Accelerating R&D with microstructure and physical analysis

BY CLARE PAYNE - SENIOR SCIENTIST & FRED GATES - TECHNICAL SPECIALIST

7 June 2023

 

 

Our technical experts answer your questions and explain how we use a range of analytical techniques to resolve some of the most pressing product development issues.  

How can we be sure the texture of our vegan yogurt protypes will meet consumer expectations during shelf-life and outperform the competition?

 

 

Testing the viscosity of each prototype tells us a lot about how they will perform during shelf-life. We use rheological analysis to investigate key textural parameters, such as scooping resistance and mouthfeel, and benchmark these findings against competitor products as well as consumer expectations.  Roundtable sensory evaluation of competitor products and prototypes or formal consumer science methods can be used to determine which parameters are drivers of liking as well as which products are preferred.

 

From a manufacturing point of view, measuring viscosity gives you crucial information about the behaviour of your prototypes during heating, cooling, pumping and other important processes. This helps to ensure the desired texture is maintained by identifying (and preventing) problems with ingredient separation. We can also gain valuable insights into the potentially negative impact of transportation on shelf-life and product quality.

Crucially, if differences are detected between prototypes and competitor brands at the start or during shelf-life, microstructural analysis can be used to find out why. We can, for example, use specific techniques to visualise the size of fat or water droplets that correlate with the best sensorial profile. Or to pinpoint the reason why prototypes aren’t behaving as expected. 

 

It’s also worth considering the benefits of accelerated instability testing. By fast screening prototypes at the beginning of the NPD process, those that are found to separate quickly can be discarded early on. At RSSL we have the capability to assess instability, including emulsion stability, using a LUMiSizer dispersion analyser. This reduces the number of options we put forward for further testing, cutting your costs and ultimately streamlining time to market.

 

 

 


Supply chain issues are forcing us to change the flour ingredient in our savoury dipping sauce and we want to use this opportunity to explore plant-based and gluten-free options. How can we screen them for robust shelf-life stability?

 


Making this change will directly impact the viscosity of the dipping sauce, so you need to be sure that protypes made with alternative flour ingredients provide the same consumer experience at every stage of use. How does the dipping sauce look in the jar? What happens when it’s scooped out with a spoon or poured out? How does it behave when used as a dip with vegetables, crisps or breadsticks? 

 


We can answer these questions by developing and carrying out a series of rheological tests designed to characterise the viscosity of each prototype. And then benchmarking the results against the current recipe. What we’re looking for is an optimal texture that performs well in all areas, ideally one that is thick enough to cling to the bread stick or spoon but not so thick that it’s difficult to extract from the jar. 

 


An equally important issue to consider is sedimentation. Over time, some plant-based and gluten-free flours can form undesirable lumps or distinct layers during shelf-life, often due to ingredient incompatibility and interactions. We can identify these so called flocculated or agglomerated materials with specific microscopic techniques, such as Confocal Laser Scanning Microscopy (CLSM). If we go further and use CLSM in conjunction with particle size distribution analysis, we can also determine the scale of the issue and whether layer separation is likely. 

 


Ultimately, flour is an important functional ingredient. Therefore, any change will impact everything from emulsification and stability to mouthfeel and texture, which is why we would also recommend arranging informal sensory testing  to provide a detailed description of the texture of each new dipping sauce formulation. 

 

 

 


We are developing a vegan royal icing topping, using various vegan alternatives instead of the traditional egg white ingredient, but our prototypes are not performing well. Can you help us understand why?

 

This is all about investigating viscosity and flow properties – both of which are key to understanding the performance of your vegan royal icing prototypes. We do this by studying the rheology of the vegan icing when first mixed together and immediately after application. At this stage, its structure needs to allow enough initial flow to coat the intended product but without running off.  With these test results we can optimise the flow properties by selecting ingredients that will achieve the required level of spreadability. 

 

Once the icing is set, we use a rheological creep measurement to determine how much it could potentially flow or change over time under normal gravity conditions and a penetration test to measure hardness. You essentially want it to be stable, maintain its structure and remain in place during shelf-life. In this case, we would want to know whether the vegan ingredients will provide similar stability and hold as traditional egg white proteins. 

 

Microscopy, specifically Confocal Laser Scanning Microscopy (CLSM), can help us find out because it enables us to see and quantify what happens to the molecular structure of the protein in the vegan icing. Even small changes can significantly affect its functionality so, once identified, we can then resolve any performance issues by making relevant adjustments to the formulation as part of the product development process.  

 

We are reformulating our vanilla sponge cake to make it healthier but want to keep the same aerated texture during shelf-life. How can we evaluate lower fat/sugar recipes to ensure we achieve the best balance? 

The challenge here is to ensure the air bubbles are stable and evenly distributed in the reformulated sponge cake. This is because they provide much of the cake’s structure and volume, so need to be optimised to create the light and moist texture consumers expect.  


Fat crystals have a particularly important role as they help to stabilise the air bubbles, allowing them to expand without breaking during baking. You certainly don’t want the air bubbles to collapse. The goal is to create a stable matrix of suspended fat, water and air in a smooth batter. 


So we need to find out whether the different fats and ingredient combinations used in the reformulated concepts will create less stable air bubbles. Microscopy techniques allow us to visualise these important interactions and understand how they perform under different processing conditions. But that’s only part of the picture. 

 

 

We also need to know if the sponge cake’s structure, porosity, volume and shape will change over time. If it’s a sandwich cake, for instance, is the cream filling likely to leak out during shelf-life? There are also a raft of physical properties that we can analyse such as the first bite, bounce, crumb structure and moisture. Without forgetting the importance of a visually appealing golden cake crust, which we assess using a highly accurate iDigieye imaging system.

 

 

 

 

After scaling up our new range of dairy, vegan and low sugar ice cream products, we have identified several sensory and quality problems. Can you help us investigate?


The issues you’re experiencing will largely be the result of the scale up from the factory, compared to the process followed in the development kitchen. The full-scale processing equipment and freezing techniques may be affecting the product microstructure by, for example, changing the size and distribution of air bubbles, fat droplets, sugar crystals and ice crystals. And this in turn can affect the texture and performance of the ice cream during shelf-life. The actual over-run for each of the frozen products should also be assessed for any differences.  


We can help by carrying out a Design of Experiment trial (DOE) to determine which ingredients and processing techniques will deliver the best results. For instance, evaluating the use of powdered ingredients with different particle sizes, or the impact of using different speeds and settings for mixers, pumps and aerators on the production line.


At the same time, we use a combination of specialist analytical tools and imaging techniques to monitor microstructural changes in the ice cream during shelf-life. These findings are then linked to sensory attributes so that we can better understand how to resolve any issues and improve product quality. 
An excessive softness, for instance, could signify the ice cream has large areas of air bubbles that have coalesced. A grainy texture may be found to have much coarser ice crystals compared to softer products. While a dense texture may be due to poor emulsion stability or fat droplet aggregation prior to aeration or freezing. Whatever the sensory or quality issue, we can determine the cause and either reformulate the ice cream concept in question or suggest alternative production techniques for better results. 

 

 

 


We have moved to a large-scale production site and want to understand if the new storage conditions will impact the processability of the raw materials used in our powdered beverage? 


The best approach would be to use a combination of different analytical techniques to investigate how different environmental conditions, such as temperature and humidity, affect powder flowability and integrity during storage, production and transport.  


For instance, we can identify the critical point at which moisture conditions will impact raw materials handling. Or how different storage temperatures will affect crucial powder properties such as bulk density, moisture content and water activity. We can then apply these learnings to your specific storage and production conditions. 


What might this look like? We know that bridging of irregular shaped powder particles can happen when particulate materials interlock or bond together, potentially resulting in the formation of an arch above the outlet of a container. But if we scan the powder samples before and after storage under the appropriate conditions to determine the particle shape and size distribution, we can recommend how to improve flowability. Changing the type of milling could be a possible option. 


Similarly, data from a shear cell test will flag up if powders are likely to consolidate or compact, causing issues during hopper/silo storage and transport. It’s also important to understand the so-called ‘wall friction’ of the powders because it tells us how much energy and force is needed to move the powder through the processing equipment. This can not only be used to improve the equipment design, but also prevent blockages or the build-up of stagnant, decaying material which has serious implications – both in terms of unwanted cleaning down time and food safety. 


All these data outputs are combined and used to generate simple models which define the optimum storage and operational ranges for your powder materials. Once developed, we can also test these parameters by storing your powder samples in a controlled environment which mimics your chosen storage and processing conditions - and then refine the model if necessary.  

 

 

 

 

How RSSL can support with microstructure and physical analysis

 

Using a range of analytical techniques, we can characterise the physical properties and microstructure of food. These insights help us work with you to address the development and production challenges that come up along the way. Whether you are at the beginning of your R&D process, tackling reformulation, or have hit unexpected quality issues, our investigations will give you the answers you need.  Click through to find out more or contact us via the form below for further information.

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