Project Topics
Get Complete Project Material File(s) Now! »
Wheat Consumption and end use.
Two thirds of the wheat production (Table 2) is used directly in products for human consumption and the rest is used as an ingredient in compound feedstuffs, starch production and as a feed stock in ethanol production. Since the beginning of the 21th century, wheat production and consumption have increased considerably, with an exception for the year 2006/2007 as the result of the drought in major producing countries.
Common wheat (Triticum. aestivum) which is better known as hard wheat or soft wheat, depending on grain hardness, represents more than 90% of total wheat production. The flour milling industry is the main consumer of common wheat. Wheat flour obtained from the milling of these grains is used in the baking and confectionary industries and for home cooking. Because of its quality, attributes, particularly its very hard endosperm and high yellow pigment concentration, durum wheat is used to produce semolina which is the main raw material of pasta making. Some durum wheat is also milled into flour or into coarse durum grain grits to respectively manufacture medium-dense breads or produce couscous. Many importing nations have specific requirement concerning the qualities of the wheat they would like to import. For this trading purpose, different categories have been introduced such as grain hardness (soft, medium or hard) and color (red, white and amber). These categories are also subdivided into classes based on growing habit (spring or winter). For example, wheat in the USA is divided into eight classes: hard red spring wheat, hard red winter wheat, soft red winter wheat, durum wheat, hard white wheat, soft white wheat, un-classed wheat and mixed wheat. In addition, hard red spring wheat, durum wheat and soft white wheat classes are further divided into subclasses (USDA, Grain inspection handbook, Wheat, 2014, accessed via the website at http://www. gipsa.usda.gov/fgis/handbook/grain-insp/grbook2/wheat.pdf). Another important criteria used in wheat trade is grain grading which assures that a particular wheat stock meets the required set standards customers.
Wheat like other cereals are graded based on test weight, moisture content, maximal percentage damaged and foreign materials. Grain protein content and alpha-amylase activity (enzymatic activity associated with the germination of the grain) are also frequently considered as grading factors in wheat trading. These factors are important in evaluating the end-uses of wheat and can be tested rapidly upon reception of the wheat stock. Grain lots presenting important levels of amylase-activity may be totally rejected as a food item because these lots may present degraded starch within the kernel which would have a detrimental impact on the baking potential of flour obtained with such grain. Grade-determining factors constitute an effective means for describing wheat for marketing purposes.
Wheat consumption
Despite its use in the form of baked good for human consumption, wheat is also used as an ingredient for feeding animals and poultry. In 2011, 142 million tons (21 % of worldwide production) (Table 2) were used to feed animals. This proportion is higher in industrialized countries: in EU-27, 41% of wheat production was used as feed (FAO, 2011). Feed wheat is often surplus to human requirements or low-quality wheat unsuitable for the human consumption (low test weight or damaged wheat) but wheat is also grown for feed purposes (Lalman et al., 2011). Indeed, wheat grain has long been recognized as an excellent energy feed resource for livestock. However, the inclusion of wheat grain in feed depends on the relative market prices of the major feed grains. During periods when maize, barley or sorghum are expensive or when wheat market is depressed, wheat can be used as an economical feed source for beef cattle (Lalman et al., 2011). In recent years, the biofuels industry has been using wheat as the primary feedstock for ethanol production. The wheat used is generally downgraded wheat damaged by frost, disease or rains. According to Statista estimates, approximately 9 million tons of wheat were used for ethanol production in 2014, double the amount used in 2010 (Statista, 2014, accessed via the website at http://www.statista.com/statistics/202229/wheat-for-eu-ethanol-production-from-2010).
Currently, among different cereal crops, ethanol production from maize and rice has the highest yields (table 3). In the UE, wheat is the main feedstock for bioethanol plants whereas in the US the primary feedstock is maize.
Wheat is the leading source of vegetable protein in human food, having a higher protein content than other major cereals such maize or rice. Common wheat is used in bread (leavened, flat and steamed), noodles, biscuits and cakes. Leavened breads which are popular in almost all parts of the world are made using hard to medium-hard wheat classes. Pastries, cookies or cake are made with soft wheat flours. The noodle is a staple food widely consumed in northern China and made from unleavened dough which is rolled flat and cut into a variety of shapes. The demand for instant noodles (fried and steam precooked) is increasing in the western hemisphere (World instant noodles association, 2014). Medium to medium-soft wheat grain hardness is preferred for Asian noodle (table 4). Durum wheat is used globally in alimentary pasta and regional foods (flat breads, couscous and bulgur) in North Africa and West Asia (Peña et al., 2008). Because of the awareness of a healthy lifestyle is increasing, more consumers in developed countries are willing for more nutritious wheat based food products with less fat or simple carbohydrate and enhanced benefic compounds such as vitamins or fiber. In order to assess this requirement, new wheat products like bread prepared with whole wheat flour, with multigrain flours or other functional ingredients have emerged from the bakery industry (Dewettinck et al., 2008).
Genetics, wheat genetic improvement and wheat grain quality 3.1. Genetics and Wheat genetic improvement
Wheat genetics is more complicated than that of most other domesticated species. The genus name for wheat, Triticum, comes from the Latin, tero (I thresh). The current binomial name, Triticum aestivum, refers to hexaploid (2n = 6x = 42 ) bread wheat (genomes A, B, D), distinguishing it from tetraploid (2n = 4x = 28) durum wheat (Triticum durum) (genome A and B) which is used primarily for pasta production. The ancestral diploid wheat species are T.monococcum, Aegilops speltoides, and T. tauschii and a wild Aegilops species that is probably most closely related to the modern Ae. Speltoides (Khlestkina and Salina, 2001). Each of these have seven pairs of chromosomes (2n = 2x = 14). Tetraploids forms of current domesticated wheat are derived from a wild tetraploid progenitor, identified as the wild emmer Triticum turgidum ssp. Dicoccoides. This species has an allotetraploid genome (AABB) resulting from spontaneous amphidiploidization between the diploid wild wheat Triticum urartu (AA genome, (Dvorak et al., 1998) and an unidentified diploid Aegilops species (BB genome). Around 9,000 BP a cultivated emmer (T. dicoccum, genome AABB) spontaneously hybridized with another goat grass (Ae. Tauschii, genome DD) to produce an early spelt (T. spelta, genome AABBDD) (Dvorak et al., 1998; Matsuoka and Nasuda, 2004). About 8,500 BP, natural mutation changed the ears of both emmer and spelt to a more easily threshed type that later evolved into the free-threshing ears of durum wheat (T. durum) and bread wheat (T. aestivum) (figure 6) (Peng et al., 2011). However, recent experimental evidence suggests that T. spelta is not the ancestral form of free-threshing common wheat (Dvorak et al, 2006). Apparently the sources of cultivated wheat ancestry are complicated by multiple factors including gene flow from wild cereals (Dvorak et al, 2011).
Complex traits such as yield, grain quality, disease, pest resistance and abiotic stress tolerance are controlled by specific genes that are distributed along wheat chromosomes. The A, B and Ae.tauschii (D) genomes have been estimated to contain approximately 28,000 (Choulet et al., 2010), 38,000 (Hernandez et al, 2012) and 36,371 (Massa et al., 2011) genes respectively. Recently Brenshley et al. (2012) estimated the number of genes in the hexaploid wheat genome to range between 94,000 and 96,000. In 2014, Choulet et al. produced the first reference sequence of the bread wheat chromosome 3B. Based on this success and methodology, the international wheat genome sequencing consortium (IWGSC), aims to finish sequencing the twenty other chromosomes within three years.
The major improvement during the last years, in wheat genomics and the sequencing through the development of specific bioinformatic tools and the used of thousands of molecular markers, are the achievement of continuous efforts initiated in the early 1950’s. Development of biotechnology tools to accelerate the process of selecting parent lines that carry the desirable genetic materials for specific traits are essential, as it allows the appropriate selection at an early stage of selection process and thus avoid the need for ongoing propagation of undesirable lines. Simply inherited traits are selected early. Other traits such as yield and grain quality that involve many genes have traditionally been part of the mid- to late-generation selection schedule and are largely determined on the basis of actual phenotype.
Marker-assisted selection (MAS)
Plant molecular breeding is the applications of molecular biology or biotechnology to improve or develop new cultivars, which includes two major approaches, MAS and genetic transformation (Moose and Mumm, 2008). MAS is an indirect selection process whereby a marker (morphological, biochemical or DNA-based or molecular) linked to the trait of interest (disease resistance, productivity, abiotic stress tolerance and quality), is selected instead of the trait itself. Plant molecular breeding has advanced so rapidly that several types of molecular markers have been developed and used for decades. The very first genome map in plants was reported in maize (Helentjaris et al., 1986) using restriction fragment length polymorphism (RFLP). However, these markers utility has been hampered due to the requirement of radioactive isotope, time consuming of the technique and because of their inability to detect single base changes. With further advance of biotechnology, several types of polymerase chain reaction (PCR)-base markers were developed and used in plant breeding programs. These markers include, random amplification of polymorphic DNA (RAPD), sequence characterized amplified region (SCAR), cleaved amplified polymorphic sequences (CAPS), single sequence repeats (SSR), amplified fragment length polymorphisms (AFLP), direct amplification of length polymorphisms (DALP), single nucleotide polymorphisms (SNP) and diversity array technology (DarT). It has to be mentioned that the success of MAS require very tight linkages between markers and the trait.
Traits such as yield or baking quality are quantitative traits that depend on the cumulative actions of many genes and the environment. For breeders, it is important to detect in the selection process the lines which performed best for the traits of interest. Thus, it is assumed that those lines have a combination of alleles most favorable for the fullest expression of the quantitative traits. Another way to state this point is that the breeder would like to identify as early as possible those lines which contain those quantitative trait locus (QTL) alleles that contribute to a high value of the trait under selection. QTL analysis is predicated on looking for associations between the quantitative trait and the marker alleles segregating in the population (Kearsey and Farquhar, 1998). The other use of QTL is to identify candidate genes underlying a trait. Once a region of DNA has been identified as contributing to a phenotype, it can be sequenced. However, accurate QTL localization can be problematic as in the traditional QTL approach only recombination from the bi-parental cross are considered (Bordes et al., 2010). Lately, association mapping based on the concept of linkage disequilibrium, has proven to be an efficient strategy to decipher the genetic basis of complex traits (Ingvarsson and Street, 2010). Using a core collection of 372 bread wheat accessions for association analysis of flour and dough quality traits, Bordes et al. (2010) have shown that out of 803 markers tested, 130 markers were associated with at least one trait studied. Association mapping was also successfully used by Plessis et al. (2013) to identify 74 loci associated with wheat grain storage protein content and composition and allometric scaling parameters of grain nitrogen allocation.
Wheat grain quality
In order to satisfy the increasing global demand and consumption of agricultural crops for food, particularly of wheat, researches on the improvement of yield potential of new wheat varieties have to be performed (Edgerton, 2009). Nevertheless, increasing yield potential without affecting negatively the quality of the grain is difficult, mainly because increases in grain yield are generally accompanied by a decrease in the grain’s protein content, which is strongly associated with bread-making quality (Peña, 2002). Therefore, wheat breeders need to give grain quality aspects the same importance that they give to yield potential and diseases resistance.
Table of contents :
Chapter 1 : Literature review
1. Position of Europe and France in the world’s wheat production
2. Wheat Consumption and end use
Wheat type and Classes
Wheat consumption
End-uses
3. Genetics, wheat genetic improvement and wheat grain quality
3.1 Genetics and Wheat genetic improvement
Marker-assisted selection (MAS)
3.2 Wheat grain quality
Grain hardness
Starch
Proteins
4. Wheat grain : Development, structure and constituents
4.1 Grain development
4.1.1 Growth stages from Germination through Maturation
4.1.2 Endosperm development
4.2 General structure and major chemical components of wheat grain
4.2.1 Wheat grain structure
4.2.2 Major chemical components of wheat grain
Macronutrients
Micronutrients
4.3 Vitamins
4.3.1 Definition and classification of vitamins
4.3.2 Thiamin (Vitamin B1)
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by Thiamin deficiency
4.3.3 Riboflavin (Vitamin B2)
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by Riboflavin deficiency
4.3.4 Niacin (Vitamin B3)
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by Niacin deficiency
4.3.5 Pantothenic acid (Vitamin B5)
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by Pantothenic acid deficiency
4.3.6 Pyridoxine (Vitamin B6)
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by Pyridoxine deficiency
4.3.7 Vitamin A and Carotenoids
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by vitamin A deficiency
4.3.8 Vitamin E
Chemical properties and biochemical functions
Biosynthesis
Dietary sources and bioavailability
Syndromes caused by vitamin E deficiency
5. Approach to improve wheat vitamin content
5.1 Influence of growing conditions, genetic and processing on nutritive value
5.1.1 Growing conditions
5.1.2 Grain selection and genetic approach
5.1.3 Influence of processing
Fractionation processes
Breadmaking
5.2 Analytical methods for the determination of water-soluble and fat-soluble vitamins and carotenoids
5.2.1 The Water-soluble vitamins
Extraction methods
Methods of analysis
5.2.2 The Fat-soluble vitamins and carotenoids
Extraction methods
Methods of analysis
References
Chapter 2 : Aims
Chapter 3 : Methodologies
1. Development of a LC-MS/MS method for the simultaneous screening of 7 water-soluble vitamins in processing semi-coarse wheat flour products
2. Change in B and Fat-soluble vitamin contents in industrial milling fractions and during toasted bread production
3. Effects of environment and variety on B and Fat-soluble vitamin contents in a worldwide bread wheat core collection and association study
Chapter 4 : Development of a LC-MS/MS method for the simultaneous screening of 7 water-soluble vitamins in processing semi-coarse wheat flour products (Publication n°1)
1. Introduction
2. Results and Discussion
3. Conclusion
4. References
Chapter 5 : Change in B and E vitamin and Lutein, β-sitosterol contents in industrial milling fractions and during toasted bread production (Publication n°2)
1. Introduction
2. Results and Discussion
3. Conclusion
4. References
Chapter 6 : Effects of environment and variety on B and E vitamin and Lutein, β-sitosterol contents and quality traits in 195 bread wheats in a worldwide core collection (Publication n°3)
1. Introduction
2. Results and Discussion
3. Conclusion
4. References
Chapter 7 : Association study for the B and E vitamin and Lutein, β-sitosterol contents of flour in a worldwide bread wheat core collection (Publication n° 4)
1. Introduction
2. Results and Discussion
3. Conclusion
4. References
Chapter 8 : Conclusion and Perspectives
1. Evaluation of the developed analytical method
1.1 General conclusion
1.2 Perspectives about improving techniques
2. Evaluation of food processing on vitamin contents and bioavailability
2.1 General conclusion
2.1 Perspectives about grain processing
3. Evaluation of the core collection in term of agronomic and nutritional traits
3.1 General conclusion
3.2 Genetic and agronomic perspectives
4. Evaluation of the core collection for association analysis of nutritional traits
4.1 General conclusion and perspective
5. Conclusion
