Nanolaminates: Edible Coatings
Nanofibres: Artificial Food
and Regulatory Status
Many biological structures and systems have nanoscale features which
affect their properties and behaviour. As our understanding of
synthetic nanotechnology increases, we are beginning to see more and
more clearly how these relationships between size, shape, and
functionality work in biological systems.
As we understand more and more about biological processes, it seems
likely that some of the first applications of this knowledge will be to
food processing. In developed countries, the vast majority of the food
consumed undergoes some sort of processing which changes its biological
properties and nutritional values. There is a constant R&D effort
to improve these processes, and using our knowledge of nanotechnology
to inform this development is becoming more and more common.
Nanotechnology has the potential to affect the food production
industry at almost every stage, through agriculture, storage and
transport, manufacturing, packaging, and disposal. This article will
focus on one particular aspect of these applications - using
nanotechnology to add additional value or functionality to food
This is an area which is particularly controversial, as it involves
human ingestion of significant quantities of nanomaterials. The
benefits must therefore be shown to greatly outweigh any risks, and a
deep understanding of the products' effects on the body must be
Many functional ingredients in food, such as vitamins, antimicrobial
agents, flavourings, etc., can benefit from being encapsulated in a
delivery system, rather than being used in a free form in the food. A
good delivery system can ensure that biologically active ingredients
like vitamins or antioxidants can reach the site in the body where they
can be most effective without degrading. It can also help to release
the ingredient at a controlled rate, to keep the concentration in the
body at the optimum level.
Various nanoencapsulation systems have been proposed which could
provide many of these features. They generally revolve around micelles
and emulsions - droplets which form when oily material is dispersed
into water. These are of interest because they form spontaneously under
certain conditions, and could easily contain oil-soluble functional
ingredients within an aqueous environment.
The problem with most emulsions is that they are dependent on
conditions - just as they spontaneously form under certain conditions,
they can also spontaneously disassociate if the temperature or
concentration changes too much - not very useful for a system which may
need to remain stable through various areas of the human digestive
tract. Stabilization of some materials also requires addition of
significant amounts of surfactant, or emulsifier, which has to be
food-grade, and may adversely affect the taste or texture of the food.
Figure 1. Nanoemulsions can
be used as delivery systems for active ingredients in food products.
Using multiple layers of encapsulation with a range of materials could
keep the nanocapsules stable, and control the release of the ingredient
within the body.
The most promising solutions are more complex systems, which are
assembled in several steps, composed of several layers of biocompatible
surfactants and polymers (proteins, carbohydrates, etc.). The
manufacturing techniques needed to produce multilayer emulsions like
this would be a simple progression from the methods currently used to
make emulsions in food processing, so integration of this technology
would be relatively easy.
These systems can retain their payload through a variety of
environments, and be tailored to release the active ingredient at the
right point, triggered by specific environmental parameters like pH or
|Figure 2. The taste,
texture and shelf-life of fresh fruit such as strawberries could be
improved with a
multifunctional edible nanolaminate.
Manipulation of materials at the nanoscale can allow
to create edible laminate films. These are constructed from several
nanolayers of various materials, added one at a time by taking
advantage of the electrostatic attractions between one layer and the
This layer-by-layer approach allows very detailed
control over the
properties of the nanolaminate, which is the main benefit over the
conventional edible coatings, such as waxes and gums, often used as
barrier layers to prolong shelf life.
Materials which could be used as functional components
nanolaminate food coating include lipids or clays, as moisture
barriers, biopolymers like carbohydrates, as an oxygen and carbon
dioxide barrier, or nanoparticulates and emulsified nanodroplets, which
could contain active ingredients to improve taste, texture or
The recent resurgence in using electrospinning to produce nanofibres
with a wide distribution of sizes and properties for bulk applications
has led to discussion of using these nanofibres in food technology.
The electrospun fibres used in other applications are usually
composed of synthetic materials, which may be useful in food packaging.
However, recent work has moved towards applying the technology to
biopolymers, primarily for medical applications. Electrospun
biopolymers could be used in food products as a texture modifier or
filler. It is even conceivable that completely synthetic food could be
constructed from a mesh of electrospun protein and carbohydrate fibres,
embedded with nanoencapsulated flavourings and vitamins, and coated
with a nanolaminate to enhance colour and texture, and preserve the
Concerns and Regulatory Status
Food giant Tate & Lyle has taken advantage of a partnership with a nanotech spin-out from the
University of Nottingham to produce one of the
first food products using micro- or nano-technologies in the UK.
nanostructured salt crystals to deliver salty taste at a lower
concentration, without the issues of agglomeration usually encountered
with very fine salt powders.
Whilst nanotechnology-enhanced packaging for food products is
beginning to emerge on the market, commercial applications of
in food have been slow to develop, compared to the rate of research in
the last few years. This is largely due to consumer reluctance to
accept nano-enhanced food, and an unclear legislative position.
Consumers in the Far East seem much more accepting of nanotechnology
as a positive move for the food industry than those in the US, and
certainly more than in Europe. In the UK in particular, manufacturers,
legislators alike seem hesitant about adopting the new technologies,
primarily due to concerns over long term health and environmental
Key figures in the industry are pushing for more development,
however. Nanotechnology could increase the shelf-life of food, and
enhance the effectiveness of flavour-enhancing and colour-enhancing
additives, allowing the overall quantity of additives to be reduced. It
could also make processed food healthier, by delivering fats, sugar and
salt in nanoformulations which deliver taste at lower concentrations,
and by delivering vitamins and other nutrients using nano-carrier
Despite these benefits, it seems unlikely that the food industry in
Europe will begin to take full advantage of food nanotechnology for
quite some years.
- "Functional Materials in Food Nanotechnology" - Weiss et
al, J. Food Sci. 2006. DOI: 10.1111/j.1750-3841.2006.00195.x
- "Nanotechnology for Food Applications: Current Status and
Consumer Safety Concerns" - Dr. Quasim Chaudry, DEFRA.
- "Nanotechnology in Food" - ETH Zurich