Case Study: Vacuum Homogenizing Emulsifier in High-Viscosity Food Paste Production
In the food processing industry, high-viscosity pastes such as nut butters, salad dressings, and dairy-based spreads require strict control over texture, particle fineness, emulsification stability, and hygiene standards. Traditional production methods often struggle to balance these requirements, leading to quality inconsistencies and inefficient processes. This case study explores how a customized vacuum homogenizing emulsifier addressed core technical challenges in food paste production, improved product quality, and optimized operational efficiency, while adhering to food safety regulations.
1. Background and Production Challenges
The production facility focuses on processing natural food pastes and emulsified sauces, with a focus on products with high oil content and viscosity. Prior to upgrading equipment, the facility relied on conventional planetary mixers and colloid mills for production. Long-term operation exposed several persistent issues that hindered product quality and scalability.
First, particle fineness and texture uniformity were subpar. Conventional mixers lacked sufficient shearing force to fully break down solid particles (e.g., nut fragments, spice particles) and disperse oil droplets evenly. This resulted in a grainy mouthfeel, with average particle sizes ranging from 40-60 μm, and visible agglomerates in some batches—compromising consumer acceptance. Second, emulsification stability was inadequate. The oil-water phases in products like salad dressings and composite nut butters failed to fuse completely, leading to stratification and oil separation after 2-3 months of storage, even under refrigerated conditions (4-8℃).
Third, air bubble inclusion was a recurring problem. Traditional mixing processes introduced air into the material, creating micro-bubbles that affected the product’s appearance (dull texture, surface porosity) and accelerated oxidative deterioration of unsaturated fatty acids—shortening shelf life by 20-30%. Additionally, the multi-step production process was time-consuming: each batch required separate mixing, grinding, and deaeration, taking approximately 3 hours to complete. High energy consumption from prolonged equipment operation and frequent maintenance of colloid mill components further increased operational costs.
To resolve these issues, the facility sought a solution that could achieve fine particle dispersion, stable emulsification, bubble-free texture, and compliance with food safety standards (FDA, EHEDG). After rigorous pilot testing and performance evaluation of multiple equipment types, a customized vacuum homogenizing emulsifier was selected for integration into the production line.
2. Equipment Selection and Technical Adaptation
Considering the characteristics of food pastes—high viscosity (5,000-80,000 mPas), high oil content (30-60%), sensitivity to oxidation, and strict hygiene requirements—the selected vacuum homogenizing emulsifier was customized to match the production process. Key technical features are as follows:
The emulsifier adopts a dual-stage rotor-stator structure with a maximum rotational speed of 12,000 rpm and linear speed of 45 m/s. The adjustable gap (0.1-0.4 mm) between the rotor and stator generates intense shearing, cavitation, and turbulent forces, effectively breaking down solid particles into micro-sized dispersions (≤5 μm) and promoting complete fusion of oil-water phases. A frequency conversion motor enables stepless speed adjustment (1,500-12,000 rpm), adapting to different material viscosities and formulation requirements.
In terms of vacuum performance, the integrated high-efficiency vacuum system achieves a vacuum degree of -0.095 to -0.098 MPa, which is maintained throughout the emulsification process. This eliminates air bubbles generated during mixing, prevents oxidative degradation of sensitive ingredients (e.g., polyunsaturated fats, natural antioxidants), and ensures a smooth, bubble-free product texture. The sealed chamber design prevents air re-entry, maintaining stable vacuum performance during continuous operation.
Food safety and hygiene were prioritized in material selection: all product-contacting parts are made of 316L stainless steel, undergoing electrolytic polishing to achieve a surface roughness Ra ≤ 0.4 μm. This design prevents material adhesion, reduces cross-contamination risks, and facilitates cleaning-in-place (CIP) operations—complying with FDA food contact material standards and EHEDG hygiene guidelines. A jacketed temperature control system with ±1℃ precision regulates processing temperature between 25-60℃, avoiding thermal degradation of nutrients (e.g., vitamins, natural oils) and ensuring consistent product flavor.
To enhance operational flexibility, the emulsifier features a modular design with a customizable chamber volume (200-2,000 L), supporting both small-batch pilot production and large-scale mass production. An automatic control system with a touchscreen interface monitors and records key parameters (rotational speed, vacuum degree, temperature, processing time) in real time, ensuring batch-to-batch consistency.
3. Implementation and Process Optimization
Before full-scale production, the technical team conducted multi-batch pilot tests to optimize emulsifier parameters for different product formulations, focusing on nut butters, oil-in-water salad dressings, and dairy-based spreads. The tests aimed to determine the optimal combination of rotational speed, emulsification time, temperature, and phase addition sequence to achieve desired particle size, emulsification stability, and texture.
Pilot test results identified formulation-specific optimal parameters: For nut butters, a rotational speed of 9,000 rpm, emulsification time of 20 minutes, and temperature of 45℃ achieved complete particle dispersion and oil fusion. For oil-in-water salad dressings, 8,000 rpm, 15 minutes of emulsification at 35℃, and gradient addition of the water phase to the oil phase under vacuum yielded the best stability. Under these parameters, particle size was consistently controlled below 5 μm, and no air bubbles or phase separation were observed in preliminary storage tests.
Based on these results, the production line was adjusted to integrate the vacuum emulsifier into the existing workflow, optimizing the process as follows: Raw materials (e.g., roasted nuts, oils, stabilizers) are preprocessed (crushed, melted, dissolved) and preheated to the specified temperature. The preprocessed materials are then added to the emulsifier chamber in the optimized sequence, and the vacuum system is activated to reach the target vacuum degree. The emulsifier operates under preset parameters, with materials circulated through the rotor-stator area 4-6 times to ensure uniform dispersion. After emulsification, the vacuum is maintained for an additional 5-8 minutes to remove residual bubbles, and the product is cooled to 25℃ before discharge to the filling station.
This optimized process eliminated the need for separate grinding and deaeration steps, integrating three traditional operations into one. The automatic parameter control system reduced manual intervention, minimizing human error and ensuring consistent process execution across batches.
4. Application Results and Performance Improvements
After the vacuum homogenizing emulsifier was put into formal operation, the production line achieved significant improvements in product quality, production efficiency, and operational costs, with measurable results across key metrics:
In terms of product quality, particle fineness was drastically improved—average particle size was reduced from 40-60 μm to 2-5 μm, eliminating graininess and delivering a smooth, creamy mouthfeel. Emulsification stability was enhanced: all products passed 6 months of refrigerated storage testing (4-8℃) and 3 months of ambient temperature storage testing (25±2℃) without stratification, oil separation, or texture changes. The elimination of air bubbles improved product appearance (uniform luster, no porosity) and extended shelf life by 30-40% by reducing oxidative degradation. Batch consistency was significantly improved, with key quality indicators (viscosity, particle size, pH) fluctuating within ±5%—a marked improvement from the previous ±15% variation.
Production efficiency was greatly enhanced: the batch processing cycle was shortened from 3 hours to 45 minutes, a reduction of 75%. The emulsifier’s high throughput capacity increased daily production volume from 6 tons to 22 tons, enabling the facility to meet peak market demand. The automatic control system and simplified process reduced labor intensity—each operator could monitor two production lines simultaneously, and batch record documentation time was cut by 60% due to real-time parameter recording.
Operational costs were reduced across the board: energy consumption per ton of product decreased by 35% due to the emulsifier’s high efficiency and frequency conversion speed regulation. Maintenance costs dropped by 40%—the wear-resistant rotor-stator components extended service life by 2-3 times compared to colloid mills, and the easy-to-clean design shortened CIP time by 50% and reduced detergent consumption. Additionally, compliance with food safety standards reduced the risk of quality non-conformities, with the product inspection pass rate increasing from 89% to 99.6%.
Consumer feedback also improved noticeably—complaints related to grainy texture and oil separation decreased by 92%, and repeat purchase rates for core products rose due to consistent quality.
5. Summary and Insights
The application of the customized vacuum homogenizing emulsifier successfully resolved the technical bottlenecks of traditional food paste production, achieving a balance between product quality, production efficiency, and food safety compliance. The key to this success lies in the precise alignment of the equipment’s technical capabilities with the unique requirements of high-viscosity, high-oil food formulations—its high shear force ensures fine particle dispersion, vacuum function eliminates bubbles and oxidation, and food-grade design meets strict hygiene standards.
For food processing enterprises producing emulsified pastes and sauces, the selection of equipment that matches material characteristics and conducting thorough pilot testing are critical to process optimization. The modular and automated design of the emulsifier also provides scalability, allowing the facility to adapt to new formulations and production scales by adjusting parameters or modifying chamber volume.
In an era of increasing consumer demand for natural, high-quality food products and stricter food safety regulations, the adoption of efficient, stable, and compliant processing equipment has become essential for enhancing competitiveness. This case provides practical insights for the optimization of high-viscosity food paste production processes, demonstrating the value of advanced emulsification technology in driving quality improvement and operational efficiency in the food industry.
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