Capturing changes in structure and rheology of an oily brittle snack food during in vitro oral processing

• Published in: Food research international 2013-11, Vol.54 (1), p.544-551
• Main Authors: Boehm, Michael W., Baier, Stefan K., Stokes, Jason R.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Brittle snack food; Brittleness; Comminution; Food industries; Foods; Fundamental and applied biological sciences. Psychology; In vitro oral processing; In vitro testing; lipid content; mastication; mechanical properties; microscopy; mixing; Oil; oils; Polycarbonates; potatoes; processing stages; rheological properties; Rheology; Rheology-structure relationships; saliva; sensory properties; snack foods; Snacks; Starch; Texture
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2013.07.052

Oral processing of solid foods is a highly dynamic and complex process; this creates a major challenge to elucidate the role of various components, hierarchical structures and phases on foods’ organoleptic properties. Textural properties of brittle foods at first bite (e.g., ‘crispiness’) can be predicted from the foods’ mechanical properties, but, beyond this, we cannot rationally design food because comminution transforms it through chewing as well as mixing, dilution, hydration and enzymatic breakdown in saliva. In order to overcome these challenges, in this work we use a combination of confocal microscopy and rheology to probe the changing status of brittle snack foods during key oral processing stages, which have been mimicked by an in vitro method based on mortar-and-pestle comminution processes and dilution using a physiological buffer. Using the ubiquitous potato chip (PC) with variations in oil content, we discover that there is no difference between the PC fracture properties, yet there is a dramatic difference in their rheological properties following comminution and dilution in a physiological buffer solution. We rationalise how oil would affect the bolus rheology using structural models then consider the implications on oral processing and perception. Our approach provides valuable insights into how the sensory properties of brittle foods can vary dramatically even when small changes in formulation leave the initially perceived texture unaltered. •Sensory properties of ‘oily’ brittle foods are dynamic during oral processing•Texture at first bite predictable from mechanics, but not beyond•Dynamics captured using in vitro formed bolus to avoid in vivo variability•In vitro bolus rheology differentiates influence of oil on similarly brittle foods•Potential for rational design of brittle foods based on oil and solids content