Acidified Sausages

The following information is reprinted with permission from "The Practical Guide to Making Salami" by Stanley Marianski.

Acidification and Acidulants

The Food Safety and Inspection Service (FSIS) accepts both natural fermentation and/or chemical acidification as proper methods for generating acidity. Fermentation, a form of naturally occurring acidification, has long been used for food preservation. However, there is another method called acidification or acidulation, which employs natural substances known as acidulants and can be applied to control the growth of undesirable microorganisms, including pathogens. Acidulants increase the acidity of meat through chemical reactions that do not involve lactic acid bacteria. Hence, there is no bacterial fermentation and no need for sugar. Acidulation is usually performed alone, but it can be combined with a starter culture, too. Acidulants immediately react when exposed to moisture in meat and work faster at higher temperatures. This greatly shortens the process of lowering pH; however, a high dosage of acidulant results in a harder texture and imparts a tangy taste to the sausage. Hence, acidification is generally used in the production of less expensive semi-dry products. Acidulants do not cure meat directly; however, by lowering pH, they contribute to developing a red color. The acidity they develop speeds up the chemical conversion of sodium nitrite to nitric oxide, which in turn reacts with meat myoglobin and creates a pink color, so they act as an accelerator. Still, they do it by reacting with sodium nitrite, which must be present to begin with. The typical curing accelerators used in the meat industry are sodium erythorbate and ascorbic acid.

The benefit of acidification is that pH is easier to control, and the sausage can be produced in a chamber that lacks temperature and humidity control. It must be realized that acidification creates products of much lesser quality than bacterial fermentation. The most popular acidulants are:

• Gdl (glucono-delta-lactone) - used to make cottage cheese, tofu, bakery products, and fermented sausages.
• Citric acid - used to add an acidic taste to foods, soft drinks, and wine.

Glucono-delta-lactone (Gdl)

Gdl is manufactured by microbial fermentation of pure glucose to gluconic acid but is also produced by the fermentation of glucose derived from corn or rice. Gdl can be found in honey, fruit juices, wine, and many fermented products. Since Gdl lowers the pH, it also helps preserve food from deterioration by enzymes and microorganisms. Glucono-delta-lactone is often used to make cottage cheese, tofu, bakery products, and fermented sausages. In natural bacterial fermentation, acidity is generated by lactic acid bacteria, but in chemical acidulation, Gdl, under the influence of the meat's own water, breaks down to gluconic acid, decreasing the pH in a controlled manner. Gluconic acid is non-toxic and completely metabolized in our bodies. Compared to other food acids, glucono-delta-lactone can be considered to be a slow-release acidulant. After dissolving in water, gluconic acid is produced in about 60 minutes. It can reach the lowest pH within a few hours, depending on the meat's initial pH, its moisture content, the amount of Gdl, and the temperature. Gdl works well at 71-75° F (22-24° C), but like any chemical reaction, it will work faster at higher temperatures. Decreasing the temperature may only slow it down; to stop the reaction, we have to freeze the meat.

Gdl is usually added at 0.2-0.8% (2-8 g/kg). As it is a natural acid, adding more than 1% (10 g/kg of meat) may cause a more pronounced sour flavor. Once Gdl is added to the sausage mass, the meat's pH starts dropping down, and the reaction will continue for as long as there is remaining Gdl and free water inside of the sausage.
Adding 0.1% (1 g/kg of meat) Gdl lowers pH by 0.1 pH.

• Initial meat pH = 5.8, adding 0.4% Gdl lowers pH to 5.4
• Initial meat pH = 5.8, adding 1.0% Gdl lowers pH to 4.8

The addition of sugar lowers the meat's pH during fermentation, but adding Gdl will speed up the process. Gdl is a pH-neutral, whitish powdered natural food acid (roughly a third of the sourness of citric acid) that contributes to the tangy flavor of various foods.

In the USA, Gdl is classified as GRAS, Generally Recognized As Safe, as per 21 CFR 184.1318 for use in food with no limitation other than current good manufacturing practice as a curing and pickling agent, leavening agent; as pH control agent and as sequestrant (a food additive which improves the quality and stability of foods). Gdl is cleared by the Meat and Poultry Inspection Division as an acidifier in meat and poultry products at the following amounts:

• 0.5% - 8 oz of Gdl (0.5%) to 100 lb meat or meat byproducts.
• 1.0% - 16 oz (1 lb) of Gdl to 100 lb meat (Genoa salami only).

In Europe, glucono delta-lactone is approved quantum satis (as needed) unless otherwise restricted for use as an acidity regulator and a sequestrant. Gdl was a great acidulant in the past; however, with the recent entry of easy-to-administer cultures, its popularity is fading away. By introducing a fast-fermenting culture with the right amount of sugar, we can achieve the same results yet produce products with a better flavor. Gdl is a slow-release acidulant that provides a slow but continuous hydrolysis to gluconic acid, which takes place gradually in about 40-60 minutes after dissolution in moisture in meat. In water, it hydrolyzes to gluconic acid very quickly. During its hydrolysis, the initial sweet taste of Gdl becomes only slightly acidic, resulting in the final flavor being much less tart than that of other acidulants.

Citric Acid

Citric acid is a weak organic acid found in citrus fruits. It is a natural preservative that adds an acidic taste to foods, soft drinks, and wine. It is safe for human consumption. Citric acid is a white crystal material with a strong acid taste that is fully soluble in water. It acts faster than Gdl; adding 1 g of citric acid to 1 kg of meat lowers the pH of meat by about 0.3 - 0.4 pH units.
To lower the pH of meat from pH 5.8 to pH 4.8 (one pH 1.0 unit), around 3-4 grams of citric acid/1 kg of meat is needed. The easiest way to mix such a small amount uniformly with ground meat is to dissolve 4 g of citric acid in 60 ml (2 oz fl) of water. Add citric acid last while mixing ingredients, then stuff the mixture into the casing without delay. Although both Gdl and citric acid introduce a sour taste, it is accepted that Gdl is slightly milder. To protect meat from flies and spoiling bacteria, hunters mix citric acid with water and spray the meat with a spray bottle. Note that citric acid tends to lump together if stored above 75% humidity.

Acidulants are available in two forms:

• Powdered - little crystals that react immediately when exposed to moisture.
• Encapsulated - little crystals that are coated with vegetable oil that melts down at varying temperatures, from 122-150º F/50-66º C.

Adding 1% (10 g/kg) powdered Gdl or 0.3% (3 g/kg) of citric acid to meat will:

• Rapidly increase acidity and will prevent flavor forming bacteria from reacting with meat.
• Contribute negatively to binding properties of minced meat as the acid will start cooking proteins. That is why the sausage mixture should be stuffed into the casing without much delay.

Using a Fine Spray Bottle

Introducing 0.1 -0.3% (1-3 g/1000 g of meat) of powdered citric acid presents a formidable challenge, as a uniform distribution of acidulant is important for proper acidification. Water removal is not a crucial factor in heated acidified products since it will evaporate during cooking, thus, a practical approach is to dilute 1-3 g of citric acid in 30 ml (1 oz fl) of water and mix it with meat. The solution can also be dispersed as a fine mist from a fine spray bottle.

Encapsulated Acids

Applying strong substances such as citric acid, lactic acid, or Gdl (glucono-delta-lactone) will also cook (denature) proteins in meat. Thus, adding Gdl or citric acid in powdered form to minced meat will start cooking the meat to a small degree, affecting the binding between meat particles and negatively affecting the texture. Encapsulated acids such as Gdl/gluconic, citric, lactic, and fumaric are coated with a hydrogenated cottonseed oil coating, which prevents them from reacting with meat during mixing and stuffing, as these stages of processing are performed below the melting point of encapsulated acid. Then, as the meat is heated to 122-150º F (50-66º C), the coating melts down, exposing the acidulant, which starts reacting with moisture and generates acidity. Thus, the temperature triggers the start of acidification. The rate of acid release is basically dependent upon the temperature and the available moisture.

Why and When to Use Encapsulated Acidulants

Using powdered acidulants for making semi-dry sausages is easy to justify as they drastically shorten the processing time by eliminating natural fermentation. The benefit of using encapsulated acidulant is that it provides more time for Staphylococcus spp. flavor-producing bacteria (naturally present in meat) to develop flavors. However, this requires that no heat treatment can be performed during the first 24 hours. The temperature must be maintained below 60º F (16º C); otherwise, pathogenic S. Staphylococcus will start growing. Adding 0.1% (1 g/kg) of dextrose would allow lactic bacteria to generate a slight acidity, providing some safety, yet will not prevent flavor-forming bacteria from working.

The heating requirement limits the use of encapsulated citric acid to fast-acidified semi-dry sausages, such as partially cooked pepperoni pizza toppings or sausage. Given that summer sausage or other semi-dry sausages are cooked later in the process, adding encapsulated acidulants (citric acid, Gdl, lactic acid) is fine, as encapsulated acidulants will start melting after the internal meat temperature reaches 122-150º F (50-66º C). This means the flavor-forming bacteria can receive sufficient time to develop flavor before the heat is applied and the encapsulated acidulant melts down and lowers pH. Encapsulated acid must be the very last ingredient that we add during mixing. Heavy mixing/kneading might break the encapsulation, releasing the acid prematurely, which would negatively affect the bind and texture of the sausage.

Starter cultures create a better quality product but cost money and are not available in many parts of the world. To compound the problem, in many areas, the climate is hot, refrigeration is scarce, and equipment is very basic. Under those conditions, using Gdl or citric acid is quite practical as it allows for the safe manufacture and storage of meat products.

Acidic Liquids

Cooking meat is usually associated with heat treatment. Heating changes the structure of meat proteins during a process known as denaturation. Acids can change the structure of the meat in the same way as heat. The best example is the Spanish Ceviche technique, originally from Peru, for cooking fish by soaking it in lemon juice. Mild acids such as lemon juice (pH 2.5) cook fish relatively easily because its flesh has a weak collagen structure. However, intermuscular collagen links in red meat are numerous and stronger. Vinegar is another acidic liquid.

Lemon juice is an excellent substitute for citric acid. One teaspoon of powdered citric acid weighs 3.8 g, equivalent to 60 ml (1/4 cup or 2 oz fl) of lemon juice (4 Tablespoons). It should drop the pH by one full unit. 1 gram of powdered citric acid equals to ~ 15 ml (1 Tablespoon or 3 tsp) of lemon juice. Vinegar is twice as strong as lemon juice.

pH of Acidic Liquids

• Soy sauce - pH 4.6
• Red wine - pH 3.3
• Rice wine - pH 3.3-4.5
• Lemon juice - pH 2.0-3.0
• White vinegar - pH 2.4. There are different strengths of vinegar, European about 10% acetic acid by volume, American 5%.

Using Gdl for Making Semi-Dry Sausages

Gdl can be used not only for making super-fast semi-dry type sausages but also to increase the safety of dry sausages in the initial stage of processing. It can also be used with starter cultures to get a better flavor and aroma. If added at a low amount, the low flavor profile of Gdl itself makes it possible to acidify sausages without interrupting the work of color and flavor-forming bacteria. Minced meat, all ingredients, and Gdl are mixed together, filled into casings, and then dried at 59° F (15° C) for a day or two. After that, the sausages are cooked to be shelf-stable. Although it is possible to use chemical acidulants to produce a fast-fermented sausage in one day, the sausage will have only a sour taste and no flavor of its own, as no bacterial reactions will take place with the meat. The pH drop will be so rapid that flavor-forming bacteria will become inactive. However, adding sugar, spices, and herbal extracts will give it its own unique flavor.

Semi-dry sausages - adding 1.0% (10 g/kg) of powdered Gdl will drop pH below 5.0 quickly. Then, the sausages can be smoked (optional) and cooked at 145º F (63º C) for at least 4 minutes. By eliminating natural fermentation time, which can last 12-18 hours, an acidified summer sausage could be made by following the recipe, including powdered or encapsulated Gdl, stuffed into casings, smoked, and cooked to 161°F (72°C) at internal temperature. All can be accomplished within one day.

Using Gdl for Making Dry Sausages

Dry sausages - if not using cultures or relying on natural fermentation, adding 0.5% (5 g/kg) of Gdl will drop the initial pH of fresh pork from 5.8 to about 5.3. It will become a safety hurdle in the initial stage of the production, yet still allowing naturally occurring in meat flavor forming bacteria to react. Add 3% salt, 2.5 g sodium nitrite (Cure #1)/kg, and flavorings, then mix with minced meat and stuff into casings. Leave the sausages in the refrigerator for two days to acidify and then move them to the smoking/drying chamber. Apply cold smoke < 64° F (18° C) if desired. Dry the sausages at 53-57° F (12-14° C), 75% humidity, until they lose 33% of their original weight.

Dry sausage with Gdl and culture - combining 0.4% GdL with T-SPX will produce a satisfying product. Maintain high humidity during the first two days of production, as Gdl works better at high moisture levels. Then, continue drying. The texture of the sausage may become a bit harder than with starter culture alone.

Stopping Acidification

Acidification is a chemical reaction, so heating will not prevent acidulants from lowering pH. The acidification rate will be even faster at higher temperatures and will continue until no more acidulants remain. A very good acidification rate with Gdl (release of gluconic acid) occurs at 70-74º F (21-23º C).

Summary on Acidified Sausages

Recently, citric acid has become popular with hobbyists, but there needs to be some clarification about its applications. Many believe they create a fermented sausage because it exhibits an acidic taste or that adding encapsulated citric acid cures the meat. Relying on acidulants alone produces lower-quality sausage, as acidulants introduce only an acidic taste and no flavor or aroma. On the other hand, bacterial fermentation, whether natural or with cultures, directs bacteria to react with proteins and fats, which develop complex flavors. Additionally, enzymes naturally occurring in meat react with proteins and fat. When lactic acid bacteria consume sugar, they create through fermentation not only lactic acid but many other components that enhance the flavor of the sausage. On the other hand, acidulants, by lowering pH, accelerate the development of color but do not contribute to flavor; they only supply acidity. By using encapsulated acids, we can run bacterial fermentation in the first stage of production and then cook the sausage so that the capsules melt, freeing the acidulant. This, however, eliminates the production of traditional salami, given that they are not supposed to be heated. Adding a large amount of powdered acidulant into the mix will introduce a degree of safety. However, it will prevent lactic, curing, and flavor-forming bacteria from reacting with meat. Acidification is a method of choice for people who need more time or are not willing to learn more about fermentation. However, it is widely employed in mass production operations, where saved production time increases profits.

The benefits of using acidulants:

• Shorten the production process by eliminating the fermentation stage.
• With Gdl, the pH can be lowered directly in the sausage mass, so the development of pathogen and spoilage-causing microorganisms can be reduced.
• Simplify production as there is a lesser need for precise control of temperature, humidity, and airspeed.
• There is no need to worry about drying, worrying about Aw, or checking moisture loss by weighing the test sausage.
• Given that natural fermentation is usually absent, control of humidity is less important. A liquid smoke-flavored sausage can be acidified and then cooked.
• Faster and improved color stability allows for applying less nitrite. The color is more intense, the sausage is firmer, and the cut-resistance is improved.
• Acidulants are inexpensive, are available online and in stores, need no refrigeration, and have almost unlimited shelf life. They can be used at the moment's notice.

Bockwurst Style Sausage Acidified with Lemon Juice

No Gdl or citric acid, just lemon juice. Squeeze lemons to produce 60 ml (4 Tbsp) of lemon juice. Filter the juice through a paper towel or coffee filter.
Optional: For lemon aroma, grate lemon skin, discarding white inside pith. The skin of the lemon consists of both the pith and the zest. The pith is the white inside part that is closer to the pulpy interior. The pith can be bitter and can add an unpleasant note to the flavor. On the other hand, zest adds a purer, more intense flavor without the bitterness.

Semi-fat pork, 1000 g, (2.2 lb)
Salt, 18 g, 3 tsp
White pepper, 2.0 g, 1 tsp
Ginger, ground 0.5 g, 1/4 tsp
Lemon peel, grated 2.0 g, 1 tsp
Chives, chopped, 3.0 g, 1 Tbsp
Parsley, chopped, 4.0 g, 1 Tbsp
Nutmeg, 0.5 g, 1/4 tsp
Lemon juice, 60 ml, 4 Tbsp
Water, 30 ml, 2 Tbsp

Cut back fat into 1/4” (6 mm) cubes.
Grind pork, beef, and veal with 1/8” (3 mm) plate, slowly adding water.
Mix ground meat with all ingredients.
Add fat cubes and mix again.
Stuff into 28 - 32 mm natural casings forming 2.5” (8 cm) long links.
Cook in water at 176º F (80º C) for 30 minutes. Refrigerate.
Reheat in hot water before serving.

Note: adding lemon juice to minced meat immediately starts reacting with meat proteins and may create a woody, breadcrumbs-like texture. It is recommended to use at least 30% fat, and some emulsified connective tissue will also contribute to better binding and texture.