Additives That Lower Water Activity of Food

Various additives employed for lowering water activity of food are known as:

Correct Answer: Humectants

Humectants are food additives that lower the water activity (Aw) of food by binding free water, thereby preventing microbial growth and extending shelf life.

Commonly Used Humectants

• Glycerol (Glycerin) — most commonly used; GRAS status; used in confectionery, cured meats
• Sorbitol — sugar alcohol; used in dried fruits, confectionery
• Propylene glycol — used in semi-moist pet foods and some human food applications
• NaCl (salt) — lowers Aw; traditional humectant in curing
• Sugar (sucrose) — lowers Aw; used in jams, dried fruits

Why Water Activity (Aw) Matters

• Most bacteria require Aw > 0.91 to grow; moulds can grow at Aw as low as 0.70.
• Lowering Aw is one of the most effective ways to preserve foods without refrigeration.

Note: Humectants Paradox

Despite binding water and lowering Aw, humectants keep the food texture moist and pleasant — they prevent drying out while simultaneously preventing microbial growth.