Dissertation for obtaining a Master's degree ((M.Sc))
Major: Food Chemistry
Persian summary
Iran is the main habitat of walnut. Iranian walnut is an economically important species and has a lot of nutritional value. In this research, random walnut samples were collected from 100 walnut trees in two areas of Baghstan located in Tehran province and Erengeh located in Alborz province in Mehr 2013. Also, according to Iranian Standard No. 18, correct walnut kernels were used, and since different geographical conditions have a significant effect on the nutritional quality of the fruit of the plant, 15 soil samples from two depths of 0-30 and 30-60 cm was randomly or zigzag removed from the soil of the two mentioned areas. Instantaneous or discontinuous sampling method was used for water sampling in both studied areas. Analyzes were performed according to international standard protocols. Dry digestion method was used to determine the concentration of calcium and potassium and wet digestion method was used to determine the concentration of iron, zinc and copper for both walnut and soil samples, and the analysis was measured by flame atomic spectrometry. Gas chromatography was also used to determine the amount and type of fatty acids. The results obtained from this research showed that the difference in the nutritive value of walnuts in two regions depends on the soil ecology of those regions. It was also found that the walnut kernels of the two studied regions had significant differences in terms of fatty acids, protein, crude fiber, and mineral elements calcium, potassium, and zinc, so that the content of oleic acid, protein, calcium, potassium, and zinc in Erenge walnut kernels was significantly (P<0.05) higher than Baghistan samples, and the palmitic acid and crude fiber content in Baghistan walnut kernel samples was significantly (P<0.05) higher than Erenge samples. On the other hand, the content of oil and fatty acids, protein, calcium and iron in walnut kernels from two regions and copper and zinc in Erenge walnut kernels showed a higher level than the USDA standard. Key words: walnut kernels, nutritional value, mineral elements, atomic spectrometer.
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Introduction
Walnuts are about 50 species, among which the genus juglans with 21 species is the most important plant of this family. Walnut is one of the native trees of Iran, and Persian walnut is considered the most important type of walnut in terms of food and economic value. On the other hand, walnut is one of the garden products that has a high domestic consumption and a significant position in the world markets. Iran has suitable conditions for walnut cultivation and walnuts are grown in most regions of the country. According to the statistics of the World Food Organization (FAO) in 2012, the global production of this product was more than 3 million tons, and among the producing countries, Iran ranks second after China with a production of 450,000 tons. According to the statistics of the Information Technology Center of the Ministry of Agricultural Jihad during the solar years 1367 to 1387 Hijri, the annual growth of the area under walnut cultivation in Iran was on average more than 9 thousand hectares per year. Therefore, during the mentioned years, the cultivated area of ??this crop in the country has grown a lot and has reached from less than 10 thousand hectares in the 60s to more than 200 thousand hectares in 2017. Among the ten major walnut producing provinces, Tehran province ranks sixth with a cultivated area of ??823,222 hectares and a production rate of 290 tons. The high nutritional value of walnuts and having the highest amount of omega-3 fatty acids among other plant foods make this product unique. Also, with the increasing number of cardiovascular diseases, the world's attention to this product has increased, which is due to the presence of polyunsaturated fatty acids in walnuts, which reduce the risk of chronic heart disease due to the reduction of total and LDL cholesterol and the increase of HDL cholesterol, in such a way that most countries make serious planning and sufficient investment to plant and exploit the product.So that walnut kernels have a special place in Iranian foods and desserts. The widely used role of walnut can be seen in traditional Iranian dishes such as Fasanjan and sweets and traditional desserts such as baklava, qatab and walnut bread. We have chosen this valuable food item due to its extraordinary nutritional value and the importance of its consumption in Iran.
Chapter One
Generalities
1-1 The purpose of the thesis
Walnuts have many nutrients. which include protein, essential cherry acids, fiber and minerals such as iron, copper, zinc, calcium and potassium. Fats are the main source of energy and the source of essential fatty acids in the body. Protein and minerals are essential substances for the body and are used for all biochemical activities such as the production of enzymes, hormones, and energy. Walnuts, having essential fatty acids, minerals, protein, and fiber, are considered a valuable food for the body. According to the above, achieving high quality and nutritional value in walnuts is of great importance. Geographical conditions, such as ambient temperature, weather and soil fertility, have a significant effect on the amount and nutritional quality of plant fruit. Soil is the most important factor affecting the nutritional value of fruit. Because minerals and other nutrients are absorbed directly by the plant roots. Therefore, the high nutrient reserves of the soil can have a direct effect on the nutritional value of the fruit of the plant. Iran has different geographical conditions and the favorable conditions have led to the growth of different plant species with different nutritional values. Evaluation and comparison of nutrients such as protein, fiber, fatty acids and minerals in walnuts of different regions with different geographical conditions and comparing it with international standards can provide suitable solutions to improve the quality of walnut kernels. Therefore, the purpose of this thesis is to evaluate the comparison of the amounts of protein fatty acids, to compare the amounts of protein fatty acids, crude fiber and five mineral elements in walnut kernels planted in two regions of Tehran and Karaj with different geographical conditions and to compare it with international standards. It belongs to Juglandaceae, which includes 21 species [63]. It is an important and multipurpose tree, as it is used in horticulture for its fruit, in forestry for its valuable wood, and in medicine as a medicinal plant [27]. Iranian walnuts are the only species that are widely suitable for walnut production. It also has the highest commercial and economic value [60]. In the plateau of Iran, walnut is found in the latitudes of 29 to 39 degrees north and longitudes of 45 to 64 degrees east, from low-altitude lands with a height of 2500 meters, domesticated or wild in the north, west and center of Iran [45]. Nutritionally, walnut kernels are very nutritious and their composition varies depending on the variety [52]. Walnuts are rich in valuable minerals such as phosphorus, potassium, sodium, calcium, magnesium and essential elements such as iron, copper, and zinc [67]. Minerals play an important role in human health. They are effective in the formation of the structure of bones and teeth, as well as helping to maintain the natural rhythm of the heart, muscle contraction, nerve conduction and acid-base balance, and regulating body metabolism by becoming a part of enzymes and hormones, and therefore they are important in the body [67]. Iron is an essential element that exists in hemoglobin, myoglobin, and a large number of enzymes, so it is considered an essential mineral in the daily diet. Zinc is also an essential component of some metabolic enzymes, and apart from its important role in their structure, it also affects their function [67].