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

Our results

  1. Introduction
  2. Research and Innovation 2018 - For Food and Biobased Products
  3. Dry-cured ham: a process simulator can now define routes of manufacture that yield lower-salt products
  4. Does organically-farmed meat contain fewer chemical contaminants?
  5. The way in which proteins aggregate when heated may change their sensitising potency
  6. Enhancing the viability of spray-dried probiotic bacteria by stimulating their stress tolerance
  7. Human milk digestion in the preterm infant: impact of technological treatments
  8. Research & Innovation 2017 - For Food and Biobased Products
  9. To stick or not to stick? Pulling pili sheds new light on biofilm formation
  10. When biopolymers selfassemble: a balance between energy and entropy.
  11. Mimicking the gastrointestinal digestion in a lab-on-a-chip:the microdigester
  12. How a milk droplet becomes a powder grain
  13. Research & Innovation 2016 - For Food and Bioproducts
  14. A new process for the biorefining of plants
  15. Under the UV light : the bacterial membrane
  16. Reverse engineering or how to rebuild ... bread!
  17. Green Chemistry: a step towards lipid production in yeast
  18. Individually designed neo-enzymes for antibacterial vaccines
  19. Multi-scale mechanical modelling: from the nanometric scale to the macroscopic properties of bread crumb
  20. Minimill: 500 g to assess the milling value of soft wheats
  21. Microbial production of lipids for energy or chemical purposes
  22. The discrete role of ferulic acid in the assembly of lignified cell wall
  23. Eco-design of composites made from wood co-products
  24. Analysis of volatile compounds enables the authentication of a poultry production system
  25. Nanoparticles as capping agents for biopolymers microscopy
  26. Pasteurisation, UHT, microfiltration...All the processes don't affect the nutritional quality of milk in the same way
  27. Integration of expert knowledge applied to cheese ripening
  28. Controlling cheese mass loss during ripening
  29. The shape memory of starch
  30. Research & Innovation 2015 - For Food & Biobased Products
  31. Behaviour of casein micelles during milk filtering operations
  32. Overaccumulation of lipids by the yeast S. cerevisiae for the production of biokerosine
  33. Sequential ventilation in cheese ripening rooms: 50% electrical energy savings
  34. An innovative process to extract bioactive compounds from wheat
  35. Diffusion weighted MRI: a generic tool for the microimaging of lipids in food matrices
  36. Characterization of a major gene of anthocyanin biosynthesis in grape berry
  37. New enzyme activity detectors made from semi-reflective biopolymer nanolayers
  38. Improving our knowledge about the structure of the casein micelle
  39. Heating milk seems to favour the development of allergy in infants
  40. Fun with Shape
  41. Using volatile metabolites in meat products to detect livestock contamination by environmental micropollutants
  42. SensinMouth, when taste makes sense
  43. A decision support system for the fresh fruit and vegetable chain based on a knowledge engineering approach
  44. SOLEIL casts light on the 3D structure of proteins responsible for the stabilisation of storage lipids in oilseed plants
  45. A close-up view of the multi-scale protein assembly process
  46. Controlling the drying of infant dairy products by taking water-constituent interactions into account
  47. Polysccharide nanocrystals to stabilise pickering emulsions
  48. Discovery of new degradative enzymes of plant polysaccharides in the human intestinal microbiome
  49. A durum wheat flour adapted for the production of traditional baguettes
  50. Virtual modelling to guide the construction of « tailored-made » enzymes
  51. How far can we reduce the salt content of cooked meat products?
  52. Diffusion of organic substances in polymer materials: beyond existing scaling laws
  53. Smart Foams : various ways to destroy foams on demand !
  54. Dates, rich in tannins and yet neither bitter nor astringent
  55. Sodium content reduction in food
  56. 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