A STUDY ON CONTENTS OF NITRATE, VITAMIN C AND CRUDE FIBRE IN SOME SPECIES OF HORTICULTURAL PLANTS, AND OF ORGANIC CONTAMINANTS IN ALGERIAN AROMATIC HERBS AND SPICES. A STATISTICAL ANALYSIS

This thesis consists of two parts. The Part I is dedicated to the study of contents of Nitrate, vitamin C and crude fibre in some species of horticultural plants; the Part II is dealing with the study of organic contaminants in Algerian aromatic herbs and spices. A statistical analysis is done. In Particular in the Part I a set of fresh horticultural plants, used in Mediterranean diet is considered. and a statistical analysis is done. The nitrate, the vitamin C and the crude fibre contents in these vegetables, measured in the laboratory, are taken into account and their frequency distributions, averages, variances and standard deviations are worked out, by statistical methods. Also some graphic representations are given. From the results it is shown the importance to follow a diet rich in vegetables in order to reach the recommended doses of vitamin C and crude fibre, to have health benefits, following the directives of nutrition national and international organizations. Vitamin C (or ascorbic acid) is a water soluble vitamin having nutraceutical properties. It is an important antioxidant widely present in vegetables and fruits with functions to prevent several diseases in the human organism. It strengthens the immune system and offers several benefits. Vitamin C contrasts the negative influence of nitrates, that combined with amines, present in food or derived from protein degradation processes, occurring in the stomach, can produce nitrosamines, that are acknowledged as carcinogens. Crude fibre refers to the indigestible carbohydrate component, present in plant cell walls, having a fibrous structure. Crude fibre is the measure of the quantity of indigestible cellulose, pentosan, lignin and other components of this type present in foods. It increases the bulk and speeds up the passage of food through the digestive tract, reducing the absorbtion of toxic substances. The nitrate contents, ingested by human organism by the consumption of the analyzed fruits and vegetables, does not constitute a risk for human health, when the assumption of these vegetables is limited, in agreement with the values recommended by the nutrition directives to prevent diseases. The Part II is dealing with a statistical analysis of the content of 119 organic contaminants in some aromatic herbs and spices, purchased in markets of some Algerian cities. These aromatic herbs and spices are very important in the economy of Mediterranean countries for their production, export and import. Algeria is one of the major producers and exporters in UE market. From the measured values of the contents of the analyzed contaminants (ng/g), illustrated in Tables and by graphic representations, it is seen that this content (ng/g), ingested by human organism by the consumption of the analyzed herbs and species do not constitute a risk for the human health, when its assumption is limited, in agreement with the values recommended by the directives of international and national nutrition organizations. Aromatic herbs and spices are employed in several sectors like 7 medical sciences, cosmetics, and culinary science. Furthermore, they are anti inflammatory, anticancer, antimicrobial. The organization of this thesis is the following. In the Chapter I we introduce a statistical variable, illustrating the measured nitrate contents in 26 fresh horticultural plants, working out its frequency distribution, its average, variance and standard deviation with some statistical graphic representations. Furthermore, the acceptable daily intake (ADI) of nitrate content of each fresh edible plant per 60 kg of body weight is calculated, discussing the results and the recommendations, given by international and national nutrition organizations. In the Chapter II the Mediterranean diet is introduced, emphasizing the motivations that have pushed the promotion of this diet in preventing diseases. To this aim the contents of vitamin C and crude fibre in the horticultural plants, considered in Chapter I, are examined as two statistical variables, of which, knowing the frequency distribution, applying statistical methodologies, the average value and the standard deviation are calculated. The benefits of consuming vegetables containing vitamin C and crude fibre are discussed, according to the Mediterranean diet and the national and international nutritional guidelines. The Chapter III is addressed to present the materials and methods used in order to analyze the samples of aromatic herbs and spices, purchased in different Algerian cities. In Chapters IV, V and VI the results, organized in Tables and Figures for the measured residues of organic contaminants (ng/g) in samples of aromatic herbs and spices purchased in the markets of Algerian cities Oran and Tlemcen, Constantine and Annaba, Algeri and Bijayad are worked out. The obtained results are discussed and it is seen that the values of the measured contaminants contents (ng/g) do not constitute a risk for the human health because their values do not exceed the maximum levels (MLs) permitted by the directives of international and national nutritional organizations. Finally, the Appendix A deals with the organic contaminants and their chemical classes, analyzed in the aromatic herbs and spices taken into account.