A Gum Worth Its Weight in Gold
By Donna Berry
Contributing Editor
For starters, LBG is extracted from the seeds of carob pod, which grows on the carob tree (Ceratonia siliqua), part of the pea family (Leguminosae), that has been highly valued by humans and animals for thousands of years.
Biblical scholars believe John the Baptist, later known as St. John, sustained himself in his desert life by eating carob pods. The belief is so well-established that a common name for the carob tree is St. John’s Bread. John the Baptist is also the likely source of the name locust bean, as it is reported that he subsisted on “locusts and wild honey.” The locusts are believed to be the carob pods, not the insect, and they actually have a sweet, honey-like taste.
This is where there’s some disconnect, for reasons unknown. There actually is a tree called the locust tree, Robinia pseudoacacia, a genus native to the United States and Mexico that also belongs to the family Leguminosae. Its common name arose from its resemblance to the carob tree, which was known as the locust tree in biblical times (again, here’s that disconnect). This duplication of common names causes confusion, so botanists have given the two trees their own unique scientific name; however, for some unexplained reasoned, the ingredient processed from the carob tree is usually referred to as locust bean gum.
The carob tree, an evergreen that can rise upward of 50 ft. above the ground, is native to the Mediterranean region. In addition to being consumed by the likes of John the Baptist, the carob tree’s seeds, which are quite consistent in weight, were used as weights by early merchants to determine the value of precious gems and gold dust. The Greek word for the carob pod— keration—became “carat” and eventually “karat.” One carob seed, weighing about 200 mg, would be balanced by a one-karat diamond or ruby. The karat value for gold is still used, not as a measure of weight, but of the amount of gold in an object.
A golden ingredient
 The synergism of LBG and guar maximizes functionality in products such as cream cheese and bakery fillings. Photo: Gum Technology Corporation |
“First, the whole, washed carob pod is kibbled, which is the term used to describe breaking up the pods and separating the seeds from the pods. Kibbling is accomplished by a machine called, you guessed it, the kibbler,” says Paul Flowerman, president, P.L. Thomas & Co., Morristown, NJ. “It is kibbled to separate the pod from the five to 15 seeds in each pod. When the seeds are removed, the pod is kibbled to various grades for animal feed, and even more finely to produce a very fine chocolate substitute appropriately named carob.”
The real money for the carob-pod processor is in the seed. “First, the tiny seeds have to be polished, a difficult process as the seed skins are very tough. This is accomplished by either a mechanical or acid process, or a combination of the two,” says Flowerman. “Once the seeds are split, they are milled, or ground, and, using a sieve, the tiny plant embryo, or germ fragments, are separated from the endosperm.”
The endosperm is the source of the valuable carbohydrate galactomannan. The endosperm is further processed to produce various grades of LBG. “It is a completely natural product with no chemical modification or additives,” says Mar Nieto, TIC Gums Inc., Belcamp, MD. “In addition, LBG is a source of soluble fiber.”
Like guar, LBG is a galactomannan. The LBG molecule has about 3.5 mannose units for every galactose residue. This non-ionic molecule typically is made up of about 2,000 residues. The galactose residues prevent strong chain interactions; but, as many as 11 unsubstituted mannose residues may line up in a row. Junction zones may form between such clear areas when there are more than six unsubstituted residues. These nano-crystalline links only dissociate in hot water. If the galactose residues were perfectly randomized or blocked, it is likely that each molecule would have more than four such areas capable of acting as junction zones, thus allowing cold-water gel formation.
“Being a long-chain polysaccharide, LBG is capable of binding large amounts of water as it hydrates. Therefore, it affects the rheology of the aqueous medium into which it is dispersed,” says Joshua Brooks, vice president sales and marketing, Gum Technology Corporation, Tucson, AZ. “Unlike guar or tara gum, also both galactomannans, LBG requires heat in order to fully hydrate. Heating provides the additional energy required to activate the long-chain molecules and allows these molecules to sweep through the surrounding water molecules promoting hydration.”
Nieto says, “For complete hydration and maximum viscosity, LGB requires heating to 180°F for two to five minutes. Viscosity after heating can be close to 3,000 cps. In contrast, guar gum, a cold-water soluble gum, has a 1% usage level viscosity of about 3,500 cps without heating.”
Because LBG only develops viscosity after heating, it is readily dispersible in aqueous systems without excessive viscosity build up. Being non-ionic, LBG is not affected by ionic strength or pH, but will degrade at pH extremes at higher temperatures.
LBG is pseudoplastic, or shear-thinning. “When fully activated, on its own LBG will form a pseudo gel, like a hair gel that is firm enough to take the shape of its container but spreads when poured,” says Brooks.
Synergizing for functionality
Brooks provides this analogy describing LBG’s water-holding capabilities compared to other common gums: “LBG is like a balloon. If you fill a balloon with water, it only holds the water as long as it is not broken. Once the balloon breaks, the water is freed and the balloon cannot be reused. Thus, once the LBG sac is broken, it never returns.“A sponge-type gum, such as guar, absorbs water. And like a sponge, guar can fill with water, release water, reabsorb water and absorb even more water,” says Brooks. “This makes for a very desirable marriage: LBG and guar gum. The two work together very well.”
An application example is cream cheese. Cutting through cream cheese breaks some of the hydrated LBG molecules. But the guar picks up the water, preventing syneresis.
“That is what is so unique about LBG; it has extremely functional synergistic interactions with other gums. Besides guar, it also works well with xanthan and certain carrageenans,” says Brooks. “Combined with xanthan at a 1-to-1 ratio, when heated, LBG will form a true, elastic gel, which is a gel that takes the shape of its container and maintains that same shape once it is released from the container, much like gelatin. The heat provides the energy to promote cross-linking between the xanthan molecules and LBG.
“With kappa carrageenan, LBG also creates a true gel, similar to a gelatin product,” adds Brooks. “This synergistic blend is often used in shelf-stable gel desserts such as fruit-cup gel products.”
Flowerman adds, “No other hydrocolloid works quite as well as LBG, with a little going a long way.”
When it comes to select frozen products, particularly ice cream, LBG is the stabilizer of choice. “Since LBG is hydrophilic, it is very effective in preventing syneresis and for controlling the formation of ice crystals in all types of frozen applications,” says Brooks. “In frozen soups, gravies or ice cream, this water-binding capability will prevent or retard ice crystal formation as the finished product goes through numerous freeze-thaw cycles, from the time of manufacture until the consumer gets it home and freezes. There will be additional freeze-thaw in the consumer’s freezer as well.”
LBG also has application in meat products. “Combined with all three types of carrageenan, this stabilizer system is readily injected or tumbled onto meat and helps the meat retain moisture,” says Flowerman. He notes that according to the Federal Register, carrageenan, LBG and xanthan gum blends in combination, are “not to exceed 0.5 percent in formulations; not permitted in combination with other binders approved for use in cured pork products.”
Nieto adds, “Bakery fillings such as pumpkin pie, fruit pie and fruit tart fillings also benefit from the addition of LBG. When added to the recipe at about 0.2%, the result is a filling that is bake stable and not prone to boil out. While cold-water-soluble gums thin out when heated, LBG actually develops its viscosity during the baking step, helping to bind the water and the product together, thereby preventing boil out.”
A variety of straight LBG ingredients are available to the industry. Some grades contain dark seed skin specks, similar to those found in vanilla bean ice cream, while others have no specks at all, the only difference being aesthetics. Degree of viscosity development also varies, based on the initial quality of the seed and the way it is kibbled. Hydrated LBG powders eliminate lumping that can occur when regular LBG is added too quickly to hot water.
Flowerman concludes by saying that, in the past two years, the LBG industry has been troubled with dramatic price increases and uncertain supplies. However, nothing beats the functionality and naturalness of LBG, so it pays to work closely with suppliers to identify the best synergistic combination of ingredients— the biggest karat.
Donna Berry, president of Chicago-based Dairy & Food Communications, Inc., a network of professionals in business-to-business technical and trade communications, has been writing about product development and marketing for 11 years. Prior to that, she worked for Kraft Foods in the natural-cheese division. She has a B.S. in Food Science from the University of Illinois in Urbana- Champaign. She can be reached at donnaberry@dairy-food.com.
