EVALUATION OF IRON, FOLIC ACID AND MACRO-NUTRIENTS CONTENT OF DRIED AND FRESH SPINACH
Dry and fresh spinach (Spinacia oleracea L.) is considered to be one of the extremely nutritious vegetables, rich both in phytochemicals and core nutrients. Nowadays, phytochemicals in plants are raising interest in consumers for their roles in the maintenance of human health.
Variation in the content of bioactive compounds and core nutrients is the main concern in vegetable production. Factors such as cultural practices especially fertilization may affect the nutritional and medicinal properties of the plants.
Therefore, three parallel trials for NPK to investigate the response of dry and fresh spinach leaves to nitrogen (N), phosphorus (P) and potassium (K) on chemical composition were conducted, with treatments arranged as follows: 0, 45, 75, 105, 120 kg·ha-1 N and P and 0, 60, 85, 106, 127, 148 kg·ha-1 K in a randomized complete block design (RCBD) with four replications… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
Background of Study
Spinach is a leafy and extremely nutritious vegetable, rich both in core nutrients and phytochemicals. It is a vegetable that is provided fresh, frozen, or canned to the consumer. Spinach harvested after a shorter growth period than normal is called dry and fresh spinach and is marketed fresh to the consumer. This is a fairly new product that has turned out to be popular in recent years because of its nutritional value (Hedges and Lister, 2007).
Its nutrients comprise a range of vitamins and minerals, as well as phytochemicals. The major micronutrients in spinach are vitamins A (from β-carotene), C, K and folate, and the minerals, calcium, iron, and potassium. The phytochemicals of most importance are the carotenoids, flavonoids, β-carotene, lutein, and zeaxanthin and phenolic compounds (Bergquist, 2006).
A number of studies have shown spinach to have strong antioxidant activity and high levels of antioxidant compounds such as phenolics and carotenoids (Hedges and Lister, 2007)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
Spinach is an important agricultural crop, not only because of its economic importance but also for the nutritional values of its leaves, mainly due to the fact that they are an excellent source of nutrients and phytochemicals.
Spinach is increasingly becoming important in health because of its micronutrients and phytochemicals. It has an additional advantage of being low in calories, which is very important in weight management. Therefore, it is becoming the food of choice for many people because of its nutritional importance.
Nowadays, phytochemicals and antioxidants in plants are raising interest in consumers for their roles in maintaining human health. Phenolics and flavonoids are known for their health-promoting properties due to protective effects against cardiovascular disease, cancers, and other diseases (Kaur and Kapoor, 2001; Sardas, 2003)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
To determine the effect of different rates/levels of application of N, P, and K fertilizers on chemical composition and minerals in dry and fresh spinach… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
LITERATURE REVIEW ON MINERAL NUTRITION AND QUALITY OF DRY AND FRESH SPINACH
The History and Botany Dry and Fresh Spinach:
- Origin and Distribution
Spinach originates from central and south-western Asia (Boswell, 2010). It is thought that it was first cultivated in ancient Persia (Iran) and eventually into Africa. From there it spread to Europe and now it is widely grown all over the world. (Asai et al., 2004; Boswell, 2010). It was probably introduced into Europe during the Middle Ages; and brought to North America by European settlers (Asai et al., 2004).
Botanical Description of dry and fresh spinach
Spinach (Spinacia oleracea) is an edible flowering plant in the family Amaranthaceae (LeStrange et al., 1999). Common spinach, Spinacia oleracea, was long considered to be in the Chenopodiaceae family, but in 2003, the Chenopodiaceae family was combined with the Amaranthaceae family under the family name ‘Amaranthaceae’ in the order Caryophyllales.
Within the Amaranthaceae family, Amaranthoideae and Chenopodioideae are now subfamilies, for the amaranths and the chenopods, respectively. It is an annual plant, which grows to a height of up to 30 cm (Boswell, 2010)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
Other Phytochemicals in Dry And Fresh Spinach
According to Pompella et al. (2003), glutathione is a significant antioxidant in plants, animals, fungi and some bacteria and archaea, preventing damage to important cellular components caused by reactive oxygen species such as free radicals and peroxides.
It is produced within the body and is rare in foods. One of the major functions of glutathione is to protect DNA from oxidation, but it also detoxifies carcinogens, boosts the immune system, supports liver health, and reduces inflammation (Joseph et al., 2002)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
The Health Benefits of Dry and Fresh Spinach
Fruit and vegetables contain a wide range of substances that are suggested to be part of these health-enhancing effects. Numerous studies have been conducted with regard to the health benefits of fruits and vegetables.
There is strong evidence that a diet rich in fruits and vegetables has a positive result on human health, offering protection against degenerative diseases of aging, such as heart disease, cardiovascular disease, Alzheimer’s disease, cataracts and several forms of cancer (Williamson, 1996; Liu et al., 2000; Gandini et al., 2000; Liu et al., 2001; Joshipura et al., 2001; Kang et al., 2005)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
RESEARCH METHODOLOGY AND DESCRIPTION OF STUDY AREA
This section of the thesis deals with the details of experiments that have been carried out. Chapter 3 provides a description of the study area, followed by a clarification of data collection methods and analysis techniques. The study employed a quantitative research approach to address its objectives.
MATERIALS AND METHODS
The study was carried out at Agricultural Research Council – Vegetable and Ornamental Plant Institute (ARC-VOPI) in Roodeplaat farm, situated in the sourish mix of bushveld, 25 km north of central Pretoria, KwaMhlanga (R573) road; GPS coordinates: 25,56S;28,35E (Gauteng province, South Africa). The area is a relatively cool subtropical climate with summer rainfall and cold, dry winter.
Experimental site design and treatment details
Experimental site design
Dry and fresh spinach (Spinacia oleracea L.) cv. Ohio was used as a model crop in the studies reported in this thesis. Three trials were conducted to determine the optimum fertilizer rate(s). Seedbeds were prepared and filled with virgin red soil. A total of twelve seedbeds were prepared for all three trials.
Each trial had five treatments, replicated four times. For each trial, four seedbeds were allocated and twenty plots were demarcated for planting. Each experimental plot size was 1.2m x 1m… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
Plate 1: A bed of dry and fresh spinach demarcated into five different plots and five different treatments of N, P and K as shown in Table 2… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
RESEARCH FINDINGS AND DISCUSSION
This results section presents the findings of the study in relation to the research objectives based on the collected and analyzed data. In these experiments, chemical composition analysis was done for minerals (magnesium, iron, zinc, and selenium) and bioactive compounds (total phenolic content, total carotenoid content, total flavonoid content, total antioxidant activity, and vitamin C).
The results show the variations in bioactive compounds of dry and fresh spinach in relation to different rates of applied nitrogen phosphorus and potassium fertilizers as well as the NPK treatment combinations.
The response of chemical composition of dry and fresh spinach to nitrogen nutrition
Table 3 indicates the variations in concentration on total phenolic content, total antioxidant, total carotenoid content and vitamin C, magnesium, iron, zinc, and selenium concentrations in dry and fresh spinach as a result of nitrogen applied at different rates… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
The response of total phenolic content to nitrogen nutrition
Results in Table 3 and Figure 3.1 show that Total phenolic content increased quadratically in response to nitrogen application. The total phenolic content level peaked at 45kg∙ha-1. The application of 45kg∙ha-1 improved the total polyphenol content reaching a maximum at 8.1 mg∙g-1 (Table 3 and Figure 3.1). The total phenolic content increased from 0 to 45kg∙ha-1.
The results showed that the total phenolic content of dry and fresh spinach deteriorated with increasing nitrogenous fertilizer rate ranges from 75 to120 kg∙ha-1. The difference between the highest (8.1 mg∙g-1) and lowest (3.07 mg∙g1) mean value on Total phenolic content was 5.03 mg∙g-1 on a dry mass basis (Table 3 and Figure 3.1).
Figure 3.1: Total phenolic content concentrations of dry and fresh spinach at different rates of nitrogen application (dry weight basis)… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
Besides the maximization of yield in vegetable production research, the main output is to produce healthy vegetables. The question would be what are healthy vegetables? Healthy vegetables referring to vegetables with optimal levels of health-promoting compounds such as total phenolic content, total carotenoid content, total flavonoid content, total antioxidant activity, vitamins, etc. Minerals and bioactive compounds concentration in vegetables can be improved to some limits by best agricultural practices… (Scroll down for the link to get the Complete Chapter One to Five Project Material)
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