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total solids

Total Solids (TS)

Total solids in the food industry refer to the sum of all solid material present in a food product after the complete removal of water and other volatile substances under specified drying conditions. It is expressed as a percentage of the product’s total weight and includes all non-water components: proteins, carbohydrates, fats, minerals, fibers, salts, and other dissolved or suspended solids. TS of food raw materials are here.

Total solids in Food Industry & Science

  • Quality Control – TS affects texture, taste, stability, and shelf life.
    Process Control – important in dehydration, concentration, and evaporation processes.
  • Standardization – ensures consistency in dairy products, juices, syrups, sauces.
  • Economic Value – higher TS can mean higher yield (e.g., in tomato paste, milk powder).
  • Regulatory Compliance – certain foods have minimum TS requirements (e.g., fruit jams, maple syrup).

Typical Components in TS

  1. Carbohydrates – starches, sugars, fiber
  2. Proteins – casein, whey, gluten, soy proteins
  3. Lipids – animal fats, vegetable oils
  4. Minerals (Ash) – calcium, sodium, potassium, magnesium, phosphates, chlorides
  5. Organic Acids – citric, lactic, malic acids
  6. Vitamins & Phytochemicals – ascorbic acid, carotenoids
  7. Other Solids – emulsifiers, stabilizers, pigments

Measurement Methods

  1. Gravimetric Oven-Drying Method (Most Common)
    Sample weighed → dried at 105 °C ± 2 °C in a convection or vacuum oven until constant weight is achieved → cooled in a desiccator → weighed again. Loss in mass = water content; remainder = total solids.

  2. Vacuum Oven Method
    Lower temperatures (60–70 °C) under reduced pressure; used for heat-sensitive foods.

  3. Infrared Drying
    Rapid drying using IR heat; results comparable to oven method.

  4. Refractometry
    Measures soluble solids (°Brix), often used for syrups, fruit juices — note: measures soluble solids, not total solids unless insolubles are negligible.

  5. Microwave Drying
    Fast method using microwave energy to evaporate water.

Industry Examples

Maple Syrup – must have ≥ 66% total solids (mostly sugars) to meet legal definition.
Milk – typically ~12–13% total solids (fat, protein, lactose, minerals).
Tomato Paste – high-quality paste: ≥ 28% total solids.
Fruit Jam – regulated to have ≥ 68% soluble solids (close to TS if pectin & fiber included).
Chocolate Syrup – TS determines viscosity and sweetness.