្រុង.

អត្ថប្រយោជន៍សេដ្ឋកិច្ចបានកើនឡើង: អត្រានៃការបដិសេធ Foil បានធ្លាក់ចុះពី 15% ទៅ 3%, ការសរេប្យេចាាបរត្យេយយ 2 មួយលានស៊ីអិនប្រចាំឆ្នាំ. សហគ្រាសក៏បានពង្រីកចំណែកទីផ្សាររបស់ខ្លួនពី 10% ទៅ 15%.

អេកូ - ឆ. សេចក្តីសន្និដ្ឋាន និងទស្សនវិស័យ

សរុបមក, incomplete cleaning of recycled aseptic croissant packaging aluminum foil leads to croissant oil residues. These residues not only reduce purity (ពី 99.7% ទៅ 99.4%) but also breach the aseptic barrier (microorganisms rise from ≤1 CFU/cm² to 10² CFU/cm²).

This directly threatens croissant safety. The solution lies in “aseptic cleaning + precise detection”—combining hot air pre-degreasing, alkaline main cleaning, and UV sterilization in an aseptic environment. This controls residues below 10mg/m² while preserving the foil’s sterility and barrier property.

សម្លឹងទៅមុខ, three areas require further development for this specialized foil.

តីមយយ, develop bio-based green cleaners (ឧ។, plant surfactants) that balance degreasing and sterility—reducing environmental impact.

ទីពីរ, create AI adaptive cleaning systems that adjust parameters in real time to match oil residue levels—improving process efficiency.

ទីបី, advance combined detection technologies (NIRS + rapid microbial testing) to ensure full-life-cycle safety of the foil.

នៅស្នូលរបស់វា, recycling aseptic croissant packaging aluminum foil must never compromise sterility. Only by integrating aseptic requirements into every cleaning step can we achieve a “win-win” of resource recycling and food safety. This drives sustainable development in the aseptic croissant packaging industry.