Research on the Application Technology of Diatomite Filter Aid in the Condiment Industry

I. The Key Role of Diatomite Filter Aid in Condiment Production
Diatomite filter aid, as an efficient and safe food-grade filtration medium, plays a crucial role in the refining process of condiments. This material is refined from natural diatomite fossils through high-temperature calcination at 900-1200°C, featuring unique physical properties: porosity of 80-90%, specific surface area of 15-30 m²/g, and pore size distribution ranging from 0.5 to 20 μm. In the condiment industry, diatomite filter aid is mainly used in the clarification and filtration processes of soy sauce, vinegar, and condiment sauces, effectively removing impurities such as protein precipitates, colloidal substances, and microorganisms.

According to GB 14930.1-2022 "National Food Safety Standard - Standards for the Use of Food Additives", food-grade diatomite filter aid is listed as an allowable food processing aid. Compared with traditional filtration methods, diatomite filter aid has three major advantages: high filtration accuracy, capable of removing particles larger than 0.5 μm; strong chemical inertness, not affecting product flavor; and a wide operating temperature range (0-100°C). In actual production, diatomite filter aid is typically used in a combined process of pre-coating and main filtration, achieving efficient clarification of condiments through mechanical interception and adsorption.

II. Application Practice of Diatomite Filter Aid in Soy Sauce Production
In soy sauce production, diatomite filter aid is mainly applied in the clarification and filtration process of raw soy sauce. Fermented mature soy sauce contains a large amount of suspended matter (0.5-2.5% content), which needs to be removed through precise filtration. The specific process parameters are: pre-coating thickness of 3-5 mm (diatomite dosage of 1-1.5 kg/m²), operating temperature of 20-25°C, and filtration pressure difference of 0.1-0.3 MPa. Research shows that the filtration system using diatomite filter aid can increase the light transmittance (660 nm) of soy sauce to over 95%, while retaining over 90% of amino acid nitrogen.

For different grades of soy sauce products, different specifications of diatomite filter aid should be selected: ordinary soy sauce is recommended to use products with a permeability of 1.5-3.0 Darcy, while high-end soy sauce should use high-precision diatomite filter aid with a permeability of 0.5-1.5 Darcy. Production data from a large soy sauce enterprise shows that optimizing the grade ratio of diatomite filter aid (coarse: medium: fine = 2:5:3) can stabilize the filtration speed at 15-20 L/m²·min, while extending the filtration cycle by 30-40%.

III. Technical Characteristics of Diatomite Filter Aid in Vinegar Refining
In vinegar production, diatomite filter aid can effectively solve the problem of colloidal stability that is difficult to handle with traditional filtration methods. The protein-polyphenol complexes in vinegar are effectively removed through the deep filtration effect of diatomite filter aid, extending the product's shelf life by more than 50%. Experimental data shows that diatomite filter aid treated with acid washing (pH 4-6) performs better in vinegar filtration, with a total acid retention rate of over 98% and no introduction of metal ion contamination.

Typical process conditions for vinegar filtration are: diatomite filter aid dosage of 0.5-1.0 g/L, filtration temperature of 15-20°C, and terminal filtration accuracy of 1-3 μm. It is worth noting that for different raw material vinegar (such as rice vinegar, fruit vinegar, etc.), the pore size distribution of diatomite filter aid should be adjusted: medium pore size (2-5 μm) is suitable for rice vinegar, while fine pore size (1-3 μm) is needed for fruit vinegar. Production practice shows that the optimized diatomite filter aid system can reduce the turbidity of vinegar to below 2 NTU, meeting the superior grade standard of GB 18187-2000 "Brewed Vinegar". 

IV. Innovative Application of Diatomite Filter Aid in Compound Seasoning Sauces
For compound seasoning sauces containing multiple ingredients (such as oyster sauce, condiments, etc.), diatomite filter aid demonstrates unique adaptability. By optimizing the particle size distribution and addition method of diatomite filter aid, the filtration problems of high-viscosity materials can be effectively solved. Specific measures include: adopting a "coarse-fine" gradient filtration process, with the coarse filter layer (20-30 μm) accounting for 60% and the fine filter layer (5-10 μm) accounting for 40%; controlling the filtration temperature at 40-50°C to reduce viscosity; adding an appropriate amount of diatomite filter aid (0.3-0.8%) as a filtration aid.
An application case of a certain condiment enterprise shows that using diatomite filter aid to treat oyster sauce products can reduce the insoluble solid content from 1.2% to below 0.3%, while maintaining the unique flavor substances of the product. Microbial testing data indicates that the total colony count of the seasoning sauce treated with diatomite filter aid can be reduced by 1-2 orders of magnitude, significantly improving the hygiene quality of the product.

V. Key Points of Quality Control and Process Optimization
To ensure filtration effect and product safety, diatomite filter aid for condiments must meet strict standards:
1. Hygiene indicators: Heavy metal content (calculated as Pb) ≤ 5 mg/kg, arsenic ≤ 3 mg/kg, in compliance with GB 14930.1 requirements;
2. Physical properties: Permeability 0.5-5.0 Darcy (depending on the product), moisture ≤ 0.8%;
3. Microbial indicators: Total colony count ≤ 1000 CFU/g, no pathogenic bacteria detected.
Process optimization suggestions:
1. Pre-coating optimization: Double-layer pre-coating technology (coarse layer 1-2 mm, fine layer 2-3 mm) can increase filtration efficiency by 20%;
2. Dynamic control: Adjust the addition rate of diatomite filter aid (0.1-0.5 g/L) according to turbidity changes;
3. Temperature management: Most condiments are suitable for filtration at 20-50°C. For every 10°C increase in temperature, the filtration speed increases by 15%;
4. Equipment selection: Plate and frame filter press is recommended for high-viscosity products, while candle filter is suitable for low-viscosity products.

VI. Technological Development Trends and Prospects
The technology of diatomite filter aid for condiments is developing in three directions:
1. Functionalization: Developing modified diatomite filter aid with antibacterial functions can reduce the use of preservatives;
2. Intelligence: Applying online monitoring technology to achieve precise control of diatomite filter aid addition;
3. Greening: Promoting the resource utilization of waste diatomite (such as soil conditioner).
Market analysis shows that with the increasing quality requirements of the condiment industry, the application of diatomite filter aid will become more widespread. It is estimated that in the next five years, the consumption of food-grade diatomite filter aid in the condiment field will grow at an average annual rate of 5-8%. Technological innovation will drive products towards higher efficiency and safety, providing strong support for the quality improvement of condiments.