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What are “physicochemical characteristics”?

Physicochemical characteristics” describe the physical and chemical properties of a product, often a food or ingredient. They provide insight into the product’s stability, safety, and shelf life.

Typical physicochemical parameters include:

  • pH value
  • Water activity (aw)
  • Density
  • Melting point
  • Solubility
  • Viscosity
  • Conductivity

These parameters are important for understanding microbiological stability, taste, texture, and shelf life.

What is the pH value?

The pH value indicates how acidic or alkaline (basic) a product is.

  • pH 0–7 = acidic

  • pH 7 = neutral (like pure water)

  • pH 7–14 = basic (alkaline)

Examples:

  • Lemon juice: pH ≈ 2–3

  • Milk: pH ≈ 6.5

  • Soap: pH ≈ 9

A low pH often inhibits bacterial growth, which is why acidic foods (like yogurt or jam) tend to have a longer shelf life.

What is Water Activity (aw)?

Water activity (abbreviated as aw) indicates how much free water is available in a product for microbial growth (bacteria, yeasts, molds).

The value ranges between 0 and 1:

  • aw = 1 → pure water

  • aw < 0.6 → almost no microorganisms can grow

  • aw ≈ 0.9 → most bacteria can grow

Examples:

  • Dry biscuits: aw ≈ 0.3

  • Bread: aw ≈ 0.95

  • Dried fruit: aw ≈ 0.6–0.7

Water activity is not the same as moisture content; it indicates the availability of water for biological processes, not the total amount of water present.

Why are pH and Water Activity important?

Together they determine:

  • Shelf life (how long the product stays safe and stable)

  • Microbiological safety (which organisms can grow)

  • Texture and flavor stability

  • Required preservation method (refrigeration, drying, pasteurization, etc.)

Would you like me to adapt this into a short, professional definition suitable for inclusion in a product specification sheet (for example, within your PIM)?