This summary is intended for clients who need a systematic understanding of the key quality metrics for tomato concentrates and sauces, detailing the meaning of each value and its impact on product selection (such as Paste, Sauce, Ketchup, Soup, Frozen Food, etc.).
I. Core Metric: Brix (Soluble Solids)
1. What is Brix?
| Metric | Definition | Measurement Method |
| Brix ($^\circ\text{Bx}$) | Total Soluble Solids (TSS): Represents the grams of dissolved solid material per 100 grams of solution. | Measured using a refractometer, based on the solution’s refractive index. |
| Actual Composition | In tomato products, it includes natural tomato sugars, acids, and minerals, as well as added sugars and salts. | |
| Significance | Primarily reflects the product’s concentration level and sweetness. Higher Brix means lower water content and higher concentration. |
2. Main Brix Grades, Appearance, and Usage Differences
We mainly distinguish between the grades of Tomato Paste/Concentrate used as raw material:
| Brix Range | Terminology | Appearance Assessment (Viscosity) | Primary Uses (Relevant to Client Products) |
| 28%-30% | Double Concentrated | Medium Viscosity. Pours slowly but steadily. Easily pumped and transported. | Base for final Ketchup, most Soups, Dipping Sauce, Salsas (formulas requiring higher flow). Most versatile. |
| 30%-32% | Premium Double Concentrated | Slightly higher viscosity, good flow. | Higher quality Ketchup, thicker Salsas, base material for pasta Sauces. |
| 36%-38% | Triple Concentrated | Extremely High Viscosity. Paste-like, very difficult to pour, requires scooping, holds its shape when poured. | Used for Pizza Sauce (must be stable under heat), Frozen Food (strict moisture limits), high-viscosity Paste bases. |
II. Viscosity Metric: Bostwick Consistometer
1. Introduction to the Bostwick Consistometer
- Definition: The Bostwick Consistometer is a standardized tool used to measure the viscosity/consistency of semi-fluid materials.
- Measurement Method: Measures the distance (in centimeters) that a sample of the product flows down a graded trough in $30$ seconds.
- Numerical Significance: The shorter the distance flowed, the higher the consistency (higher viscosity).
| Metric | Definition | Function |
| Bostwick | Directly reflects the product’s flowability over a set time. | Ensures product manageability during filling and pumping, and guarantees consistent texture and appearance for the final retail product. |
2. Viscosity and Heat Treatment: Hot/Cold Break
Viscosity is not only determined by Brix but also by the heat treatment method applied to the raw tomatoes:
| Processing Method | Effect | Viscosity | Applicable Products |
| Hot Break | Rapid heating above 90°. This process deactivates Pectinase enzymes. | High Viscosity （HMC- High Mold Count) | Pizza Sauce, Frozen Food, high-viscosity Paste, etc. |
| Cold Break | Heating at a lower temperature 65°-75°). Pectinase enzymes are not fully deactivated and continue to break down pectin. | Low Viscosity ({LMC – Low Mold Count) | Ketchup, Soups, Drinks (for dilution), Dipping Sauce, etc. |
III. Net Solids and Other Chemical Metrics
1. NTSS (Net Total Soluble Solids)
| Metric | Definition | Significance and Role | Change from Standard Brix (TSS) to NTSS |
| NTSS | Net Total Soluble Solids | Measures the solids derived purely from the tomato. Calculated by subtracting non-tomato solids (e.g., added salt) from TSS (Total Brix). | NTSS is always slightly lower than the Brix value. For example, a 30°Bx product with 1.0% added salt will have an NTSS of approximately 30 – 1.1 =28.9Bx (based on conversion factors). |
| Role | Assesses purity, prevents manufacturers from falsely inflating the total Brix by adding excessive salt, and is a key metric for valuing tomato concentrate in international trade. |
2. Other Key Chemical Metrics
| Metric | Definition | Role and Significance | Impact on Product Selection |
| Total Acidity | Total acidity (usually expressed as a percentage of Citric Acid). | Affects the product’s flavor balance and microbial safety （pH） | High acidity (low pH ) is more shelf-stable and has a “tangier” flavor; low acidity is “milder.” |
| Lycopenemg/100g | Lycopene content (milligrams per 100g). | A key indicator of nutritional value, reflecting the tomato variety, maturity, and concentration. | High Lycopene content generally suggests a healthier raw material and a deeper red color. |
3. Color Metrics: L, A/B
| Metric | Definition | Role and Significance |
| L | Lightness: Ranges from 0 (pure black) to 100 (pure white). | A lower L value indicates a darker tomato color. |
| A/B | Redness Ratio: The ratio of the a value (red-green axis) to the b value (yellow-blue axis). | A higher A/B ratio means the product is redder (less yellow or brown). This is the most important metric for tomato color and quality. |
| Role | Ensures color consistency and visual appeal, and is crucial for distinguishing high-quality raw materials. |
Summary and Next Steps
| Client Target Product | Recommended Brix/Concentrate Type | Recommended Viscosity/Heat Treatment | Key Focus Metrics |
| Ketchup | 28-30 | Cold Break (Easy pumping and filling) | Bostwick (Must achieve good pouring speed), Total Acidity (Affects taste). |
| Pizza Sauce | 36-38 | ||
| Frozen Food | 36-38 | ||
| General Soup/Dip | 28-30 | Cold Break or Standard Viscosity | Total Acidity (Affects shelf life). |
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