Clean Label Mold Inhibitors | American Society of Baking
Commercial Baking Ingredients:

Clean Label Mold Inhibitors

Also known as natural mold inhibitors

What are clean label mold inhibitors?

Clean label mold inhibitors are natural preservatives that help control mold growth and prolong the shelf life of food. Products like whole wheat, multigrain and artisan bread are good uses for these ingredients.

These ingredients provide bakers with a wide range of benefits. Although, they may present unique challenges.1 Examples include:

  • Vinegar
  • Raisin and prune juice concentrates
  • Fermented/cultured flour
  • Starch
  • Whey
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Clean label mold inhibitors in bakery applications have become a core subject in the development of new products. High-speed bakers are starting to replace chemical preservatives, like calcium propionate and sorbates, with natural mold inhibitors.


There are two main clean label mold inhibitor categories, based on what they do. First is pH reduction in dough or batter, and then disrupting mold cellular membranes and processes.2

Category 1: pH reduction2,3,4,5

  • Vinegar
  • Prune/plum  juice concentrate (PJC)
  • Raisin juice concentrate
  • Culture whey products
  • Cultured flour

Category 2: cell disruption2,6

  • Cinnamon
  • Cloves (Syzygium aromaticum)
  • Natamycin

Commercial production

  • Vinegar: produced through the fermentation of carbon sources using food-grade microorganisms, like acetic bacteria.
  • Fruit juice concentrates: prepared by a series of soaking or washing steps of raisins, plums or prunes in water. Then, the liquid containing leached organic acids is evaporated under vacuum to a 70° Brix syrup.
  • Cultured whey products: obtained by fermenting pasteurized sweet whey, with a culture of food-grade lactic acid bacteria (LAB).
  • Cultured wheat flour/starch: similar to cultured whey products.
  • Cinnamon, cloves: natural spices 
  • Natamycin: produced through fermentation of carbon sources, using the food-grade microorganism Streptomyces natalensis.


Category 1: pH reduction1,2,3,4

Relevant aspects / benefits Amount used (baker’s %) Associated challenges


Active component: Acetic acid

  • Vinegar is a dilute solution of acetic acid in water.
  • Strength of vinegar is measured in “grains.” 1 grain is equal to 0.1% of acetic acid.
  • Commercial bakers use 100-grain or 200 grain vinegar (10% or 20% acetic acid, resp.)
  • Does not contribute to color.
  • pH: 2.3–3.4 (100–300-grain)
0.5–2.0% (50-grain), or0.25–1.0% (100-grain)
  • Because it’s a weak acid, it dissociates poorly in aqueous media. So, this limits its effectiveness in lowering pH to inhibitory levels. This is a challenge in applications that require shelf-life equal to CalPro treated breads. (1)
  • Too much vinegar creates undesirable odors and off-flavors. Yeast levels should be increased because low pH slows down yeast activity. (2)
  • Dough with too low of a pH takes longer to fully proof. Also oven spring may not be sufficient for optimum volume. (3)

Prune/plum  juice concentrate (PJC)

Active ingredients: Malic (1–2%), benzoic and salicylic acid occur naturally in prunes.

  • Contains 14% sorbitol which lowers water activity, thus, contributing to mold growth inhibition.
  • pH: 2.0–3.0
  • 25–30% moisture
  • Very rich in glucose, fructose and sucrose (65–70°Bx).
  • Contributes to pleasant flavors and color.
  • (1) See above
  • May cause excessive crust darkening due to additional sugars that can participate in browning reactions. (4)
  • At high concentrations it may slow down yeast activity, as a result of high osmotic pressure built up in the dough. (5)
  • Additional water coming from the juice concentrates requires lowering dough water absorption. (6)

Raisin  juice concentrate (RJC)

Active ingredient: Tartaric (1–2%) and propionic acids (500–600 ppm)

  • Very rich in glucose, fructose and sucrose (65–70°Bx).
  • Contributes to pleasant taste and color.
  • pH: 2.0–3.5
  • 25–30% moisture
  • (1) (4) (5) (6)

Cultured whey products / Cultured wheat

Active ingredient: Acetic, propionic and lactic acids

  • Follow supplier’s instructions for proper formulation.
Varies depending on formulation
  • (1) (2) (3)

Category 2: cell disruption1,2,3,5

Relevant aspects / benefits Amount used (baker’s %) Associated challenges

Cinnamon, cloves

Active components: Cinnamaldehyde, eugenol, acids and alcohols

  • Contribute to unique flavors and aromas
1.0–2.0% (dry spice solids)
  • Slight overscaling might create flavors and aromas that are too strong or harsh.
  • Effect on yeast activity and growth must be evaluated.
  • Slightly expensive alternative.


  • Strong antifungal action
Spray a 7–20 ppm solution on the surface of  baked foods.
  • Expensive alternative.

FDA regulation

Clean label inhibitors fall into the category of natural food ingredients. These can be added to food products with no limitations. Natamycin is the only exception, where  maximum usage levels cannot exceed 20 milligrams per kilogram of product (20 ppm).6


  1. Sahi, S.S. “Applications of Natural Ingredients in Baked Goods.” Natural food Additives, Ingredients and Flavourings, Woodhead Publishing Limited, 2012, pp. 318–332.
  2. Albers-Nelson, R. “Clean Label Mold Inhibitors for Baking”. Oklahoma State University Cooperative Extension FAPC-173, 2010.
  3. Sanders, S.W. “Using Prune Juice Concentrate in Whole Wheat Bread and Other Bakery Products.” Cereal Foods World, 36, 1991, 280–283.
  4. Fagrell, E. “Raisin Usage in Baked Goods.” AIB Research Department Technical Bulletin. Volume XIV, Issue 4, 1992, 1–8.
  5. Peter, K.V. Handbook of Herbs and Spices, 2nd Edition, Woodhead Publishing Limited, 2012, pp. 182–215.
  6. U.S. Food and Drug Administration, CFR – Code of Federal Regulations Title 21, Part 172: Food Additives Permitted for Direct Addition to Food for Human Consumption, Accessed 29 May 2019.