Approximate composition analysis and nutritive values of different varieties of edible seeds

Abstract

Saad, et al.: Approximate composition analysis and nutritive values of edible seeds 102 Asian Journal of Medical Sciences | Jun 2021 | Vol 12 | Issue 6 important role in human metabolism, and the interest in these elements is the relationships between trace element status and oxidative diseases.3 The differences in mineral composition in corn products may be due to genetic factor and environmental factors like irrigation frequency, soil composition and fertilizer used.4 Legumes are known as an excellent source of dietary protein. While the proteins present in legumes are not considered “complete”, as compared to most animalderived proteins, when combined with foods such as whole grains (e.g., whole grain bread), a balanced intake of essential amino acids can be easily achieved.5,6 Sunflower seeds are a nutrient dense food has been found to have a potential role in chronic inflammatory conditions, bacterial and fungal infections, cardiovascular diseases, skin diseases and even cancers. These benefits of sunflower seeds are attributed to the presence of phytosterols, unsaturated fatty acids, proteins, variety of vitamins and minerals.7 Pumpkin seed and seed oil are a rich natural source of phytosterols, Proteins, polyunsaturated fatty acids, antioxidant vitamins, carotenoids and tocopherols and various elements.8-10 In 2000, a study was done by Pari and et al., found that important plant foods in select traditional diet of indigenous communities such as maize, pumpkin, and beans have moderate to high phenolic phytochemicals. A combination of these plant foods can be targeted for management of hyperglycemia and hypertension associated with NIDDM.11 In addition, Chickpeas also have a low glycemic index.12,13 When consumed long term, chickpea intake also significantly improved glycemic control in a 20-week crossover study of 45 individuals with elevated cardiovascular disease (CVD) risk factors.13 In recent years, several studies have highlighted the health properties of pumpkin seed oil against many diseases, including hypertension, diabetes, and cancer.14,15 The plant kingdom has proven to be the most useful in the treatment of diseases and they provide an important source of all the world’s pharmaceuticals.16 Antibacterial efficacy of sunflower seeds has been highlighted in clinical study by Bashir M et al., (2004) that was conducted in Egypt based on topically applied sunflower seed oil to prevent invasive bacterial infections in preterm infants (<34 weeks gestational age). Their study indicated that topical application of sunflower seed oil 3 times a day resulted in a significant improvement in skin condition and a highly significant reduction in the incidence of nosocomial infections compared with infants not receiving topical prophylaxis. No adverse effects were reported as a result of topical therapy.17 The previous evidences about the health effects of seeds consumption give direction abovementioned to carry out this experimental study about the nutritive values of different varieties of edible seeds. Nevertheless, our study is the first of its kind in Benghazi as no other study have reported from this region, where the study was designed to elucidate the nutritive values of different varieties of edible seeds. The aim of our study was to select 5 types of most popular seeds (corn, sunflower seeds, watermelon seeds, pumpkin seeds and chickpeas) which were usually consumed by the locals due to common preference and economic price, as well as the high availability throughout the year in order to determine the approximate composition and nutritive values of edible portions of different varieties of popular seeds and analyze the heavy metals contents. MATERIALS AND METHODS Determination of moisture Moisture was determined by A.O.A.C method by weighing accurately about 5 gm of sample in a previously dried and tarred dish and placed the dish with its lid underneath in the oven for 2 hours. The time should be reckoned from the moment the oven attains 100o C after the dishes have been placed. Then the dishes were removed after 4 hours, cooled in the desiccator and weighed. Determination of total ash Ashing of food samples was done using a muffle furnace. Ash was determined by A.O.A.C method. Two grams of each sample were placed in a crucible and heated to 550°C in muffle furnace to eliminate organic components. The crucible and its contents were then cooled and weighed, and the ash evaluated as a proportion of the original dry weight of samples. Determination of crude fat Crude fat content was determined by extracting the fat from the sample using a solvent extraction, then determining the weight of the fat recovered. The solvent extraction method is more pronouncedly known as Soxhlet method. Generally, the basic of Soxhlet method is extraction of a lipid from a solid material. Lipid of food is soluble in organic solvent and insoluble in water, because of this, organic solvents like petroleum ether; which has been used in this procedure; has the ability to solubilize fat then fat was extracted from food in combination with the solvent. Later the fat was collected by evaporating the solvent. Almost all the solvent is distilled off and can be reused. Approximately 2.0 gram of samples were weighed accurately into extraction thimbles. The dried boiling receiving flask was weighed correspondingly and filled with about 300 ml of petroleum ether at boiling point 40-60°C. After that, the soxhlet apparatus was assembled and allowed to reflux for 6 hours. The thimble was removed with care and petroleum ether collected from the top container and drained into Saad, et al.: Approximate composition analysis and nutritive values of edible seeds Asian Journal of Medical Sciences | Jun 2021 | Vol 12 | Issue 6 103 another container for re-use. After that, the flask was dried at (105-110co) for one hour, when it was almost free of petroleum ether, it was cooled in a desiccator and weighed. Determination of crude protein The crude protein content of the seeds samples was determined using the Kjeldahl method of AOAC. The principle of Kjeldahl method is digestion sample of seeds with a strong acid so that it releases nitrogen which can be determined by a suitable titration technique. The amount of protein present is then calculated from the nitrogen concentration of the food. Digestion, Neutralization and Titration are the basics steps to determine crude proteins. Firstly, two grams of seeds sample had been weighed into a digestion flask and then digested by heating it in the presence of sulfuric acid (an oxidizing agent which digests the food), anhydrous sodium sulfate (to speed up the reaction by raising the boiling point) and a catalyst, such as copper sulphate (to speed up the reaction). Digestion converts any nitrogen in the food into ammonia, and other organic matter to C02 and H20. Ammonia gas is not liberated in an acid solution because the ammonia is in the form of the ammonium ion (NH4 +) which binds to the sulfate ion (SO4 2-) and thus remains in solution: N(food) → (NH4)2SO4. Secondly, Neutralization after the digestion has been completed the digestion flask is connected to a receiving flask by a tube. The solution in the digestion flask is then made alkaline by addition of sodium hydroxide, which converts the ammonium sulfate into ammonia gas:(NH4)2SO4 + 2 NaOH ® 2NH3 + 2H2O + Na2SO4. The ammonia gas that is formed is liberated from the solution and moves out of the digestion flask and into the receiving flask which contains an excess of boric acid. The low pH of the solution in the receiving flask converts the ammonia gas into the ammonium ion, and simultaneously converts the boric acid to the borate ion: NH3 + H3BO3 (boric acid) → NH4 + + H2BO3 (borate ion). Finally, Titration: The nitrogen content is then estimated by titration of the ammonium borate formed with standard sulfuric or hydrochloric acid, using a suitable indicator to determine the end-point of the reaction. Determination of mineral in foods by atomic absorption, spectrophotometer Atomic absorption spectroscopy (AAS) determines the concentrations of minerals in samples. It is a process involving the absorption by free atoms of an element of light at a wavelength specific to that element. At first sample solution is aspirated into the spray chamber through capillary tube. The liquid sample is aerolized and mixed concentration. nitric acid, about 1g of sample has weighted mixed with 10ml of concentration. nitric in the spray chamber and burned in a flame and the individual atoms of the sample are released to form a cloud inside the flame. The atoms of the element get free. To bring it from ground state into an excited state by passing UV light is required through hollow cathode lamp. On absorbing UV light at specific wavelengths, the ground state metal atoms get transitioned to higher electronic state. The region of the spectrum to be measured is selected by a monochromator. The isolated spectral line falls on the photomultiplier, the detector and the output are amplified and sent to a readout device meter, digital or analogue or through a computer data processing system. The data is processed through software.