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Caustic Soda in Food Processing: Peeling, CIP and Food Grade

Manglore Chemical
30 Oct

Caustic Soda in Food Processing: Peeling, CIP and Food Grade

Caustic soda is used throughout the food industry, from peeling fruit and vegetables to cleaning processing lines. Because it may contact food or food surfaces, the grade, the dose and the rinsing all matter. This guide covers the main uses and what to check.

Lye peeling

Many fruits and vegetables, such as tomatoes, peaches and potatoes, can be peeled by passing them through a hot caustic solution. The caustic softens the skin, which is then removed by water sprays or rubbers. Strengths range from a few percent up to around 20% depending on the product, used hot for a short time. Thorough washing afterwards removes residual alkali, and the process must be controlled to avoid excessive peel loss.

Cleaning-in-place (CIP)

Dairies, breweries, juice plants and other food factories clean tanks, pipes and heat exchangers with hot caustic, typically around 0.5 to 2% NaOH at 70 to 85 °C. Caustic removes fats and proteins; an acid step then removes mineral deposits. A final rinse with potable water completes the cycle.

Other uses

  • pH adjustment in some food processes and in effluent treatment.
  • Bottle washing in beverage plants.
  • Edible oil refining, to neutralise free fatty acids.

Food grade or technical grade?

Where caustic soda is added to food or used in a way that can leave residues on food, use food grade caustic soda meeting a recognised food additive specification, with limits on heavy metals, arsenic and other impurities. For CIP followed by a full potable-water rinse, many plants use high-purity technical flakes, but your food safety plan and auditors decide. Always check the certificate of analysis for:

  • purity (typically at least 99% NaOH);
  • heavy metals (as Pb), arsenic and iron;
  • chloride and carbonate.

Safety and hygiene

  • Store caustic away from food ingredients and from acids.
  • Label CIP chemical tanks clearly and lock out dosing during maintenance.
  • Verify rinsing with pH checks before production restarts.
  • Provide eyewash stations at chemical dosing points.

For food companies operating in Oman

Caustic soda flakes 99%, with the COA showing heavy metals, arsenic and iron results, are available in Oman from ready stock in Barka. See muscatchemical.com/caustic-soda.