JUNE 2004--Nearly a dozen new beverages featuring kombucha have been launched in the last year. Kombucha-based drinks feature the kombucha culture, made up of bacteria and yeast, which has been part of Asia's food culture since approximately the second century B.C. Traditionally, the culture finds nourishment from sugar and black tea, which is fermented to produce a healthful drink. Some speculate that kombucha provides health-promoting properties that target rheumatic diseases, depression, diabetes, multiple sclerosis and cancer.

Its modern forms include an entry from Extremedrinks (ExtremeGroup, London), a company that introduced kombucha energy drinks in Portugal, France, the Netherlands, New Zealand, Norway, Sweden and the U.K., notes Mintel International's (Chicago) Global New Products Database. All these introductions are far-removed from its Asiatic origins.

Many traditional ethnic foods utilize bacteria like kombucha to produce lactic, citric, acetic and other acids. Louis Pasteur identified microorganisms as the root of food spoilage in 1864; however, our ancestors already had learned they could ferment foods by using such acid-producing organisms. Yogurt, for example, long ago was “developed” by Asiatic nomads who may have discovered that milk placed in a goatskin pouch on a hot day produced a food that was safe to eat and lasted much longer than the fresh milk. Other ethnic-oriented, fermented foods, such as sourdough bread and sausages, originally became a part of American cuisine because of their extended shelflife, eventually becoming mainstream foods.

Today, acidifier additives are used for flavoring, health benefits and other functions besides food preservation. For example, since acidulants can stabilize the pH of food products by participating in buffering systems, they also beneficially impact a product's flavor and texture. The use of acidifiers is ubiquitous in processes involving other products such as cheese, wine, pickles and canned foods.

Historical Preservation

Whether from natural fermentation or as an ingredient formulated into a food, acidifiers can hamper microbial growth. Some retorted and pasteurized foods take advantage of this ability to prevent bacteria proliferation. Products with lower pHs have reduced time or temperature requirements during thermal processing.

Recently, two salt forms of lactic acid--sodium and potassium lactate--were approved by the USDA as additions to certain processed meats, such as sausages, as a way to reduce the risk of Listeria monocytogenes, a bacterium associated with food borne illness.

The various organic acids have differing abilities to inhibit microbial growth. Lactic and acetic acid have a mild effect when compared to benzoic or sorbic acid, both which are used as microbial preservatives. Such antimicrobial organic acids work by disrupting cell membranes and lowering the pH of a cell's content. Even acidifiers that are not good preservatives themselves can play a crucial role in microbial control. For example, although citric acid does not inhibit microbial growth very well, it improves the effectiveness of benzoic acid. As citric acid drops the pH of a product, an increasing percent of the benzoic acid molecules move to their undissociated, antimicrobial form.

Appeasing the Palate

As flavoring agents, acidifiers are known to enhance certain tastes and mask undesirable aftertastes. A tangy flavor is a trademark of many semi-dried meats like pepperoni and salami, introduced during the Middle Ages when famine and diseases abounded. Although refrigeration makes the preservation method less necessary today, the desirable taste enhancement by acidifiers remains a crucial characteristic of these sausages.

For example, Hillshire Farm (Cincinnati, Ohio) recently launched a Beef Summer Sausage that contains lactic acid starter cultures. Lactic acid is a prime source of flavor and functionality for many fermented food products. However, today, many industrial manufacturers use encapsulated citric or lactic acids to replace the fermentation process as the source of the tangy meat flavor.

Of all the acidifiers in commercial use, citric acid is one of the most common. Some feel that citric acid has a more “neutral” taste compared to acetic acid, which expresses a vinegar taste. Citric acid, however, may not be perceived to be as mild as lactic acid.

While cola soft drinks generally are acidified with phosphoric acid, citric acid is used in a large variety of other soft drinks and fruit-type beverages, where it modifies the sweet flavors and preserves the syrups. Additionally, certain flavored fountain syrups are color stabilized by citric acid.

Many acids, such as lactic and citric acid, are added to enhance the flavors of fruits, berries and other ingredients added to candy formulas. However, a tart taste is not always desired. Many formulators have turned to glucono-delta-lactone (GDL), which has relatively little acid flavor. Thus, it is useful in mild-tasting products such as commercial potato or chicken salads or dairy-based spreads in which a reduced pH is needed for an extended shelflife.

Malic acid naturally is present in apples and fermented fruits and vegetables. Its taste can harmonize well in formulas of products that are apple or certain other fruit flavors. Research indicates the taste profiles of malic acid and aspartame are complementary. In diet beverage formulations, this attribute can be used to enhance overall flavor. One Asian processor appears to have taken advantage of these malic acid properties. In January 2004, Elisha (Singapore) debuted a mineral water containing aspartame, malic and citric acid featuring green apple, peach, orange, lychee and carambola flavors.

Colorful Functions

Acidulants also can be used to impact the color of products. For example, certain acids can be applied to fresh cut fruits and vegetables (for example, guacamole dip), to reduce enzymatic browning.

Although not an antioxidant in its own right, citric acid can chelate certain pro-oxidants such as iron. It can be part of antioxidant systems in food products to protect against color and flavor deterioration.

Dippin' Stix by Reichel Foods (Rochester, Minn.) utilizes lactic, acetic and phosphoric acid in the fat-free ranch dip that is packaged along with fresh carrots. The acids likely play a multiple role, from improving flavor to guarding against microbial deterioration.

Along with flavor and color preservation or enhancement, acidifiers and their salts (e.g., lactic acid and calcium lactate) also can be used for pH regulation and mineral enrichment.

Formulators can consider the benefits of other acidulants besides the ones mentioned. For example, fumaric acid, a dicarboxylic acid, is the trans-isomer of malic acid. Since it is non-hygroscopic, it is appropriate for free-flowing powders and increases shelf stability of some products. Although fumaric acid has low solubility, it improves dough machinability, and is a key functional ingredient in tortilla chip production..

On the Border Guacamole Cafe Style Tortilla Chips, from Truco Enterprises (Dallas), appeared on shelves in April 2004. The product contains citric acid as part of the dehydrated avocado ingredient system. Fumaric acid also is listed on its ingredient statement.

A Look Backward

Some may consider Russian kefir the granddaddy of all fermented dairy products, and a direct descendant of the original nomadic formulation. A huge demand arose for kefir in the early 1900s, after doctors lauded it as the source for eternal youth and targeted its ability to cure cancers, digestive disorders and many other ailments.

Recently, the food manufacturing community has fixated on probiotics, a trend that probably finds its roots in the curative nature of certain fermented foods, as well as a growing interest among consumers in health-related products. A look at the GNPD shows the interest is truly international. In April 2004 alone, strawberry- and orange-flavored yogurt milks with added fiber and probiotic cultures were introduced in the Czech Republic, by Mlékárna; in South Korea, Probio GG Yogurt, an apple-flavored yogurt drink enriched with oligosaccharides and containing live probiotic acidophilus and bifidus cultures, was launched under the Maeil brand; and, Russians were offered another take on fermented milk beyond kefir, as the Amsterdam-based company, Wimm-Bill-Dann, introduced ProBio Light Sour Milk under the Bio-Max brand. The database notes that it contains “bifido-ferments.”

Although large-scale production of kefir began in the 1930s, most manufacturers do not enjoy international distribution. With time, such products are evolving from traditional ways of preparation to being formulated and processed by methods that create consistent, safe end products with extended shelf lives. Current versions entering the marketplace, while based on kefir, incorporate the popularity of fruit juices and other mainstream ingredients. Acidifiers also will play a role. For example, in kefir drinks outside the U.S., it is not unusual for the ingredient list to include a sweetener such as sucrose, fructose or other sugars, along with microbial cultures, juices and/or extracts and citric acid.

Dannon's (Allentown, Pa.) DanActive cultured dairy drink, contains L. casei and, possibly, could represent another modernized version of kefir. DanActive claims to naturally defend the body's immune system. With a consistency more similar to milk than yogurt, it comes in strawberry, vanilla, orange and an “original” flavor.

Although the majority of probiotic products are dairy-based, the health appeal of fermented products like kombucha teas could find manufacturers on an anthropological search for new ways to utilize acidifiers.

Going Global: Globe Trotting with Lactic Acid

The industrial scale-up of indigenous fermented foods is worth exploring, considering the popularity and worldwide growth of yogurt, soy sauce, cheese and wine throughout the centuries.

Fermented cereals are common in many parts of Africa. Ogi, produced in Nigeria and Benin, is a soft or stiff gel porridge fermented from maize, sorghum or millet, with lactic acid bacteria and yeasts. It is used as a weaning food for infants. Microbiological and nutritional studies by several African scientists report that the lactic acid bacteria are the major organisms responsible for the fermentation and nutritional improvement of ogi. Today, there are very few scaled-up industrial productions of ogi outside of Nigeria. In fact, many indigenous fermented foods are not found on grocers' shelves.

Like ogi, some fermented products are culturally isolated to specific regions of the world, whereas others, like sourdough bread and sauerkraut, now are common and mass-produced across the world.

An updated version of ogi could be Nestle's (Frankfurt, Germany) probiotic baby formula, Alete, which contains natural bifidus cultures to balance intestinal flora and help with problems such as constipation and diarrhea. Also available from Nestle France (Marne la Vallee) is P'tit Brasse' baby food, containing whole milk, sugar, banana purée, lactic acid and lactic ferments.

Kikkoman's (Tokyo) Korean Kimchi Pot Soup is a cooking sauce used to decrease the time it takes to make the traditional fermented cabbage version. The sauce, launched in October 2003, advertises the inclusion of fermented bean paste with prawns. JT Foods' (Tokyo) Senoby Drink, a pasteurized fermented lactic acid liquid drink, has calcium lactate and appeals to consumers seeking additional calcium in their diets.