How To Test Anti Caking

The food processing and handling industry is heavily reliant on anti-caking agents to safeguard manufacturing efficiency and preserve the value of powdered ingredients and products. Driven by innovation and evolving customer preferences, this is an manufacture showing good for you expansion with the food handling and processing equipment market predicted to showroom a compound annual growth rate (CAGR) of half dozen.v% upwards to 2026.^one

Against this backdrop there is rising need for new, high-performance additives that meet changing needs, notably to displace ingredients that are controversial or of undesirable provenance. For instance, silica is an effective, widely used anti-caking amanuensis but employ is becoming increasingly controversial due to concerns over nanoparticles.²

In this commodity we describe collaborative work on new anti-caking agents carried out past Omya (Oftringen, Switzerland) a leading global producer of calcium carbonate, and Freeman Technology (Tewkesbury, UK) a global leader in pulverization characterization engineering science. A primary focus is the application of avant-garde powder testing (FT4 Powder Rheometer) to assess heterogeneous caking beliefs – crusting – to rigorously assess potential candidates.

The Caking of Food Ingredients: Mechanisms and Impact

Powders left undisturbed for protracted periods of time can gain forcefulness, losing the flow backdrop that in many instances ascertain their value. This process is known as caking and it can proceed via a range of chemical, electrical, and mechanical mechanisms; with food ingredients the absorption and migration of moisture almost e'er plays a defining role. The adsorption of moisture on to the surface of powder particles, or into the powder bulk, tin trigger chemical caking – for example by hydration, partial dissolution, and recrystallization - or induce plastic menstruation, through modification of the particle surface and, by extension, particle-particle interactions. Multiple mechanisms may occur simultaneously or sequentially, and the net result varies from soft easily broken aggregates to irreversibly fused material with properties far removed from those of the original material.

Powdered ingredients used past the food industry range from dry basis spices and extracted flavorings to core ingredients such as cocoa and milk powders. Such ingredients showroom considerable diversity with respect to surface chemical science and physical properties and caking behavior is correspondingly complex. For any given material, the uptake of moisture is directly influenced past storage atmospheric condition (relative humidity, temperature, and pressure) but stored powders typically only accept one surface exposed to the surrounding environment. Caking behavior is therefore complicated past the ease or otherwise of wet migration through the pulverization, even as the properties of the pulverization bed are modified by, for example, liquid bridging or recrystallization. The supposition that caking is ever homogeneous is unreliable; crusting is commonplace.

The consistent processing and ease-of-use of powdered ingredients is reliant on their flow properties, with caking potentially impacting critical operations such as hopper belch, blending, dosing and, in certain instances, dissolution. Decision-making caking to acceptable levels is therefore crucial. The goal is to plant strategies that maintain ingredients in an optimal country without incurring unnecessary expense. While storage under conditions of controlled temperature and humidity may exist essential, anti-caking agents can transform sensitivity to moisture, making menses backdrop much easier to maintain. As a effect, they are a vital class of additive for the food industry.

Developing New Anti-Caking Agents

The provenance and safety of food ingredients is constantly under review and is an important driver for innovation and reformulation. With respect to anti-caking agents, silica is oft considered the "gilded standard" with potential to reduce caking by:

dispersing sparingly across particle surfaces, thereby increasing the altitude between particles, and decreasing van der Waals forces of attraction
absorbing wet to reduce the effect of liquid bridging
completely coating particles to prevent adhesion.

Via these mechanisms, incorporating silica at different concentrations can improve the caking behavior of all types of pulverization - dry/hard, moist, and soft/high fat materials, respectively. Nevertheless, the use of silica is becoming more controversial. Silica anti-caking agents have a fine particle size distribution to impart the high specific surface surface area that underpins their efficacy. Though typically made upward of aggregated nanoparticles with a diameter in excess of 100 nm at that place is concern that the textile potentially subjects users to exposure to particles beneath this "nano threshold." Regulations over nanoparticles and the potential health risk associated with them continue to evolve but some countries have at present banned silica every bit an anti-caking amanuensis with the European Nutrient Safe Authority (EFSA), for instance, calling for meliorate label and specification to provide an assurance of safety.^two

The status of silica provides impetus for the introduction of new anti-caking agents with a more robust prophylactic contour. Calcium carbonate has considerable potential in this respect. A natural textile with an established prophylactic profile, it is already used to fortify foods, including dairy and non-dairy drinks. Replicating the impressive performance of silica is a pregnant challenge but Omya has fabricated considerable progress in this regard, cartoon on its expertise in calcium carbonate product development. The following studies illustrate the levels of operation accomplished with new functionalized calcium carbonate (FCC) anti-caking agents.

Assessing the Performance of Anti-Caking Agents

The purpose of anti-caking agents is to preserve the flow properties of powders. Comparative assessments of the operation of new anti-caking agents therefore rely on the measurement of pulverization flowability. Dynamic pulverisation testing with a powder rheometer is uniquely suitable for this purpose considering it offers:

high sensitivity: enabling the detection of even subtle differences in caking beliefs
relevance: test conditions tin can be selected to assess the touch on of environmental conditions and consolidation, for example, and dynamic properties have been securely correlated with performance in many unit operations such every bit blending, carrying and belch
the ability to narrate heterogeneous caking behavior or crusting.³

The effigy at the beginning of this article shows how Basic Flowability Energy (BFE), a baseline dynamic pulverization property is measured using the FT4 Pulverization Rheometer. The centric and rotational forces acting on the blade of the instrument are recorded every 40 ms every bit it rotates downward through the pulverization bed, to construct a plot of energy slope as a role of bed summit. Values of BFE are generated by integration, by determining the area under the bend. Nevertheless, differences in period characteristics inside the sample are easily detected since the position of the blade can be determined with a high degree of accuracy, at any given fourth dimension. With dynamic testing it is possible to notice crusting, to rails the bear upon of moisture migration through the powder bed, and to quantify the strength of aggregated material. Via humidity cycling experiments information technology is also possible to determine whether caking is reversible. These capabilities make dynamic testing extremely valuable for all types of caking studies.

Case Written report i: Comparing the Performance of New Anti-Caking Agents

An experimental study was carried out to compare the operation of two FCC anti-caking agents, Amanuensis one and Amanuensis 2, with that of a commercially bachelor silica product. Dynamic powder backdrop were measured for four samples: milk powder and milk powder with 1% w/w silica, ane% w/w Amanuensis 1, and 1% w/w Agent two. Baseline powder characterization tests were carried out nether ambient weather condition (FT4 Pulverization Rheometer) and caking behavior was then quantified via repeat testing following storage under weather of controlled relative humidity, subsequently iv½ days at 63% RH and after 2½ days at 74% RH.

In an initial analysis of the data Caking Index (CI) was determined, where CI is the ratio of the Total Energy (TE) of the caked fabric to the BFE of the fresh powder before storage. The CI of the sample containing the silica anti-caking amanuensis was found to be unexpectedly high given that the silica was known to be effective in preventing caking. Effigy 1 shows the data that underpin these calculations.

Image courtesy of Freeman Engineering science

Effigy 1: A plot of energy as a function of acme for the milk sample containing the silica anti-caking agent shows clear prove of crusting.

These results show evidence of crusting in the superlative ~10 mm sample after storage for four½ days at an RH of 63%, with the peak of the graph indicating greater resistance to flow in this surface area. Storage at the higher RH (74%) produces a stronger crust in a shorter timeframe. However, in both cases the chaff is relatively thin and the material beneath is unchanged with respect to menstruum characteristics; both traces return close to the baseline bend.

Image courtesy of Freeman Engineering science

Image courtesy of Freeman Engineering

Figure 2: Crust depth and force information for the 4 samples indicate that the new anti-caking agents result in a thicker but weaker crust compared with the silica production.

Comparable data for each of the samples quantify differences in crust depth and strength (run across effigy 2). In the absenteeism of anti-caking agents, the milk pulverization cakes extensively, to a depth of ~23-33 mm, depending on storage atmospheric condition, though the caked textile has relatively footling forcefulness. The crust that develops with Agent 1 and Agent 2 is thinner than in the absence of an anti-caking agent merely thick relative to silica peculiarly subsequently storage at the low RH (63%). However, the strength of crust developed at loftier RH with Agents ane and ii is lower than with silica; at lower RH the strength of the adult crust is more comparable.

These data propose that all the anti-caking agents promote the formation of a relatively impermeable chaff at the air-powder interface that inhibits moisture migration into the rest of the powder. They besides provide evidence that the new agents perform relatively well compared with the silica leading to the formation of a thicker chaff with comparable or lower strength, depending on storage conditions.

In a final extension to the study, the observed caking parameters were correlated with the properties of the freshly blended samples, measured under ambience conditions prior to caking, to investigate the feasibility of predicting caking behavior from this baseline assay. This analysis revealed two particularly potent and interesting relationships:

* Crust depth was found to correlate strongly with Stability Index (SI - R2, 63% RH = 0.9542, 74% RH = 0.9267), where SI is the ratio of BFE measured after seven measurement cycles to initial BFE. Instability in BFE measurements is potentially due to moisture uptake during measurement, providing a rationale for this correlation.

* The maximum energy in the chaff, an indicator of crust strength was found to correlate strongly with permeability equally quantified by pressure level drop across the sample at xv kPa (R2, 63% RH = 0.8954, 74% RH = 0.9570). A rationale for this relationship is that depression permeability inhibits moisture migration promoting the development of a stronger crust at the air-powder interface.

Taken together the results from this study show how dynamic data can sensitively narrate and differentiate Agent 1 and Agent 2 via multiple, relevant metrics, to provide an assessment of their performance relative to silica, with some potential to predict beliefs. This contrasts markedly with culling techniques, such as moisture uptake measurements, which provided no differentiation between Amanuensis 1 and Agent two and far more express insight.

Case Written report 2: Comparing Caking Behavior in Different Substrates

A second set of experiments was carried out to compare the operation of anti-caking agents with two different substrates: milk pulverisation and a commercial spice alloy. Dynamic pulverisation backdrop were measured (as in case study one) for the raw powders and for blends of each pulverization with i% w/due west of either silica or Agent two. Baseline characterization was carried out under ambient conditions and caking behavior was quantified via repeat testing following storage at 75% RH for two days and half-dozen days, for the milk and spice samples, respectively. This reflects the storage times required for meaning crust formation to exist observed for each substrate.

Image courtesy of Freeman Technology

Epitome courtesy of Freeman Technology

Figure 3: Plots of free energy equally a function of height for the milk (left) and spice (right) samples, with and without the anti-caking agents show that substrate has a meaning bear upon on caking beliefs.

Data for the milk powder (figure 3 – left) are comparable to those generated in case study 1, as expected. Nonetheless, unlike beliefs is observed with the spice alloy (effigy 3 – correct). Here silica limits caking to the top half of the sample simply baseline free energy values of the silica-spice alloy are significantly higher than either the raw cloth or the Agent 2 alloy. Furthermore, while both the raw spice and Agent two blend exhibit a clear peak energy value, flowability fails to converge to the baseline value in either case; free energy values are higher subsequently storage throughout the entire sample. This caking beliefs could exist described as hybrid, somewhere between crusting and uniform caking throughout the pulverization sample and indicates that with the spice blend a greater proportion of the pulverisation bed will be affected by any caking that occurs.

Image courtesy of Freeman Technology

Effigy iv: Dynamic data measured for the milk and spice blend show that the issue of anti-caking agents depends on substrate.

A complete comparing of data for the ii substrates in the presence and absence of silica and Agent ii demonstrates notable differences. In full general, far stronger crusts grade with the spice blend, relative to the milk powder. However, Agent 2 reduces chaff energy and strength significantly, relative to silica; the associated increase in crust depth is less marked. Agent 2 has a positive touch on CI for the spice alloy, relative to the absenteeism of a caking agent, though silica gives the everyman CI value.

As in case report ane, this set of experiments was expanded with an analysis of dynamic and bulk properties of the fresh blends, prior to storage. These data (effigy 5) illustrate how the inclusion of anti-caking agents impacts the properties of the raw powders, providing useful insight with respect to the potential for changes in procedure operation, as well as helping to rationalize observed caking behavior.

Image courtesy of Freeman Technology

Image courtesy of Freeman Engineering science

Image courtesy of Freeman Technology

Figure 5: Dynamic and majority properties for the milk and spice blends prove that the impact of the anti-caking agents varies significantly with substrate.

The inclusion of silica substantially reduces the compressibility of both the milk powder and the spice blend. Agent two reduces the compressibility of the milk powder, though not the spice blend, and to a bottom extent than the silica. Lower compressibility is associated with more efficient particle packing and makes powders less prone to changes in flowability during storage. However, it can also requite ascent to high BFE values, since less compressible powders tend to flow poorly under the forcing weather condition associated with BFE measurement. This effect is observed with the spice-silica blend, though not so much with the analogous milk powder sample. Strong correlations were observed between compressibility and CE (caked energy) (R2, milk powder = 0.9981, R2, spice blend = 0.9275).

SE data provide a further example of the contrasting beliefs observed with different substrates. While both anti-caking agents reduce the SE of the milk powder the opposite effect is observed with the spice blend. SE quantifies how hands the pulverization flows when in an unconfined, low stress state. Higher values may therefore exist straight associated with compromised functioning in unit of measurement operations where the powder is flowing under gravity, for case, in filling or dosing applications.

Finally, equally in case study 1 a strong correlation was observed betwixt SI and chaff energy (R2, milk powder = 0.9970, R2, spice blend = 0.9860), for both powders, and information technology is reasonable to rationalize this trend as before, with reference to the ability of SI to provide an indication of propensity for wet uptake.

This second set of data provides farther evidence of the complexity of caking beliefs and the insight generated by dynamic powder properties, into crusting and the relative suitability of different anti-caking agents for unlike substrates.

Looking Ahead

The food processing industry relies heavily on anti-caking agents to achieve the manufacturing efficiency and product performance required. Improving and refreshing the additive portfolio is vital in response to changing requirements, to formulate new foods and to eliminate ingredients with an undesirable provenance or health profile. The work presented hither demonstrates the value of dynamic powder testing for comparison the functioning of anti-caking agents and the efficacy of new functionalized calcium carbonate anti-caking agents, with two different substrates. A crucial feature of dynamic testing is the ability to notice and characterize not-homogeneous caking or crusting to provide unique and rigorous insights that directly support the introduction of additives with a target functioning profile. The results generated show that functionalized calcium carbonate anti-caking agents deliver functioning approaching that of silica--a gold standard anti-caking agent--thereby demonstrating considerable potential for food processing applications.

Laura Shaw is applications specialist, Freeman Engineering science; Dr. Renata Negrini is technical service manager food, Omya International AG; Marcel Lexis sometime innovation engineer consumer goods, Omya International AG; Jamie Clayton is operations director, Freeman Technology; Lalit Sharma is innovation manager food, Omya International AG.

References

1 McKinsey and Co. "Food Processing and Handling: Ripe for Disruption"

2 N Michail "EFSA heighten ruby-red flag for silicon dioxide safety over nanoparticles"

iii Brockbank K, Armstrong B, Clayton J. Measurement and quantification of caking in excipients and food products with emphasis on the non-homogeneous interaction with ambient wet. Particuology 2020, 56: 75-83

Source: https://www.powderbulksolids.com/instrumentation-control/developing-new-anti-caking-agents-using-powder-testing-identify-high

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