Sugar and size and everything nice - Sugar Flowability analysis

This article focuses on various types of sugar, with a particular focus on Sugar Flowability Analysis, and the methods used for testing. Sugar naturally occurs in various produce, such as fruits and vegetables, with concentrations that vary. Sugar cane contains 12-14% sucrose, making it high in sucrose content. In contrast, sugar beets, with 16-18% sucrose, have the highest natural sucrose levels. Sucrose, a disaccharide, consists of glucose and fructose. The extraction process for both sugar cane and sugar beets follows a similar method. Secondary refining produces specialty sugars for different industries.

The Coarseness of sugars

Coarse sugars are typically used as end products, especially in certain candies. Granulated sugar forms when a saturated sugar-water solution crystallizes on a surface that promotes crystal nucleation. Heating the water before adding sugar enhances dissolution, leading to larger crystals. The result is a white, clear crystalline structure with medium grain sizes between 0.5 and 1 mm. This sugar flows freely and is widely used in food due to its functional properties.

Finer sugars, on the other hand, are often required for specific applications, such as baked goods. Powdered sugar, with particle sizes ranging from 10 to 30 μm, functions both as an end product and as an ingredient in candies, toppings, and foods like tomato sauces and pastes. Due to its smaller particle size, an anti-caking agent is often necessary to maintain flowability. Common agents include starches like cornstarch and additives such as tricalcium phosphate.

Powdered sugar’s flowability depends on its granulated sugar base, which is free-flowing and easy to process. By adding the appropriate anti-caking agent, we can optimize flowability, making powdered sugar ideal for homogeneous dry powder mixes.

Flowability and particle size Distribution

Cohesive materials often flow “en masse” or as agglomerates, creating distinct flow patterns like core flow and non-flow. Core flow, also known as ratholing or funnel flow, occurs when only the central core moves, typically in a last-in, first-out pattern.

Applied stress significantly impacts the powder’s flow properties. This stress typically arises during the filling and emptying of large bags or when discharging material from a silo or hopper. Forces exerted by the powder on the layers beneath, combined with the resulting flow behavior, can be analyzed effectively using shear measurements.

Shear testing measures internal friction after applying consolidation stresses, offering valuable insights into consolidated flow properties. These insights are crucial for designing efficient hoppers. Engineers use shear data, product density, and wall friction to calculate the optimal hopper half-angle and outlet diameter, ensuring smooth and controlled flow tailored to the material’s characteristics.

Flow function

The flow function visually represents powder flow behavior, enabling comparisons of flow characteristics across different powders under specific stresses.

It defines the relationship between Unconfined Failure (Yield) Strength (kPa) and Principal Consolidation Stress (kPa). The flow function classifies powders into five categories: free-flowing, easy-flowing, cohesive, very cohesive, and non-flowing.

Equipment and Methodology

For these flowability investigations, we used the AMETEK Brookfield powder flow tester and the Anton Paar MCR Powder Rheometer. These methods assess powder flow characteristics in both small and large sample sizes, ranging from a few grams to several hundred grams. We conducted each measurement in duplicate, applying eight different consolidation stresses per test.

Testing Results of the Sugar Flowability Analysis

Figures 1 through 3 present the testing results, showing the flow function for each sample. Figure 4 offers a comparative overview of all three samples. The results demonstrate strong repeatability, indicated by the near-overlap of independent measurements in Figures 1 to 3. High-pressure results from the small sample cell align closely with low-pressure results from the large sample cell, as shown by the smooth transition between overlapping data points. Figure 4 further emphasizes the consistency of the flow function across the samples, providing a clear comparative overview.

Sugar and size and everything nice - Sugar Flowability analysis

Figure 1

Figure 2 - Sugar Flowability analysis

Figure 2

Figure 3 - Sugar Flowability analysis

Figure 3

Figure 4 - Sugar Flowability analysis

Figure 4

Sugar Flowability Analysis

Figure 4 demonstrates that Sample 3 has the best flow properties, classifying it as easy-flowing. Sample 2 falls under the cohesive category, while Sample 1 shows the highest cohesiveness of the three. Consequently, Sample 1 is expected to encounter the most severe flowability issues, with Sample 2 experiencing moderate challenges. Based on these results, the client adjusted the anti-caking agent in Samples 1 and 2 to better match Sample 3’s composition, thus improving flowability across all samples.

How we can help you with Sugar Flowability Analysis

Industry innovation drives the creation and adoption of improved products, processes, and services, from raw materials to final production. Companies today focus on producing accessible and sustainable products while emphasizing efficient production cycles and reducing their environmental footprint. Research and development play a key role in achieving these goals, and Delft Solids Solutions offers significant support in this area.

With advanced laboratory infrastructure, we specialize in particle and powder technology, covering five key areas:

  • (Bulk) powder behavior
  • Surface and porosity properties
  • Particle size and shape
  • Material composition
  • Powder processing

At Delft Solids Solutions, we develop and optimize materials through techniques like milling and mixing. Additionally, we evaluate and enhance the impact of various unit operations on these processes.