February 2020

NEW Hair Suppleness Rig

The cosmetics industry frequently promises softer, suppler hair after the use of their products, or promises that certain traditionally harmful methods (such as bleaching) will have no adverse effect. The difficulty comes in testing these properties in an imitative, repeatable way. The Hair Suppleness Rig allows the measurement of the resistance of a hair sample to being run through a set of smooth bars, representative of running fingers through the hair on a human head.

Some changes to the physical properties of hair are intentional (the addition of conditioners or serum for added smoothness), whereas some are unintentional (bleaching, which induces brittleness and stiffness). No matter the property in question, the quantification of hair properties is important to the development of new hair products and treatments. Sensory panels are useful, as hair is a product with a complex pattern of properties and variables, so it is a challenge to measure its properties exactly as a consumer might feel them when they are styling their hair, or what they take to mean ‘softness to the touch’. However, instrumental testing is much faster to perform, and the results of an instrumental test do not rely on the operator, unlike those of a sensory test, no matter how thorough sensory training has been. Consequently, instrumental quantification of hair properties should be a standard part of any hair testing routine.

Assessments of hair such as tensile testing and three-point bend testing are useful for keeping a record of more fundamental properties, but imitative tests such as the measurement of combing force, volume and body measurement via laser profiling, and this suppleness test are useful for representing hair in the way in which it is felt and used in reality.

The force detected by the loadcell when a hair sample is pulled through this rig is made up of several factors:
1) The stiffness of the hair fibres (as they have to constantly bend on their way up through the rods).
2) The friction between hair strands (as they rub against each other constantly when the tress is being pulled upward).
3) The friction between the hair strands and the rig (as they are pulled against the surface of the rig itself).

An alteration to any of these factors will have an effect on the measured force. A higher force represents a higher resistance to motion through the rods of the rig. A suppler hair sample will have a lower resistance to motion, and in turn, suppler hair on a person’s head feels flexible and smooth when fingers are run through it.

This is similar to subjecting a sample to a three-point bend test, but the bending configuration is slid along the length of the tress- i.e., continuous three-point bending. Bending tests can be challenging to set up in a reproducible way, particularly for suppler samples that cannot support their own weight without drooping, so this test is a simpler alternative that can be directly related to the consumer’s perception of their own hair texture.

To discover other ways of testing hair and hair products using a Texture Analyser, click here.

Making up for texture in egg-free food

The rise in demand for a plant based diet brings with it a wide range of challenges. However, there is one ingredient in particular that can cause big problems in its absence: the humble egg. Eggs play an important part in a lot of cooking because they have so many interesting functions. They can add shine to the top of pies, emulsify sauces, aerate chocolate mousse and add moisture and fat to cake.

When a whole egg is used in a recipe, they combine the individual properties of the yolk and white. They emulsify, bind ingredients and solidify when heated to provide mechanical support. When sugar is added, eggs are excellent at trapping air, adding lightness to a recipe. Whole eggs are used in waffles, brownies, muffins, cookies and sponge cake to name a few. The components of an egg may be used separately, too. When an egg white is whipped, it forms a stable foam. This is useful in macarons, marshmallows and meringues. A yolk, when used alone, exploits its high fat content and emulsification properties. Yolks are used alone in ice cream, custard, creme brulee and pastry cream.

Vegans have long been replacing eggs in their cooking with weird and wonderful ingredients. Now most supermarkets have a ‘plant based’ aisle, manufacturers have caught up with the home cooks and are selling products made with replacement ingredients, or else adjusted recipes. Egg free does not necessarily mean a product is vegan – dairy products may be included for those following an egg free diet. As with any new food product, it is crucial that its texture is tested thoroughly before it is released onto the market, or else it will be passed over in favour of a brand who have carried out the necessary research and set the gold standard.

The first product that springs to mind as ‘impossible without eggs’ is meringue. However, egg free meringue is made a possibility by the fact that chickpea water, otherwise known as ‘aquafaba’, forms into soft peaks when whipped, just like egg whites. The most important attribute of a meringue is its crispness. As meringues often come in irregular shapes, their crispness is most easily measured using a penetration test. A 2mm cylinder probe allows multiple test sites on the same sample, and is best applied to areas with a flat surface. A crisp meringue will show a definite force peak with a sharp drop off; a flaccid meringue will show a more gradual peak.

Eggs help to give brioche its fluffy texture, rich flavour and yellow colour. They can be replaced, however, with the addition of buttermilk and yellow food colouring, but this can compromise the fluffiness of the loaf, impacting both its softness and volume. Brioche volume can be measured using a simple measurement in the Volscan Profiler within 30 seconds. This is a benchtop laser-based scanner that measures the volume, density and dimensional profiles of solid products.

Brioche softness is often tested by the consumer in-store by squeezing it between the thumb and fingers, creating a ‘V’ shape with the hand. The Bread V Squeeze Rig imitates this process and allows the bakery’s R&D department to perform repeatable, scientific analysis of the freshness and appeal of bread products. Its V-shaped ‘fingers’ are pressed into a packaged or unpackaged loaf, and the force required to compress the bread is measured. Post-test calculations are then used as an indication of freshness – the lower the force and higher the value of springiness, the fresher the loaf. This non-destructive test offers simplicity and speed as the loaf requires no sample preparation and can be analysed within its packaging.

Volscan ProfilerC; Bread V Squeeze Rig; Compression platen

In a similar vein, sponge cake relies on eggs for its richness and structure, although some recipes call for golden syrup or even vinegar replacements. As its name suggests, springiness is of high importance in a sponge cake – when squeezed, it should push back and return back to its original size. This property can be measured using a relaxation test, during which the Texture Analyser compresses a sample by a specific amount over a given time period. The analysis capabilities of Exponent software allow the springiness to be calculated from the force-time graph.

Although a crisp English biscuit rarely contains any eggs, its chewy American counterpart relies on them. This chewiness is difficult to replicate, but careful research and recipe control can give success. This usually calls for a recipe adjustment (in the form of increased water and fat contents) rather than an additional ingredient. A three-point bend test is a quick and simple way to assess chewiness. Unlike the desired sudden force drop in a meringue penetration test, a three-point bend of a chewy cookie should show a shallow profile, just as a customer would feel a gradual increase in force as they tear it in half between their hands.

3 Point Bend Rig; TTC Spreadability Rig; Back Extrusion Rig

Moving into the realm of semi-solids, both eggless pastry cream and eggless mayonnaise can be bought in specialist shops. Pastry cream replaces eggs with custard powder or potato starch; mayonnaise can use thickened soya milk. In both cases, their consistency should be soft and smooth. As mayonnaise is generally used as a sauce base or spread thinly on sandwiches, it has a lower viscosity than pastry cream (which must hold its shape), so their tests will not necessarily be the same. Pastry cream is well-suited to the Spreadability Rig, which holds a small volume of sample in a female cone and displaces it completely with a male cone. This has the added advantage of measuring the sample’s adhesiveness during the unloading period.

Mayonnaise is often tested using the Back Extrusion Rig. This rig is comprised of a sample container that is centrally located beneath a disc plunger. The disc plunger performs a compression test, which extrudes the product up and around the edge of the disc. This test measures the consistency of viscous products. Using the back extrusion principle (i.e. using a disc on the probe adapter) the consistency can also be determined directly in containers straight from the production line. This rules out pre-stressing of the material caused by transfilling; this cannot usually be avoided when using other methods.

The egg free concept is such an important area of research that Campden BRI, who provide the food industry with scientific, technical and advisory services, have a new ‘club’ dedicated to egg replacements, with the aim of finding the most suitable replacement for each product category based on an increased understanding of the mechanisms of plant-based egg replacements. To learn about Texture Analysis techniques for your egg free range, contact Stable Micro Systems today.

How to speed through your sample testing

For texture analyser users who are looking for ways to increase their sample testing throughput and improve the convenience of probe attachment to their texture analyser, we have some innovative options.

Users can now choose to have a converter fitted to their probes to allow for quick removal and replacement between tests.

A ‘magnetic’ coupling or ‘quick-twist’ attachment of the probe are available (in batches of 5). These quick probe removal and replacement options are the first of their kind in texture analysis and support the need for test procedures that have efficiency and/or convenience in mind.

Whilst a magnetic coupling might be the favoured attachment action it is not suited to the testing of samples that do not have a flat surface or samples that have an adhesive force measurement exceeding 1.5kg. The ‘quick-twist’ probe attachment is suited to all applications and load cells. These have Community Design Registration – proving our commitment to new innovation testing solutions.

The Multi-head Indexing Probe is another application for the Automated Linear Indexing System that allows adhesives to be tested without manual intervention between tests or the need to clean/dry probes in between sample tests.

This thereby allows for ‘walk-away’ time from testing due to the system being able to automatically index to a new probe after each test.

The video shown above gives an example of how the Automated Indexing System can operate with this Multi-head Indexing Probe.

The Multi-head Indexing Probe is also available separately for those users who just wish to speed up their testing whilst manually indexing the probe to the next clean probe during testing, to avoid stopping to clean and dry between tests.

Both ways of using this Multi-head Indexing Probe serve to increase your sample throughput to get your data collected in less time by saving the necessary cleaning to the end of multiple tests.

To discover other ideas for how to increase your sample throughput click here.

Texture analysis in research: Dentistry

According to Statista, the global dental market is projected to grow to around 37 billion dollars by 2021, and current indicators show that the market will keep moving forward, primarily driven by the implant sector. Its success is due to progress in the fields of medical technologies and implant materials.

When ceramic structures are used in the mouth, there is often a risk of wear between teeth and the ceramic part. Scientists from Boston’s University School of Dental Medicine have been researching this effect when different dental ceramic systems are used. Disc shaped specimens were held in resin and they used their TA.XTplus Texture Analyser along with a multiple sample vertical friction wear device to perform wear simulation. No differences were found in the linear and volumetric reduction of enamel cusps abraded against enamel disks or ceramic specimens. Read more

Meanwhile, Mars Inc. have been fabricating animal jaws. They have recently released a patent, entitled ‘Animal dentistry apparatus and methods’. Chewable products are often used to improve the oral hygiene of animals as the chewing action can help to remove plaque. It is useful to understand the mechanical properties of these products as they can affect their performance in cleaning teeth; existing mechanical measurement techniques involve their compression with cylindrical probes. This patent addresses the shortcomings of in-vivo measurements with existing test methods for chewable products. They used their TA.HDplus Texture Analyser to perform tests with a mechanical jaw assembly. Read more

Over in Hangzhou, researchers from Zhejiang Gongshang University have been investigating the locking up of food between posterior teeth and its influence on chewing efficiency. Food particles are intra-orally locked up between antagonistic posterior teeth during each chewing cycle, and this can affect the selection of particles for subsequent breakage, hence also affecting chewing efficiency. The two aims of this study were to determine the extent of locking up and to examine the relationship between locking up and chewing efficiency. The researchers used their TA.XTplus Texture Analyser to perform penetration tests on sheet bolus samples. Relationships between locking up and chewing efficiency were successfully found. Read more

Scientists from Zhejiang University of Technology have been researching the fabrication and evaluation of dental fillers using customised moulds via 3D printing technology. In view of the high incidence and long-term treatment of dental caries, personalized dental fillers with long therapeutic action have broad application prospects in the dental clinic. The objective of this study was to fabricate and evaluate novel dental fillers using state-of-the-art 3D printing technology. To mimic the support from peripheral tooth tissue, the compression behavior of the optimal dental filler was determined with customized compression molds designed according to the printed mold, using their TA.XTplus Texture Analyser. The study confirmed that 3D printing was successful in designing and fabricating personalised dental fillers with high mechanical strength and “on-demand” drug release characteristics. Read more

To read more about dentistry applications using a Texture Analyser click here.