Source: Link Testing Instruments Co.,Ltd.
In the dairy industry, particularly for perishable products such as high-end yogurt and cheese, nitrogen packaging is a crucial process for extending shelf life and maintaining flavor and texture. The residual oxygen (O₂) content inside the packaging is a key indicator of process effectiveness and directly determines whether the product remains stable within its shelf life. The following case study demonstrates how a dairy company used a headspace gas analyzer to address packaging quality issues encountered during the initial launch of a new product.
I. Specific Problem: Abnormal Swelling and Flavor Deterioration in High-End Yogurt
A dairy company introduced a new nitrogen-filled packaging line for its newly launched "0-additive" premium set yogurt. After the product was launched, some sales outlets reported that some products showed slight swelling of the packaging and a slight sour taste, even though there was still a considerable time before the expiration date. Laboratory microbiological testing ruled out hygiene problems in the production process, and the focus of suspicion shifted to the oxygen content inside the packaging—residual oxygen might have promoted the growth of aerobic bacteria or triggered oxidation reactions.
The quality team faced a dilemma: where did the problem originate? Was it insufficient nitrogen displacement efficiency after filling, substandard barrier properties of the packaging material, or defective sealing? Traditional laboratory testing methods were time-consuming and could not meet the needs of rapid troubleshooting and adjustment on the production line.
II. Systematic Investigation Using a Headspace Gas Analyzer
The technical team decided to use the LTDK-190 headspace gas analyzer to conduct rapid, multi-point gas sampling and analysis at the production site to create a "map" of the problem.
Step 1: Real-time Diagnosis on the Production Line
Test points and objectives: Randomly sample finished products immediately after sealing at the outlet of the nitrogen-filling packaging machine every 15 minutes.
Test method: Use the instrument's standard fine sampling needle to penetrate the easily punctured area of the aluminum-plastic composite film in the headspace of the packaging and extract approximately 8ml of gas for analysis.
Real-time data findings: Two hours of continuous monitoring showed that the headspace oxygen content of most samples fluctuated between 0.8% and 1.5%, but about 5% of the samples showed a sudden increase in oxygen content to over 3.5%. The data showed that the nitrogen-filling process itself met the standards (the design target was <2.0%), but there was an unstable "pulsed" failure.
Step 2: Tracking During Warehouse Storage
Test points and objectives: Sample products from the finished product warehouse from different production dates (Day 1, Day 7, Day 14).
Test method: Conduct non-destructive puncture testing to analyze the changes in oxygen content inside the packaging after different storage times. Key Data Comparison:
The oxygen content of samples from the first day of production matched the data from the end of the production line.
In samples from the 7th and 14th days of production, the oxygen content in some packages increased significantly, from an initial 1.2% to 2.8% or even higher. The oxygen content in other products from the same period remained stable.
Visual inspection and leak testing of the packages with elevated gas content did not reveal any obvious leakage points.
Analysis Conclusion: The increase in oxygen content during storage clearly indicates non-uniformity in the oxygen barrier properties of the packaging material (aluminum-plastic composite film) within the batch, leading to slow oxygen permeation.
Step 3: Identifying the Root Cause
Verification Test: The team contacted the packaging film supplier and provided samples from both the problematic and normal batches. Using the same analyzer under controlled laboratory conditions, both parties conducted comparative oxygen permeability verification tests on the bare film (by measuring the oxygen content increase rate of specific packaging bags filled with nitrogen).
Final Confirmation: The data confirmed that some rolls of packaging film in the problematic batch had localized weak points in their oxygen barrier layer (usually aluminum foil or silicon oxide coating), resulting in substandard and inconsistent overall barrier performance. Unstable nitrogen filling on the production line amplified this problem.
III. Data-Driven Solutions and Process Re-engineering
Based on the above data, which was precise down to specific processes and batches, the company implemented targeted measures:
Supply Chain Management Optimization:
The company added a "daily sampling headspace oxygen simulation test" to the assessment of packaging film suppliers. This involves creating nitrogen-filled test bags using standard processes in the laboratory, and then measuring the oxygen content after 24 hours using an HGT-01H analyzer as one of the acceptance criteria.
A portable analyzer was incorporated into the supplier's on-site audit tools to verify their production process control capabilities.
Production Process Control Strengthening:
An "online sampling station" was established at the end of the nitrogen-filling packaging machine. The headspace oxygen content of finished products is sampled every half hour using an analyzer, and the data is recorded in real time. The control limit is set at ≤2.0%. If the limit is approached or exceeded, equipment maintenance personnel are immediately notified to check the nitrogen filling valve, pressure, and sealing ring. Utilizing the instrument's data storage and Bluetooth printing functions, critical quality records are generated for each production batch, facilitating traceability.
Problem Batch Handling and Prevention:
All product batches produced with the defective packaging film were accurately identified and recalled, preventing the spread of risk.
During new product development and packaging changes, "headspace oxygen content tracking testing during the storage period" was designated as a mandatory verification item to assess long-term preservation effects in advance.
IV. Implementation Results and Summary
By introducing a headspace gas analyzer and establishing an on-site rapid testing process, the dairy company successfully contained a quality issue that could have led to a large-scale recall within a limited scope. In the following six months, product complaints due to packaging gas problems dropped to zero, and the stability of the nitrogen filling process on the production line also improved.
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