• Reduce text

    Reduce text
  • Restore text size

    Restore text size
  • Increase the text

    Increase the text
  • Print

Rangées de graines.. © INRA, Elena Schweitzer © Fotolia

Our results

  1. Introduction
  2. Human milk digestion in the preterm infant: impact of technological treatments
  3. Research & Innovation 2017 - For Food and Biobased Products
  4. The way in which proteins aggregate when heated may change their sensitising potency
  5. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  6. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  7. When biopolymers selfassemble: a balance between energy and entropy.
  8. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  9. How a milk droplet becomes a powder grain
  10. Research & Innovation 2016 - For Food and Bioproducts
  11. A new process for the biorefining of plants
  12. Under the UV light : the bacterial membrane
  13. Reverse engineering or how to rebuild ... bread!
  14. Green Chemistry: a step towards lipid production in yeast
  15. Individually designed neo-enzymes for antibacterial vaccines
  16. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  17. Minimill: 500 g to assess the milling value of soft wheats
  18. Microbial production of lipids for energy or chemical purposes
  19. The discrete role of ferulic acid in the assembly of lignified cell wall
  20. Eco-design of composites made from wood co-products
  21. Analysis of volatile compounds enables the authentication of a poultry production system
  22. Nanoparticles as capping agents for biopolymers microscopy
  23. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  24. Integration of expert knowledge applied to cheese ripening
  25. Controlling cheese mass loss during ripening
  26. The shape memory of starch
  27. Research & Innovation 2015 - For Food & Biobased Products
  28. Behaviour of casein micelles during milk filtering operations
  29. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  30. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  31. An innovative process to extract bioactive compounds from wheat
  32. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  33. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  34. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  35. Improving our knowledge about the structure of the casein micelle
  36. Heating milk seems to favour the development of allergy in infants
  37. Fun with Shape
  38. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  39. SensinMouth, when taste makes sense
  40. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  41. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  42. A close-up view of the multi-scale protein assembly process
  43. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  44. Polysccharide nanocrystals to stabilise pickering emulsions
  45. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  46. A durum wheat flour adapted for the production of traditional baguettes
  47. Virtual modelling to guide the construction of « tailored-made » enzymes
  48. How far can we reduce the salt content of cooked meat products?
  49. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  50. Smart Foams : various ways to destroy foams on demand !
  51. Dates, rich in tannins and yet neither bitter nor astringent
  52. Sodium content reduction in food
  53. Research & Innovation 2014

The shape memory of starch

Shape memory polymers are “intelligent” materials capable of changing shape in response to an environmental stimulus such as temperature variation. We have shown that starch, a natural biopolymer, has just these properties, which can be modulated by temperature or humidity. It is therefore possible to develop shape memory objects from starchy raw materials such as cereal flours.

Updated on 06/17/2013
Published on 06/11/2013

Studying the properties of glassy-state starchy materials

“Classic” shape memory polymers are molecules with a complex structure (often copolymers) whose chemical synthesis is difficult and expensive and whose impact may be harmful for the environment.  Their use is therefore generally reserved for high added-value applications such as biomedical materials, temperature tracers or micromechanics.  
Study of the transformation and the properties of glassy-state starchy materials, particularly their ability to store residual stress, made it possible to develop a process to produce shape memory material using starch.  

...the shape recovery

Shape memory starch is made using a precise thermomechanical cycle, illustrated in Fig. 1.  It is obtained by extrusion under classic conditions (T=120°C; water content: 25%). It is first given an F1 shape (a twisted cylinder in the example) under heat, as soon as it leaves the extruder, and frozen into shape by rapid cooling.  
It is then given a new, temporary F2 shape (unfolded cylinder in the example), when it is subsequently heated at a temperature greater that that of its glassy transition (Tg).  This shape is set by cooling at room temperature, under mechanical stress.
It returns to its initial shape (F2 to F1) spontaneously if the temperature of the object becomes greater than its Tg, for example, almost instantaneously when heated in a microwave, and slower in hot water or when cooked in an oil bath.  

Cycle thermomécanique. © INRA
Cycle thermomécanique © INRA

Figure 1. Thermomechanical cycle for extruded potato starch

Shape recovery can also be obtained by hydration when the starchy material is placed in a humid environment, as illustrated in Fig. 2.  The initial form, F1 (the initials “INRA” printed in relief on the extruded samples), is totally erased when the sample is thermomoulded into a 3.5-cm bar (2 minutes at 300 bars and 120°C).
The initials (INRA) re

appear after 72 h when the samples are hydrated under high relative humidity (RH=97% at 20°C).

Figure 2. De haut en bas : échantillons d’amidon de pomme de terre avec colorants alimentaires vert et rouge et échantillon de farine de maïs. © INRA
Figure 2. De haut en bas : échantillons d’amidon de pomme de terre avec colorants alimentaires vert et rouge et échantillon de farine de maïs © INRA

Figure 2. From top to bottom: potato starch samples with green and red food colouring, and corn flour sample

The mechanisms involved (macromolecular orientations) can be revealed by the study of residual stress stored in samples in their temporary F2 shape.  Therefore, the initials, “INRA”, not visible under normal light, can be seen under polarised light (Fig. 3).
Figure 3. Le sigle « INRA » cachée dans la forme F2 est visible en lumière polarisée.. © INRA
Figure 3. Le sigle « INRA » cachée dans la forme F2 est visible en lumière polarisée. © INRA

Figure 3. The initials, “INRA”, not visible in the F2 shape, are visible under polarised light.

Uses in the agri-food and biomedical sectors...

Starch shape memory can by used for classic applications of shape memory polymers, such as humidity tracers integrated into food product packaging.  Since the products are edible, applications can also be developed in the agri-food sector, for example, cereal products with varying shapes.
A partnership with INSERM should also make it possible to validate the applications of these materials in the biomedical sector, including the development of implants that could be reabsorbed by the body or delayed release systems for active ingredients.  

Other works are under devopment with ADEME to study the mechanism of residual stress in starchy raw materials
Protected by european patent (04/2008) : EP 08300188.3

See also

  • Chaunier, L. and Lourdin, D. 2009. The shape memory of starch. Starch/Stärke. Vol. 61 : 116-118