Vinegar (EU) is a historic food preservative. In the push for clean labels, vinegar is an item in which consumers are familiar and stock in their pantry. Within food processes, vinegar is incorporated to restrict bacteria and mold growth. It is also a flavoring agent, and is a typical ingredient used to make authentic Italian pasta filata-style mozzarella cheese (EU) and whey ricotta cheese (EU). In fresh fruits and vegetables (EU), vinegar can be used in a wash to reduce surface bacteria and viruses.
Vinegar is produced using a two-step fermentation process. First natural carbohydrates in a liquid are fermented by yeast into ethanol (EU) and in a second step the ethanol is fermented into acetic acid by acetobacter bacteria. With the numerous options for starting material there are many different types of vinegars available with varying flavor profiles.
Vinegar is primarily acetic acid (E260), however diluted acetic acid cannot be labeled as vinegar. Depending on the starting sugar source, resulting vinegars contain other organic acids. For example, wine vinegar (EU) starts from grapes and the result contains acetic and tartaric acids (EU); balsamic vinegar (EU) contains acetic, tartaric and malic acids (EU); apple cider vinegar (EU) stemming from apples contains acetic, malic and citric acids.
In addition to lowering pH, organic acids found naturally in vinegar have different levels of lethality to various bacteria strains. For example, in a study comparing lactic, acetic, citric and malic acids, lactic acid (EU) tends to inhibit E.coli at a higher rate while acetic acid tends to inhibit Listeria at a higher rate. All performed better, when compared to hydrochloric acid at a similar pH, indicating that these organic acids may transfer into bacterial cell membranes and damage more easily than inorganic acids.
Grain strength is equal to the acetic acid content of vinegar. On the store shelves, 50 grain, or 5% acetic acid is normal. For industry vinegar producers make more concentrated vinegars with the majority equal to 120 grain or 12% acetic acid. Vinegar grain (EU) is easily adjusted to meet formulation requirements by mixing with water before processing. Depending on the type of vinegar, pH ranges from 2.3 to 3.4 for white vinegar (EU), while other vinegars like cider vinegar (EU) can have a higher pH range.
Acidified Foods – Lowering pH:
In acidified foods like pickles (EU), vinegar is used to lower the pH of a finished product to under 4.6 to help prevent the growth of pathogenic bacteria like Clostridium botulinum. Typically processors achieve a final product pH closer to 4.2 and monitor the subsequent heating process closely (hot-filling or boiling water bath) to ensure the safety of the food. For more information, in the US acidified foods are regulated by the FDA under 21 CFR 113 &114 and USDA under 9 CFR G.318 & 381; “Better Process Control School” is required for all processors.
Bakery – Mold reduction:
Bakery product (EU) mold growth over shelf life, especially in the summer months, is a product challenge. While using artificial preservatives are very successful in reducing mold growth, vinegar has also shown to be a natural mold inhibitor. To use vinegar in bakery as a mold inhibitor generally 100 grain vinegar is added to dough at levels less than 1% to lower the pH of the dough.
When working with vinegar be aware that the finished product may carry some vinegar flavor if used at levels too high so balance the shelf life requirement with desired end flavor profile. Research around vinegar as a dough acidulate indicates that too much vinegar can negatively impact the effectiveness of yeast. To counter this, the formula yeast percentage should be increased and the finished dough should be given a longer proof time to achieve the desired rise.
Meat – Bacteria Reduction:
Meat (EU) offers an idea environment for both spoilage and pathogenic bacteria growth. Several studies on both raw and ready to eat meats have been conducted over the last few years. Results indicate that vinegar may be a viable solution for the meat industry as processors look to reduce artificial preservatives.
One study showed that high use levels (2%) of acetic acid treatments on raw meat in a spray or dip has the potential to produce an off color, off flavor or odor; these product changes were reduced when paired with lactic acid. Another studied indicated that using 2% of a buffered vinegar, with a pH of 6-6.5, resulted in microbial protection with minimal off notes. Both studies showed suppressed bacteria growth over shelf life.
Additional Development Thoughts:
When working with vinegar you’ll need to consider that vinegar may change the flavor of your product. In a production environment, vinegar can be corrosive to equipment. In establishing claims, consider the starting vinegar source to make gluten free claims and if labeling naturally preserved consider the GMO status of the raw materials to make the vinegar. Vinegar is seen by the consumer as a clean ingredient and vinegar can aid in increasing product quality by reducing both pathogenic and spoilage bacteria growth.
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