If fire was humankind’s first flavor enhancer, salt emerged as its second. In fact, salt is one of the most amazing workhorse food ingredients ever discovered, not only in terms of enhancing flavor but also for delivering texture, taste, and appealing mouthfeel. It’s been an important preservative and food protection agent for thousands of years. The question now facing the industry, however, given the undeniable reality that too much salt can also be harmful, is whether the ingredient is functionally irreplaceable.

Consider salt’s provenance: Throughout history, the availability and use of this remarkable mineral was pivotal in the rise of civilizations all around the world. At the same time, medical science has taught us that excess salt is too much of a good thing—so much that it becomes a very bad thing indeed. Too much sodium can cause cardiovascular health problems—hypertension, stroke, and kidney disease, to name a few—and most of the sodium in the typical Western diet comes from high added salt content.

From a taste viewpoint, salt has an impressive track record. It’s one of the main “basic” flavors and improves the taste of many foodstuffs by suppressing bitterness, making food more palatable and also relatively sweeter. Today it’s used liberally to add flavor to a plethora of different manufactured and processed foods and restaurant menu items—too liberally, according to many global health authorities.

In October 2021, FDA issued a final guidance with voluntary targets and recommendations for salt over the next two and a half years. The agency’s goal is to persuade the food industry to voluntarily reduce sodium content from an average of 3,400 mg per person per day to 3,000 mg. While this goal is still well above the generally recommended sodium daily target of 2,300 mg per day, the objective is to foster a gradual reduction in sodium content, such that technical and market constraints around sodium reduction can be overcome over time.

Reducing sodium content is certainly achievable; that bears stating. However, there are limits on stealth reduction using the simplified strategy of just using less salt. In practice, formulators can’t go beyond a 10% to 15% reduction of sodium content without running into significant taste, texture, and shelf-life challenges—changes consumers notice immediately, and not in a positive way. The very large challenge lies in naturally protecting (or enhancing) taste while also preserving food safety at a reduced sodium level.

In this article, we identify ways to successfully achieve these objectives.

Industry Change

Although the FDA sodium guidance is voluntary and a way to signal to industry that mandated sodium reduction may be on the way, the current heightened consumer focus on health and wellness, especially amid the COVID-19 pandemic, already demands that the industry make changes. Voluntary guidance also tends to work its way into federal nutrition policy and food-assistance programs, such as school meal initiatives, and “recommendations” from FDA are often also integrated into state and local policies around food procurement, supplemental assistance, and education.

For the food industry, the reformulation race has already started to find solutions that will replace salt’s role in the protection, preservation, and flavor of food. Although meat sits near the top of the list (meat applications are notoriously difficult in terms of meeting sodium targets), with dairy applications such as processed cheese close behind, plant-based meat substitutes, perhaps counterintuitively, often carry significantly higher salt content than their animal counterparts.

Let’s not forget to mention processed meats, cheeses, plant proteins, sauces, marinades, salty snacks, etc. These are all challenging categories for formulators facing multiple concurrent problems involving taste, texture, and shelf life when seeking to reduce salt content. On the practicality side, reducing sodium can also create shelf-life challenges: Many preservative solutions currently on the market, both clean label and conventional, are sodium based, so they can actually end up contributing more sodium to the final product.

The challenges, taken together, are substantial, so food product developers must consider all variables while simultaneously balancing consumer concerns around taste and food safety when they decide to join the salt-reduction game.

Preserving Quality and Safety

For thousands of years, sodium’s critical role has been to preserve food quality and safety. Today, many preservatives are based on organic acids that also contribute sodium to the final product.

One notable modern sodium application is curing meat with nitrite salts. While sodium tends to be naturally present in very small quantities in meat, nitrite salt preservatives can add substantially more. Pork, for example, generally contains 63 mg of sodium per 100 mg, while bacon has 1,480 mg. Herring contains 67 mg but, in its preserved form (kipper) it has 990 mg.

One way of addressing safety and quality solutions is by using the Leistner hurdle concept, which postulates that pathogens in food products can be eliminated or controlled by enacting a number of “hurdles” as building blocks in the foodstuff protection plan, strategies that ensure a product’s safety and avoid wastage by extending shelf life. Some of these hurdles include high or low temperatures, increased acidity, reduced redox potential, the use of biopreservatives, and reduced water activity through the addition of salt, sodium, drying, curing, or conserving. Each hurdle seeks to at least inhibit unwanted microorganisms, and salt is the oldest and most common of these methods.

Viewed from the hurdle standpoint, what occurs when you simply remove sodium? For one, safety can be compromised as resistance to contamination from threats such as Listeria is diminished. Quality can also be put at risk through diminished resilience to spoilage. Furthermore, a shorter shelf life leads to higher food waste, as well as increased supply chain and transportation costs, given that products must be consumed faster and distributed more frequently.

Reducing salt content presents preservative challenges that can also lead to increased sodium content through the use of added preservatives. Fortunately, there are natural, non-sodium-based preservatives that can protect product quality during the reformulation process.

Protecting Taste and Texture

When sodium is reduced, several things happen as the physiological response to the five basic tastes is disrupted: Saltiness is reduced, sourness increases, bitter or “off” tastes become noticeable, and sweetness and umami lose balance. Overall, reducing sodium throws disequilibrium into the organoleptic harmony of foods, allowing bitterness to stand out more and decreasing sweetness. After just a small reduction in salt content, the consumer begins to notice. Therefore, in taste, it’s vital to consider sodium’s overall contribution in terms of temporal taste perception—be it upfront, in the middle, or in terms of aftertaste—and apply solutions that will close the taste gaps or simply mask the previously disguised off tastes.

To complicate matters, salt has many roles in texture and functionality through water binding, in terms of “slice-ability” (enabling protein denaturation or gelation), or in dough rheology to tighten gluten strands. Processed meat is one key category in which salt contributes to mouthfeel and texture—weighty challenges that occur over and above taste and preservation. Whereas taste can be added back in using natural means, such as stocks and broths, as well as many different spices and seasonings, mouthfeel and flavor require a wide variety of natural solutions. A “tool-box” approach that offers many possible solutions is the best way to harmonize and rebalance sodium-reduced products. Whether the challenge is meat, snacks, meat alternatives, dairy, meals, or sauces, it is vital to break down the challenges across taste, texture, and shelf life.

Replacing salt and sodium in foods requires a systems approach by a knowledgeable ingredient supplier that combines solutions that work together to build back taste, shelf life and texture. Here are some solutions that might work to reduce sodium:

• Given the current industry challenges in securing sodium lactate supplies, buffered vinegar liquid and dry, low- and no-sodium preservation solutions must be considered.
• Using texture in meat applications as an example, you can source highly functional stabilizers, texturants, and brines tailored to perform in reduced-salt applications. These can be combined into a taste and preservation portfolio that delivers a fully integrated solution.
• Other sodium-reduction solutions revolve around accessing science in its many forms: flavor creation, modulation, fermentation, dairy, and smoke, grill, and other preparation processes. For example, it’s possible to develop natural flavor solutions in salty snacks that allow for a sodium reduction of up to 250 mg per serving.
• To rebuild the taste sensation, late-lingering flavor, juiciness, continuity, and succulence provided by salt, manufacturers need to leverage a variety of ingredient and flavor solutions. Umami stock can help build middle impact and the perception of sodium, complete with a natural, pantry-friendly ingredient statement. Natural stocks and broths are also excellent flavor enhancers produced through traditional kitchen cooking methods. Natural barbecue cooking is another key strategy.
• Natural salt replacement solutions are derived from fermentation, extraction, and flavor expertise to deliver on salt and umami taste while reducing the amount of sodium in a given product. Solutions can be applied to prepared meals, soups, sauces, snack seasonings, savory spreads, and vegetarian, white meat, and tomato-based products. These can lower salt content by up to 50% depending on the application, deliver salty and umami taste perception, ensure a balanced taste with a clean aftertaste, provide a natural, clean taste experience not based on potassium chloride, allow for declarations of “natural flavoring” or “yeast extract” on package labels, and optimize frozen, chilled, and ambient applications (pasteurized, sterilized).

Reformulating for Success

Clearly, salt reduction is vastly more complex than just removing salt and sodium. In reformulating, it’s crucial to use a “total concept” approach that involves making improvements to address shelf life, texture, and taste, and using preservation solutions that contribute little or no sodium to the final product. Food manufacturers also need to consider practical implications; items such as packaging inventories (i.e., ingredient declarations and nutrition fact panels will change) are also part of the agenda.

Within the next 18 to 24 months, it is highly likely that consumers will begin to notice shifts in the marketplace based directly on the FDA voluntary guidance; starting early is key. Experience tells us that it takes food manufacturers six months to one year to reformulate and validate consumer safety and taste acceptance of food products. This lengthy process can be hastened through partnering with ingredient suppliers to address changes simultaneously and holistically—a “complete formula” strategy versus just tackling the sodium aspect.

For the food manufacturing industry, the drive to reduce sodium should be viewed as an opportunity to regroup, reimagine, and repackage, not only to reduce sodium but also to build on clean labeling and enhanced preservation/natural flavor innovations. Fortunately, the targeted solutions needed are already available.

Vimalarajah is VP of business development, Americas–Food Protection & Preservation, at Kerry Taste & Nutrition in Beloit, Wisc. Reach him at joy.vimalarajah@kerry.com.

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Honey is a natural food product loved by the global population. However, its limited production, relatively high price, and complex composition make it vulnerable to adulteration. In fact, it ranks in the top 10 most adulterated food products worldwide.

Honey adulteration is a form of food fraud, which is the deliberate and intentional substitution, addition, tampering, or misrepresentation of food, and it’s a major trend impacting the honey industry today.

Wiley has partnered with Agilent Technologies to bring together a special collection of articles detailing the advanced technologies available to detect adulteration and determine the authenticity of honey products. This important compendium features content from Agilent Technologies and Wiley publications, including Food Quality & Safety. In this collection, you’ll read about:

• Detection and estimation of rice syrup in honey;
• Food authenticity testing best practices;
• Preventive measures you can take against food fraud;
• Major honey authentication issues, such as production and origin; and
• Pollen composition, physicochemical parameters, and phenolic and mineral contents of honey samples from Portugal.

We think this series of essential articles will help you combat food fraud in your operations and ensure that your customers are getting a quality product.

Discover this important compendium of content from Agilent Technologies, Food Quality & Safety and Wiley publications. Download the application note to learn more, courtesy of Agilent.

• Application note: Detection and estimation of special marker for rice syrup (SMR) in honey
• Fire up your next food authenticity project
• Food fraud: A criminal activity. Implementing preventative measures that increase difficulty in carrying out the crime
• A comprehensive review on the main honey authentication issues: Production and origin
• Authentication of honeys from Caramulo region (Portugal): Pollen spectrum, physicochemical characteristics, mineral content, and phenolic profile

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How do food manufacturers of sauces and dressings distinguish their premium brand products? Taste comes first and foremost. Not far behind is the handling property—namely, visual appearance in the bottle and flow behavior when poured on salad. Consumers judge “thickness” and “creaminess” in the supermarket by holding the bottle and moving it gently from one side to another. Perception of how the dressing is likely to pour comes from this simple action. In general, careful application of dressing requires controlled flow from the bottle so that just the right amount comes out. Customer dissatisfaction arises when too much dressing gushes suddenly from the bottle or the squeezing action cannot get sufficient quantity to expel within a short time frame.

Figure 1: Rheometer with Vane Spindle
Image credit: AMETEK

Food scientists responsible for formulation of dressings must evaluate flow properties and then set guidelines for QC during manufacturing. Yield stress is one property of interest; this defines how much squeezing force or shaking action is needed to initiate easy flow of salad dressing. Viscosity is essentially “resistance to flow;” it quantifies the physical property that relates to flow rate of salad dressing during pouring. Creep is the property that characterizes how the salad dressing behaves after it deposits on the salad. The point of interest is whether it clings firmly to the coated items or does flow continue causing it to drain off the salad.

All three properties are important, but viscosity alone has been the traditional parameter of interest. In recent years, premium brand manufacturers have also focused on yield stress and creep for the following reasons:

• Visual inspection of salad dressing in the bottle is equivalent to making a judgement on yield stress;
• Ease of use when initiating flow requires a yield stress that can be readily overcome by shaking or squeezing; and
• Adherence to salad components like lettuce and tomato requires minimal creep flow.

Flow Behavior

Figure 2a: Illustration of Yield Stress Curve
Image Credit: AMETEK

Figure 1 shows a rheometer with vane spindle used by R&D to characterize the flow behavior of salad dressings. The vane is immersed into a container of salad dressing and rotated at very low speed, perhaps 1 rpm, to determine “yield stress.” Figure 2a illustrates the type of data curve that results when plotting stress on the y-axis and strain on the x-axis. The slope of the rising curve is called “modulus” and its value relates to the “stiffness” of the dressing.

Figure 2b: Comparison of Yield Stress Curve for Two Salad Dressings
Image credit: AMETEK

The steeper the slope, the stiffer the formulation. When the peak value for stress is measured, this correlates with “yield stress” for the dressing. Figure 2b compares two salad dressing formulations for yield stress.
The upper curve shows the premium brand that has both higher modulus and yield stress. This stands to reason since dressings with more body are generally preferred by consumers who suspect that “thinner” formulations may be watered down.

Figure 3a: Illustration of Creep Flow Behavior
Image credit: AMETEK

Figure 3a shows the data curve that characterizes creep behavior. Low stress is applied to the vane spindle by the rheometer to simulate the action of gravity acting on dressing after it is poured on salad. The data curve shows flow movement of the dressing as a strain value on the y-axis plotted against time on the x-axis. The flatter the strain curve, the less movement of dressing after application to salad. Figure 3b compares the same two dressing formulations. Note that the premium brand has lower creep profile. This makes sense because the non-brand is more likely to not cling as readily to salad.

Figure 3b: Comparison of Creep Flow for Two Salad Dressings
Image credit: AMETEK

Viscosity is measured by rotating the spindle at different speeds and recording the value. General observation for dressings is that viscosity reduces as rotational speed increases. This means that there is less resistance to flow the faster the dressing moves. The graph in Figure 4 shows data for two dressings. The x-axis parameter is “shear rate,” which is proportional to rotational speed. Shear rate accounts for the shape of the spindle and the ratio of spindle diameter to container diameter. The curves for both dressings look similar; the premium brand is slightly higher in value than the non-brand.

Traditional use of viscosity flow data might have led to the conclusion that the two dressings were relatively similar. Use of yield stress measurements and creep flow data gives a different assessment. The premium brand is more likely to have the rich creamy appearance in the bottle when evaluated in the supermarket. Its flow behavior after pouring allows it to cling to salad.

Figure 4: Viscosity Flow Curves for Two Salad Dressings
Image credit: AMETEK

Manufacturers who strive for the higher value dressings are willing to invest in the tests that verify these differences in flow behavior. QC is now tasked with measuring not only viscosity flow curve, but also yield stress and creep. Advancements in instrumentation make it possible for rheometers to be programmed to perform all three tests at once. This allows the technician to set up the sample as before, run the test with the push of a single button, and automatically record data while tending to other tasks in the lab. Increasing use of rheometers in QC is enabling high-end manufacturers to keep pace with growing consumer demand while producing consistent high-quality dressings.

Ridley is sales manager for RS rheometer and powder flow tester at AMETEK Brookfield. Reach him at barry.ridley@ametek.com. McGregor is director of global marketing and high-end lab instrument sales. Reach him at bob.mcgregor@ametek.com.

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Credit: METTLER TOLEDO

Moisture content influences the taste, texture, weight, appearance, and shelf life of foodstuffs. Even a slight deviation from a defined standard can adversely impact the physical properties of a food material. For example, substances which are too dry could affect the consistency of the end product. Conversely, excess moisture may cause food material to agglomerate or become trapped in the piping systems during production. Also, the rate of microbial growth increases with total water content, possibly resulting in spoiled batches that need to be disposed of. However, water is also an inexpensive ingredient adding to the weight of the final product. Hence, obtaining an optimal analytical value for moisture is of great economic importance to a food manufacturer. For these reasons, food analysts engage in the delicate balancing of moisture and total solids to ensure consistent product quality, safety, and profitability.

Legal Requirements

International and national standards define the permitted thresholds for moisture content in commercially sold products. Regulatory bodies such as the BRC (British Retail Consortium), IFS (International Featured Standards), or GFSI (Global Food Safety Initiative) heavily influence the production, processing, and sale of foods. For food manufacturers, this translates into increased workload around quality assurance and the development of efficient and cost-effective solutions. According to the stated legal requirements, methods of analysis and procedures must be clearly described and tested. Many food producers themselves have strict criteria for measurement accuracy, reliability, and traceability to ensure the consistent quality of their products. These standard operating procedures encompass the entire measurement process, including sample volume, number of required measurements, maximum tolerable deviation, and procedures for correcting errors.

Water Properties in Food

As mentioned in chapter 6 of Food Analysis by S. Suzanne Nielsen, official methods and procedures for moisture analysis are important since the method used to determine moisture may lead to varying results for moisture content, depending on the form of the water present in a food. In the simplest scenario, water retains its properties by existing “freely,” i.e. it is only surrounded by other water molecules. Free water (also known as bulk water) can be adsorbed on surface particles, held in narrow capillaries, or stored in the pore systems deep within the food material. For instance, dried fruit or meats have complex cellular structures where water is bound by adsorption to the surface or transported deep within the cells by capillary action. Adsorbed water can also become physically bound to other elements present in the food material such as proteins, or exist as chemically bound water (e.g. certain salts such as Na2SO4·10H2O). In a bound state with other molecules, water most often evaporates at a higher temperature compared to free water molecules. Consequently, physically or chemically bound water takes on varying physicochemical properties, making it very challenging for the food analyst to accurately measure the moisture content.

Technologies for Moisture Analysis

A summary of technologies used for moisture determination are listed below.

• Thermogravimetric analysis (oven drying, halogen/IR drying, microwave drying, etc.)
• Chemical analysis (Karl Fischer titration, calcium carbide testing)
• Spectroscopic analysis (IR spectroscopy, microwave spectroscopy, proton nuclear magnetic resonance spectroscopy)
• Other (e.g. gas chromatography, density determination, refractometry, etc.)

This article focuses on thermogravimetric analysis (TGA). Moisture content is derived from the loss of product weight during drying by measuring the change in mass of a sample while being heated at a controlled rate until no more change in weight is observed.

Balance and Drying Oven

The drying oven, commonly used for commercial purposes, is the established reference method for loss on drying (LoD) by TGA. In this procedure, a sample is weighed and subsequently heated to allow for the release of moisture. Following this, the sample is cooled in the desiccator before reweighing. Moisture content is calculated by the difference in wet and dry weight. In this process, measuring accuracy and the resolution of the balance are extremely important. Careful consideration must also be given to maintain identical conditions, where temperature and duration are vital for generating precise and reproducible results.

Table 1 (click to enlarge)

Advantages. Two important advantages gained from using a drying oven are sample throughput and flexibility in regards to sample volumes/sizes. This method also produces very precise results while being cost effective (see Table 1).

Disadvantages. This method requires extended heating periods and cooling phases, meaning it usually takes hours to produce results. Procedures are laborious and tedious, involving many manual steps. Therefore, the potential for error is high, since weighing is performed manually and in separate stages during the drying process as opposed to a moisture analyzer with an integrated precision balance which allows for the continuous and automatic recording of results. Typical pitfalls include mixing up samples, manual transcription errors or the miscalculation of weighing results. The risk of committing such errors increases with large sample volumes (see Table 1).

Moisture Analyzer

Moisture results can be obtained more rapidly using a moisture analyzer. The measurement principle does not differ from that of the thermogravimetric method. The main distinction lies with the type of heat source used: In the oven, samples are heated by convection while a moisture analyzer heats samples via the absorption of infrared energy.

Advantages. The most important advantage is the rapid measurement time, thanks to the efficient heat source. Results can be obtained within 2–10 minutes. Samples are heated quickly and evenly, and obtained measurements show good repeatability. Handling is also straightforward and the risk of error is reduced (see Table 1).

Disadvantages. All thermogravimetric methods, including the moisture analyzer, carry the risk of decomposing constituents or the loss of volatile components during heating. This results in a further decrease in weight, which is not explained by the release of water. Finally, samples can only be measured one at a time and the automation of measurements is not feasible (see Table 1).

Halogen Technology

The technology of halogen drying can measure moisture content in virtually any substance. Halogen technology uses a halogen heating device in combination with an integrated precision balance for the measurement and recording of sample weight before, during, and after the release of moisture. Thanks to its innovative heating technology, halogen moisture analyzers (HMAs) are capable of producing fast and precise measurements.

Furthermore, automated moisture determination eliminates transcription and calculation errors. Most HMAs offer a number of predefined methods, which can be stored and easily accessed via the display menu. Some manufacturers also allow users to set individual user rights to ensure that quality criteria are met. The calculated results are stored in the instruments or can be printed out or transferred to PC via USB or other interfaces.

Reference Methods

Table 2 (click to enlarge)

Reference methods are of much use to food manufacturers who must comply with legal requirements for the maximum or minimum amount of water present in diverse foods. Up until now, moisture content determination in a drying oven is the established reference method. Values determined by other methods must, therefore, always be referenced against the LoD method in the drying oven.

METTLER TOLEDO, as an example, has a library of validated measurement methods for over 100 food products saving users time in developing methods for different food specimens. If a substance is not included in the library, it is possible to adapt a method from a comparable food sample. For instance, Table 2 compares procedures and results for moisture analysis in ground hazelnut using a drying oven and METTLER TOLEDO HMA. Based on six measurements, the mean value of the moisture result was calculated. The results reveal that a moisture analyzer produces identical results to a drying oven. In addition, the standard deviation for both methods is comparable and very small.

Conclusions

Moisture content is a critical indicator of food quality, safety, and shelf life, thus moisture analysis serves an important quality control function in various stages of the food production chain, from raw material testing in the laboratory to incoming goods inspection. Several analytical procedures are available to measure moisture content in diverse food samples. Selecting the correct procedure for a particular sample or application is pertinent to the food industry’s success since the accuracy of moisture measurements are highly dependent on the analytical method used.

Compared to the traditional drying oven, faster determination of moisture content via LoD can be achieved using alternative methods. For example, an HMA is straightforward to operate and produces reliable results in just 5-15 minutes, compared to 2-4 hours when using a drying oven. In addition, the automation of weighing measurements and calculations allows for fully compliant and reliable results.

Dr. Appoldt is head of strategic product group moisture at METTLER TOLEDO. Reach her at yvonne.appoldt@mt.com. Raihani is global lab marketing at METTLER TOLEDO. Reach her at gina.raihani@mt.com.

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Viscosity measurement is a universal necessity in QC labs throughout the food industry. If the item in question can flow, you can bet that there is a test method specified by R&D for viscosity. This requirement ranges from “thin” fluids, like milk and canned soups, to “average viscosity” soft solids, like salad dressings and yogurts, to “thick pasty” or “hard” materials, like peanut butter and cheese. Given the wide variety of food types that may need to be measured, choosing the proper viscometer can be daunting.

Viscometers are relatively basic instruments that measure torque using a rotating spindle immersed in the material. Resistance to spindle rotation is the physics that constitutes the basis for viscosity measurement. Continuous contact with the material is necessary to provide a steady torque signal. Mathematical calculation converts the torque reading into a viscosity value with established scientific units: “centipoise” (cP) in the U.S. and “milliPascal-seconds” in Europe and Asia.

Pre-Test

Normally R&D will specify the viscosity test method and the recommended instrument. This is based on evaluation testing by R&D to characterize the food item for its flow behavior. The following are important questions that must be answered.

1. How much of the food material is available for testing? Is there any limitation in the available quantity?
2. What type of spindle is needed to test the material?
3. What is the appropriate torque measurement range for the instrument?
4. Is temperature measurement or control needed for the test?
5. How long does the spindle rotate in the material before taking the reading?

Sample size for the viscosity test is not usually an issue for food manufacturers. There is more than enough material available in most cases. If temperature control of the sample is required, then working with a small sample size is preferable in order to minimize the time needed to achieve equilibration.

One important consideration that affects the test is the type of container holding the food item. If the test is performed in a standard 600 mililiter (mL) lab beaker, then there is no issue; if performed in the container that packages the item, then volume of material available for testing may affect the choice of spindle.

Spindles

Figure 1. Types of Spindles.

Various spindle types used for viscosity measurement appear in Figure 1. Most common are the first two which are either cylindrical in design or have a disc near the bottom of the shaft. The cone spindle is ideal for very small sample size (less than 2 mL) while the SC4 type requires 16 mL or less. T-bar is used with paste-like materials. Vane can measure mixtures with suspended solid particles as well as thick pasty substances. Spiral is appropriate for simulating processes that use augurs to move material. Fortunately, the spindles are not expensive and can connect interchangeably to any standard bench-top viscometer. Initial choice is most likely cylinder or disc, but could in future transition to one of the others for reasons indicated.

Torque

Torque range for the viscometer is chosen based on the expected viscosity range for the food material. Most common choices are “LV” for “low viscosity” or “RV” for “regular viscosity,” also referred to as “medium viscosity.” “HA” and “HB” cover the high viscosity range, but are much less frequently selected. However, the chocolate industry has elected to standardize on viscometers with “HA” torque.

The maximum torque that can be measured for each range is as follows:

LV = 673 dyne^.cm
RV = 7,187 dyne^.cm
HA = 14,374 dyne^.cm
HB = 57,496 dyne^.cm

The minimum torque recommended for use in each case is 10 percent of the maximum. Therefore, LV range goes from 67.3 to 673 dyne^.cm (centimeter) and RV from 718 to 7,187 dyne^.cm. The theoretical viscosity values that can be measured with each are very broad, ranging from under 10 cP to over 1 million cP. Practically speaking, LV is typically used in the range from 1 to 100,000 cP while RV is used from 100 to over 1 million cP. Because the overlap in range coverage is significant, there is another consideration that determines which one to select.

Measurements

The combination of spindle and rotational speed determines the precise viscosity range that can be measured. Viscometer manufacturers provide this information in tables for easy lookup. Viscosity measurement is oftentimes targeted to fall in the middle of the torque range—around 50 percent on a scale of 0 to 100 percent. This provides flexibility for possible variance in measurements that may occur from batch to batch during production.

Temperature measurement is easily accomplished during the viscosity test. Today’s instruments can be ordered with built-in temperature probes. The display on the instrument reports the viscosity in cP, torque in percentage, and temperature in degrees Celsius or Fahrenheit. Best practice is to record the temperature and viscosity readings together, since viscosity will change inversely relative to variances in temperature. If temperature control is required, then use of a bath is likely. A key decision is whether to immerse the sample in the bath or use circulation to an external fixture designed to hold the sample while temperature equilibrates

Don’t forget to consider time of spindle rotation for the viscosity test method. QC’s objective is to make the measurement as quickly as possible. Some food materials exhibit decreasing viscosity as the spindle rotates. This behavior is called “thixotropy,” which is sensitivity to shearing action versus time. In this case it is important to establish the time interval for making the viscosity measurement.

Obtaining a clearly defined test method from R&D guarantees that QC’s job will execute successfully. Discussion with instrument manufacturers will ensure that the proper viscometer model with the appropriate accessory equipment is chosen within the budget available for the job.

McGregor is director of Global Marketing/High-End Lab Instrument Sales for AMETEK Brookfield. Reach him at bob.mcgregor@ametek.com.

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Image Credit: © fosupaksorn – Fotolia.com

Softness is a key parameter used to judge the freshness and, consequently, the quality of bread. Bakers are therefore interested in maintaining the softness of their bread for as long as possible. Any loss of bread crumb softness is often referred to simply as staling. Staling is defined as any change other than microbial spoilage that occurs after baking, making bread less acceptable to the consumer.

Physical or sensory changes associated with staling include: loss of crumb softness, flexibility, and strength; increase in crumb resilience; tendency to become crumbly; loss of flavor; and change in mouthfeel.

Staling Mechanisms

Starch, which makes up approximately 70 percent of flour, is regarded as the main flour component involved in staling. After baking, the gelatinized starch in bread tends to re-associate or, to use another term, retrograde.

After cooling and during the first hours after baking, the initial crumb structure is set by amylose gelatinization, creating a network in which the gelatinized starch granules are embedded. Re-crystallization of amylopectin side chains leads to the increasing rigidity of the starch granules and an overall strengthening of the crumb structure, measured as an increase in crumb firmness. Other factors, however, also have an impact on bread firming, particularly the distribution of water between protein and starch, which undoubtedly, plays an important role.

Figure 1 (click for larger image, photo credit: Dupont)

Starch retrogradation, though, is the main factor with regard to time determined changes in crumb softness. Functional ingredients that limit retrogradation are instrumental in improving crumb softness.

Starch consists of two fractions: amylose and amylopectin in a ratio of approximately 1:3. Both macromolecules comprise glucose units, although with structural differences. Amylose is a relatively small (molecular weight is approximately 250,000), linear and water-soluble macromolecule, while amylopectin is a very large (molecular weight is approximately 205,000), bulky, branched, and water-insoluble molecule.

Figure 1 on page 38 shows the changes that occur from the dough stage to fresh bread and, finally, to old or stale bread. The restoration of bread freshness by heating (toasting) is also indicated. In the dough stage, unswollen starch granules contain crystalline amylopectin, amorphous amylose, and polar lipids. The granules are embedded in gluten, which forms the continuous phase. During baking, the starch granules absorb water and swell. The amylopectin crystals are gradually disrupted at temperatures above 140 degrees Fahrenheit, and gelatinization takes place. Some of the amylopectin molecules expand into the inter-granular space and, at a somewhat higher temperature—around 176 degrees Fahrenheit, some of the

 Figure 2 (click for larger image, photo credit: Dupont)

amylose that has not formed complexes with polar lipids leaks from the swollen granules. Within hours after baking, the amylose molecules develop a network, and a sliceable crumb structure is formed, giving the fresh bread its initial firmness. During aging, reformation of the amylopectin’s double helical structure and reorganization into crystalline regions takes place. While the re-association of amylose occurs within hours, the retrogradation of amylopectin takes days.

How Enzymes Work

Enzymes have been applied in bread making for decades. Bakery enzymes such as amylases help modify starch during the baking process. Slowing starch retrogradation, they ensure bread stays soft for longer than bread made without enzymes.

The varying action patterns of the most important amylases are shown in Figure 2. One effect of the enzymes is to reduce starch retrogradation by modifying the starch.

There are two main types of amylase enzymes: endo-amylases, such as classic fungal and bacterial α-amylases, that primarily hydrolyze starch at random within the amylose and amylopectin molecules; and exo-amylases that primarily hydrolyze starch from the non-reducing ends of starch molecules, cutting off two or four glucose units.

Figure 3 (click for larger image, image credit: Dupont)

In practice, starch granules only become susceptible to enzyme attack upon gelatinization, which means the baking amylases need to be heat stable in order to be efficient. The curve in Figure 3 shows a typical temperature pattern when baking a loaf of bread. The functionality of amylases is highly influenced by the temperature profile of the baking step. A standard fungal α-amylase only has a couple of minutes in which to act on the gelatinized starch, and consequently, has no anti-staling effect. The bacterial α-amylase is active even at elevated temperatures and may cause excessive starch degradation, as it primarily weakens the inter-granular amylose network. Therefore, a narrow window of optimal dosage exists. G4-amylase and maltogenic α-amylase are optimized to modify gelatinized starch in the temperature range of 60 to 90 degrees Celsius, which is considered important for obtaining a strong anti-staling effect.

The amylopectin fraction in starch granules is more complex than that shown in Figure 2. A more comprehensive structure is shown in Figure 4 on page 39, which illustrates that the amylopectin structure consists of amorphous and crystalline regions. Endo-amylases are most likely to attack in the amorphous regions. This gives the gel structure more freedom of movement and reduces crumb rigidity. Exo-enzyme attack reduces the possibility of a re-association of amylopectin side chains.

The action pattern of specific amylases effectively combines the shortening of amylopectin side chains with balanced amylose fragmentation. Enzymes preferentially attack starch from its non-reducing ends. In this way, they shorten the amylopectin side chains and reduce the amount of amylopectin available for retrogradation, slowing the actual rate of firming. This provides substantial crumb softening and improved resilience and elasticity without excessive weakening of the amylose network. In addition to superior softness and resilience, specific amylases can generate a moister, more flexible bread crumb.

Figure 4 (click for larger image, image credit: Dupont)

Starch is not the only component acting in the staling process. Proteins and arabinoxylans also contribute to the firming of bread crumbs. For this reason, most enzyme products are optimized with additional enzyme activities specifically designed for individual applications.

Specific amylases, such as maltotetrahydrolases, are mainly responsible for the anti-staling effects; although phospholipase enzymes and bacterial xylanases can provide some additional softness. The amylases help products retain original production freshness by primarily modifying the amylopectin portion of the wheat starch, which greatly reduces recrystallization over time, resulting in softer product. The enzymes used for improving volume are usually selected from hexose oxidase, glucose oxidase, xylanase, and phospholipase, often in combination. There are several mechanisms involved in increasing volume. Phospholipases modify naturally occurring lipids in the wheat flour, producing emulsifiers that strengthen the protein structure. Xylanases specifically modify the arabinoxylan polysaccharides naturally present in flour. This releases water that can be absorbed by gluten to produce stronger networks and greater volume. Hexose oxidase and glucose oxidase oxidize small amounts of sugars in the product, resulting in production of very small amounts of hydrogen peroxide, which helps to cross-link gluten proteins also generating stronger networks and increased volume.

Enzymes used in baking help breads and bagels retain their original freshness for longer, thereby reducing food waste, energy consumption, and their carbon footprint. Enzymes used in cakes and muffins enhance softness, moisture, and reduce crumbling, helping improve taste perception and convenience in the on-the-go market. Other baked goods that benefit in similar ways to bread would include buns and rolls, bagels, pretzels, English muffins, tortillas, etc.

Enzymes are of course present in flour, yeast, bacteria, and several other common raw materials used in bakery products, and therefore were used unknowingly for thousands of years before their discovery and the introduction of commercial enzymes. Commercial industrial enzymes were introduced as a way to better control the amount and type of enzyme activity in baked goods and to give bakers better control. Enzymes can play an important role in the vast majority of baked goods with only a few exceptions.

The products that tend to benefit the most are those that require fresh keeping, and in particular, those that also have a specific volume requirement. Most traditional pan breads are expected to be soft and light in texture and are now also expected to have shelf lives of up to three weeks. Anti-staling enzymes can help baked goods retain their original freshness for extended periods and can be used to improve volume and dough handling properties.

How to Evaluate Freshness

Expert sensory evaluation of bread is usually done three and 10 days after production, comparing the market standard to the new recipe. Parameters such as foldability, softness, moistness, crumbliness, and freshness are measured.

Some common tests to evaluate freshness over the course of several days are measuring firmness (units in HPa), also called crumb softness; and crumb resilience (units in %).

In Summary

By applying custom enzyme, emulsifier, and softener solutions, you can obtain optimal performance baked goods with enhanced consumer appeal, fewer returns, and improved consumer loyalty. Your potential product benefits include longer-lasting softness, fine homogeneous crumb structure, fresh mouthfeel, and improved resilience.

Aside from their specificity, enzymes often offer other benefits that stretch beyond the product itself. Enzymes can often replace substances or processes that may present safety or environmental issues, help reduce salt and sugar content of foods, and enhance nutritional value. Enzymes are very specific and will work under mild reaction conditions, allowing selective reactions in the presence of sensitive substances. Today enzymes are already used in a variety of foods from beer, dairy, oils and fats, meats, and of course, bakery products. However, innovative new applications and solutions are continuously being found together with food producers to help meet the needs of the growing population.

Saral is the global business director food enzymes for DuPont Industrial Sciences, Netherlands. Reach her at Defne.Saral@dupont.com.

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Factors Influencing the Freeze-Thaw Stability of Emulsion Based Foods

Many of the sauces used in frozen meals are oil-in-water emulsions that consist of fat droplets dispersed within an aqueous medium. This type of emulsion must remain physically and chemically stable throughout processing, freezing, storage, and defrosting conditions. Knowledge of the fundamental physicochemical mechanisms responsible for the stability of emulsion-based sauces is needed to design and produce high-quality sauces with the desired sensory characteristics. This review provides an overview of the current understanding of the influence of freezing and thawing on the stability of oil-in-water emulsions. It focuses on the influence of product composition and homogenization conditions. CLICK HERE for complete article. Comprehensive Reviews in Food Science and Food Safety, Volume 13, Issue 2, pages 98-113, March 2014.

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Food dyes may be useful for more than just giving your cherry Jell-O that vivid red hue. In research described at the annual meeting of the Biophysical Society in early February, a team of food scientists from Rutgers University in New Jersey has found that common food dyes have the potential for use as edible probes of food quality.

Standard fluorescent dyes used as probes in other fields are generally unsuitable for food quality testing, as they are either too toxic for human consumption or too expensive. But the Rutgers scientists say that the edible colors that already either occur naturally in, or are added to, many foods have the potential to act as fluorescent probes.

“Almost every food you eat is fluorescent under some circumstances,” says Richard Ludescher, PhD, a professor of food science at Rutgers. “With a range of applications, we are trying to establish the idea of using molecules that are naturally in or routinely added to food as intrinsic sensors of the quality of the food.”

Sarah Waxman, an undergraduate student in Dr. Ludescher’s lab, presented preliminary findings at the Biophysical Society meeting. The group tested the fluorescent properties of five edible food colors commonly added to food or medications consumed by humans: Allura Red, Sunset Yellow, Brilliant Blue, Fast Green, and a yellow dye called Tartrazine. All five colors fluoresced in a way that was easily distinguishable from the background; they emitted almost no light in pure water, but the light intensity increased when the dyes were added to thicker solutions.

“We’ve established that these molecules respond to viscosity in simple solutions like sugar water and glycerol water,” says Dr. Ludescher. “Next, we need to find out how they respond in more complicated compositions like foods—a pudding, for example. Could we develop a probe for pudding that allows you to measure its viscosity during manufacture?”

The group’s work is supported by funding from the USDA.

Shaw writes frequently about science, medicine, and health while serving as a regular contributor on notable medical publications.

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Texture analysis is the science that measures the mechanical properties of food products and correlates these findings to the way that human beings use their senses to evaluate foods. More than 65 years of research have resulted in a set of definitions that relate peoples’ sensory properties to instrumental measurements based on a standard test known as Texture Profile Analysis or “TPA.”

Food Products

The image at right shows an example of a texture analyzer with cylinder probe used to measure the firmness of sliced bread. The TPA test is a two-cycle procedure that pushes the probe into the bread a defined distance, measures the resistant force, pulls back out, then repeats the same compression cycle. Figure 1a shows the graph of force versus time for the two-cycles; force is on the y-axis, time is on the x-axis. Note that the peak load P1 in the first cycle is higher than the peak load P2 in the second cycle. Once the bread compresses during the first cycle, it does not fully recover to its original position. The texture analyzer records the probe position and the force load is measured throughout the TPA test, which generally takes less than 30 seconds to perform. Figure 1b shows an alternative way to present the same data using distance (position of the probe) on the X-axis. These measurements are used in mathematical calculations that define properties of the sliced bread, such as “springiness” and “chewiness.”

Table 1 lists the defined properties that can be quantified with measurements from a texture analyzer. The two primary characteristics are “hardness” and “adhesiveness.” “Hardness” is exactly what it sounds like—how firm is the object that is under compression. French bread with a crusty exterior will give significantly more resistance to the probe compared to the sliced white bread. “Adhesiveness” is the amount of work required to extract the probe from the food item. Another way of thinking about this is how sticky the food item might be and how difficult it is to pull the probe away. For bread there is no resistance when the probe is extracted, but for salad dressings there can be noticeable resistance.

Using the data related to the hardness and adhesive force measurements, other parameters such as “springiness” and “chewiness” are calculated. Note that “springiness” is exactly what you might think—how much does the bread spring back after being compressed. “Chewiness” on the other hand is an expression that you instinctively understand, but the mathematical calculation shown in the Table may seem complex—the product of hardness, corrected cohesiveness, and springiness. Rest assured that food scientists have successfully used the various terms in Table 1 to characterize food items for years.

Packaging

Exploding QC interest in the use of texture analysis to certify the physical properties of food products coming out of the manufacturing process is now spilling over into related industries, like packaging materials for these same products. Texture analyzers, as explained above, are nothing more than simple instruments that compress or pull apart an item and measure the force and energy required to make it happen. They mimic the consumer who uses the sense of touch when evaluating a food item by hand or when popping the food item into the mouth and taking bites. Texture analyzers can also qualify the integrity of the packaging used to ensure that the food item survives transit from the manufacturing plant to the supermarket shelf to the end user who consumes the item.

Simple examples of tests on packaging materials include actions that consumers use everyday when opening items like yogurt containers with lids that must be peeled off. A peeling jig can be used with a texture analyzer to measure the adhesive strength needed to remove the lid from a sealed container. Tests like these are performed at different angles to simulate the approach taken by customers around the world. The preferred orientation for taking the lid off may be explained by the manufacturer in the information on the side of the container. Peel strength needed to open the container can be adjusted to accommodate the user group for which the product is intended, such as senior citizens and children.

Film materials are used extensively to package all kinds of food items. The ability of film to stretch without tearing is one of its important properties. A film support fixture makes it possible to evaluate the tear strength of the film. The texture probe has the shape of a punch that pushes down on the film sample, which is clamped in place during the test. The rate of travel for the probe can vary from 0.01millimeter (mm)/second to 10 mm/second and is usually selected according to the packaging process on which the film will be applied. R&D labs may conduct tests at different speeds to simulate multiple ways in which the film might be used. The test results not only qualify the film for use in packaging processes, but also provide guidelines for choosing films with specific tear strengths.

One of the more popular fixtures for general purpose testing using the tension mode is the dual grip assembly. This general-purpose device has two separate clamps that fasten the sample material and pull it apart. The bottom clamp is fixed to the base table while the top clamp attaches to the probe drive on the instrument. The top clamp moves upward at the start of the test and the instrument displays the measured force as the material stretches. The test objective is to measure the maximum force that a material can withstand when in tension mode.

A sliding friction test can also be performed on packaging materials in accordance with ASTM D1894. The objective is to measure how easily two materials slide over each other. The instrument measures the force needed to pull a weight robed in one material across the surface of a second material. The rate of travel for the weight is usually between 1 mm/second and 10 mm/second. When there is too much resistance between the materials, the friction may cause damage to one of the materials. This is an important test because it confirms, for example, that boxes of a specific food item, such as cereal packaged in a large container, will arrive at their destination with the printed information on the outside of the box in tact. Customers often judge a product by appearance on the shelf, so this test confirms that the surface of the package withstands the rigors of shipment.

The field of texture analysis has proliferated over recent years with the advent of many fixtures that can measure the firmness and robustness of packaging materials. The objective is to ensure survival of both the food item and its container from the production plant to the end user’s kitchen, as well as to insure that the customer use of the item is optimized for ease and acceptability.

McGregor is general manager, global marketing/high-end lab instrument sales, at Brookfield Engineering Laboratories, Inc. Reach him at r_mcgregor@brookfieldengineering.com.

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Nutritional and Physical Properties of Organic Beauregard Sweet Potato as Influenced by Broiler Litter Application Rate

Organic farming has been on an upward trend in recent years. However, the manures used like broiler litter have variable nutrient content, making it important to establish optimal application rates for maximum crop yield and quality. Additionally, some states like Alabama restrict the amount of broiler litter to control excessive nutrients accumulation that can lead to surface and ground water contamination. In this study, the nutritional and physical properties of organically grown Beauregard sweet potato were evaluated to determine the effect of application of broiler litter at rates of 0, 0.5, 1, 2, and 3 tons per hectare in meeting the application rate recommended by Alabama Cooperative Extension Program.  CLICK here for complete article. Food Science and Nutrition, Volume 2, Issue 4, July 2014, Pages 332–340.

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