innovative iron fortified bakery products

+ 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 deficiencyNutritional iron deficiency (ID) is estimated to affect 1.5–2bn people worldwide (WHO, 2007).

Innovative iron-fortified bakery productsM I C R O E N C A P S U A T I O N T E C H N O L O G Y T O I M P R O V 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

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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. 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.

IntroductionBased 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

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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 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

++ table 1: Type of encapsulates

Type of encapsulates Shape Morphology

Reservoir Type

(core-shell type)

Spherical The active agent is in the core of the capsule

Matrix type Asymmetrical The active agent is distribuited in the wall

material. It can be also in the surface of the

capsule

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++ table 2: Microencapsulation processes classification

Type of encapsulates Methods

Chemical + Coacervation

+ Interfacial or in-situ polymerization

+ Emulsion-solvent evaporation

+ Molecular encapsulation

Physical-chemical + Encapsulation by supercritical fluids: co-precipitation, inclusion

complex

Physical or mechanical + Spray drying

+ Spray chilling or cooling

+ Extrusion coating

+ Fluidized bed

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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 projectResearch carried out throughout the project execution will provide stable microcapsules resistant to bread processing conditions, and

A

B

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a) Samples before

simulated processing

conditions;

b) Samples after


conditions at 90°C;

c) Samples after


conditions at 180°C

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

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Above: SEM images of

microencapsulated iron

Below: SEM images of

microencapsulated iron

after thermal simulation

at 180°C.

++ figure 2

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

++ table 3: Summary of the results 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 oxidation. Green colour means low oxidation.

Microencapsulated iron is protected against oxidation during thermal processing at 180ºC.

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Particle size

distribution of

microencapsulated ironParticle Size (µm)

Volu

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(%)

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++ figure 4

Sensory tests. Bread

with two types of

microencapsuated iron

(M4&M5) compared to

bread without capsules.

(control)

++ figure 4

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/

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 +++

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AuthorsDaniel Rivera1,

Elisa Gallego1,

MariPaz Villalba1,

Andrea Gianotti2

1 ainia technological centre,

2 University of Bologna

Parque tecnológico de Valencia

c/ Benjamin Franklin, 5-11

E46980 Paterna

Email: [email protected]

Phone: +34 96 136 60 90

Fax: +34 96 131 80 08

++ figure 5

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Evolution of tempera-

ture during the baking

process

Baking process of enriched bread with MI-FeBAKE4FUN – June 2014

Time (min)

Tem

per

atu

re (

°C)