Microencapsulation technology to improve iron bioaccesibiity of enriched bread products

1. Innovative iron-fortified
bakery products
MI C R O E N C A P S U AT I O N T E C H N O LO G Y T O IMP ROV E I R O N B I O A C C E S I B I L I T Y O F E N R I C H E D
B R E A D P R O D U C T S
+According to recent estimates, iron defi-ciency
due to poor nutrition affects be-tween
1.5 and 2bn people in the world. This
problem is found not only in developing coun-tries;
in some cases deficiencies of mineral
micronutrients have been found in the so-called
“first world”, due both to bad eating habits and
to the consumption of highly processed energy-dense
but micronutrient-poor diets. Thus the
successfully production of baked goods con-taining
a high amount of micronutrients can
help in solving the problem.
The BAKE4FUN project responds to the needs
of that category of consumers who are attentive
to the provenance and origin of foods and estab-lishes
its purchasing decisions not only on the
quality/price ratio, but also on nutritional,
health and sustainability aspects.
The idea is to develop new formulations and
innovative technologies to produce iron-fortified
bakery products that, due to the use of einkorn,
also have better nutritional and health charac-teristics
compared to other products commonly
available in the marketplace. In particular, micro-encapsulated
iron and whole organic einkorn
flour rich in antioxidant compounds will be used.
The effect of the biological leavening agents
(sourdough fermentation) and the impact of
microencapsulation on the bioavailability of
iron as well as on the antioxidant properties of
functional bread will be studied. This article
will focus on iron-enriched bread products
using microencapsulation technology.
The problem of iron deficiency
Nutritional iron deficiency (ID) is estimated to
affect 1.5–2bn people worldwide (WHO, 2007).
F U N C T I O N A L B A K E R Y P R O D U C T S
S C I E N C E
8
© eranicle - Fotolia.com

2. In developing countries this is usually due to a
limited food supply, but ID also represents a
public health problem in some industrialized
countries where consumers try to consume a
preventive diet, i.e. reducing food intake or the
consumption of specific foods that may lead to
a decrease of micronutrient intake and status.
Because iron is present in many foods, and its
intake is directly related to energy intake, the risk
of deficiency is highest when iron requirements
are greater than energy needs. This situation
happens in infants and young children, adoles-cents,
and in menstruating and pregnant women
(Zimmermann and Hurrell, 2007). The fortifica-tion
of foods with iron is more difficult than it is
with other nutrients, such as iodine in salt and
vitamin A in cooking oil. Most bioavailable iron
compounds are soluble in water or dilute acid,
but often react with other food components to
cause off-flavors and color changes, fat oxidation,
or both (Hurrell, 2002). The choice of the food that
is going to be a vehicle for the iron compound is
as important as the choice of the form of iron
used in enrichment programs. Bread and bakery
products made with cereal flours are a staple
food in many countries and are therefore of
global importance in international nutrition
(Cauvain, 2004). Although iron-fortified wheat
flour has existed in the market for many years,
and the market for functional bakery foods is
continuously increasing, to date the efforts of
industries devoted to innovative formulations/
technologies have not overcome the most im-portant
hurdle for consumers’ acceptance of iron
fortified foods, that is the negative effect of the
added iron on the sensory quality of bakery
products. Consequently iron-fortified foods are
usually rejected by consumers due to unacceptable
changes of their sensory characteristics. According
to Regulation (EC) 1924/2006 regarding nutri-tional
health claims made on foods, if it is it
claimed that a product is a “source of iron”, that
means it contains at least a significant amount of
2.10 mg Fe per 100 g of product. If the nutritional
claim indicates “high iron content”, that means
the product contains at least twice the value of
the source.
On the other hand, contact with the other com-ponents
of bread can reduce intestinal iron ab-sorption.
F U N C T I O N A L B A K E R Y P R O D U C T S 9
For example, high levels of phytic acid
in cereals must be taken into account, and their
sensitivity to fat oxidation during storage, par-ticularly
if they contain added highly bioavailable
compounds such as ferrous sulfate.
The breadmaking process also has important
effects on iron availability. Bakery processes
include aggressive mediums for iron compounds,
e.g. an acidic pH, temperature in the oven, humid-ity,
etc., that oxidize iron compounds, reducing
its bioavailability. Microencapsulation technology
appears to be a solution in this case.
Moreover many questions still remain open on the
iron bioavailability of fortified foods. A report
by the Scientific Advisory Committee on Nutrition
(SACN) on Iron and Health (2010) evidenced
that although iron-fortified foods make a sub-stantial
contribution to intake, the evidence
from efficacy trials suggests that foods such as
flour fortified with elemental iron are unlikely to
make a valuable contribution to increasing iron
stores (owing to low solubility and low intestinal
uptake).
As the SACN recommended, there is a need for
research studies to study the extent to which
foods fortified with iron, e.g., cereals and cereal
products, contribute to the supply of absorbed
iron and to achieving adequate iron status,
particularly in vulnerable groups. The impact of
the different variables of bakery food processing
must be clarified in order to formulate and
produce iron-enriched bakery products having
an actual possibility of ameliorating iron status.
Introduction
Based on this information, a consortium formed
by ainia together with European Universities,
and small and medium bakery companies from
Poland, Italy and Spain led by the University of
Bologna, started a project named “BAKE4FUN”
(Innovative biotechnological solutions for the
production of new bakery functional products).
One of the project’s main objectives is to design,
validate and develop innovative health-promoting
bakery products by using innovative technologies
that may increase the stability and bioavailability
of iron, without losing sensorial quality. The
S C I E N C E

3. ++ table 1: Type of encapsulates
Type of encapsulates Shape Morphology
Reservoir Type
(core-shell type)
Spherical The active agent is in the cor e of the capsule
Matrix type Asymmetrical The active agent is distribuited in the wall
source: ainia ++ table 2: Micr oencapsulation processes classification
main technological hurdle in the production of
novel iron-fortified bakery products is repre-sented
by giving the new products sensorial and
palatability characteristics allowing them to be
used by the general population.
Microencapsulation technology is a good option
to increase iron stability and bioavailability,
avoiding sensorial changes that may provoke a
rejection of bakery food products. Encapsula-tion
may be defined as a process to entrap one
substance with another substance, thereby pro-ducing
particles with diameters from few nm up
to few mm. The substance that is encapsulated
may be called the core material or active agent.
The substance that is encapsulating may be
called the shell, coating, wall or matrix. The car-rier
encapsulating material for food products or
processes should be food grade and must be able
to form a barrier for the active agents and its
surroundings (Jin et al., 2008). Two main types
of encapsulates might be distinguished (table 1).
Possible benefits of microencapsulated ingredi-ents
within the food industry can be:
+ Improved stability in the final product and
during processing (i.e. less evaporation of vola-tile
material. It can be also in the surface of the
capsule
active agents and/or no degradation or
reaction during food processing).
+ Controlled release (differentiation, release by
the right stimulus).
+ Superior handling of the active agent (e.g.
conversion of liquid active agents into a powder,
which might be dust free, free flowing and
might have a more neutral smell).
+ Immobility of active agents in processing
systems.
+ Adjustable properties of active components
(especially odor profile, particle size, structure,
color).
Microencapsulation techniques can be classified
into chemical processes and mechanical or
physical processes (table 2). These labels can be
somewhat misleading, as some processes classi-fied
as mechanical might involve or even rely
upon a chemical reaction, and some chemical
techniques rely on physical events.
A number of different processes are involved in
the release of food ingredients from microcap-sules.
The more significant steps in this release
mechanism are: dissolution/erosion/permeation
Type of encapsulates Methods
Chemical + Coacervation
+ Interfacial or in-situ polymerization
+ Emulsion-solvent evaporation
+ Molecular encapsulation
Physical-chemical + Encapsulation by supercritical fluids: co-pr ecipitation, inclusion
complex
Physical or mechanical + Spray drying
+ Spray chilling or cooling
+ Extrusion coating
+ Fluidized bed
source: ainia
F U N C T I O N A L B A K E R Y P R O D U C T S
1 0
S C I E N C E

4. or diffusion of the capsule material, and diffusion
through the polymeric matrix. Once bioactive
compounds are microencapsulated, they can
produce desired effects following the selected
release mechanism. Specifically for iron and
mineral microencapsulation as food additives,
the main advantages are a combination of those
previously mentioned. The increase in the bio-accessibility
is achieved thanks to the protection
of iron compounds that otherwise could be
damaged, due to light, temperature, oxygen,
etc.; thanks to the protection against interac-tion
with other compounds (as phytates); or
thanks to avoiding the unpleasant flavor of bio-accessible
forms of iron. It also enables release
under intestinal conditions, where the iron is
going to be absorbed. Highly soluble compounds
of iron like ferrous sulfate are desirable food for-tificants
but cannot be used in many food vehicles
because of sensory issues.
Iron instability and thereafter its bioavailability
is related to a specific chemical form of iron or
to iron interaction with the food matrix in chal-lenging
conditions along the food chain i.e.: flour
storage, the breadmaking process, packaging,
storage and distribution of bread, and during
storage, distribution and use. In fact added fer-rous
sources are susceptible to oxidation during
the storage and processing of food products.
This is influenced by the food matrix (pH is an
important factor) and by processing conditions
(mainly temperature). (Hurrell, 1997)
The microencapsulation of iron can enhance
iron absorption and mitigate undesirable inter-actions
between the fortificant iron and food
vehicles. Iron microencapsulation consists of a
thin coating of inert material used to prevent the
iron from oxidizing the food. This thin coating
protects the iron from the food (and food from
the iron) and also masks the taste of the iron.
The coating dissolves in the stomach, releasing
the iron salt, to be absorbed along with iron con-tained
in the foods that constituted the meal.
Reasearch activities within the project
Research carried out throughout the project
execution will provide stable microcapsules
resistant to bread processing conditions, and
++ figure 1
A
B
C
F U N C T I O N A L B A K E R Y P R O D U C T S 1 1
© ainia
S C I E N C E
++ figure 1
a) Samples before
simulated processing
conditions;
b) Samples after
simulated processing
conditions at 90°C;
c) Samples after
simulated processing
conditions at 180°C

5. will release the iron at the small intestine level for
its absorption and passage into the bloodstream.
The research includes the identification and
selection of different chemical forms of iron,
screening and selection of the covered material
and suitable microencapsulation technology.
In the context of the BAKE4FUN project, a
microencapsulation process has been developed
to produce different iron compounds that can be
used for fortified bakery products. This selected
microencapsulation process was developed with
spray drying, using a type of modified starch as
the wall material. The results of the microencap-sulation
process on iron have been tested using
different techniques and methodologies to assess
the protection given to the iron compounds.
Thus microencapsulated iron samples were
tested at a laboratory scale in order to evaluate
their resistance to aggressive media, simulating
the bread-making process conditions. Thus
microencapsulated iron samples were tested at
different temperatures that may be reached
during baking either in the core of bread or on
the surface (crumb and crust). In this context, to
assess the protection of the microencapsulated
particles, samples with microcapsules and non-microencapsulated
were tested before and after
baking temperatures (figure 1). In addition, the
level of oxidation was measured. The wall integ-rity
and particles morphology were checked by
Scanning electron microscopy (SEM) (figure 2)
and particle size distributions were measured
using dynamic light scattering to determine the
actual particle size distribution. After evaluating
the results, the microcapsules selected comply
with the following characteristics:
u Resistance to temperatures reached in the
center (dough) and surface (crust) of bread during
its processing.
Samples during simulated conditions of tem-perature
can be seen in figure 1. Microencap-sulated
iron using modified starch shows good
© ainia
F U N C T I O N A L B A K E R Y P R O D U C T S
1 2
S C I E N C E
++ figure 2
Above: SEM images of
microencapsulated iron
Below: SEM images of
microencapsulated iron
after thermal simulation
at 180°C.
++ figure 2

6. F U N C T I O N A L B A K E R Y P R O D U C T S 1 3
++ table 3: Summar y of the r esults of oxidation after thermal simulation
Type of samples Free iron Microencapsulated iron
Initial oxidation
Oxidation after 90°C
Oxidation after 180°C
Red Colour means high o xidation. Green colour means low oxidation.
Microencapsulated iron is protected against oxidation during thermal processing at 180ºC.
results for colour after thermal processing,
which indicates that the wall resisted baking
conditions.
The morphology of microencapsulated iron and
the wall integrity after thermal conditions can be
seen especially by SEM in figure 2. It can be seen
that microencapsulated iron keeps its integrity
after 180°C in the oven.
Iron compounds have been protected against
oxidation in the oven using starch as wall mate-rial.
Measurement of the oxidation level after
thermal processing at 180°C shows that there is
no significant oxidation of microencapsulated
iron, in contrast to what happens to unencapsu-lated
iron (table 3).
vThe particle size of the microcapsules is very
similar to the flour particle size, which makes it
easier to manipulate the ingredients.
Selected microencapsulated iron results in a
particle size of about 10 microns, as can be seen in
figure 3. This range is similar to the flour particle
sizes and may be suitable for use as bakery
ingredients.
Finally, the microencapsulated iron samples
selected were tested in bread baking at a pilot
plant scale to evaluate in real conditions how the
baking process and the temperatures reached
during baking affect the sensory characteristics
of enriched bread. The following graph shows the
evolution of the temperature reached in different
bread positions during the baking process in the
oven (figure 5). TL 1 represents the temperature
reached during the baking near the crust. TL2
to TL4 represents the evolution of temperature
reached during baking in the bread core. The
graph shows that the temperature at the surface of
the bread reached 140°C and in the core of the
bread the temperature reached around 100°C.
Breads after the baking process were tested to
assess significant changes in sensory character-istics
due to possible wall cracking that may
release iron prematurely (during the baking
process and not at the intestine level). Those
microencapsulated that modified the sensory
characteristics of the bread negatively were
rejected. Figure 4 shows two breads produced
with microencapsulated iron (named M4 and M5)
with dataloggers inside to detect the temperature
source: ainia
S C I E N C E
© ainia
++ figure 3
++ figure 3
Particle size
distribution of
microencapsulated iron
Particle Size (μm)
Volume (%)

7. © ainia
F U N C T I O N A L B A K E R Y P R O D U C T S
1 4
S C I E N C E
++ figure 4
Sensory tests. Bread
with two types of
microencapsuated iron
(M4&M5) compared to
bread without capsules.
(control)
++ figure 4

8. during baking in comparison with control bread
produced without any added iron. As can be
seen, no significant differences are detected
from the sensory point of view. They did not
present any off-flavors in comparison to control
bread either.
Future work to be carried out includes the iron
bioaccessibility and bioavailability studies in en-riched
breads, since the other important issue to
take into account in enrichment of bread is the
amount of iron that will be utilized by the body.
Bibliography
+ Scientific Advisory Committee on Nutrition
(SACN). Iron and Health; TSO: London, UK,
2010
+ Zimmermann, M.B., Zeder, C., Chaouki, N.,
Saad, A., Torresani, T. and Hurrell, R.F. Dual
fortification of SALT with iodine and micro-encapsulated
iron: a randomized, double- blind,
controlled trial in Moroccan schoolchildren.
Am. J. Clin. Nutr. 77, 425–432. (2003)
+ Jin, T.; Zhang, H.; Journal of Food Science 73,
M127, 2008
+ Hurrell, R.F. 1997. Preventing iron deficiency
through food fortifi cation. Nutr. Rev. 55:
210-222.
+ Assessing the iron status of populations: re-port
of a joint World Health Organization/
F U N C T I O N A L B A K E R Y P R O D U C T S 1 5
Centers for Disease Control and Prevention
technical consultation on the assessment of
iron status at the population level, 2nd ed.,
Geneva, World Health Organization, 2007.
Available at http://www.who.int/nutrition/
publications/micronutrients/anaemia_iron_
deficiency/9789241596107.pdf
+ REGULATION (EC) No 1924/2006 OF THE
EUROPEAN PARLIAMENT AND OF THE
COUNCIL of 20 December 2006 on nutrition
and health claims made on foods
For more information about the project see
www.bake4fun.eu +++
© ainia
S C I E N C E
Authors
Daniel Rivera1,
Elisa Gallego1,
MariPaz Villalba1,
Andrea Gianotti2
1 ainia technological centr e,
2 University of Bologna
Parque tecnológico de Valencia
c/ Benjamin Franklin, 5-11
E46980 Paterna
Email: informacion@ainia.es
Phone: +34 96 1 36 60 90
Fax: +34 96 1 31 80 08
++ figure 5
++ figure 5
Evolution of tempera-ture
during the baking
process
Baking process of enriched bread with MI-Fe
BAKE4FUN – June 2014
Time (min)
Temperature (°C)