Novel Macromolecules in Food Systems

443 Pages·2000·8.693 MB·1-448\443

by  G. Doxastakis and V. Kiosseoglou (Eds.)

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Preface
The presence of proteins and polysaccharides in both natural and processed foods is
crucial since they perform multifunctional roles such as thickening, stabilization,
gelation and encapsulation. As a result they determine to a large extent the self life,
texture and nutritional quality of foods. The need, on the one hand, to develop new
better performing macromolecules, as compared to their traditional competitors and,
on the other, to exploit underutilized agricultural and animal raw materials, has
prompted food scientists to become involved in new biopolymer research for food
applications. The list of these so-called "novel" macromolecules is steadily
expanding aided partly by the application of recent advances in biological and
physical sciences.
As," however, new research and technological information is continuously
accumulating it is becoming increasingly difficult to keep track of new innovations in
the field of novel macromolecules as well as of the development of novel uses for the
traditional ones. The aim of this book is to provide fundamental understanding of a
number of novel uses of traditional biopolymers and to establish the relationship
between structure and physicochemical properties of novel macromolecules in
particular food applications where they may replace or complement the function of
their more established counterparts.
It was not our intention to cover all new developments appearing in the literature
as the list is a very extensive one, but to concentrate on a number of cases which
appear to be promising or are not covered in detail elsewhere. In the seventeen
chapters of this book the latest information on preparation methods, chemistry,
structure and functionality in-food systems of novel biopolymers or a number of
novel applications of traditionally utilized macromolecules, is featured. An emphasis
is placed, where possible, on fundamental biopolymer structure - function
relationships. The first chapter constitutes a brief introduction to the topic and sets
the stage for the following chapters which can be grouped into those dealing with
novel proteins and with novel polysaccharides. The next two chapters can be placed
at the interface between the two types of food biopolymers as they discuss the
properties and applications of novel Maillard-type protein- polysaccharide conjugates
and the use of proteins and polysaccharides in the development of novel textures
mimicing low fat spreads and soft cheeses. The final chapter deals with the legal
matters concerning biopolymers intended for food use.
Our sincere thanks are due to all the contributors for their effort and patience and
to the publishers for their trust and understanding during the course of this venture.
The Editors
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LIST OF CONTRIBUTORS
.W Arguelles-Monal, IMRE, Universidad de La Habana, La Habana 10400, Cuba.
C.I. Beristain, Institute ed Ciencias Basicas, Universidad Veracruzana, 91000,
Mexico.
C.G. Biliaderis, Department of Food Science and Technology, School of Agriculture,
Aristotle University of Thessaloniki, 54006, Thessaloniki.
G.A. Blekas, Laboratory of Food Chemistry and Technology, Department of
Chemistry, Aristotle University of Thessaloniki, GR 45 006, Thessaloniki, Greece.
E.E. Braudo, N.M. Emanuel Institute of Biochemical Physics, Russian Academy of
Sciences, 4 Kosygin st., Moscow, 117977, Russia.
I.S. Chronakis, Physical Chemistry, Center for Chemistry and Chemical Engineering,
Lund University S-22100 Lund, Sweden.
C.T. Cordle, Ross Products Division of Abbott Laboratories, 526 Cleveland Ave.,
Columbus, OH 43215, USA.
.G Doxastakis, Laboratory of Food Chemistry and Technology, Department of
Chemistry, Aristotle University of Thessaloniki, GR 45 006, Thessaloniki, Greece.
R.J. Gamvros, Nestle Hellas s.a., 4 Patroklou str., Marousi Athens, Greece.
F.M. Goycoolea, Centro de Investigacion en Alimentacion y Desarrollo, A.C. Apdo.
Postal 1735, Hermosillo, Sonora 83000, Mexico.
T.A. Grinberg, Institute of Microbiology and Virology, National Academy of
Sciences of Okraine, 451 Zabolotny st., 341 Kiev, 252627, Ukraine.
.G Harauz, Department of Molecular Biology and Genetics, University of Geulph,
Guelph, Ontario, NIG2WI Canada.
.I Higuera-Ciapara, Centro de Investigacion en Alimentacion y Desarrollo, A.C.
Apdo. Postal 1735, Hermossillo, Sonora 83000, Mexico.
M.S. Izydorczyk, Department of Food Science, University of Manitoba, Winnipeg,
Manitoba, R3T 2N2 Canada.
.Y Kakuda, Department of Food Science, Ontario Agricultural College, University of
Guelph, Guelph, Ontario, NIG 2WI, Canada.
.A Kato, Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi
University, Yamaguchi 753, Japan.
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.S Kasapis, Department of Food Science and Nutrition, College of Agriculture, Sultan
Qaboos University, P.O. Box ,43 A1-Khod 123, Sultanate of Oman.
.V Kiosseoglou, Laboratory of Food Chemistry and Technology, Department of
Chemistry, Aristotle University of Thessaloniki, GR 45 006, Thessaloniki, Greece.
M.I. Mahmoud, MIM Nutri-Tek Consulting, 2061 Cardington Ave., Columbus, OH
43229, U.S.A.
M.F. Marcone, Department of Food Science, Ontario Agricultural College,
University of Guelph, Guelph, Ontario, NIG 2WI, Canada.
.M Milas, Centre de Recherches sur les Macromol6cules V6g6tales (CERMAV-
CNRS), Joseph Fourier University, BP ,35 38041 Grenoble cedex ,9 France.
.K Nishinari, Department of Food and Nutrition, Faculty of Human Life Science,
Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-Ku, Osaka 558-8585, Japan.
.A Paraskevopoulou, Laboratory of Food Chemistry and Technology, Department of
Chemistry, Aristotle University of Thessaloniki, GR 45 006, Thessaloniki, Greece.
.R Pedroza-Islas, Departmento de Ingenierias, Universidad Iberoamericana, 01210
Mexico.
.C Peniche, Centro de Biomateriales, Universidad de La Habana, La Habana 01 400,
Cuba.
T.P. Pirog, Institute of Microbiology and Virology, National Academy of Sciences of
Okraine, 451 Zabolotny st., 341 Kiev, 252627, Ukraine.
.M Rinaudo, Centre de Recherches sur les Macromol6cules V6g6tales (CERMAV-
CNRS), Joseph Fourier University, BP ,35 38041 Grenoble cedex ,9 France
.K Vareltzis, Laboratory of Food Technology, Department of Food Hygiene and
Technology, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki,
GR 45 006, Thessaloniki, Greece.
E.J. Vernon-Carter, DIPH(IQ), Universidad Autonoma Metropolitana-Iztapalapa,
09340, Mexico.
P.J. Wilde, Institute of Food Research, Norwich Research Park, Norwich NR4 7UA,
United Kingdom.
R.Y. Yada, Department of Food Science, Ontario Agricultural College, University of
Guelph, Guelph, Ontario NIG 2WI, Canada.
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A Brief Introduction to Novel Food Macromolecules
G. Doxastakis and V. Kiosseoglou
Laboratory of Food Chemistry and Technology, Department of Chemistry, Aristotle
University of Thessaloniki, 54006, Greece.
Inovation in food production has a long history since for more than a hundred years new
food products and processes are developed continuously in the western world. This pace of
inovation has accelerated during the last two decades. The need to satisfy nutritional,
technological and quality requirements of the consumer are often stated as the driving forces
behind the pursuit of novelty, although competition between the food companies and profit
maximization must have certainly had a profound influence.
The development of new products would not have been possible without the application
of recent advances in biological and physical sciences. Biotechnology, in particular, has
immensely contributed towards the production of new foods and food ingredients and it may
have a dramatic influence on the way food is grown and processed in the future. There are
many who believe that it is the key to enhanced productivity, improved quality and nutrition
of food supply. As inovation, however, is accelerated, consumers are gradually becoming
suspicious of such technological changes which they feel are outside their control and
consider food biotechnology as something to be feared and tightly regulated. These
understandable consumer concerns have led international organizations, professional bodies
and governments to try to evolve guidelines and regulations in order to provide the consumer
the assurance he needs while at the same time not placing undue constraint on beneficial
inovation. The European Commission, for example, has recently proposed regulation
guidelines to cover the different new foods and food ingredients which are characterized as
"novel". This term, according to the proposal, should include all those products which have
not hitherto been used for human consumption within the Community to a significant degree
and which could be: a) foods and food ingredients produced from genetically modified
organisms, b) foods and food ingredients with a new or intentionally modified primary
molecular structure, c) foods and food ingredients consisting of or isolated from
microorganisms, d) new plants, animals or microbes, or new ingredients isolated from them,
which have not hitherto been used as food or which have been consumed in only small
amounts, and e) foods and food ingredients produced by or subjected to a new process which
may bring about significant changes in the structure, composition or nutritional value and
metabolism of the food and the food ingredient or introduce new contaminants.
The regulation guidelines proposed by the Commission aim to cover all new materials,
new products and modifications of processing methods that could expose the consumer to
food ingredients to which he has not up to now been subjected to a significant extent.
Therefore, they intend to assist the manufacturer in the preparation of adequate documentation
of data required to support a petition regarding a novel product and to design a range of tests
appropriate to each case and, furthermore, to provide guidance to European government
authorities in their job to assess the safety of novel foods and food ingredients. The concept
of novelty, therefore, is determined by what has not been hitherto consumed in significant
quantities and by the possibility of introducing toxic contaminants, antinutrients or other types
of hazard. In this context, a number of physical modifications such as denaturation of
proteins by heat or mechanical treatment or new presentations of commonly used ingredients
in product development, as is the case of low fat spreads and soft cheeses, should not be
considered as novel, since there is no real potential for introducing a hazard.
From the food scientist's point of view, however, such technologies are quite novel and an
understanding of the physicochemical changes behind such modifications is required in order
to control them in a favourable way. Irrespective, therefore, of the legal aspects and the
consumer concerns one cannot overlook the scientific side of the story regarding the
introduction of a new food or food ingredient or the application of a new technology. In this
respect a definition of novel food or ingredient should be a wider one and cover not only those
materials with unknown impact on the human diet but also all new food ingredients for which
basic understanding of their function in food is lacking or is scarce.
Food macromolecules, that is polysaccharides and proteins, are indispensable ingredients
of many natural and processed food materials thus determining their texture, stability and/or
nutritional value. It is common in regulatory practices throughout the world to separate the
"food ingredients" that are considered to provide nutrition from the "food additives" that
perform technological functions, and macromolecules are not an exception to that rule.
Generally speaking, the food technologist has at his disposal a rather limited number of
polysaccharides of plant or microbiological origin which, with the notable exception of starch,
are nutritionally inert and are, therefore, characterized as "additives". Traditional
polysaccharide applications often mimic in vivo functions in nature as is the gelation of pectic
acids by calcium binding which mimics the development of structure in the cell walls of
plants. Unlike polysaccharides, proteins are incorporated in foods not only for their
functional properties, which determine their texture, stability and organoleptic quality, but
also for their nutritional value. Thus, the use of milk proteins in cheese curd formation, egg
albumen and yolk in bakery products, and vegetable and meat proteins in sausages aid the
formation and stabilization of food structure and at the same time provide the human diet with
nutrients and energy. Thus, proteins may be characterized as "food ingredients".
Polysaccharides and proteins are used either alone or in composites, especially when the
creation of a new texture is required. A number of synergistic functions of traditional
macromolecules are employed in order to improve consumer choice and the quality of
available food products. The development of water continuous spreads and soft cheeses with
textural properties similar to those of traditional "full-fat" products, for example, is based on
the manipulation of the phase behaviour of polysaccharide and/or protein dispersions.
Traditionally used proteins, such as casein, whey proteins, gelatin and soy proteins and
polysaccharides, such as, alginate, starch or its derivatives and inulin can all be used to creme
novel structures resembling those of the established "full-fat" products but with a much lower
caloric content.
Although such technologies are useful in extending the use of established polysaccharides
and proteins, the modem food industry cannot overlook the promise presented by the new
macromolecules which may outperform the traditional ingredients and at the same time result
in the decrease in the cost of production since they may be plentiful and available at a low
price. Chitin, for example, is a waste product of the seafood industry and available, therefore,
in large quantities. Like cellulose it is insoluble, whereas the deacetylated product chitosan is
soluble in dilute acids. Structural similarities between cellulose and chitosan suggest potential
applications of chitosan as a thickening, bulking or gelling agent in food systems.
Furthermore, the chitosan molecule is negatively charged and this can be exploited in novel
applications involving chitosan-protein interactions. The development of foam stabilizers is
an example of chitosan-protein synergism. Konjac mannan, a natural polysaccharide used for
centuries in Japan, is another example of a novel macromolecule that possesses interesting
functional properties. Its use in the Western countries could present a useful alternative to
traditional polysaccharides.
Unlike proteins, natural polysaccharides do not exhibit surface activity with the notable
exception of gum arabic which can adsorb at oil/water interfaces and act as an emulsifier due
to the presence of a polypeptide chain in association with the polysaccharide. Since the
supply of gum arabic suffers from seasonal shortages and its price is increasing, potential
alternatives, such as mesquite gum an exudate of the mesquite (Prosopis) tree, could offer a
solution to the problem. Like gum arabic, mesquite gum possesses surface activity and
exhibits useful emulsifying properties because of the existence of a small protein moiety in
association with the polysaccharide chain.
However, the high cost involved, both in terms of time and money, in gaining approval to
use a new additive in food could be prohibitive. In addition to safety, licencing authorities
require evidence of need. In other words, the new additive has to be unique or outperform
materials already in use. It is not surprising, therefore, that although a number of new
polysaccharides have been identified in the last two decades, with bacteria providing the best
source, only very few of them to date gained approval for use in food. Gellan gum, a
microbial polysaccharide with unique gelling properties, represents such an example. It first
became known in the early 80's and was granted approval not very long ago. Although its
use in food is now permitted, it is still striving to find its place in the international market as a
replacer of traditionally used polysaccharides and, therefore, it may be considered as a novel
polysaccharide.
The situation with the novel proteins is rather different. For a start, unlike
polysaccharides which are composed entirely of one, two or three monosaccharides, protein
molecules are much more complicated consisting of about 20 different amino acids. The side
chain of each amino acid exhibits its own hydrophobicity and is capable of reacting with other
food constituents resulting in a dramatic alteration of the protein functionality. Thus, a wide
range of protein allows materials differing in molecular structure and functionality to become
available at a relatively low price. However, little is known about their three-dimentional
structure and structure- function relationships which constitute a major obstacle in their
optimum exploitation. Furthermore, while a number of chemically modified polysaccharides,
such as amidated pectins, propylene glycol alginate and microcrystalline cellulose, are well
established food additives, chemically modified proteins (e.g. by esterification or amidation of
the carboxyl group, acylation of amino groups, etc.) with enhanced functionality may never
obtain food clearance on the grounds of safety. The only chemical reaction permitted is the
hydrolysis of proteins into lower molecular weight fractions which may exhibit better
solubility or foaming ability than the original material.
A number of new protein materials originating from unexploited or underutilized sources
such as pea, lupin, cotton and tomato seeds, algae, fish etc. may present useful alternatives to
established proteins. Adequate processing methods are needed to eliminate antinutritive
factors or naturally occuring toxic substances in some of the raw materials, which may appear
in the isolated proteins. Futher problems, such as low digestibility (e.g. algal proteins) or the
development of unacceptable flavour as in the case of fish protein processing, have to be
addressed for the successful utilization of these unconventional sources.
A major obstacle which prevents the full exploitation of novel proteins is the lack of
fundamendal understanding of their structure-function relationships. This is a genetic
problem associated with the complicated physicochemical structure of both traditional and
novel proteins. Extensive research is, therefore, needed to unravel the structural properties of
novel proteins and to evaluate their performance as potential ingredients in food applications.
Depending on the food in question, a new protein should possess one or more of the following
properties: solubility, water retention capacity, emulsifying and foaming performance, and
coagulating and gelation ability. Even if these materials do not exhibit exceptional
functionality, as compared to their established competitors, a good case can be made for their
use as food ingredients. Thus, functionality should be weighted against the nutritive quality of
the material and the need to exploit the available sources of protein. The world population is
steadily increasing at a rate of approximately 90 million people per year and human diet of
about one-third of the developing world does not contain enough calories for an active life, a
problem that is faced even by people in the developed countries. Global hunger is not just a
problem of inadequate distribution of food, although it is certainly aggravated by this, and
will become even more serious in the future. The world can no longer afford to waste or
underutilize in the form of animal feed, huge amounts of protein on the grounds of limited
functionality. However, to achieve optimum use of these sources extensive research is needed
to investigate their properties either alone or in combinations with more established proteins
or polysaccharides.
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/ Dr. W.Junk Publisher, The Hange, Boston Lancaster, 1981.
3. I.S. Chronakis and .S Kasapis, Carbohydrate Polymers, 28 (1995) 367.
4. B. J. F. Hudson (ed.), New and Developing Sources of Food Proteins, Chapman
and Hall, London, N. York, 1994.
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.11 C. .S Penet, Food Techn. 45 (1991) 98.
.21 R. C. Righelato, Food Techn. Intern. Europe, (1991) 29.
.31 C. Robinson, Trends in Food Sci. Techn., 9 (1998) .38
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Lupin Seed Proteins
G. Doxastakis
Laboratory of Food Chemistry and Technology, Department of Chemistry
Aristotle University of Thessaloniki, Greece
.1 INTRODUCTION
Lupin belongs to the legume group of plants. Lupins are able to grow in marginal soils
and use less soluble forms of phosphorous and other earth minerals. This enables the crop to
grow in many environments and is widely cultivated throughout temperate climate zones in
both the Southern and the Northern hemispheres, ranging from Russia and Poland to the
Mediterranean countries and from Western Australia to Southem Chile and South Africa. 1 .
Lupins have been exploited by man since ancient times. The story has been retold recently
2. At the start of the christian time the white-flowering L. albus was well established in
Roman agriculture and had been cultivated in Greece for at least several centuries. The plant
may have been known in Egypt and Mesopotamia a long time before even that. The Greek
world for L. albus was thermos and other names for the plant throughout the Mediterranean
area appear to be derived from this: termis (Egypt), turmus (Arabic), altramuz (Spain),
turmusa (Aramaic). This may indicate that the plant was first cultivated as a crop in Greece.
Gross 3 studied the evolution of lupins in a biological - cultural perspective and found
evidence of the use of lupin in human and animal nutrition since the early days of human
history. He reported two different regions where lupin was first cultivated: the Andean
regions of Peru between the year 2000 and 1000 B.C. during the chavinoid culture period, and
in Egypt after 330 B.C.
Interest in a wider utilization of lupin seeds is mainly due to its similarity to soyabeans as
a high source of protein and to the fact that it can be grown in more temperate climates and is
tolerant of poor soils 4-6.
Lupin meal contains a high proportion of essential amino acids so it has good potential to
be a valuable crop both for its protein (35-40% w/w) and oil (11% w/w) content 7. Lupin
oil is an excellent source of unsaturated fatty acids (78% w/w), of which 25-30% w/w are
polyunsaturated 7,8. The polysaccharide lupin fractions are typically non-starch. Lupin
seeds contain significant amounts of oligosaccharides of the raffinose family 9.
The increasing interest in protein- rich plant seeds, such as lupins, for use in human and
animal nutrition also focuses attention on the substances known as antinutritional factors
(ANFs). The most important ANFs in legume seeds are protease inhibitors, lectins, tannins,
saponins and phytic acid (phytates) 10. Alkaloids are of particular concern in lupin seeds,
which otherwise offer promise as a rich source of protein. Many of the ANFs can be
eliminated or inactivated to a large degree by heating and processing during food preparation.
Wet milling and processing thechniques employed during protein concentration and isolation
are known to be effective in the detoxification of seed materials 11 .
The use of lupin products as a source of protein for humans will depend not only upon
their nutritional quality, but also on their ability to be used as, or incorporated into, foods
which will be readily consumed. So, the functional properties rather than the nutritional value
of proteins will largely determine their acceptability as ingredients in prepared foods 12-17.
Proteins from leguminous seeds have gained increasing importance as functional large-
capacity raw materials for the food industry 18,19. One of their important functions,
associated with emulsion stability, is their ability to adsorb at the oil-water interfaces, unfold
and stabilize the oil droplets by forming cohesive and mechanically strong interfacial films
which exhibit viscoelasticity 20-24. On the other hand, proteins play an important role in
the stabilization of foams by retarding liquid film drainage between bubble walls and
accumulating at the bubble surface to produce a viscoelastic adsorbed layer which protects the
film against rupture and prevents or retards Ostwald ripening 25. Difficulties in studying
the functional properties of vegetable proteins arise from the complexity and variability of
the system. In fact, the composition, conformation and structural rigidity of proteins vary
depending on the operating conditions of the process. On top of that, other constituents, such
as polysaccharides, phytin, etc., interact with protein during the isolation process and give
various functional properties to their products 24-29. This is due to the protein-
polysaccharide complexes which exist in lupin seed protein isolates (LSPI) and alter their
functional properties 14,30.
This chapter discusses the physicochemical and functional properties of lupin seed flour
and lupin protein concentrate and isolate with regard to their utility as novel ingredients in
high-quality, nutritious foods that may have high consumer acceptance.
2. COMPOSITION AND STRUCTURE
2.1 Biochemical composition
Among the common legume seeds, those containing high amounts of lipids can be
distinguished from those having starch as energy storage components. The former are mostly
found in Lupinae and Glycinae subfamilies, to which lupin and soybean species belong, while
the second group includes Viciae and Phaseolae, the pea and fababean species. Lupins, as
non-starch leguminous seeds, exhibit a biochemical composition closer to soybean, especially
characterized by a high protein content. Seeds of 54 varieties 6~L. luteus, .L albus and .L
angustifolius, grown at on site, contained 35-44, 31-35 and 30-38% protein respectively 31.
When nitrogen assays are used for the determination of "real" protein, it should be
remembered that for most legume seeds the conversion factor is close to 5.5-5.7 because of
the high degree of amidation of these proteins 32,33. For lupin the conversion factor is
close to 5.5.
Seed proteins can be subdivided into two categories, namely, the storage proteins, which
account for the major portion of the proteins, and the "housekeeping" proteins, which are
essential for the maintenance of normal cell metabolism. The storage protein fraction of seeds
contains relatively few different types of protein while the "housekeeping" protein fraction is
made up of relatively small amounts of numerous protein species.
Seed storage proteins may be defined as proteins accumulated in the developing seed
which on germination are rapidly hydrolysed to provide a source of reduced nitrogen for the
early stages of seedling growth 34. The major storage proteins of legumes and other
dicotyledonous plants are globulins (soluble in dilute salt solutions) and those of