The Latest on Current Sources, Future Applications of Gums & Fibers
World of Gums and Fibers: Ingredient technologists and product developers are discovering that some ingredients are revealing valued nutritional attributes in a range of food products
The “clean label” trend is increasing the reliance on natural gums and fibers for stability, functional properties, quality, and safety. In the process of researching them further, ingredient technologists and product developers are discovering that some of these ingredients are revealing new and highly valued nutritional attributes in a range of food products.
These gums and fibers are being included in new and reformulated products, especially beverages, bakery and confectionery, sauces and dressings, meat and poultry, and — most recently — in dairy, egg, and meat analogs.
Meanwhile, the growing demand for plant-based ingredients is raising the tide for new breeds of plant-derived gums, such as tara and karaya, and new modifications of traditional pectins and cellulose gums. Sought for their thickening, stabilizing, emulsifying, gel-forming, and water-retention properties, this hydrocolloid class of ingredients is being increasingly valued for their prebiotic and dietary fiber attributes.
Market reports and forecasts suggest growth in the global market for all of these ingredients, irrespective of which gum or fiber, by at least 50% in the next decade. Meeting this demand will require understanding these ingredients’ unique functionalities for efficacy of use and efficient production from naturally occurring sources, including underutilized food chains such as waste streams.
At the Source
Traditionally, gums were ingredients such as pectin from fruit pomace, or modified starches and modified celluloses from starches, including from wood and non-wood parts of plants. Gums have been derived from guar beans, locust beans, and konjac tuber; from tree exudates such as gum Arabic, gum ghatti, and tragacanth; and from seaweed, such as agar, alginates, and carrageenan.
Today, many of these ingredients may additionally be derived from new sources, including natural agricultural products or by-product streams of food processing, and the list is growing. Gums such as xanthan, gellan, and bacterial celluloses such as curdlan (a water-insoluble beta-glucan) are derived from microbial fermentation.
Citrus fiber is a consumer- friendly ingredient to boost fiber; cut sugar and fat; stabilize emulsions; and provide texture, viscosity and suspension. PHOTO COURTESY OF: CP KELCO CO. (WWW.CPKELCO.COM)
Cereal beta-glucans, arabinoxylans, and xyloglucans are being extracted and modified from hemicellulose (commonly from oats or barley) for use in food products for their functionality and potential health benefits. Other beta-glucans are derived from mushrooms, usually reishi, shiitake, oyster mushrooms, and maitake.
When extracted from by-product streams of food processing, such as apple pomace from juice processing or okara from tofu processing, these hydrocolloids are even more appealing to consumers because of the sustainability and reduced waste factors.
Gums have to be essentially isolated fractions in order to provide the desired functionality of viscosity, gelation, or stabilization. For example, the in situ components such as the pectin in an apple or the carrageenan in seaweed do not provide the functionalities of extracted pectin or carrageenan.
Gum polysaccharides are heteroglycans with complex monosaccharide compositions that vary greatly in their structure, type of linkages, and degree of branching. Each variation contributes to unique attributes and functionality.
By the Sea
Agar and carrageenan – in kappa, lambda and iota forms – are gums derived from red seaweeds. Another common food gum, alginate, is derived from brown seaweeds. These natural, marine-origin gums have a long history of use in food. Carrageenan has been used for decades as a thickener and emulsifier to improve the texture of products like ice cream, yogurt, cottage cheese, soy milk, and other processed foods. In the early 2000s, it began to gain negative publicity in the popular media, but an education campaign that focused on its source as a natural, seaweed-derived ingredient (plus increasing recognition of seaweed as a highly nutritious and nutraceutically beneficial resource) has kept carrageenan from falling prey to hysteria. Seaweed hydrocolloids continue to increase in favor based on the production of such bioactive polysaccharides such as laminarin, a beta-glucan obtained from brown algae.
The source of a gum also provides additional diversity in the category. Some gums, for example galactomannans from basil seed, cassia, fenugreek, guar, locust bean, and tara, contain just two monosaccharide types in their molecular backbone: mannopyranose and galactopyranose. But it is these molecules’ structure, degree of branching, and mannose:galactose ratio that affect degree of solubility and thickening ability and make each of these distinctly different.
Gums have a remarkable tendency to absorb water and swell. Thickening and stabilization happen when numerous hydroxyl groups form hydrogen bonds with water molecules. Swelling happens when gums imbibe and entrap a large number of water molecules between their chains and branches.
The swelling index is a measure of the ratio of increase in weight or volume upon absorption of water to the original dry weight or volume. This can range from 1.5 for corn fiber gum to 5.7 for gum Arabic, and greater than 45 for gellan gum.
Chobani, LLC, includes gellan gum in its new oat beverage products to preferentially hold the water and prevent the oat blend from separating. In Mars, Inc.’s M&M’s brand chocolate candies, gum Arabic preferentially binds with any moisture in the chocolate and prevents the color in the coating from bleeding onto the wrapping or the other M&Ms. The preferential binding of water by gellan gum also is used effectively to prevent moisture from fading natural colors, such as anthocyanins, in confectionery products.
The global pectin market is now believed to have topped $1B and is projected to reach $1.5B by 2025, at a CAGR of 6.5%. Pectin is used in combination with locust bean gum for cold-set gelation in Chobani’s Greek Yogurt Lemon & Cream. The pectin and gum are dissolved in a warm mixture to form a dispersion which, upon cooling, results in an enthalpically stabilized inter-chain helix with the protein molecules to form a stable three-dimensional gel. The result is a formulation that’s smooth and creamy instead of being grainy.
Pectin derived from citrus peel and apple pomace — both waste-stream items — is a clean-label thickening and gelling agent with a long history of use in food making. It is often used in salad dressings to replace high-methyl ester pectin with a >50% degree of esterification. It also is used in canning applications with high amounts of sugar and in conjunction with low-methyl ester pectin (with the addition of calcium ions) with a <50% degree of esterification.
Some plants, such as sugar beets, potatoes, and pears, contain pectins with acetylated galacturonic acid in addition to methyl esters. Acetylation prevents gel formation but increases the stabilizing and emulsifying effects of pectin. Thickening and gelling agents from alternative sources, such as sunflower heads and sugar beet pulp, are environmentally friendly and are a desirable replacement for harsh hot-acid methods of extraction.
Instead, such “cleaner” pectins are derived via mild extraction methods, including microwave-assisted extraction, ultrasound, and enzymatic extraction. These methods produce modified pectins with functional properties for use in medical foods and nutraceuticals.
Ingredient technologists are turning to ancient foods, such as chia, for new sources of functional, clean-label fibers and gums. PHOTO COURTESY OF: Functional Products Trading SA/Benexia (www.benexia.com)
Tara gum is a high-viscosity galactomannan polysaccharide composed largely of linear chains of (1, 4) beta-d-mannopyranose units with alpha-d-galactopyranose units attached by (1, 6) linkages. Derived from the seeds of the pea-style pods of the leguminous plant tara (Caesalpinia spinosa L.), it is similar to guar gum in its cold-water solubility and thickening characteristics but is not as stringy as xanthan or guar gum.
Tara holds a distinct advantage for ice cream products that experience repeated freeze/thaw cycles because of its ability to stay smooth without becoming slimy or stringy. It offers another advantage over guar gum in that it is odorless and tasteless and better suited for confectionery, as guar gum can contribute an off odor and flavor to some formulations.
Tara gum is soluble in hot water and partially soluble in cold water. It is easy to use in a variety of confections, bars, and snack foods as a coating. When added to a gel, tara gum can increase the gel’s elasticity and retain water within the structure. This helps increase the end product’s shelf life.
Second That Emulsion
Emulsion capacity is an important attribute of plant-based gums because it influences the size of oil droplets dispersed in the aqueous phase. Smaller and more numerous oil droplets mean greater emulsifier efficiency and a higher degree of absorption at the interface to prevent the droplets from coalescing. For example, when gums increase batter viscosity, they hinder movement and thereby prevent coalescence of oil droplets.
A quick and useful way to compare functionality when selecting gums for batter-based applications is to compare oil droplet size and batter viscosity. Viscosity depends on polysaccharide composition and molecular weight as well as on concentration. Gums producing higher viscosities are considered more useful in baking than less viscous gums because of cost and usage implications. In general, viscosity of dispersions decreases as the temperature increases to allow the batter to rise and set, then increases with the decrease in temperature and increase in gum concentration to set and stabilize the finished crumb structure.
Solubility greatly affects emulsification, foaming, stabilization, viscosity, and thickening and depends on the structure and molecular weight of the gums. Gums with a lower molecular weight and higher galactose substitution within the chain tend to be more soluble. This explains why galactomannans with longer molecular chains and low galactose substitution take more time or require higher temperature to dissolve in water. Just being soluble in water is not enough. The dissolution must enhance viscosity over the range of temperatures important for each application.
Gellan with Karaya
Karaya gum, also known as “gum Sterculia,” is a polysaccharide exudate comprised mostly of rhamnose and galactose units. However, it is the unusual content of saturated fatty acids (capric, lauric, myristic, palmitic, stearic, and behenic acids) and unsaturated fatty acids (palmitoleic, oleic, and erucic) that give karaya the surface activity necessary for superior emulsification and foaming capacity. This has made it a popular gum for use in products such as gluten-free batters.
Karaya’s oil-binding capacity, which ranges from 0.58 to 1.21 g/g of dry matter, depending on how it is extracted, adds to its tenderizing and stabilizing role in batters. Because of its stability in acidic pH formulations, karaya gum is increasingly being used as a thickener and stabilizer in pourable salad dressings, tart ice pops and sherbets, and even some icings and frostings.
Karaya gum absorbs water rapidly, swelling to form viscous colloidal solutions even at low concentrations (1%). This is particularly useful in stabilizing the mixture of the other hydrocolloids, such as cellulose gum, xanthan gum, locust bean gum, guar gum, and pectin. Dole Food Co. uses it in just such a manner for some of its acidic non-dairy tart desserts, including its non-dairy mango soft-serve mix.
Versatile and popular acacia gum is benefitting from increased focus by suppliers on sourcing and sustainability factors. PHOTO COURTESY OF: NEXIRA (WWW.NEXIRA.COM)
Gellan gum is an indigestible polysaccharide of glucose, rhamnose, and glucuronic acid. It is produced by bacteria from lactose (from cheese whey) or glucose (from corn starch). It is a clean-label alternative to gelatin and polysorbates in vegan varieties of gummy candies and gelatinous deserts like Turkish delight.
It is difficult to make plant-based milk analogs creamy because they lack micelles of globular proteins and the characteristic fats of dairy milk. HP Hood, LLC’s Planet Oat Oatmilk achieves a notably creamy mouthfeel via gellan gum, which also helps stabilize the liquid mixture of oats, fiber, and plant proteins. The gum allows them to stay blended without separating.
Gellan is fast becoming a preferred replacement for carrageenan and xanthan gum. The Coca-Cola Co.’s new Odwalla Smoobucha uses gellan combined with pectin. This is because the gellan gum — needed only in very small amounts — helps enhance the viscosity and keep a complex system of fruit and vegetable juices and kombucha in suspension. It also results in a mouthfeel and flavor comparable to that of dairy-based smoothies, even at only 40% of the sugar.
Niyati Parikh, VP of product development at Koia, Inc., created the plant-based beverage manufacturer’s Koia Keto drink in less than three months. “It is critical to be on track and ahead of the game with innovation because today’s consumers have such an array of options of beverages to choose from that if they the products do not meet their taste, they will switch to another brand in a heartbeat,” Parikh states. “Alternatively, when they do find what they love, they keep returning for more and become brand advocates.”
Parikh chose gellan along with locust bean gum to maintain the functional and organoleptic characteristics in the beverage. Using a base of almond and coconut milk enriched with brown rice protein, pea protein, and hemp protein, the final product stays smooth and in suspension in both Koia Keto and Koia Fruit Infusions.
Despite recent regulations and definitions by the FDA, ambiguity prevails around the term “fiber.” This is partly because the catch-all term “fiber” does injustice to the varied functionality and attributes that fibers represent. While the range of fiber ingredients available continues to grow with the advanced understanding of their functions and their physiological effects, the FDA currently recognizes only two types of fiber: soluble and insoluble.
Soluble fibers dissolve in water to form a viscous, gel-like substance in the stomach and are broken down by bacteria in the large intestine to yield a small number of calories. Insoluble fibers do not dissolve in water but pass through the gastrointestinal tract relatively intact and typically contribute no calories.
Prebiotic fiber is another type of fiber, currently not defined by the FDA, but defined in a consensus statement developed by the International Scientific Association for Probiotics and Prebiotics (I.S.A.P.P.) in 2017. The definition describes “a substrate that is selectively utilized by host microorganisms conferring a health benefit.”
Soluble, insoluble, or prebiotic, fibers are considered a “nutrient of public health concern” because low intake is associated with potential health risks. In addition, consumers are seeking products to help with intestinal regularity and a reduced risk of developing cardiovascular disease and colon cancer.
Worldwide Sport Nutritional Supplements Inc. blends three dairy proteins – milk protein isolate, calcium caseinate, and whey protein concentrate – to deliver 30g protein in each 11oz Pure Protein Shake. To provide a smooth, creamy beverage, the product relies on cellulose gel, cellulose gum, and carrageenan.
Cellulose typically has been obtained from wood. However, it increasingly is being derived from other, more “label-friendly” plant sources, such as banana fiber, flaxseed, kenaf (Hibiscus cannabinus L.) pulp, pea hull, ramie (nettle), and sisal (agave). It also is now derived from bacteria and algae.
Applications of nanofibrillated cellulose and microcrystalline cellulose derived by the physical modification of cellulose are gaining ground over different chemically modified derivatives of cellulose, such as carboxymethyl cellulose, methylcellulose, hydroxypropyl methylcellulose, and hydroxyethyl cellulose, because they offer unique and novel functionalities to complement or even replace native starches.
Bacterial cellulose – synonymous with bacterial nanocellulose, microbial cellulose, or biocellulose – is naturally crystalline and free from the pectin, lignin, and hemicelluloses that are found in plant cellulose. This cellulose exhibits different fibril shapes that possess exceptional mechanical strength and biocompatibility.
Artisanal and heritage grains, high in soluble and insoluble fiber, are excellent examples of the combination of function, form, and nutrition they bring to bakery formulations. PHOTO COURTESY OF: Briess Malt & Ingredients Co. (www.briess.com)
These qualities make it ideal as a rheology modifier and building block for mimicking the look, texture, and mouthfeel of fibrous muscle tissue in plant-based meat analogs. Carboxymethyl cellulose is used along with potato starch to hold the ingredients together and to make plant protein work like meat in Savage River, Inc.’s Beyond Meat brand burger analog.
In gluten-free formulations made with rice, the polysaccharides in gums from locust bean, guar, carrageenan, xanthan, and agar provide viscosity to the mixture. They mimic the viscoelastic properties of gluten in a wheat dough and thereby improve gas retention capacity.
Guar gum has been used to improve the mixing and shelf-life extension of bakery products through moisture retention and prevention of syneresis. This has been of high importance for those bakery items that contain liquid-rich components, such as pie fillings.
In breads, the addition of gums improves bread’s moistness by increasing water absorption and specific loaf volume. The finished baked products are softer, with better viscoelasticity and longer shelf life because of the continued water-retaining capacity. These gum hydrocolloids greatly reduce the retrogradation and recrystallization and hardening of starch and, therefore, of bread firmness.
Use of hydrocolloids such as pectin, inulin, beta-glucan, and resistant starch for their prebiotic health benefits and nutritive enhancement is growing. This is despite the FDA’s limited definition of prebiotics. Growing awareness of the health implication of prebiotic gums and fibers is increasing manufacturers’ interest in using these ingredients, even if FDA does not allow health claims or even listing the gums as fiber on the Nutrition Facts panel.
Prebiotics are plant-based fibers that feed beneficial bacteria to help them thrive and reduce harmful bacteria in our gut, as well as contributing other health benefits. Galacto-oligosaccharides (GOS) and fructans, such as chicory root fiber, inulin, and oligofructose, are dietary fibers that are scientifically proven prebiotics and fit this definition.
Rheological properties determine the consistency, mouthfeel, and ease of handling during processing. Differences in the chemical composition and structure of plant gums lead to variations in their rheological attributes. Rheology also depends on the concentration and magnitude of shear stress applied — in fact, there is a critical concentration for every gum polysaccharide below which its dispersions exhibit Newtonian behavior with viscosity independent of the shear rate. As the concentration is raised above this critical value, gum dispersions become pseudoplastic. Knowing this behavior of the gum can help processors quickly tune the desirable handling and sensory attributes. Higher shear imposed by different equipment during processing reduces viscosity for ease of handling, while weaker shear imposed while chewing in the mouth helps to retain the higher viscosity and consistency of the product.
Keep Moving, Inc.’s Gutzy Organic brand of squeezable snack pouches of “gut-friendly” organic fruits, vegetables, oats, and botanicals are blended with organic acacia fiber — gum Arabic — to provide 5-6g of fiber in a 3.9oz pouch. It should be noted that the FDA recently rejected the body of scientific evidence submitted for the physiological benefits of acacia gum as insufficient for consideration as a dietary fiber.
In response, David Istier, Keep Moving’s founder, writes, “We will comply with FDA’s ruling, which means that we have until the end of 2020 to amend our communication packaging. This ruling does not apply to prebiotics and the positive prebiotic effects of acacia on the microbiome and its gut health benefits of feeding the beneficial bacteria.”
Confectioners find acacia gum useful in providing the desired texture and mouthfeel in sugar reduction by masking the undesirable afternotes of sugar replacers and helping blunt the peak glucose response by slowing its uptake.
One does not usually associate that most common of ingredients, potato starch, with dietary fiber. But potatoes are a good source of resistant starch, and physically modified potato starch makes an insoluble, clean-label dietary fiber that can be used for fiber enrichment and calorie reduction.
Potato starch’s neutral aroma and flavor, along with its water-binding properties, makes modified potato starch a good source of fiber in baked goods — without having the tendency to harden and stale rapidly, as can happen with many fiber ingredients. In addition to reducing retrogradation in bakery products, modified potato starch also provides the texturizing characteristics of a rich formula by making the crumb appear moister.
Potato fiber is useful as a singular clean-label replacement for the long list of fibers, modified starches, cellulose fibers, and chemical-sounding hydrocolloids that tend to show up in the ingredient list of meat analogs. It’s used to help create body and moistness instead of the dry cardboard-like texture associated with soy, wheat, and pea protein that are used in these products. And, of course, potato starch has the dual advantage of being a non-GMO, gluten-free ingredient.
Glucomannan is a polysaccharide fiber naturally occurring in the tuber of konjac, sometimes called Japanese yam or elephant yam. Recently, the FDA included glucomannan as a dietary fiber based on scientific evidence that it can help reduce blood cholesterol, which qualifies as a physiological health benefit. This was good news for Terri Rogers, founder of NOoodle, LLC, whose ultra-low calorie, gluten-free noodle products (called shirataki noodles or “miracle noodles”) are popular with consumers. The glucomannan in the noodles absorbs almost 100 times its weight in water and delivers fewer than 4 calories per 100g.
Shirataki noodles have been part of the traditional Japanese diet as a way to manage calories and fiber. The glucomannan fiber in konjac is also a prebiotic that produces selective stimulation of beneficial gut microbiota and a favorable short-chain fatty acid profile.
Today’s plant-based gums and fibers are more often than not a byproduct of other processed foods. But when marketed well, they bring a powerful narrative that appeals to consumers who want their food choices to be good for them and for the planet. For product makers, these ingredients are proving to be increasingly attractive due their unique functionalities and associated health benefits.