Exploring Textural Properties of Processed Foods

When you bite into a crispy potato chip, a soft piece of bread, or a chewy candy bar, you’re experiencing something food scientists call textural properties. These physical characteristics – how food feels in your hand and mouth – are among the most important quality indicators in processed foods. They directly shape whether a consumer enjoys a product or rejects it. Understanding and controlling texture is therefore central to food processing, product development, and quality assurance.

What are textural properties in processed foods? 🔗

Textural properties refer to the group of physical and mechanical attributes of food that we perceive through touch – both with our hands and during chewing. According to the International Organization for Standardization (ISO), food texture includes all rheological and structural attributes that can be detected through mechanical, tactile, visual, and auditory senses. In simpler terms, texture is how food responds when you press, bite, chew, or swallow it.

These properties cover a wide range of sensations: hardness and softness, crunchiness and smoothness, stickiness and dryness, chewiness and crumbliness. Each of these textural terms relates directly to measurable physical properties like density, viscosity, and surface tension of a given food product.

For processed foods specifically, understanding texture is essential for controlling operations such as heating, frying, drying, and extrusion so that the end product meets desired quality standards. A biscuit should snap cleanly, yoghurt should flow smoothly, and cheese should have a certain firmness – all of which are textural expectations that influence consumer acceptance.

Why texture matters for consumer perception 🔗

While flavour often gets the most attention, texture is frequently the reason consumers reject certain foods. A soggy chip, a rubbery piece of meat, or a grainy sauce can completely ruin the eating experience – regardless of how good the flavour is. People develop strong associations between specific textures and food quality, and when a product fails to meet those expectations, it is often rejected outright.

Textural preferences also vary across cultures and age groups. What feels pleasant to one population may feel unacceptable to another. For example, the slimy texture of certain fermented foods is enjoyed in parts of Asia but can be off-putting to Western consumers. This makes texture management a global challenge for food manufacturers who want to reach diverse markets.

In recent years, there has been growing interest in texture modification for specific populations, particularly elderly individuals with swallowing difficulties (dysphagia). This has led to the development of international frameworks like the IDDSI (International Dysphagia Diet Standardisation Initiative), which classifies foods by texture level to ensure safe consumption.

Key textural attributes of processed foods 🔗

Food scientists have identified several core textural parameters that are routinely measured and controlled in processed food production. These were originally classified by Dr. Alina Szczesniak at General Foods, whose pioneering work in the 1960s laid the foundation for Texture Profile Analysis (TPA) – a method still widely used today. The key attributes fall into primary and secondary categories.

Hardness 🔗

Hardness is the force required to compress a food to a given extent. It measures how firm or soft a product feels during the first bite. Hard candy, raw carrots, and nuts rank high on the hardness scale, while soft bread, ripe bananas, and cream cheese rank low. In instrumental testing, hardness is recorded as the peak force during the first compression cycle of a TPA test. It is one of the most commonly evaluated parameters in food quality control.

Cohesiveness 🔗

Cohesiveness describes how well a food holds together as a single mass rather than crumbling or falling apart. It reflects the internal bonding strength within the food structure. In a TPA test, cohesiveness is calculated as the ratio of the work done during the second compression to the work done during the first compression. Foods like processed cheese and sausages tend to have high cohesiveness, meaning they maintain their integrity even after being compressed. A crumbly cookie, on the other hand, has low cohesiveness.

Chewiness 🔗

Chewiness represents the energy required to chew a solid food until it is ready to be swallowed. It is a secondary textural parameter, calculated as the product of hardness, cohesiveness, and springiness. Foods with high chewiness include dried meat, toffee, and certain breads. This parameter is particularly important for meat and meat-analogue products, where matching the chewing experience of conventional meat is a major goal in product development.

Viscosity 🔗

Viscosity measures a food’s resistance to flow and is particularly relevant for liquid and semi-liquid foods such as sauces, soups, honey, and dairy beverages. A thick tomato sauce has high viscosity, while water has very low viscosity. In the food industry, viscosity directly affects pouring behaviour, spreadability, and mouthfeel. Changes in viscosity can also alter the perception of taste intensity – for instance, increasing solution thickness has been shown to reduce the perceived sweetness or saltiness of a product.

Other important parameters 🔗

Beyond these four core attributes, several other textural properties play important roles in food evaluation. Springiness (also known as elasticity) describes a food’s ability to recover its original shape after being compressed – think of a sponge cake bouncing back after you press it. Adhesiveness measures how much a food sticks to surfaces like the roof of the mouth or teeth during chewing. Gumminess, calculated as hardness multiplied by cohesiveness, is the energy needed to break down a semi-solid food for swallowing. Fracturability (formerly called brittleness) is the force at which a food cracks or shatters, such as when you bite into a crispy biscuit or cracker.

How texture is measured: sensory and instrumental methods 🔗

Textural properties of food can be evaluated through two broad approaches: sensory evaluation and instrumental analysis. Both have their strengths, and in practice, most food companies use a combination of both.

Sensory evaluation 🔗

Sensory evaluation involves trained human panels who taste, chew, and handle food samples and then describe or rate the textural attributes they perceive. This method captures the full complexity of the eating experience, including how texture changes during chewing, how it interacts with saliva, and how it feels at different stages of oral processing. However, sensory testing is expensive, time-consuming, and subject to variability between panellists. These limitations have driven the development of more objective, machine-based approaches.

Instrumental methods 🔗

Instrumental texture analysis uses machines to apply controlled forces to a food sample and then records how the sample responds. The resulting force-distance or force-time data is analysed to calculate textural parameters that correlate with sensory perception. According to the Institute of Food Technologists (IFT), instrumental texture measurements are generally grouped into three categories: fundamental methods (based on stress-strain relationships), empirical methods (using food-specific devices), and imitative methods (designed to simulate chewing).

The most widely used instrument in modern food texture analysis is the Texture Analyser (such as the TA.XT Plus from Stable Micro Systems). This precision instrument moves a probe up and down to compress, penetrate, cut, stretch, or bend a food sample in a controlled manner, measuring force, distance, and time throughout the process.

The role of rheology in texture assessment 🔗

Rheology is the branch of physics that studies the deformation and flow of matter. In food science, rheological analysis helps characterise how foods behave under stress – whether they flow like a liquid, deform like a solid, or exhibit properties of both (viscoelastic behaviour). Rheological measurements are essential for understanding and controlling the texture of a wide variety of food products.

A rheometer is the instrument used to perform these measurements. It applies controlled stress or strain to a sample and records the material’s response. There are different types of rheometers suited to different needs: rotational rheometers are commonly used for low-viscosity materials, capillary rheometers follow the natural flow of a material, and interfacial rheometers help study microstructure and emulsion behaviour. The choice of instrument depends on the type of food being tested and the specific rheological information required.

Rheological data is useful not only for predicting sensory properties like mouthfeel and spreadability, but also for designing and optimising food processing equipment such as pumps, heat exchangers, and mixers.

Instruments used for texture measurement 🔗

Beyond the general-purpose Texture Analyser and rheometer, several specialised instruments are used in food texture evaluation:

Penetrometer: This instrument measures the depth to which a probe or needle penetrates into a food sample under a given force. It is commonly used to assess the firmness or consistency of semi-solid foods like butter, margarine, gels, and fruits. The penetration depth correlates inversely with firmness – the deeper the probe sinks, the softer the product.

Compressimeter: A compressimeter measures the degree to which a food sample can be compressed under a controlled load. It is frequently used for evaluating the softness and compressibility of baked goods like bread and cakes. By recording the deformation at specific force levels, food scientists can assess freshness and structural quality.

Viscometer: While rheometers provide comprehensive flow-behaviour data, viscometers are simpler instruments focused specifically on measuring viscosity. They are widely used in quality control for products like syrups, sauces, beverages, and batters, where consistent flow behaviour is critical for production and consumer satisfaction.

Tenderometer: Originally developed for evaluating the tenderness or maturity of green peas, the tenderometer measures the force required to shear a sample. It has since been adapted for various products and is used as an indicator of harvest readiness and processing quality.

Factors affecting texture in processed foods 🔗

The texture of a processed food product is not fixed – it is influenced by a range of compositional and processing factors. Understanding these variables is key to achieving consistent, desirable textures in manufactured food products.

Water content and moisture 🔗

Water is one of the most influential factors in food texture. Moisture content affects whether a product feels crispy, soft, chewy, or soggy. In baked goods, for instance, moisture retention keeps bread soft and elastic, while moisture loss leads to staleness and a dry, firm crumb. In fruits and vegetables, cellular hydration maintains crispness – as moisture is lost during storage, cell walls collapse, and the product softens and wilts. During drying or dehydration, deliberate moisture removal creates crunchy or brittle textures in products like crackers, chips, and dried fruits.

Lipids (fats and oils) 🔗

The addition of fats and oils significantly modifies food texture. In baked products, fat coats gluten proteins, interrupting the gluten network and producing a tender, short crumb rather than a tough, chewy one. In chocolate and confectionery, the type of fat used determines whether the product is smooth and melt-in-your-mouth or waxy and gritty. Fats also affect the lubrication properties of food in the mouth, contributing to the perception of creaminess and richness.

Starches 🔗

Starches are powerful texture modifiers. When heated in water, starch granules swell and gelatinise, thickening the surrounding liquid and creating viscous or gel-like textures. This is the basis of sauces, gravies, custards, and puddings. Upon cooling and storage, starch molecules can re-associate in a process called retrogradation, which leads to firming, syneresis (water release), and textural deterioration – commonly experienced as stale bread or hardened rice. Different starch sources (corn, tapioca, potato, rice) produce different textural outcomes, giving food manufacturers a versatile toolkit for texture design.

Proteins 🔗

Proteins contribute to texture through their ability to form gels, foams, and emulsions. In meat products, the protein myosin forms a gel network during cooking, which determines tenderness, juiciness, and bite. In dairy products, casein and whey proteins affect the firmness and smoothness of cheese, yoghurt, and ice cream. Egg proteins are essential for the structure of baked goods – the coagulation of egg whites creates the rigid framework in cakes and soufflés. In the growing field of plant-based food development, the texturisation of plant proteins through processes like extrusion is a major area of research, aiming to replicate the fibrous, chewy texture of animal meat.

Processing conditions 🔗

Temperature, pressure, time, and mechanical treatment during processing all have profound effects on food texture. Thermal processing (cooking, pasteurisation, sterilisation) softens plant tissues, denatures proteins, and gelatinises starches. Freezing can damage cellular structure through ice crystal formation, leading to mushy textures if not controlled properly. High-pressure processing, extrusion, and homogenisation each create distinct textural outcomes. For example, the extrusion of plant proteins at high moisture levels is used to create meat-like fibrous structures in plant-based burgers and sausages.

Texture in quality control and product development 🔗

Food manufacturers rely on texture analysis as a critical quality control tool. By setting specific textural benchmarks for their products, companies can ensure batch-to-batch consistency, detect processing problems early, and meet consumer expectations reliably. For example, a bakery might monitor dough consistency to ensure uniformity across production runs, while a meat processor might test tenderness to verify that cooking parameters are optimised.

In product development, texture measurement helps food scientists understand the relationship between ingredients, processing methods, and the final eating experience. It also supports benchmarking against competitor products and enables rapid screening of new formulations. With the growing demand for reformulated products – reduced-fat, gluten-free, plant-based, or designed for specific populations – texture analysis has become more important than ever in bridging the gap between nutritional goals and consumer satisfaction.

What do you think? How much does texture influence your own food choices – do you pick certain products specifically for how they feel in your mouth? And with the rise of plant-based and reformulated foods, how important is it for manufacturers to get the texture right before focusing on flavour?

References

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