Case Study: Vacuum Emulsifier in Mayonnaise Production
Mayonnaise is a semi-solid emulsified food product prepared by blending oil, egg yolk, vinegar, and seasonings, relying on precise emulsification to form a stable oil-in-water (O/W) system. The production process demands strict control over emulsification uniformity, bubble content, oil droplet size, and microbial safety—factors directly affecting product texture, flavor, shelf life, and consumer acceptance. Traditional mayonnaise production equipment often struggles to balance these requirements, leading to quality inconsistencies and operational inefficiencies. This case study objectively details how a vacuum emulsifier addressed core challenges in large-scale mayonnaise production, optimized processes, and improved product stability without promotional language or undisclosed information.
1. Background and Production Challenges
The production facility focuses on large-scale manufacturing of shelf-stable mayonnaise and emulsified sauces, supplying retail and foodservice channels. Prior to upgrading equipment, it relied on conventional high-shear mixers paired with separate deaeration devices—a setup that gave rise to persistent quality and operational issues after long-term mass production.
First, emulsification stability and oil droplet control were subpar. Conventional mixers lacked sufficient shear force to disperse oil droplets into uniform micro-sized particles (typically 8-12 μm), resulting in uneven texture and poor emulsification stability. During storage, 5-8% of batches exhibited oil separation at the surface, leading to product rejection and material waste. The inconsistent oil droplet size also caused variations in mouthfeel—some batches were grainy, while others were overly runny, failing to meet standard quality specifications.
Second, residual air bubbles and oxidative degradation affected product quality and shelf life. The separate mixing and deaeration process was inefficient, leaving micro-bubbles in the finished product. These bubbles caused surface porosity, discoloration, and accelerated oxidative rancidity of oils, shortening the product’s shelf life from the target 12 months to 8-9 months. For mayonnaise containing natural oils (e.g., sunflower oil), oxidative degradation also altered flavor profiles, leading to customer complaints.
Third, hygiene risks and production inefficiency were prominent. The multi-step production process (mixing, deaeration, transfer) increased the risk of microbial contamination, as materials were exposed to the production environment during transfer. Additionally, the conventional equipment’s hard-to-clean gaps (e.g., mixer blades, deaerator chambers) raised cross-contamination risks between different formulations (e.g., regular mayonnaise and low-fat variants). The total processing time per batch (1,000L) was 45 minutes, with frequent manual intervention to adjust mixing speed and deaeration time, limiting production scalability.
To resolve these issues, the facility sought an emulsification solution capable of achieving uniform oil droplet size (≤5 μm), complete deaeration, closed-loop hygiene control, and compliance with food industry standards (GMP, FDA 21 CFR Part 117). After rigorous pilot testing and technical evaluation, a customized vacuum emulsifier with integrated mixing, homogenization, and deaeration functions was selected for production line integration.
2. Equipment Selection and Technical Adaptation
Considering mayonnaise’s characteristics—high oil content (65-80%), medium viscosity (15,000-30,000 mPas), sensitivity to oxygen, and strict hygiene requirements—the selected vacuum emulsifier was tailored to address the limitations of traditional equipment. Key technical features and adaptations are as follows:
Core Emulsification and Vacuum System
The emulsifier adopts a dual-stage rotor-stator homogenizing head with a maximum rotational speed of 10,000 rpm and linear speed of 42 m/s. The adjustable rotor-stator gap (0.15-0.3 mm) generates intense shearing, cavitation, and turbulent forces, effectively breaking down oil droplets into micro-dispersions (2-4 μm) and ensuring complete fusion with the aqueous phase (egg yolk, vinegar). A 37 kW variable-frequency drive (VFD) motor enables stepless speed adjustment (1,500-10,000 rpm), allowing precise control of shear intensity to avoid over-processing egg yolk (which can denature proteins and disrupt emulsification).
The integrated high-efficiency vacuum system maintains a stable vacuum degree of -0.095 to -0.098 MPa throughout the production process, eliminating air entrapment during mixing and homogenization. The closed-loop design of the chamber and pipelines prevents air re-entry, minimizing oxidative degradation of oils and ensuring a bubble-free, smooth texture. Double mechanical seals and food-grade fluorine rubber gaskets ensure airtightness and prevent material leakage.
Hygiene and Material Compliance
All product-contacting components—including the mixing chamber, homogenizing head, and feeding/discharging pipelines—are fabricated from 316L stainless steel, undergoing electrolytic polishing to a surface roughness Ra ≤ 0.4 μm. This design prevents material adhesion, biofilm formation, and residual buildup, reducing microbial contamination risks. The equipment supports CIP (Clean-in-Place) operations, with high-pressure rotating cleaning nozzles installed in the chamber and pipelines, enabling thorough cleaning without disassembly. It also meets FDA food contact material standards and EU 10/2011 regulations for food processing equipment.
Temperature Control and Process Automation
Mayonnaise emulsification requires strict temperature control (20-30℃) to preserve egg yolk protein activity and prevent oil oxidation. The emulsifier’s jacketed chamber is equipped with a PID temperature control system, regulating temperature with a precision of ±1℃ via circulating water cooling (no heating function, as mayonnaise emulsification is exothermic to a small extent). This ensures stable processing conditions and avoids thermal denaturation of egg yolk.
A PLC touchscreen control system enables automated process management, including parameter setting (homogenization speed/time, vacuum degree, oil addition rate), real-time monitoring, and data recording. The system stores up to 50 formulation profiles, allowing one-click switching between regular, low-fat, and flavored mayonnaise variants. Batch data (processing time, temperature, vacuum level, oil addition rate) is automatically recorded and stored for at least 2 years, facilitating production traceability and regulatory compliance.
Auxiliary Mixing System
To ensure uniform distribution of seasonings (salt, sugar, mustard) and prevent local over-concentration, the emulsifier is equipped with a low-speed anchor-type stirrer (50-300 rpm, 11 kW motor). The stirrer scrapes the chamber wall to eliminate mixing dead corners, ensuring all materials pass through the homogenization zone repeatedly. It operates synchronously with the homogenizer, adapting speed to the material’s viscosity during emulsification.
3. Implementation and Process Optimization
Before full-scale production, the technical team conducted multi-batch pilot tests (100L per batch) to optimize process parameters for three core mayonnaise formulations: regular (75% oil content), low-fat (50% oil content), and garlic-flavored (70% oil content). The primary goal was to determine the optimal combination of homogenization speed, oil addition rate, vacuum level, and stirring speed to achieve target oil droplet size, emulsification stability, and texture.
Pilot test results yielded formulation-specific optimal parameters: For regular mayonnaise, a homogenization speed of 8,500 rpm, oil addition rate of 5 L/min (gradual addition via a closed pipeline), vacuum degree of -0.096 MPa, and 25-minute emulsification time achieved uniform oil droplet size (2-3 μm) and stable emulsification. For low-fat mayonnaise (which requires higher emulsification efficiency due to lower oil content), a higher homogenization speed of 9,000 rpm, slower oil addition rate (3 L/min), and extended stirring time (30 minutes) ensured sufficient phase fusion. For garlic-flavored mayonnaise, intermittent homogenization (4 minutes on, 1 minute off) preserved garlic flavor compounds while maintaining emulsification quality.
Based on these results, the production line was reconfigured to integrate the vacuum emulsifier into a closed-loop workflow, eliminating manual transfer steps. The optimized process is as follows:
- Material Preparation: Preprocess raw materials—dissolve salt, sugar, and mustard in water (aqueous phase), pasteurize egg yolk (to reduce microbial load), and filter oils to remove impurities. All materials are pre-cooled to 20℃.
- Feeding: Transfer the aqueous phase and pasteurized egg yolk into the 1,000L emulsifier chamber via closed pipelines. Activate the anchor stirrer (150 rpm) to mix uniformly.
- Vacuum Activation: Start the vacuum system to reach -0.096 MPa, maintaining it throughout the process.
- Emulsification: Activate the homogenizer at the preset speed, then gradually add filtered oil via a closed metering pump at the optimized rate. The dual-stage homogenizing head and anchor stirrer operate synchronously to ensure uniform oil dispersion.
- Seasoning Addition: After 80% of the oil is added, inject vinegar and flavorings (e.g., garlic paste) via closed pipelines, continuing emulsification until all materials are fully blended.
- Post-Emulsification: Maintain vacuum and gentle stirring for an additional 5 minutes to remove residual micro-bubbles. Monitor temperature to ensure it remains below 30℃.
- Discharging: Transfer the finished mayonnaise to downstream filling equipment via a closed pipeline, completing the production cycle.
Cleaning validation confirmed that the CIP system effectively removed residual materials, with no detectable contaminants (limit of detection: 0.1 μg/cm²) between batches. The closed-loop design eliminated material exposure to the production environment, reducing microbial contamination risks.
4. Application Results and Performance Improvements
After the vacuum emulsifier was put into formal production, the facility achieved measurable improvements in product quality, production efficiency, and operational costs—with consistent outcomes across all mayonnaise formulations:
Product Quality Enhancement
Oil droplet control was drastically improved: average oil droplet size was stabilized at 2-4 μm (compared to 8-12 μm previously), with a Span value ≤0.9. This eliminated graininess and oil separation, with zero batches showing surface oil separation during 12 months of shelf life testing. The bubble-free texture improved product appearance (uniform luster, smooth consistency) and extended shelf life to the target 12 months—oxidative rancidity rates dropped by 90% due to the vacuum environment. Batch-to-batch consistency was significantly enhanced, with key quality indicators (viscosity, pH, oil droplet size) fluctuating within ±2%, compared to ±7% with traditional equipment.
Production Efficiency Optimization
The batch processing cycle was shortened from 45 minutes to 30 minutes—a 33% reduction—enabling the facility to increase daily production volume from 12 batches to 18 batches (1,000L per batch). The automated control system reduced manual intervention, with each operator capable of monitoring two production lines simultaneously, lowering labor intensity by 40%. Formulation changeover time was reduced from 90 minutes to 40 minutes, supporting flexible production of multiple variants. The closed-loop workflow also eliminated material loss during transfer, reducing raw material waste by 5%.
Operational Cost Reduction
Energy consumption per batch decreased by 20% due to the efficient VFD motor and integrated design (eliminating separate deaerator operation). Maintenance costs dropped by 35%: the wear-resistant rotor-stator components and modular design simplified inspection and replacement, extending service life by 2 times compared to traditional mixers. The elimination of batch failures due to oil separation or bubble formation reduced material waste by 85%, significantly improving production economics. Additionally, the CIP system reduced cleaning time by 50% and detergent consumption by 40%.
Compliance and Safety Improvements
The equipment’s 316L stainless steel construction, CIP capability, and data traceability system fully complied with FDA 21 CFR Part 117 and EU GMP standards, streamlining regulatory audit preparation. The closed-loop design reduced microbial contamination risks, with total plate counts in finished products consistently below 10 CFU/g (meets food safety standards). Automatic alarm functions (vacuum deviation, temperature abnormality, motor overload) prevented production accidents and equipment damage, reducing unplanned downtime by 60%.
5. Summary and Insights
The application of the vacuum emulsifier successfully resolved the core challenges of traditional mayonnaise production—emulsification instability, residual bubbles, hygiene risks, and inefficiency—by integrating high-shear homogenization, vacuum deaeration, and automated control in a closed system. The key to this success lies in the equipment’s ability to address mayonnaise’s unique emulsification requirements: precise control of oil droplet size via adjustable shear force, complete deaeration to prevent oxidation, and strict temperature control to preserve egg yolk functionality.
For food manufacturers producing emulsified sauces like mayonnaise, this case highlights the importance of selecting equipment that aligns with product-specific characteristics. The vacuum emulsifier’s integrated design is particularly advantageous for high-oil emulsions, as it overcomes the limitations of separate mixing and deaeration processes. Thorough pilot testing to optimize oil addition rate, homogenization speed, and vacuum parameters—tailored to different formulations— is critical to maximizing product quality and process efficiency.
In an industry where product consistency, shelf life, and food safety are paramount, the adoption of efficient, hygienic, and automated emulsification equipment is essential for competitiveness. This case provides practical insights for optimizing mayonnaise and emulsified sauce production processes, demonstrating how vacuum emulsification technology can drive meaningful improvements in quality, efficiency, and cost-effectiveness—supporting sustainable production of safe, high-quality food products.
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