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The secrets of a delicious baguette of bread: when perception chimes with mastication and hydration

Bread offers a broad range of complex perceptions that are difficult to predict because it is in the mouth and during mastication that the texture, flavours and aromas express themselves. INRA scientists and their colleagues have now identified the volatile compounds that are indicative of the release and perception of bread aromas and the physical properties that give rise to the perception of texture and aroma.

Pain.. © INRA, SLAGMULDER Christian
Updated on 11/09/2017
Published on 08/11/2017

Emblematic of France, the baguette – or bread in general – offer a vast range of textures and aromas that titillate many of our palettes.

When eating solid foods such as bread, numerous mechanisms linked to the oral process give rise to olfactory, gustatory and texture perceptions: broken down by mastication, hydrated and lubricated by saliva, solubilised or recombined, the food is gradually transformed in the mouth into a food bolus ready to be swallowed. These mechanisms govern the release kinetics of stimuli which are then likely to interact with sensory receptors, giving rise to perceptions and hence to the acceptability of products by consumers.

For this reason, knowledge of the concentrations of palatable and aromatic compounds in the initial product is not sufficient to explain the sensory differences that may exist between products in the same family but with different structural or textural characteristics. The perception of bread products is linked not only to their characteristics (composition, structure, interactions between ingredients, etc.) but also depends on the oral process implemented by an individual when consuming the product, and the integration of all signals, including sensory interactions.

Understanding the mechanisms that cause the release of compounds of interest and their associated perceptions that will enable the controlled formulation of breads which reflect the objectives and preferences of consumers, was the goal fixed by scientists at AgroParistech and INRA, working in partnership with the company Lessaffre.

Perception of texture: it’s all in the crumb – or nearly

The scientists thus demonstrated that the structure of crumb and its hydration capacity play a major role in texture perception. Statistical models enabled the identification and ranking of the physical and physicochemical mechanisms responsible for these perceptions. Sensory properties such as “soft", "dry" and "stodgy" led the way, and were more influenced by changes to the properties of the food bolus than by the initial characteristics of the breads.

Aroma release and perception: the importance of the oral process

The team also revealed the important role of the oral process in the dynamics of aroma release and perception during the consumption of bread, with dilution of the bolus by saliva being the principal factor that influences the release of aroma compounds. Analysis of the aroma compounds present in the air exhaled by the tasters enabled characterisation of their release at three key points in the oral process which gave rise to aroma perception.

Statistically significant links were established between the sensory and olfactory perceptions of bread and the ions associated with the aroma compounds released during the oral process. Eating the crust with the crumb contributed to a perception of "toasty" and "toasted cereal" notes linked to the molecules that form during cooking and are released from the first instants of mastication. Inversely, crumb alone gave rise to fermented and aromatic notes related to the molecules released more slowly in the mouth during hydration.

Although crumb structure mainly governs the texture perceptions via the properties of boluses during the oral process, the crust has a greater influence on aroma perceptions.

Overall, these findings will be crucial to the formulation of new products – which could be rich in fibre, gluten-free or other – or the development of breads for specific populations. The impact of crumb structure on the bread hydration rate is probably an essential property that could facilitate bolus formation in older people whose mastication may be impaired. On the other hand, this property could also be modulated for people suffering from dryness of mouth.

The breads and tasters, in practice

The scientists thus offered the tasting panel breads formulated using the same raw materials but displaying different crumb and crust structures.

Evaluation of the physicochemical and sensory characteristics of of the products, and of the boluses resulting from the transformation of bread in the mouth during consumption, made it possible to construct mathematical models and identify “tracer” aroma compounds. The latter were then followed in vivo in order to understand the impact of bread structure, and how it is broken down in the mouth, on aroma release and perception.

Breads and tasters, in practice

Scientists have submitted to the tasters breads formulated from the same raw materials but with different structures of crumbs and crusts.

The evaluation of the physicochemical and sensory characteristics of the products and bowls resulting from the processing of breads in the mouth during their consumption made it possible to construct mathematical models and to identify "tracer" flavor molecules. The latter were then followed in vivo in order to understand the impact of the structure of the breads and their destructuring in the mouth, on the release and the perception of the aromas.

Find out more

Jourdren S. et al. 2017. Gaining deeper insight into aroma perception: An integrative study of the oral processing of breads with different structures. Food Research International, 92, 119.

Jourdren S. et al. 2017. Effect of Bread Crumb and Crust Structure on the in Vivo Release of Volatiles and the Dynamics of Aroma Perception. J. Agric. Food Chem., 65: 3330