CHAPTER ONE

Aloe vera (Aloe barbadensis miller)  is a perennial plant of 
Liliacea with turgid green leaves joined at the stem in a rosette pattern, Aloe vera leaves are formed by thick epidermis (skin) covered curticle surrounding the mesophyll, which can be differentiated into chlorenchyma cells and thinner walled cells forming the parenchyma cells (filet). The parenchyma cells contain a transparent mucilaginous jelly which is referred to as aloe Vera gel. Potential use of aloe vera products often involves some type of processing example heating, dehydrating and grinding processing may cause irreversible modification to the polysaccharides affecting their original structure which may promote important changes in the proposed physiological and pharmaceutical properties of these constituents.
However, aloe vera jel juice was not very popular due to their laxative effect and majority of them contained absolutely no active  muscilaginous polysaccharides or acemannan. Colour changes have little relation to the therapeutic effectiveness of the stabilized gel and it is totally unacceptable in some products. An efficient processing technique was used to improve product quality, to preserve and maintain almost all of the bioactive chemical entities naturally present in the Aloe Vera leave during processing. The production process of aloe vera leaves involves crushing, grinding or pressing of the entire leaf of the aloe vera plant to produce an aloe vera gel juice followed by various steps of filtration and stabilization of the gel. The resulting solution is then incorporated in or mixed with other solution or agents to produce a pharmaceutical, costmetic or food product.
1.1    AIM OF STUDY
To extract Aloe vera gel from the plant and stabilize using sodum benzoate, citric acid and lime.

Aloe vera is a succulent plant of the lilly family native to the cape of good hope and growing wild in much of Africa and Madagascar. Commercial growers cultivate it in the Caribbean, the Mediterranean, Japan and the USA. It produces a ring of dagger shaped fleshy leaves that grow up from the base of plant. Each Aloe vera plant grow up to nearly 2kg in weight. It is from the leaf that the soothing aloe vera jel is extracted.
The Aloe vera plant is drought resistant and grows mainly in subtropical desert like savanna. When the leaves are cut the plant can close off it’s cell to retain fluid. Aloe vera can grow to 20meters in height but usually grows only to about 1.5meters. each plant has about 15leaves and blooms intermittently. It produces erect spikes of drooping yellow, orange or red tubular flowers on the woody stem
Russian research has shown benefits to condition other than those for which aloe vera is most well known. These include improvements in bone tuberculosis and broken bones, inflammatory gynecological conditions, paralysis caused by polio, ear, nose and throat conditions and bronchial asthma. They have also been found that aloe vera can help slow aging process[1].
Both Russia and the United States have carried out extensive research into the use of aloe vera for all types of burns[2]. They found that compounds within aloe vera can help the burn heal and can also have a  cleansing and antibacterial effect[3]. The United States have developed a cream containing 70% aloe Vera juice extract that prevents partially damaged tissues from dying and allows new skin cells to close off the area, thereby promoting healthy new skin beneath the scrab rather than scar tissue.[4]
Research has also been carried out into whether Aloe vera can play a role in the treatment of cancer. Aloe vera appears to cause the release of tumor necrosis factor alpha that blocks the blood supply to cancerous growths[5]. A study in Japan showed that drinking Aloe vera juice regularly may be effective in preventing the onset of lung cancer in smokers[1]. The first recorded evidence of the healing properties of the Aloe vera are fond on ancient Egyptian texts dating from around 1500BC. The Egyptians referred to Aloe vera as the plant of immortality. Arab traders were probably responsible for the spread of Aloe vera into Persia, India and the far East.
In the first century AD, the Greek physician Dioscorrides wrote in his Material Medica that Aloe vera extract could be used to treat wounds, stomach complaints, constipation, hemorrhoids, headaches, all mouth problems, hair loss, insect bites, kidney ailments and skin irritation.[6] In Africa, aloe vera was used for stomach aches and to prevent infection from insect bites.[6] Chinese used Aloe vera for treating eczema during the sung dynasty. [8] In I India during the forth century BC, people believed that Aloe Vera grew in the garden of Eden, they called it “the silent healer” and used it to heal skin conditions and inflammation. In the early Christian era, Aloe vera could be found in all advanced medicinal texts[9].
Eventually, Aloe vera was introduced into the Americans. In Mexico, the juice was used to treat skin complaints and wounds. Aloe vera was sold in the street market of Latin America as an aphrodisiac. Jesuit Preists were encouraged to take Aloe vera with them when going to the new world to spread the bible. As the popularity of aloe vera increased during the 18th century, so trade wars occurred between the British, Spanish and Dutch to establish Aloe in the new world. During the late 18th and early 19th centuries, many wealthy collectors of exotic plants added aloe vera to their collections and many discoveries about its properties were made during this period.[10]
By late 19th century, synthetic laboratory drugs were taking procedence over botanical compounds. There was a naïve optimism that scientific advance would lead to even more effective drugs that would eventually “conquer” all diseases and herbal remedies such as Aloe vera fell from favour. Although research was carried out by the united state into the burn healing properties of Aloe vera during the 1930s to find a cure for radiation burns. It was only in the 1960s that improved techniques allowed proper stabilization of the aloe vera. Stabilization of the Aloe vera gel juice allowed it to be stored for a long period and therefore commercial production became viable. Public interest was rekindled.[11]
Previous methods of extraction concentrate only on the Aloe vera gel found in the middle of the leaf. The whole leaf processing was not used because it was difficult to prevent contamination with Aloe latex. Aloe latex is a yellow extract from the inner leaf of the plant that acts as a laxative and can cause severe cramps and diarrhoeas. The very latest processing methods now allow the whole aloe vera to be processed without the latex contamination. This is a hugely important step forward as the juice/gel can now contain the healing power of all parts of the plant rather than just the inner gel. The polysaccharide count in whole leaf juice can reach much higher values using these latest processing methods. [12]
1.3    BIOLOGICAL ACTIVITY OF ALOE VERA
The controversy over the identity of the active substance(s) in aloe vera has not settled. Also various mechanisms have been proposed for the alleged healing properties of Aloe vera. Since no single definite active ingredient has been found. It is commonly suggested that there may be some synergitic action between the polysaccharides base and other components.[13]
According to Mackee [14] vitamin D was the healing agent but row and parks [14] reported the absence of vitamin D. Morton [15] suggested a theory starting the seeming efficacy of aloe vera pulp may be attributed to its high water content i.e 96%+, providing a means of making water available for injured tissue without scaling it off from the air. This recovery would explain the instant soothing effect of Aloe vera gel has on burns but would not account for the long term effect of healing. The action of aloe vera is simply due to its moisturizing and emollient effects, hence its use in cosmetics.
Various researchers reported that the effective component for wound healing may be tannic acids [16] and a type of polysaccharide [17]. other researchers have also reported anti-imflammatory effects of complex polysaccharides. It is logical that the mucilaginous gel of Aloe vera plant which is essentially a polysaccharide  holds secrete to Aloe vera’s medicinal properties. Many researchers such as Collins[18] Fine and Brown [19]and Crew [5] have attributed pain – relieving properties to aloe vera gel. It is virtually impossible to prevent contamination during commercial extraction of Aloe vera gel. It is believed that the intact leaves anthraquinones and their derivatives may diffuse into the gel from the bundle sheath cells, this possibly supports the conclusion of Row et al.,[21] who states that the healing agent is passed from the ring into gel on standing.
The things that happen to make aloe product less desirable or cause it to become virtually non-beneficial were stem from the harvesting of the leaves processing and distribution of leaves. The fleshly removed leaves must go directly into production or must be appropriately refrigerated to prevent a loss of biological activity. Principally through the degradative decomposition of the gel matrix. The value of Aloe vera further diminishes if the processing procedures applies too much heat for too long a time. [22] Extended heating renders the product free from bacterial contamination but effectively destroys aloe’s mucopolysaccharide and consequently its efficacy.[2