Novel fortification strategies for staple gluten-free products

Full text

307
V.R. Preedy et al. (eds.), Handbook of Food Fortifi cation and Health: From Concepts to Public
Health Applications Volume 1, Nutrition and Health, DOI 10.1007/978-1-4614-7076-2_24,
© Springer Science+Business Media New York 2013
J. Jastrebova, Ph.D. (*) • M. Jägerstad, Ph.D.
Department of Food Science, Swedish University of Agricultural Sciences, Uppsala BioCenter ,
Almas Allé 5 , P.O. Box 7051, Uppsala SE 750 07 , Sweden
e-mail: jelena.jastrebova@gmail.com; margaretha.jagerstad@slu.se
Keywords Gluten-free diet • Coeliac disease • Gluten intolerance • Vitamins • Antioxidants • Minerals
• Dietary fi bre • Natural forti fi cation
Abbreviations
CD Coeliac disease
FAO Food and Agriculture Organization of the United Nations
GF Gluten-free
RDI Recommended daily intake
WG Whole-grain
WHO World Health Organization
Introduction
Gluten is the major storage protein in cereals such as wheat, rye and barley, or their crossbreds. In the
wheat fl our the gluten proteins contribute 80–85 % of the total protein content. These proteins contain
peptides with high glutamine/proline content which are resistant to digestion by human proteases and
may trigger damage to the small intestines. Gluten intolerance is a lifelong intolerance to gluten
Chapter 24
Novel Forti fi cation Strategies for Staple
Gluten-Free Products
Jelena Jastrebova and Margaretha Jägerstad
Key Points
The majority of gluten-free (GF) staple products available on the market today do not meet the • nutritional requirements and need to be forti fi ed.
Traditional forti fi cation with single vitamins and minerals improves the nutritional value of GF • foods but cannot provide products that are fully comparable with whole-grain wheat products.
Natural forti fi cation by using nutritious ingredients and/or by improving nutritional value through • bioprocessing is the best way to develop nutrient-rich GF products.

308 J. Jastrebova and M. Jägerstad
proteins [ 1 ] . A couple of decades ago, gluten intolerance was considered an uncommon disorder in the
world, with prevalence rates of 1 in 1,000 or lower [ 2 ] . However, the development of novel sensitive
and speci fi c screening methods for gluten intolerance improved considerably diagnosis rates and
resulted in an epidemiologic shift. Recent population studies have reported a much higher prevalence
of gluten intolerance and it is now estimated to be 1:100–1:200 [ 1, 3 ] .
Micronutrient De fi ciencies and Health Risks Associated
with Gluten Intolerance
The most common and severe form of gluten intolerance is coeliac disease (CD), characterised by
immune-mediated damage of the small intestinal mucosa [ 3 ] . The “classic” symptoms of CD are
diarrhoea and weight loss, but the range of symptoms is very broad and the severity of symptoms
varies widely between patients [ 4 ] . In the Western world gluten intolerance is the most common cause
of malabsorption of several important nutrients including folate, vitamins B6 and B12, calcium, iron,
copper, zinc, selenium, and fat-soluble vitamins (Table 24.1 ) [ 3– 5 ] . Several epidemiological studies
have shown CD to be a risk factor for cancer, anemia, osteoporosis, thyroid disease, type 1 diabetes,
female infertility, and dermatitis herpetiformis [ 4 ] . The prevalence of neurological and psychiatric
disorders is also considerably increased in coeliac patients [ 1, 4 ] (Table 24.1 [ 5– 13 ] ).
Untreated CD is associated with 2–4-fold increased risk of death [ 2, 14 ] . The only effective treatment
for gluten intolerance and related diseases is a lifelong withdrawal of gluten from the diet. Several
studies have shown that a strict gluten-free (GF) diet results in clinical and mucosal recovery and
improves considerably the health-related quality of life of coeliac patients [ 15 ] . However, to follow a GF
diet is dif fi cult. The availability of GF foods varies greatly in different countries and noncompliance
with the diet is not uncommon, with rates between 17 and 44 % in those diagnosed as adolescents and
more than 50 % of patients diagnosed as adults [ 4, 16 ] . Such behaviour may cause partial damage of
the intestinal mucosa resulting in continued malabsorption also after CD diagnosis and prescription
of a GF diet, which in turn may result in increased vitamin and mineral needs in noncompliant coeliac
patients. Even compliant patients may need extra vitamins to improve their health status. As shown by
Hallert et al. [ 17 ] , B-vitamin supplementation in coeliac patients on strict GF diet resulted in normalised
plasma total homocysteine levels and provided signi fi cant improvement in general well-being.
As seen from Table 24.1 , many coeliac patients have reduced intake of minerals calcium, magnesium, iron,
zinc, manganese, copper, selenium, and water-soluble vitamins B6 and folate as well as fat-soluble vitamins
A and D. Even intake of fi bres is considerably below recommended daily intake (RDI) according to most
studies [ 18 ] . Bread is one of important sources of several nutrients including vitamins B1, B2, niacin, B6,
and folate and minerals magnesium, iron, and zinc, whereas dairy and meat products are important sources
of vitamin B12 and fat-soluble vitamins. However, the nutritional value of many GF breads available on
the market is lower compared with their gluten-containing counterparts [
18– 20 ] , which makes it dif fi cult
to meet RDI levels for B-vitamins, magnesium, iron, zinc, and fi bres when following a GF diet.
Nutritional Requirements on Gluten-Free Foods and Needs for Forti fi cation
The de fi nition of GF food varies in different countries. In the United States a GF diet is based on rice
and maize that are naturally GF [ 19, 20 ] , whereas in Scandinavia and the UK a GF diet may include
wheat starch that has been rendered GF [ 21 ] . According to the latest EU regulations the content of
gluten should not exceed 20 mg/kg in GF foods and 100 mg/kg in foods specially processed to reduce
gluten content from wheat [ 21 ] .

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24 Novel Fortifi cation Strategies for Staple Gluten-Free Products
Codex Standard for GF foods requires that the GF products substituting important basic foods
should supply approximately the same amount of vitamins and minerals as the original foods they
replace (see Guidance on the levels to be added). However, many GF foods are still based on nutrient-
poor starches and re fi ned fl ours of rice, maize, potato, and wheat rendered GF and do not meet the
nutritional requirements. According to our survey of 262 staple GF foods (breads, fl our mixes, and
pasta products) produced in Europe by some leading manufactures, starch is the main ingredient of
79 % GF soft breads and 83 % GF bread fl our mixes (Table 24.2 ), which result in poor nutritional
Table 24.1 Micronutrients of special importance for coeliac patients
Nutrients De fi ciency symptoms and clinical
prevalence in coeliac patients, (%) % of patients on GF
diet not meeting RDI Major dietary sources of
each nutrient
Calcium (Ca) Impaired bone health, 30–50 [ 6 ] 46–82 [ 7, 8 ] Dairy products
11 [ 9 ]
Magnesium (Mg) Bone disease, 30–50 [
6 ] , cardiovas-
cular dysfunction 69 [ 7 ] Dairy products, vegetables,
bread
~50 [ 10 ]
54 [ 9 ]
Iron (Fe) Anemia, 49 [ 4 ] , 46 [ 6 ] , S-ferritin < cut-
off 0–38 [
11 ] 20–90 [ 7 ] Meat, bread, vegetables
65 [ 12 ]
33 [ 9 ]
Zinc (Zn) Impaired wound-healing, dermatitis,
growth and sexual development
retardation
40–45 [ 7 ] Meat, dairy products, bread
18 [ 9 ]
Manganese (Mn) Unclear 24–52 [ 7 ]
Copper (Cu) Hematologic and neurologic abnor-
malities [ 13 ] 33 [ 9 ]
Selenium (Se) Impaired antioxidant status, increased
risk for cancer and vascular
diseases
89–94 [ 7 ] Foods of animal origin
~50 [ 10 ]
Retinol (vitamin A) Night blindness, skin lesions 48 [
9 ] Foods of animal origin,
vegetables, oils
Cholcalciferol
(vitamin D) Bone disease, 30–50 [
6 ] 100 [ 8 ] Foods of animal origin
80 (in patients >65
years) [ 9 ]
~50 [ 10 ]
Tocopherol (vitamin E) Impaired antioxidant status No data Vegetable oils, germs,
cereals
Vitamin K Impaired blood coagulation, 10 [
4 ] No data Green leafy vegetables
Thiamine (vitamin B1) Nerve disease, beriberi Average intakes
meet RDI [
12 ] Meat, bread, dairy products
Ribo fl avin (vitamin B2) Skin changes Dairy products, meat, bread
Niacin Skin disease, pellagra Meat, bread, dairy products
Pyridoxin (vitamin B6) Low B6, elevated homocysteine
in blood, 20–37 [
6 ] 0 [ 5 ] Meat, vegetables, fruits,
bread
Low B6, 37 [
5 ] 11 [ 9 ]
Folate a Low folate and elevated homocysteine
in blood, 20–37 [
6 ] 80–90 [ 7 ] Vegetables, fruits, dairy
products, bread
Low erythrocyte folate, 3–34 [
11 ] 65 [ 8, 9 ]
Low plasma-folate, 20 [
5 ] 100 [ 5 ]
Increased risk for neural tube defects
Cobalamin (B12) Pernicious anemia, 8–41 [
4 ] 10 [ 8 ] Foods of animal origin
Low serum vitamin B12, 0–27 [
11 ] 4 [ 9 ]
0 [ 5 ]
a RDI for folate in UK for adults is 200 m g. WHO recommends 400 m g folate/day

310 J. Jastrebova and M. Jägerstad
quality of these products if forti fi cation is not used. The content of B-vitamins and some minerals is
commonly much lower in these foods compared with cereal products based on whole-grain (WG)
wheat and rye or cereal products based on forti fi ed re fi ned fl ours. According to the comprehensive
survey of GF products in the United States made by Thompson [ 19, 20 ] the great part of these prod-
ucts has content of thiamine, ribo fl avin, niacin, folate, and iron, which is only 66–80 % of content in
their gluten-containing counterparts. Low folate content was also reported for some GF products in
Sweden [ 22 ] . The content of dietary fi bres in GF products is only 30–50 % of fi bre content in corre-
sponding gluten-containing products [ 20 ] . The reduced nutritional value of many GF foods may lead
to low micronutrient intake (Table 24.1 ) and poor vitamin and mineral status in coeliac patients [ 5 ] .
Even antioxidant status is much lower in celiac patients [ 23, 24 ] , which may be partially caused by
low content of antioxidants in GF foods based on starches and re fi ned fl ours [ 25 ] . Therefore, the
development of more nutrient-rich GF products is of great importance.
Despite the necessity of improving the nutritional value of GF foods there is no mandatory
forti fi cation of GF products in Western countries. GF foods available on the market vary greatly in
content of proteins, fi bres, vitamins, and minerals. For one decade ago the majority of these products
were not forti fi ed [ 19, 20 ] and the situation is similar even today. Forti fi ed GF products represent only
10 % of GF staple foods in Europe (Table 24.2 ). Among starch-based GF soft breads produced in
Europe only 5 % breads are forti fi ed with fi ve B-vitamins (B1, B2, niacin, B6, and folic acid) and iron
and 9 % breads are forti fi ed with folic acid and calcium, whereas 56 % of starch-based GF soft breads
have low nutritional value (Table 24.3 ).
The use of starches as main ingredient in many GF foods makes it dif fi cult to successfully imple-
ment common forti fi cation with single micronutrients. Such forti fi cation cannot provide nutritional
value fully comparable with that of gluten-containing products, because starches lack or have low
levels of many essential micronutrients and phytochemicals. As seen from Fig. 24.1a, b , maize starch
contains no B-vitamins and the mineral content of maize starch is only 2–13 % of that of WG wheat.
Other starches (potato, rice, and wheat starches) are similar to maize starch regarding low nutritional
value (data not shown). This clearly demonstrates unsuitability of using starches as main ingredients
in GF foods. Even re fi ned fl ours of maize and rice are much lower in most micronutrients compared
with corresponding WG products or WG wheat. The content of calcium, iron, magnesium, zinc, and
copper is 3–17 times lower in re fi ned fl ours of rice and maize compared to WG wheat and up to 5
times lower compared to corresponding WG fl ours (Fig. 24.1a ). Re fi ned fl our of rice is also low in
vitamins B1, B2, and folate, whereas re fi ned maize fl our is low in vitamins B1, B2, and B6
(Fig. 24.1b ). Moreover, the absence of bran/germ fractions in re fi ned fl ours results in much lower
levels of dietary fi bres and antioxidants compared to WG fl ours because bran/germ fraction has high
content of fi bres and contributes to a greater part of antioxidant capacity in WG fl our [ 26, 27 ]
(Fig. 24.1 [ 28 ] ).
Table 24.2 Comparison of 262 staple GF foods produced in Europe a in relation to their main ingredients and enrichment
with vitamins and minerals
Product Total number Number b of products enriched
with vitamins and minerals Number b of products based on
Starch Re fi ned fl our Whole-grain fl our
Flour mixes for bread 42 12 (29 %) 35 (83 %) 7 (17 %) 0
Soft breads 109 12 (11 %) 86 (79 %) 6 (5.5 %) 17 (15.5 %)
Crispbreads 20 2 (10 %) 4 (20 %) 11 (55 %) 5 (25 %)
Pasta products 91 0 32 (35 %) 51 (56 %) 8 (9 %)
All products 262 26 (10 %) 157 (60 %) 75 (29 %) 30 (11 %)
a GF staple foods from 11 manufactures of GF foods in Europe (BiAglut, DreiPauly, DS, Finax, Gluta fi n, Glutano,
Hammermühle, Juvela, Minderleinsmühle, Orgran, Schär, Semper) are surveyed
b Numbers in brackets are expressed as percent of total number of corresponding products

311
24 Novel Fortifi cation Strategies for Staple Gluten-Free Products
WG Flours and Nutrient-Rich Seeds as Valuable Natural
Forti fi cants for GF Foods
Recently, a positive trend towards more nutritious GF foods is seen in many countries. More and more
producers develop novel GF foods with higher nutritional value by using WG fl ours of rice, maize,
buckwheat, millet, amaranth, teff, quinoa, and sorghum. In Europe, WG fl ours are used as the main
ingredient in 15.5 % of soft breads, 25 % of crispbreads and 9 % of pasta products (Table 24.2 ). The
use of WG fl ours as well as other nutrient-rich ingredients such as seeds (sesame, sun fl ower, and fl ax
seeds) and fl ours of soy, lupine, chick-pea, and chestnut become more and more common when devel-
oping new GF breads (Table 24.3 ) and pasta products. This is also a common practice in production
of GF cereals. A great part of breakfast cereals are based on whole grains and contain different
nutrient-rich ingredients such as seeds and fruits (data not shown).
As seen from Fig. 24.1a , oat, buckwheat, millet, amaranth, quinoa, sorghum, and teff have mineral
content, which is comparable or higher than that of WG wheat. The content of B-vitamins varies
greatly between different cereals and pseudocereals (Fig. 24.1b ). Compared to WG wheat, amaranth
and quinoa are considerably higher in vitamins B2, B6, and folic acid, but lower in niacin, whereas
oat is higher in B1, but lower in other B-vitamins. Buckwheat, millet, and teff are comparable with
WG wheat or better regarding B-vitamin content. Several investigations have also shown that these
alternative cereals/pseudocereals have bene fi cial composition regarding proteins, amino acids, and
dietary fi bres [ 29– 32 ] . They have also high antioxidant capacity, especially buckwheat, sorghum, and
quinoa [ 31 , pp. 149–175, 33 ] . The substitution of starches and re fi ned fl ours of rice, maize, and potato
by WG fl ours of these cereals/pseudocereals can therefore multiply the nutritional value of GF foods
by several times.
As shown in Table 24.4 , the majority of WG-based GF products have WG (brown) rice as the
main ingredient. This provides considerably higher nutritional value compared with starch-based GF
foods. WG rice has high content of vitamins B1, B6, and niacin as well as minerals magnesium and
zinc (Fig. 24.1a, b ). The levels of vitamin B2 and minerals iron and copper are around 50 % of cor-
responding values for WG wheat and antioxidant activity is comparable with that for WG wheat [ 34 ] .
Table 24.3 Survey of 86 starch-based soft GF breads produced in Europe
a
Ingredients improving nutritional value Enrichment with vitamins
and minerals Number
of breads (%) Nutritional value
No No 11.7
Low (56 % of breads)
Fibres b No 7.0
Fibres + proteins c No 37.2
Fibres +/or proteins B-vitamins, iron 3.5
Improved (44 % of breads)
Proteins + seeds B-vitamins, iron 1.2
Whole grains d No 2.3
Fibres + proteins + whole grains No 9.3
Fibres + proteins + whole grains Folic acid, calcium 7.0
Fibres + proteins + seeds e 8.1
Fibres + proteins + whole grains + seeds No 10.5
Fibres + proteins + whole grains + seeds Folic acid, calcium 2.3
a Breads from 11 manufactures of GF foods in Europe (BiAglut, DreiPauly, DS, Finax, Gluta fi n, Glutano, Hammermühle,
Juvela, Minderleinsmühle, Orgran, Schär, Semper) are surveyed
b Fibres—psyllium, sugar beet fi bre or apple fi bres or their mixtures
c Proteins—soy protein isolate/soy fl our, lupin proteins/ fl our, egg proteins, milk proteins, or their mixtures
d Whole grains—WG fl ours of maize, rice, buckwheat, millet, amaranth, teff, quinoa, sorghum, or their mixtures
e Seeds—seeds of sun fl ower, sesame, fl ax, or their mixtures

312 J. Jastrebova and M. Jägerstad
However, the levels of folate and calcium are 3 times lower in WG rice compared with WG wheat
(Fig. 24.1a, b ). Therefore the addition of other WG fl ours with higher nutrient content may be of great
interest. For example, the addition of quinoa, amaranth, or millet can provide higher folate content,
whereas higher calcium content can be obtained by the addition of amaranth, sorghum, or teff. As seen
from Table 24.4 , several breads available on the market contain mixtures of WG fl ours, which provide
high nutritional value that is fully comparable with WG-based gluten-containing breads.
Only one WG bread product is based on oat as main ingredient (Table 24.4 ) despite good nutritional
value of oat (Fig. 24.1a, b ). The use of oats in GF diet is still controversial due to frequent contamination
of commercial oats by wheat and barley. In Canada, for example, 88 % of oat samples from retail stores
Fig. 24.1 Mineral ( a ) and vitamin ( b ) content in whole-grain (WG) and re fi ned fl ours of rice and maize, maize starch,
partially debranned oat fl our and whole grains or WG fl ours of buckwheat, millet, amaranth, quinoa, sorghum, and teff
related to their content in WG wheat fl our which is taken as 100 %. Data are taken from USDA National Nutrient
Database [ 28 ]

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24 Novel Fortifi cation Strategies for Staple Gluten-Free Products
were found to contain gluten at levels higher than allowed level for GF foods (20 mg/kg) according
to the study of Koerner et al. [ 35 ] . However, the use of pure oats in GF diet can signi fi cantly increase
intakes of nutrients, e.g. iron, zinc, thiamine, and dietary fi bres and make the GF diet more diverse and
balanced [ 36, 37 ] . On the other hand, the bioavailability of iron may decrease due to higher content
of phytate in oat; yet this seems not to have in fl uenced the iron status of coeliac patients [ 36 ] . Pure oats
are well tolerated by majority of coeliac patients, but around 5 % of coeliac patients can develop oat
intolerance [ 38 ] , therefore the introduction of oats in GF diet should be done with caution.
Buckwheat and millet are the most common minor ingredients in GF bread and pasta products.
According to our survey of 109 soft GF breads produced in Europe, 22 % of breads contain buck-
wheat and 21 % contain millet. Buckwheat can also be used as main ingredient in WG GF products
(Table
24.4 ). Compared to WG wheat, buckwheat has higher content of most micronutrients
(Fig. 24.1a, b ), similar protein and fi bre content and high antioxidant capacity [ 39 ] . According to the
fi ndings of Krupa-Kozak et al. [ 40 ] , the addition of buckwheat to GF fl our mixtures provides breads
Table 24.4 Some examples of whole-grain-based GF foods produced in Europe
a
Product name Main WG ingredient Other WG ingredients Producer
Soft breads
Sliced bread with teff Whole rice (40 %) Teff (13 %), millet, buckwheat Drei Pauly
Sliced bread with buckwheat and
linseed Whole rice Millet (8 %), buckwheat bran (6 %) Drei Pauly
Wholemeal sliced bread with teff Whole rice (38 %) Millet, teff (6 %), buckwheat Drei Pauly
wholemeal sliced bread Whole rice (39 %) Whole maize 8 %, millet 8 % Drei Pauly
Sliced bread with teff and seeds Whole rice (37 %) Teff (6 %), buckwheat, millet Drei Pauly
Bread, 3-kernels Whole rice (39 %) Millet (8 %), whole maize (8 %) Glutano
Bio-Amaranth Schnittbrot Buckwheat Amaranth 19 % Hammermühle
Bio-Buchweizen Schnittbrot Buckwheat (40 %) – Hammermühle
Bio-Hirsebrot Schnittbrot Buckwheat (28 %) Millet (18 %) Hammermühle
Körnerbrot geschnitten Whole rice Buckwheat Hammermühle
Vitalbrot mit Sonnenblumenkernen
geschnitten Whole rice Millet, buckwheat Hammermühle
Vollkornbrot haltbar Whole rice – Hammermühle
Steinofenbrötchen frisch Whole rice – Minderleinsmühle
Hausbrot in Scheiben Whole rice – Minderleinsmühle
Sonnenblumenbrot in Scheiben Whole rice – Minderleinsmühle
Vollkornbrot, ballaststoffreich Whole rice – Minderleinsmühle
Solena whole-grain bread Whole rice (34 %) Millet (8 %), buckwheat (7 %) Schär
Crispbreads
Bio-Reiswaffeln Whole rice (70 %) – Hammermühle
Essential Fibre Crispibread Brown rice Sorghum Orgran
Multigrain Crispibread with Quinoa Brown rice Sorghum, quinoa (10 %) Orgran
Crispbread with buckwheat Buckwheat (68 %) – Orgran
Havreknäcke Oat Teff Semper
Pasta products
Gourmet Rice Pasta spirals Brown rice – Orgran
Buckwheat Pasta spirals Buckwheat (80 %) – Orgran
Vegetable Rice Pasta (penne) Brown rice (99 %) – Orgran
Vegetable Rice Pasta (spirals) Brown rice (99 %) – Orgran
Rice and Millet Pasta Brown rice (94.5 %) Millet (5.5 %) Orgran
Essential Fibre Pasta (lasagnette) Brown rice – Orgran
Essential Fibre Pasta (penne) Brown rice – Orgran
Essential Fibre Pasta (spirals) Brown rice – Orgran
a Breads and pasta products from 11 manufactures of GF foods in Europe (BiAglut, DreiPauly, DS, Finax, Gluta fi n,
Glutano, Hammermühle, Juvela, Minderleinsmühle, Orgran, Schär, Semper) are surveyed

314 J. Jastrebova and M. Jägerstad
with much higher protein and mineral content. Increasing concentration of buckwheat fl our (10–40 %)
affected proportionally the enrichment in proteins (up to fi vefold) and minerals, e.g. Zn (twofold), Cu
( fi vefold), and Mn (tenfold) compared to control bread.
Millet is also a good source of micronutrients (Fig. 24.1a, b ) and antioxidants [ 39 ] and has been
used as a staple food by millions of people in Asia and Africa for thousands of years. Several other
GF cereals and pseudocereals such as sorghum, teff, quinoa, and amaranth are also used as minor
ingredients in GF breads, which helps to improve the nutritional value of breads [ 41 ] . However, only
few GF products containing these nutritious cereals and pseudocereals are today available on the
market (see, for example, Table 24.4 ).
Another way to improve the nutritional value of GF foods is to add highly nutritious ingredients such
as soy, lupin, chick-pea, or chestnut fl ours or different seeds such as fl ax, sun fl ower, sesame, or pumpkin
seeds. As seen from Fig. 24.2 , the content of several micronutrients in these ingredients is 2–10 times
higher compared with WG wheat. This means that the addition of small amounts, e.g. 5–10 %, may
result in considerable improvements of nutritional value of GF products. For example, chick-pea,
lupin, or soy fl ours can be used to fortify GF fl ours with folate; the addition of just 5 % of chick-pea
fl our can provide the same amount of folate as 50 % of WG wheat fl our. Pumpkin, sesame, and
sun fl ower seeds can be used to fortify GF breads with zinc and magnesium, whereas soy fl our, and
pumpkin seeds may be useful as natural iron and copper forti fi cants.
As shown in Table 24.5 , WG fl ours of GF cereals and pseudocereals as well as nutritious seeds
may be used as valuable natural forti fi cants to increase content of micronutrients and antioxidants in
GF foods. Because these cereals/pseudocereals have different nutritional pro fi les, it is bene fi cial to
combine several of these ingredients to achieve high nutritional value (Fig. 24.2 [ 28 ] ).
The Use of Genetic Diversity and Engineering for Improving
the Nutritional Quality of GF Foods
The content of micronutrients, minerals, and phytochemicals may vary widely between different cultivars
or varieties. For example, variety has great effect on the content of several nutrients in millet [ 42 ] .
The concentration of calcium is 40-fold higher in Finger millet than in Proso millet, whereas Japanese
Barnyard millet has sixfold higher content of iron compared with Proso or Pearl millet. This gives
the opportunity to enhance the nutritional value of GF foods by choosing the right variety. Another
promising example is the large biodiversity of different yeast strains used in bread making. As shown
by Hjortmo et al. [ 43 ] , it is possible to increase up to fi vefold the levels of folate in bread by using a
high folate producing yeast strain instead of commercial baker’s yeast.
Bioforti fi cation is another ef fi cient way to enhance the content and bioavailability of micronutrients
and bene fi cial phytochemicals in food crops through genetic engineering. Novel varieties of staple
cereals with enhanced micronutrient content have been developed recently, e.g. rice bioforti fi ed
with folate, rice bioforti fi ed with iron and zinc, multivitamin maize bioforti fi ed with ascorbic acid,
b -carotene, and folate (see previous chapters). These novel varieties of GF cereals can be used in the
future to enhance the nutritional value of GF products.
Natural Forti fi cation Through Bioprocessing: Enhancing Vitamin Content
in GF Products and Improving the Bioavailability of Minerals
Typical examples of bioprocessing are germination/malting/sprouting of seeds/kernels and fermentation
by adding yeasts and/or bacteria. In contrast to traditional forti fi cation, a natural way to increase vitamin
levels is germination ( or malting / sprouting ) of plant seeds, which has been applied for decades.

315
24 Novel Fortifi cation Strategies for Staple Gluten-Free Products
By this way, levels of vitamins such as thiamine, ribo fl avin, folate, biotin, pantothenic acid, and
tocopherols can be increased 2–4 times than those in ungerminated seeds [ 44– 46 ] . Germination also
increases endogenous phytase activity in cereals, legumes, and oil seeds through activation of intrin-
sic phytase [ 47 ] leading to reduction of total phytates, that compromise mineral and trace element
absorption in humans.
Germination/malting might interfere negatively with baking performance due to increase of enzy-
matic activities such as protease and amylase leading to degradation of proteins and starch to provide
the developing plant with nutrients. Hefni and Witthoft [ 48 ] could, however, replace about 50 % of the
white wheat fl our with germinated wheat fl our, which together with added yeast doubled the folate
Fig. 24.2 Mineral ( a ) and vitamin ( b ) content in chick-pea and soy fl ours, seeds of lupin, chestnut (dried, peeled),
and fl ax and seed kernels of pumpkin, sesame, and sun fl ower related to their content in WG wheat fl our which is taken
as 100 %. Data are taken from USDA National Nutrient Database [
28 ]

316 J. Jastrebova and M. Jägerstad
content in the bread. Their results demonstrate the possibility of using germinated seeds to increase the
vitamin content in breads. Likewise, the antioxidative capacity and total phenolic content increased
approximately twofold in sprouted pseudocereals (amaranth, buckwheat, quinoa) [ 41 ] . However, when
making bread from 100 % buckwheat mixed with sprouted buckwheat, the antioxidative capacity
decreased during baking. Still, though, this bread had signi fi cantly higher antioxidant capacity and total
phenolic content than control breads made from either wheat or GF rice fl our and potato starch [ 41 ] .
Fermentation by yeast and or lactic acid bacteria is another well-known application of bioprocessing
used in bread making. Bakery yeast is a rich source of zinc and B-vitamins, especially folate. Dry
bakery yeast contains 4–24-fold higher concentrations of B-vitamins compared with WG wheat fl our;
for folate even 50-fold higher amounts [ 28 ] . Approximately 1 % of dry matter of bread constitutes
bakery yeast, hence providing around half or more of the total folate in bread [ 49 ] .
Bread making by yeast also hydrolyse phytates, especially when combined with sourdough fer-
mentation, i.e. bacterial enzymes. The phytate concentration can under optimal conditions be reduced
to near-zero values [ 50 ] . Such substantial decrease of phytates can improve mineral availability in
humans. Sourdough is traditionally made by mixing fl our and water allowing it to ferment. Bakeries
typically have their own sourdoughs which are maintained by back-slopping procedure. The microor-
ganism (lactic acid bacteria and yeast) originate mainly from the fl our but also from the micro fl ora,
associated with bakery yeast often added to the sourdough. In addition to improved technological
properties, fermentation creates a typical fl avour and increases the shelf-life, mainly due to lactic acid
production by lactic acid bacteria. Nutritional value is improved by better bioavailability of minerals
due to destruction of phytates [ 31 , p. 271].
The exploitation of sourdough in GF systems is still in its infancy, only few GF breads available
on the market are made by using sourdough. The literature data available strongly indicate that sour-
dough may undoubtedly be considered as a technological tool for improving the texture and fl avour
characteristics of GF products.
Positive Effects of Nutrient-Rich and Healthy Ingredients on Sensory
and Technological Properties of GF Products
The absence of gluten in GF fl ours makes them unsuitable for production of dough with good
viscoelastic and extensible properties. Gluten proteins from wheat play a vital role in bread making
because they form a continuous viscoelastic network in the fermenting dough, which is necessary to
Table 24.5 The use of natural forti fi cants to enhance the nutritional value and health-promoting properties of GF products
Nutrient Natural forti fi cant a
WG or bran Seeds
Ca Teff, amaranth, oat, quinoa, buckwheat Flaxseed, soy, lupin, sun fl ower, chestnuts
Mg Buckwheat, amaranth, quinoa, teff, oat pumpkin, fl axseed, sesame, sun fl ower, soy
Fe Teff, amaranth, quinoa, buckwheat Soy, pumpkin, sesame, fl axseed, chick-pea
Zn Teff, oat, quinoa, buckwheat, millet Pumpkin, sesame, sun fl ower, lupin, fl axseed
Cu Teff, quinoa, millet, amaranth, buckwheat Soy, sun fl ower, pumpkin, sesame, fl axseed
B1 Oat Flaxseed, sun fl ower, sesame, pumpkin
B2 Quinoa, millet, teff, amaranth, buckwheat Sun fl ower, sesame, lupin
Niacin Whole rice (brown), buckwheat, millet, sorghum Sun fl ower, sesame, pumpkin
B6 Whole rice (brown), amaranth, buckwheat, quinoa Sun fl ower, chestnuts, sesame, chick-pea, fl axseed
Folate Quinoa, millet, amaranth, buckwheat Chick-pea, lupin, soy, sun fl ower seed, sesame
Antioxidants All WG and bran products All seeds
a Placed in descending order regarding the content of nutrient

317
24 Novel Fortifi cation Strategies for Staple Gluten-Free Products
produce bread of high quality [ 51 ] . These properties are completely unique to wheat gluten proteins
and cannot be replicated by GF cereals such as rice and maize. A lot of research was therefore carried
out to fi nd functional ingredients which could be used instead of gluten to improve the viscoelastic
properties of GF dough [ 51 ] . A greater part of this research was performed, however, with starch-
based GF fl our mixes that lack most micronutrients. The result was development of GF breads with
good baking and sensory properties but low nutritional value.
Nutritious pseudocereals such as amaranth, buckwheat, and quinoa have higher protein content
than rice and maize and can be successfully used to improve baking properties of GF fl ours. As shown
in Table 24.6 , the addition of amaranth, buckwheat, and quinoa to bread fl our mixes can considerably
improve loaf volume, provide softer crumb as well as better sensory properties. Even other highly
nutritious ingredients such as protein-rich soybeans, lupin beans, chick-pea, chestnut, or milk protein
isolate can have positive effects on bread quality. Adding dietary fi bres such as inulin or psyllium can
also be useful from the technological point of view because they improve rheological properties of
dough (Table 24.6 [ 31, 40, 52– 61 ] ).
Guidance on Levels to Be Added
Designing GF products generally means replacing of gluten-containing cereals by GF counterparts,
which might include natural ingredients, e.g. nutrient-rich GF cereals/pseudocereals or nutritious
seeds. These ingredients do not need to be restricted for healthy or nutritional reasons. Instead, tech-
nological aspects may limit their use, e.g. baking properties, sensory characteristics, impact on colour
and shelf-life of products.
Traditional forti fi cation with micronutrients, e.g. minerals and vitamins follow legislations
outlined by international expert committees associated with World Health Organization (WHO) and
Table 24.6 Positive effects of some natural forti fi cants on quality and sensory characteristics of GF breads
Forti fi cant and its labeled
maximal content in
commercial soft GF
breads (%)
Literature data
Quality and sensory characteristics of breads compared to
GF controls
Amount added (%)
Buckwheat (40) Increasingly improved sensory quality 10–40 [
52 ]
Improved shape and volume 10–40 [
40 ]
Improved loaf volume, softer crumb, good sensory properties 25 (in batter) [
53 ]
Amaranth (19) Improved loaf volume Used as main ingredient [
54 ]
Comparable bread quality Less than 20 [
55 ]
Improved loaf volume, decreased hardness 10 [
56 ]
Softer crumb, good sensory properties 25 (in batter) [
53 ]
Millet (18) Improved loaf volume, better resistance to staling 15–70 [
31 , p. 131, 139]
Quinoa (10) Improved loaf volume, softer crumb, good sensory properties 25 (in batter) [
53 ]
Chestnut (4.5) Bread quality comparable with wheat control 46.5 [
57 ]
Lupin fl our (4) Good bread texture and pleasant taste No data [
58 ]
Pea isolate Comparable bread quality Less than 3 [
55 ]
Soy proteins Improved bread texture 7.5 [ 59 ]
Milk protein isolate/sodium
caseinate Improved shape and volume, softer crust and crumb texture 3–9 [
51 ]
Calcium caseinate,
calcium citrate Better bread quality, softer and more elastic 0.7–2 [
60 ]
Psyllium fi bres Better rheological properties of dough, comparable bread
quality 2 [ 55 ]
Inulin Increased loaf volume, reduced rate of crumb hardening,
good fl avour 5 [ 31, 61 ]

318 J. Jastrebova and M. Jägerstad
Food and Agriculture Organization of the United Nations (FAO). In 2008, The Codex standard for
foods for special dietary use for persons intolerant to gluten was adopted [ 21 ] .
Except for stating maximum levels of gluten allowed in products labelled as “gluten-free”, the
Commission made the following statement concerning essential composition and quality factors:
“products covered by this standard substituting important basic foods, should supply approximately
the same amounts of vitamins and minerals as the original foods they replace”.
For more speci fi c information on permitted vitamins and minerals that could be added to GF
products, the legislation given for forti fi cation of normal foods can be followed. Authorities on
national levels give guidelines in this respect, usually by following recommendations originally set by
Codex Alimentarius standards. Note that there might be upper limits for certain nutrients, for example
some fat-soluble vitamins, folate, and iron to minimise health hazards.
Recommendations
Starches as main ingredients in GF staple foods should be avoided. – GF staple foods based mainly on re fi ned fl ours should be forti fi ed by adding B-vitamins (thiamine, – ribo fl avin, niacin, B6, and folic acid) and iron (in accordance with legislation in each country) or
by adding nutritious ingredients such as WG fl ours and seeds.
WG fl ours of GF cereals/pseudocereals and their mixtures are recommended as main ingredients – in GF products.
The use of highly nutritious ingredients such as soy, lupin, chestnut, and chick-pea fl ours or seeds – (sun fl ower, fl ax, sesame, or pumpkin) as minor ingredients in GF products is recommended.
Bioprocessing such as germination or fermentation with yeast and/or sourdough can also be used – to further improve the nutritional value of GF products.
Conclusions
A great part of GF staple products available on the market today are based on starches and do not meet
the nutritional requirements. They have lower nutritional value compared with gluten-containing
products and need to be forti fi ed. The traditional forti fi cation of starch-based GF products with single
vitamins and minerals cannot, however, provide products that are fully comparable with WG wheat
products. These forti fi ed GF products still lack many micronutrients, antioxidants, and other health-
promoting compounds. The best way to develop nutritious healthy GF products with high content of
proteins, fi bres, micronutrients, and antioxidants is natural forti fi cation by using nutritious ingredients
such as WG fl ours of GF cereals/pseudocereals, protein-rich fl ours of soy, lupin, chick-pea, chestnut,
and different seeds as well as bioprocessing such as germination or fermentation with yeast and/or
sourdough.
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