Rye and health

264 Pages·2014·51.97 MB·English

by  Åman

Rye and
Health
Edited by
Kaisa Poutanen
VTT Technical Research Centre of Finland
VTT, Finland

and
Per Åman
Uppsala BioCentre
Swedish University of Agricultural Sciences
Uppsala, Sweden
Cover: Front cover image copyright Sean Nel, used under license from
Shutterstock.com
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International Standard Book Number: 978-1-891127-81-6
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Preface
Rye (Secale cereale) is an important food grain, especially in Northern and East-
ern Europe, where rye bread is often used daily. Other food products made of rye
include mixed-flour breads, crisp bread, flakes, porridge, muesli, and biscuits, as
well as pasta and other specific dishes. Rye grain is very rich in dietary fiber, which
is concentrated in the outer grain layers but also present at rather high quantities in
starchy endosperm. Rye is traditionally used as whole-grain bread, bringing all the
grain constituents into the human food; in addition to nutrients, it contains many
phenolic compounds such as lignans, phenolic acids, and alkylresorcinols, as well
as micronutrients (minerals and vitamins), and sterols.
The chemical composition, process-induced changes, bioavailability, and phys-
iological responses of rye foods have been extensively studied, especially in the
Nordic countries in the past 20 years. The Nordic collaborative studies have built
an active research network that is already being passed on to the next generation
of scientists. The research has produced many doctoral dissertations and has cre-
ated an array of scientific data about various aspects of rye consumption from the
perspective of health. This vast database serves as a basis for the current book.
Lately, epidemiological studies have further completed the understanding of the
significance of rye, as part of a healthy Nordic diet, in disease prevention. Recently,
the metabolomics approach has further opened a window into the numerous me-
tabolites potentially involved in mediating the health outcome.
The interest in the health effects of rye foods originated from their high dietary
fiber content and use as whole grain. Rye’s beneficial effects on postprandial glu-
cose metabolism created the concept “rye bread factor” to describe the decreased
insulin demand and its role in control of glucose. This led to a general interest in
the significance of rye consumption in reducing the risk of type 2 diabetes and
heart diseases. The interest in the role of rye intake in breast and prostate can-
cer originates in the studies of rye lignans and their conversion to corresponding
mammalian metabolites, enterolignans. Rye foods have also been a topic for stud-
ies on satiety and weight management.
We are very grateful to our Nordic colleagues for a vivid, long, fruitful, and still
continuing collaboration around rye foods, their nutrition physiology, and health
effects. We hope that the book serves as a good manual for those interested in food
uses of cereal grains and inspires more researchers to join the ongoing journey
to reveal the pathways and mechanisms underlying the physiological processes by
which rye foods may help to protect health. In the best case, it also will motivate
food producers to create new culinary adventures based on rye grain and thus as-
sist more people to have rye as an element in their healthy diet.
Kaisa Poutanen
Per Åman
Contributors
Herman Adlercreutz, Institute for Preventive Medicine, Nutrition, and Cancer,
Folkhälsan Research Center, and Division of Clinical Chemistry, University of
Helsinki, Helsinki, Finland
Per Åman, Department of Food Science, Uppsala BioCentre, Swedish University of
Agricultural Sciences, Uppsala, Sweden
Annica A. M. Andersson, Department of Food Science, Uppsala BioCentre, Swed-
ish University of Agricultural Sciences, Uppsala, Sweden
Roger Andersson, Department of Food Science, Uppsala BioCentre, Swedish Uni-
versity of Agricultural Sciences, Uppsala, Sweden
Anna-Marja Aura, VTT Technical Research Centre of Finland, VTT, Finland
Knud Erik Bach Knudsen, Department of Animal Science, Aarhus University,
Tjele, Denmark
Göran Hallmans, Department of Public Health and Clinical Medicine, Umeå Uni-
versity, Umeå, Sweden
Kati Hanhineva, Institute of Public Health and Clinical Nutrition, Clinical Nutri-
tion, Food and Health Research Centre, University of Eastern Finland, Kuopio,
Finland
Rikke Dalgaard Hansen, Department of Diet, Genes and Environment, Danish
Cancer Society Research Center, Copenhagen, Denmark
Katri Hartikainen, VTT Technical Research Centre of Finland, VTT, Finland
Hanna Isaksson, Department of Food Science, Swedish University of Agricultural
Sciences, Uppsala, Sweden
Afaf Kamal-Eldin, Department of Food Science, Faculty of Food and Agriculture,
United Arab Emirates University, Al Ain, United Arab Emirates
Kati Katina, VTT Technical Research Centre of Finland, VTT, Finland
Marjukka Kolehmainen, Institute of Public Health and Clinical Nutrition, Food
and Health Research Centre, University of Eastern Finland, Kuopio, Finland
Cecilie Kyrø, Danish Cancer Society Research Center, Copenhagen, Denmark
Helle Nygaard Laerke, Department of Animal Science, Aarhus University, Tjele,
Denmark
Anna-Maija Lampi, Department of Food and Environmental Sciences, University
of Helsinki, Helsinki, Finland
Rikard Landberg, Department of Food Science, Swedish University of Agricul-
tural Sciences, Uppsala, Sweden
Matti Marklund, Department of Public Health and Caring Sciences, Clinical
Nutrition and Metabolism, Uppsala University, Uppsala, Sweden
Ali Moazzami, Department of Chemistry and Biotechnology, Swedish University
of Agricultural Sciences, Uppsala, Sweden
Hannu Mykkänen, Institute of Public Health and Clinical Nutrition, Food and
Health Research Centre, University of Eastern Finland, Kuopio, Finland
José L. Peñalvo, Dept. of Epidemiology, Atherothrombosis and Imaging, National
Center for Cardiovascular Research (CNIC), Madrid, Spain
J. Pihlava, VTT Technical Research Centre of Finland, VTT, Finland
Vieno Piironen, Department of Food and Environmental Sciences, University of
Helsinki, Helsinki, Finland
Kaisa Poutanen, VTT Technical Research Centre of Finland, VTT, Finland
Allah Rakha, Department of Food Science, Uppsala BioCentre, Swedish Univer-
sity of Agricultural Sciences, Uppsala, Sweden
Anne Tjønneland, Department of Diet, Genes and Environment, Danish Cancer
Society Research Center, Copenhagen, Denmark
Jie-Xian Zhang, Department of Public Health and Clinical Medicine, Umeå Uni-
versity, Umeå, Sweden
CHAPTER 1
Rye and Rye Bread—
An Important Part of the
North European Bread Basket
Kaisa Poutanen
VTT Technical Research Centre of Finland, VTT, Finland, and Institute of Public
Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland
Production and Uses of Rye
Rye (Secale cereale L.) is to a large extent a European grain, as 90% of the world
rye production (18.3 million tonnes) in 2009 was in Europe (according to FAOSTAT,
the statistics platform of the Food and Agriculture Organization of the United
Nations). Even though rye production was then only 0.8% of the total grain pro-
duction, rye is, along with wheat, an important raw material of bread baking es-
pecially in Northern and Eastern Europe. The total production increased slightly,
by 0.6 million tonnes, from 2004 to 2009. The trends in European agriculture to-
ward sustainability may lead to increasing interest in rye cultivation (Altpeter and
Korzun 2007). Rye is cold resistant and can be grown in soil with low fertility, so
it can be cultivated in areas not very suitable for other cereal crops. Of the 16.5
million tonnes of European rye produced in 2009, about 30% was used for food,
the majority of it in areas close to the Baltic Sea. As pointed out by Sahlström and
Knutsen (2010), the major producers are in the same region. The Russian Federa-
tion, Germany, and Poland are the largest producers, with 12.3 million tonnes in
1
2 Rye and Health
2009, followed by Belarus and Ukraine (Table 1.1). These five countries made up
79% of world rye production and 88% of the rye production in Europe in 2009.
Rye is an important part of the cereal food culture in Germany and in the Nor-
dic, Baltic, and Eastern European countries. The staple rye food, rye bread, is often
made of whole- grain flour using sourdough technology. This makes it a good source
of dietary fiber, phenolic compounds, vitamins, and trace elements and minerals.
For example, in Finland, 90% of rye consumption (14 kg per capita per year) con-
sists of whole- grain flour (Finnish Bread Information 2012). Rye crisp bread, the
dry form of rye bread, is probably the best- known rye bread globally. Rye bread
seems to have beneficial effects on glucose metabolism and postprandial satiety,
as described later in this book. Expanding research data about the various compo-
nents of rye grain beneficial to health have increased the interest in using rye for
food and in the development of new products. Rye also has long been used as por-
ridge and in breakfast cereals. Some traditional Finnish rye foods include Karelian
pastries, made of a thin “skin” of rye dough filled with rice or barley porridge, and
Kalakukko, fish and meat baked in a thick rye cover that provides a shelf- stable
complete meal in one loaf. Mämmi, the Finnish Easter pudding, is based on the ac-
tion of rye malt enzymes on rye flour; after partial liquefaction of starch, the natu-
rally sweetened pudding is baked in the oven for several hours to reach its typical
dense texture and almost black color. In the Nordic countries, a widespread range
of modern products containing rye is also available, including pasta, biscuits, rice
substitutes, frozen dough, and snacks. Rye baking mixes, puddings, and flakes, as
well as rye hamburgers, can also be found in Scandinavian markets.
Chemical Composition of Rye Grain
The overall chemical composition of rye is shown in Table 1.2. Rye grain is rich
in dietary fiber, which is concentrated in the bran but is also present in the en-
dosperm more than it is in wheat grain (Fig. 1.1). In the HEALTHGRAIN variety
screen study, the content of dietary fiber in different rye varieties varied from 20.4
to 25.2%, whereas total arabinoxylan content was 12.1–14.8% and 3.1–4.3% in the
bran and flour fractions, respectively (Nyström et al 2008, Shewry et al 2010). Rye
also contains about 2% β-g lucan (Nyström et al 2008) and 4–7% fructan (Karppinen
et al 2003). Rye fiber is further discussed in Chapters 3 and 4.
Rye contains 11.2–15.8% protein (Nyström et al 2008, Shewry et al 2010). Rye
prolamins (secalins) behave quite differently from wheat prolamins in baking, as
they are not able to create comparable amounts of polymeric proteins and form a
Importance of Rye and Rye Bread 3
gluten- type network as in wheat baking (Gellrich et al 2003). Thus, the structure
of rye bread is very different from that of wheat bread, and the cell walls and their
polysaccharides have an important role in whole- meal rye bread baking (Parkkonen
FIG. 1.1. Micrographs of a cross section of rye grain (A) and rye bran
(B). Cell walls (blue) have been stained with Calcofluor and protein
(red) with acid fuchsin. (Courtesy Ulla Holopainen-Mantila, VTT
Technical Research Centre of Finland)
4 Rye and Health
et al 1994, Autio et al 1997). In sourdough, rye proteins are partially hydrolyzed and
probably influence the properties of bread in many ways (Tuukkanen et al 2005).
This may open interesting possibilities in terms of physiological responses.
Rye is also rich in phytochemicals, such as the phenolic compounds (Bondia-
Pons et al 2009), vitamins, and minerals. These may contribute to the typical fla-
vor of rye (Heiniö et al 2008). While phenolic acids are the phenolic compounds
present in the highest quantities, rye also contains significant amounts of lignans,
alk(en)ylresorcinols, and also benzoxazinoids. Rye also contains folate, tocols,
and sterols, the content of the latter two correlating with arabinoxylan content
(Nyström et al 2008). The genetic variation of five rye lines studied with respect to
phytochemical components was very limited compared with the strong impact of
environmental factors (Shewry et al 2010), and especially the content of phenolic
acids was more dependent on environmental conditions during cultivation than
on the genetic origin of the grain. The bioactive compounds, together with dietary
fiber, are concentrated in the germ and outer layers of the rye kernel (Nilsson et al
1997, Liukkonen et al 2003).
Frolich et al (2013) pointed out that different whole grains and whole-g rain foods
have distinct properties. Rye contains 19–22% dietary fiber, which is more than
that in other cereal grains (Åman et al 2010), and it has a wide range of distinct
bioactive compounds. As pointed out by Frolich et al (2013), the specific properties
of each cereal type, as well as the processing methods, should be considered when
evaluating the health properties of cereals. This is one of the aims of the current
book regarding rye grain and foods.
Consumption and Nutritional Significance
of Rye and Rye Bread
Rye has recently been pointed out, from a British perspective, to be “the over-
looked cereal” (Buttriss 2006). Nevertheless, Poland and Belarus have a rye supply
of more than 30 kg per person per year (Table 1.3). However, the consumption trend
is decreasing (Sahlström and Knutsen 2010). In the Nordic and Baltic countries, the
supply is in the range of 11.7–19.1 kg per capita per year. Whole- grain bread, with
rye bread as an important example, is one component in the healthy Nordic diet,
Importance of Rye and Rye Bread 5
with many demonstrated physiological benefits (Uusitupa et al 2013). In Finland,
users of rye bread make up 85% of the population, and the consumption among the
users is 124 g/day (men) and 78 g/day (women). This means that rye bread is the
most important source of dietary fiber consumption in Finland, the total of which
is 24 g/day for men and 21 g/day for women (Paturi et al 2008). Intake of dietary
fiber, especially grain dietary fiber, has been shown to be protective toward many
chronic diseases, especially cardiovascular disease and type 2 diabetes (Hauner et
al 2012). Similar findings are repeatedly reported for intake of whole- grain foods
(Ye et al 2012). The traditional forms of rye bread often use the outer grain layers
as well as the inner ones. Rye bread thus has an important role for public health.
The European Food Safety Authority has recently accepted a health claim about
consumption of rye fiber and changes in bowel function (EFSA 2011).
The consumption of rye bread decreased in Finland as eating habits changed in
the 1900s, but at the end of the century, the female population slightly increased
its rye bread consumption (Prättälä et al 2001). The declining consumption of rye
and increased use of white wheat bread during the 1900s pose challenges for the
development of new food uses of rye grain but also for consumer communication
about the importance of whole- grain rye and rye bread in nutrition and health.
Studies about barriers to whole- grain intake have shown that factors preventing
individuals from consuming whole- grain foods include taste preferences, lack of
cooking skills, price, and lack of availability of whole-g rain foods (Kuznesof et al
2012). Encouraging increased consumption of local healthy diets is a joint chal-
lenge for scientists, food producers, and health professionals. Rye and rye bread
have an established role in the diet of many countries, with much potential for
increased use and public health benefits.
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