As “clean label” moves from trend to standard, consumers want ingredient transparency, trust, and product understanding. Clean label creates cost, stability, and sensory challenges for food and beverage manufacturers, especially since there currently is no clear definition.
Consumer researcher NPD Group reports that the top consumer trend of 2016 focuses on the desire for consumers to eat “real” and “natural” foods and beverages. According to the 2015 Deloitte Food Value Equation Survey, by Deloitte Touche Tohmatsu Ltd., consumers are “making purchase decisions based on evolving value drivers.” Such evolving drivers have always been present in the minds of consumers but more than half of consumers surveyed report that they value concerns of health, wellness, and transparency. This also is coupled with a nearly as consistent demand for quality, competitive prices, and nutritionally sound products.
Phosphates added to foods and drinks fall into a consumer perception gray area. As an additive, in certain products, phosphates on the label might generate questions from consumers. But, equally, there are applications for phosphates that deliver nutritional benefit to consumers that can override any such concerns.
Among retailers and manufacturers embracing clean label ingredients, however, some are adopting stricter lists of “undesirable” or “no-no” ingredients and some phosphates appear on these lists. Since the definition of a “clean label” has yet to be fixed, these lists vary from source to source.
Phosphate ingredients can be used to create a nutrition facts panel with increased positive or reduced negative healthy components. Phosphates are allowed in some organic labeled products that are not labeled as 100% organic. For example, certain phosphates are allowed for specific applications or functions. (For the US, organic allowances are listed in the USDA National Organic Program Code of Federal Regulations Title 7: Agriculture; Chapter 1; Subchapter M; Part 205.) In general, phosphates are not considered to be “natural.”
Phosphates au Natural
Combinations of phosphoric acid with alkali sources or inorganic elements, creates a family of salts that are collectively called phosphates. Phosphates are not only indispensable for the growth of plants, they are an essential mineral for human life. Coupled with calcium, phosphate is essential for bone health. Beyond bones, phosphates are critical to maintaining the pH of blood and the function of virtually every metabolic system.
Through adenosine triphosphate (ATP), phosphate is part of the key building block of cellular energy in the body. Phosphate is widely found in food, and most phosphates in the diet come from dairy products, meats, seeds, and legumes.
The basis for all phosphates is phosphoric acid, a phosphorus atom with four oxygens bound to it. These phosphoric acid molecules can form salts in the ortho form when combined with sources of sodium, potassium, calcium, magnesium and ammonia. The salts can be condensed into chains of pyro-(2), tri- (3) tetra- (4), penta- (5) and longer chains of phosphate monomers.
The longer polyphosphates are commonly referred to as hexametaphosphate, a linear, long chain of phosphate monomers having an average chain length from 5 to 30 units. The cation as well as the anion form, mono-, di-, and tri-phosphate define the functional characteristic of each salt.
Each phosphate has a unique solubility and pH once dissolved into water. Coupled with exceptional protein interaction and hydration properties, buffering capacity, and pH modifying properties, this multifunctional ingredient class also provide a chelation capacity.
Depending on phosphate chain length, phosphates can sequester or chelate metal cations – a function that can prevent metal (iron, zinc, magnesium, calcium, and copper) catalyzed lipid oxidation, contribute to food safety and protect a functional protein from inactivation due to calcium binding.
Flavor and Function
The tart flavor found in many soft drinks is derived from phosphoric acid used as a flavor enhancement compound and pH modifier. Beyond flavor, the pH reduction also contributes to enhanced stabilization and shelf life, including decreased microbial growth. Phosphates are used in other beverages, including RTD teas, punches, and fruit beverages to stabilize the fruit components, beverage color and clarity, deliver fortification, and maintain food safety throughout shelf life.
There is some controversy, however, in that soft drink consumption has been shown in some studies to correlate to decreased bone density. It is not clear what the mechanism is, however the phosphoric acid content is often blamed, even though typical amounts found in a carbonated beverage do not exceed 0.1-0.2%. There have been some studies that suggest that unusually high levels of phosphoric acid intake when not balanced with adequate calcium intake can leach calcium from the body.
Evidence from other studies, however, suggests the caffeine in soft drinks is the culprit impacting bone density. This scientific ambiguity has led to confusion for consumers, increasing complexity regarding the use of phosphoric acid in beverages for manufacturers.
In foods, phosphate salts have the capability to stabilize flavor by inhibiting oxidation and warmed over flavors. Generally either tripolyphosphate or pyrophosphate is used to interact with iron and copper, key oxidation accelerants. Preventing oxidations avoids rancid flavors in baked goods, meat, seafood, poultry as well as dairy applications.
For every food product, the phosphates provide multiple functionalities. In meat poultry and seafood applications, the phosphates have a unique capability of interacting with the myofibril proteins to help hold and retain moisture. This reduces purge during storage and cooking, and enhances juiciness and desired mouthfeel in cooked meat products.
Phosphates, particularly the pyro- or diphosphates have the ability to extract the myofibril proteins responsible for emulsification (ex. hot dogs) and binding whole muscle pieces (ex. boneless hams, turkey deli loaves, etc.) together.
In the case of ground and comminuted products, phosphates can be added into the formulation during the blending step. For whole-muscle animal proteins, phosphates can be applied by brining, injection, or surface coating by dip or spray.
For meat and poultry applications, many countries establish an upper limit for the concentration of phosphates. For Canada and the US, this is set at a maximum concentration of 0.5% within meat products. In Canada this regulation is complex, as the 0.5% figure is based on disodium phosphate equivalent weight. While in the US, the 0.5% regulation is based on total added phosphate. For Canadian users of phosphates and phosphate blends, this means a conversion calculation is required when phosphate is being used.
Phosphate salts can be made into a solution prior to blending or injecting into a formulation. Certain phosphate salts can be successfully added to meat in dry form. Many phosphate suppliers have proprietary phosphate premixes designed for various applications and process conditions.
For animal protein applications, phosphate blends have been developed to account for the inherent variation in muscle quality as well as the processes involved in producing a quality product.
Such processes include injection, marination, vacuum tumbling, chopping, forming, and cooking. Selecting the correct phosphate for formulation is dependent on these wide ranging variables, and as such, it is worth setting a strong experimental design to evaluate the impact of various phosphates on formulation or consult with an industry expert.
Processed cheeses have long relied on phosphate as a means of emulsification, acting as creaming and buffer agents. Phosphates can act as a chelator for calcium, and, when used in combination with sodium, such as with sodium phosphates, sodium chloride, or table salt, the casein proteins are modified in the cheese. Specifically, the sodium exchanges with the calcium in casein, forming sodium caseinate, a functional casein compound.
This swap makes the casein more soluble and more able to interact with the fat component in the cheese, leading to a smoother emulsion, less oil off, specific melt characteristic and targeted texture, whether firm or soft and spreadable. The result is a cheese that is less prone to separating or splitting during heating and cooling; and more stable for freeze thaw, and reheating.
Phosphates also are used as pH modifiers in processed cheese. With addition of flavoring agents and inclusions in many processed cheese products, the pH of processed cheese can be altered into the range that is closer to the isoelectric point of the casein proteins. When the protein loses solubility, it loses its stretch and melt characteristics, gaining a brittle or crumbly texture. Phosphates in dairy applications in the US are limited to 3% or less, however, in most applications lower levels are sufficient to deliver the targeted product characteristics.
With emulsification in cheese, it is a case of a little is good, but too much can be a bad thing. Cheese can be over emulsified, losing its texture and melt characteristics, and this is seen particularly with the reworking of processed cheese during manufacture. Phosphate experts can provide technical support to ensure processors hit the “sweet spot” for performance in such dairy applications.
Modifying melt characteristics by changing emulsification can be turned to an advantage in restricted melt cheese products. These are cheese products that are formulated to not lose shape when heated. Common applications for such items are inclusions for baked goods, meat emulsions, or filled food products, such as pocket sandwiches.
Getting a Rise
Phosphates for use in baking applications have been utilized since 1859 when Eben Horsford first formulated a baking powder based upon the use of monocalcium phosphate (MCP) and sodium bicarbonate. Since that era, many different types of phosphates have been incorporated into bakery applications, cakes, muffins, biscuits, cookies, pancakes, donuts, based upon the timing of their release of carbon dioxide.
Phosphates are difficult to replace or remove in baked goods because not all acid sources are created equal. The phosphate salts are unique in their ability to delay or control the release of leavening gas until a specific point in the baking process. Most organic acids are too rapid to deliver the right timing of leavening gas.
All leavening phosphates are used in combination with sodium bicarbonate, baking soda, the source of the leavening gas, carbon dioxide. Sodium aluminum phosphate (SALP) as a leavening agent is predominantly heat-reactive. For all leavening systems, moisture is required to allow for the interaction between the acid phosphate and the baking soda. SALP is unique in that it provides the bulk of its reaction and the product expansion or volume development in the oven.
MCP has the majority of its reaction in the batter during mixing. Stabilized anhydrous MCP (AMCP) reacts late in the mixing and provides early spring to the mixture on the bench or in the oven. Sodium and calcium acid pyrophosphate (SAPP, CAPP) come in various levels of reactivity.
The type of SAPP or CAPP selected is based upon when the reaction is needed to deliver optimum volume, or to allow for process time including product formation such as cutting and depositing. Dicalcium phosphate dihydrate (DCPD) is used in high-ratio, high-sugar products such as cakes to provide late lift in the oven. Calcium leavening phosphates, CAPP, MCP, AMCP, and DCPD are often selected as tools to allow for sodium reduction and calcium fortification.
For manufacturers or retailers who restrict the use of aluminum-based ingredients, SALP can be replaced with slow SAPP or blends of leavening phosphates designed to provide the tolerance, volume, and texture of SALP-based formulations. Today, such reformulation is commonly driven by clean label lead efforts.
When preparing fermentations using live Saccharomyces yeast, free nitrogen is critical to successful yeast metabolism. One phosphate in particular, di-ammonium phosphate (DAP), is often used as a means to restart “stuck” fermentations, and promote rapid growth of the yeast for bulk culturing.
A portion of the clean label initiative is being defined as foods that are considered to be “better” for the consumer, having health driven benefits. Phosphates are often selected as a source of calcium fortification as the key minerals needed for health are calcium, phosphorus and magnesium. Some phosphates, specifically tricalcium phosphate (TCP) are similar in chemical structure to calcium hydroxyapatite, the form of calcium phosphate found in nature and in bones. TCP is also in the ideal 3:1 calcium-to-phosphorus ratio. Fortification is being delivered in all sorts of products including baked goods, functional beverages, and dairy products such as cheese and yogurt.
With the rise of dairy analog products such as soy-, nut- and grain-based “milks,” manufacturers are fortifying sustainable protein beverages, yogurts, ice creams, and cheeses with calcium phosphate as a way to achieve calcium delivery comparable to (or even exceeding)natural dairy products.
While calcium phosphate itself was previously noted for limited solubility at certain pH, curtailing its application in certain formulations, today there are soluble forms of both inorganic and organic calcium phosphates, such as calcium glycerolphosphate. These soluble calcium phosphates and calcium glycerophosphates that allow for fortification to reach at higher levels of the daily value (DV) for calcium without impacting clarity.
The consumer-driven media has focused on studies indicating the bioavailability from calcium phosphate can be lower than other forms of calcium, including calcium citrate-maleate, and calcium lactate. However, other studies demonstrate that calcium phosphates have similar bioavailability to calcium in milk.
Additionally, there is confusion over solubility versus bioavailability when it comes to calcium. Studies have shown that bioavailability is not fully dependent on solubility.
In clear beverages, and depending on the level of solubility, calcium phosphate can contribute a level of cloudiness if deployed at a fine enough particle size for suspension. This opacity serves as an advantage in neutral-pH beverages, such as certain dairy or dairy alternative beverages, non-dairy beverages, and creamers, providing an appearance of richness and a texture of creaminess.
For other dairy-based beverage systems, such as instant flavored coffees, white coffees or canned coffee drinks—where a milky or creamy appearance is critical—sodium phosphates are used as casein modifiers to create an emulsion, helping solubilize dairy proteins to retain the creamy appearance and mouthfeel of the prepared beverage.
Making Phosphates Fit
Food phosphates are commonly pooled into a single category, but as a class of ingredients, each form of phosphate has unique and specific characteristics that determine their suitability to an application. It is important to focus on the food functionality and processing characteristics prior to selection of a specific phosphate.
Different phosphates will perform differently under various pH and salt conditions. When formulating with phosphates in food products such as meats, where phosphate content is regulated, it is critical to select the phosphate based on the appropriate solubility, pH, and diphosphate content to achieve the desired outcome. Ingredient suppliers typically will work with processors and formulators to pinpoint the precise form of phosphate for a food or beverage formulation.
One current issue impacting phosphate selection is global health initiatives for sodium reduction. While the push for sodium reduction in processed foods is controversial, consumer health organization demand for healthy foods and beverages drives focus on this initiative. Given that many countries are now legislating or setting voluntary guidelines for the reduction of sodium in food products, phosphates need to be part of the strategy for sodium reduction.
In certain formulations, potassium or calcium phosphates can act as substitutes for sodium phosphates. Consideration should be given to level and allowances. The functionality and conversion ratio for regulation may not be identical.
Formulation work will be needed to achieve equivalent flavor, texture and shelf life. In general, phosphates alone cannot be the focus, but NaCl (table salt) and other strategies, flavor enhancers and maskers must be considered to achieve targets in sodium reduction and food quality.
One clean label strategy in meats is switching to starch. The elimination of the phosphate can be complicated if the product is injected, tumbled, or brined. Soluble phosphates are able to migrate into whole-muscle meat more readily than starches.
In the case of injected meat, starches can cause a “tiger stripe” effect in the meat, if not properly tumbled to redistribute the starch. Unlike the diphosphate, which directly interacts with the muscle protein causing the protein to bind water, starches do not interact with the actual protein, but do bind moisture.
In certain whole muscle products, starch is considered filler, and could impact labeling requirements in standardized meat products. Equally, fibers from sources such as citrus, celery, and pea, as well as certain alginates, all have been promoted as non-phosphate moisture retainers for meat products., Processors must be aware of the regulatory approval for inclusion of fiber sources into meat, as these ingredients could be classed as fillers.
Manufacturers will face the dilemma of clean and natural labeling versus the wide ranging functionality of phosphates in foods. Natural sources of functional phosphates have yet to be identified. Even once found, there are regulatory and labeling considerations, such as the case with celery extract as a “natural” alternative to addition of nitrites and nitrates.
The challenge with phosphates is the fact that they are multifunctional. So, although ingredient manufacturers have identified alternate emulsifiers, moisture retention, and fortification ingredients to clean up the label of products that traditionally would have included phosphates, often it takes more ingredients than a single phosphate ingredient.
While consumer demand will dictate any eventual changes to the use of phosphates in manufactured products, ingredient makers and suppliers continue to provide systems that deliver broad functions in food manufacturing.
Originally appeared in the September, 2016 issue of Prepared Foods as The New Phosphates.
Phosphates and Health
For the general public, phosphate exposure is generally safe, and indeed phosphate plays an important part of human health. Still, phosphates in foods along with other cations and anions, such as calcium, potassium, magnesium, and anions, chloride, citrate, are of particular concern to certain populations coping with disease, especially kidney disease. Organizations focused on dialysis and kidney disease have developed educational materials to help identify and minimize dietary exposure to cations and anions, and create awareness for these individuals of the importance of label declaration reading.
For some years now, ingredient makers have perfected starches that have been modified to have phosphate esters incorporated in their structure. These “phosphate ester starches,” such as phosphated distarch phosphate, and acytelated distarch phosphate, while modified and thus not necessarily suited to a “natural” claim, have exceptional freeze thaw characteristics, and low retrogradation, with better solubility and dispersion than native starch. However, in certain plants—such as wheat and potatoes—starches will naturally form phosphate esters. Manufacturers can technically apply native starch labeling, while still attaining more of the modified starch functionality with such natural esters.