Cultivation and Post Harvest Management of Aloe Vera

Aloe Vera is a very hardy plant and flourishes well in a wide range of climates and soils except at very high altitudes in submerged areas, it grows well under arid regions with minimum rainfall. It is susceptible to frost. The plant prefers red sandy soil with adequate drainage. The plant is a boon to arid zone or drought-prone areas.

It is a salt-tolerant crop and can be grown in salt-affected soils also. Successful cultivation of aloe in coastal areas of Kerala and Tamil Nadu in India is an excellent example of its salt tolerance nature. For best growth of the plant well-drained fertile sandy loam soils are suitable. Due to the shallow root system, the plant can be grown in pots also.

In India, the species is distributed in Maharashtra, Tamil Nadu, Kerala, Andhra Pradesh, Karnataka, and Madhya Pradesh. Commercial cultivation of Aloe Vera in India is done only to a limited extent.

Varieties

National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi has identified some accessions having high aloin and gel content. The high aloin content accessions are IC-111267, IC-111269, IC-111271, IC-111273, IC-111279, IC-111280, and the high gel content accessions are IC-111266, IC-111267, IC-111272, IC-111277, IC-111280. Indian Institute of Horticultural Research, Bangalore has also identified some accessions namely, AV-1, AV-7, AV-8, AV-23, and AV-46.  

Sowing

Sowing of Aloe plant should be done in the month of July-August so that initially plant will get sufficient water. Aloe Vera is propagated through root suckers and rhizome cuttings. For this, 15-20 cm. long root suckers or rhizome cuttings are planted in the field at a distance of 50 x 30 cm. Two-thirds length of the cutting is buried under the soil while the upper one-third portion is kept above the soil.

For sowing, the field should be prepared by plowing the field 2-3 times. Immediately after planting, the field should be irrigated. Since its roots do not go deep into the soil deep plowing is not required. If irrigation facilities are available they can be sown at any season. In absence of proper irrigation facilities, it should be planted in the rainy season only.

Adult and mature plants can withstand water stress for a long time, but newly sprouted seedlings need timely irrigation, especially at the time of planting, due to less succulent leaves. Therefore, initial irrigation is recommended.  To get seedlings a nursery may also be raised through seeds. One-year-old seedlings may be planted in the field.

Nutrient Management

For commercial cultivation, aloe is a new crop. Therefore, the determination of appropriate doses of fertilizers is under trial. Experiments conducted outside indicate that for high leaf and gel yield it needs high nitrogen doses. The doses of nitrogen have been found associated with the number of irrigations. More irrigations need less nitrogen while fewer irrigations need more nitrogen for getting maximum production from the crop.

Aloe crops should be given 150 kg of NPK mixture per hectare. A complete dose of phosphorus and potassium and half dose of nitrogen should be applied at the time of planting as basal dose. The rest of the nitrogen should be applied after the plants are established well in the field. In addition to the fertilizers, per hectare, 20-25 tones of farmyard manure should also be applied and mixed well in the field before planting.

Irrigation

A number of irrigations in Aloe Vera depend on the production of gel and juice. Generally, more irrigations are required for gel production. In India, a number of irrigations in this crop may be required between 4 and 10 depending on the area and climate. In dry areas, like Rajasthan, a maximum number of irrigations is required. Though it is a draught-resistant crop water scarcity adversely affects crop production. High rainfall areas of North Eastern or peninsular India need the least water requirement. In these areas soil should be well-drained otherwise water stagnation in crops may adversely affect the crop. 

Weed control

Weeding should be done time-to-time. Generally, two weddings are enough in a year. In the beginning, when plants are small weeding is essential. In a fully grown crop neither the weeds could become dominant on the crop nor is it easy to perform weeding operations in the field with conventional implements. At this stage, the entire land is covered with crops. The leaves are full of gel and juice. If they are disturbed in the weeding operation they might break, causing damage to the crop.

Insects and pests

This crop is hardly attacked by any insect and pest, which can cause serious loss to the crop. A leaf spot disease is commonly seen on the leaves of the plant, which is caused by Alternareaalternata and Fusarium solanai fungus. In this disease, initially black colored tiny dotted spots are formed on the leaf surface, which on further growth spread, meet each other, and take bigger irregular shapes. These spots remain on the upper surface of the leaf and generally do not damage the gel inside the leaf. Therefore, generally, they are not required to be treated, however, if the infestation is too much the same fungicide, preferable of organic nature, may be used. 

Harvesting

A crop once planted gives production up to five years. For maximum yield, the crop is cut after 9-10 months of planting. During this period mature leaves are more juicy, weighty, and fresh. Too many old leaves do not give good quality gel and its quantity is also decreased. Very new and immature small leaves also contain the least quantity of gel. For the production of juice mature leaves of appropriate size are cut from the base and are hung for 5-6 hr. keeping the cut portion downside.

By doing this whole juice of the leaf trickles down. For obtaining gel the leaves are cut open longitudinally and the white-colored transparent gel is scrapped with the help of a knife for further processing. For other uses, the whole plant can be cut from the base or taken out along with roots and dried. The crop should be harvested in the morning hours. Before five years the crop should not be eradicated by roots. After cutting the leaves the crop is again sprouted and gets ready for harvest by next year. This process may be continued for 5 years.    

Yield

An average crop yields about 45-50 tones of fresh succulent leaves per hectare per year. But a well-cared crop supplied with sufficient irrigation and nutrients produces healthy plants with 16-20 weighty leaves per plant. Under such conditions, if each leaf weighs 200g. then 50000 plants in a hectare area can give 60-200 tones of fresh leaves /ha.

Storage

For the purpose of gel or juice, the plant has to be used immediately after cutting leaves. Under this situation, the need for storage does not arise. But in many ‘Ayurvedic’ preparations whole plant is used in dried form. For this, it may be stored after drying the whole plant. Since its leaves contain pulp and more than 90% water, they take a long time to dry.

For fast drying, they may be dried over-fitted with a fan. While drying the temperature of the oven should not exceed 60⁰C, and preferably it should be between 50 and 60⁰C. The plants should not be kept in the oven immediately after harvest. Before keeping them in the oven they should be dried in the open air in the sunlight for some time to reduce the moisture level of the leaves. Excess moisture at high temperatures in the oven may decompose some important plant constituents. The dried plant material may be kept in jute bags for one year.  

Income

The farmers harvest the leaves three times a year. In each harvest, 6-8 tons of fresh leaves are obtained in an acre. Out of the total yield of 18 to 24 tonnes of fresh leaves, the farmers are able to generate a gross income of Rs.40,000 @ Rs.2 per kg of fresh leaves with an average yield of 20 t/a in one acre. Such farmers generally make marketing tie-up with buyers to whom the leaves are sold either as fresh or dried. This way, farmers make Rs.25,000/- as net income in one acre. It should be noted that Aloes are grown in poor or marginal soils and mostly under high alkaline soils where no other annual crops could generate this amount of income.

Drying of leaves

Aloe leaves contain 80-90 percent moisture and need to be dried under the open sun. For this, the leaf is transversely cut into 10-12 small pieces and spread on the yard. The leaves hardly take a week to get fully dried when left under the sun. Leaves should be uniformly dried by the constant stirring of leaves. Improper drying causes blemishes, fungal infections, and molds which reduced the marketability. One kg of dry leaves could be obtained by drying 80kg of fresh leaves (Drainage ration of 1.25 percent).

Processing and Product Development

Aloe vera is considered to be nature's miracle by people all over the world because it possesses numerous medicinal properties. As more and more people are learning about the benefits of aloe vera, the demand for aloe vera products are also on the rise. Although making aloe vera gel is quite simple and can be easily prepared at home, it cannot be trusted completely if one needs to use it for internal consumption. This is because while making aloe vera gel at home, there are chances that the aloin or latex gets mixed into the gel accidentally, making it unreliable for consumption as aloin is laxative in nature and can cause stomach problems. In this case, it is best to rely on aloe vera products that are prepared through a careful process. Let us take a look at how exactly aloe vera processing is done.   

Selection of leaves

The first step in the process of making aloe vera gel is the harvesting of the aloe vera leaf. Only the leaf that is fully matured (2-3 years old) is chosen for aloe vera processing. An important thing that has to be followed is that the aloe vera plant once harvested must immediately go through the process of preparing the gel. This is because the more time the aloe vera plant is kept without processing, the more its quality starts deteriorating. However, if aloe vera is not used immediately, it should be placed in a refrigerator within 4-6 hours after harvesting.

Cleaning

Once the aloe vera leaves are harvested, it has to go through a severe cleaning process. In most aloe vera processing companies, the aloe vera leaves have to go through a series of soak tanks, high-pressure sprayers, and scrub brushes to wipe out any unwanted remains that can deteriorate the quality of the end product.

Processing

Aloe vera processing can be divided into three main steps which include crushing, grinding, and pressing the whole leaf. Most manufacturing companies make use of aloe vera processing equipment for extracting whole leaf aloe vera gel. First, the tip, as well as the base of each aloe vera leaf, is removed and it is cut into small pieces. These aloe vera pieces are placed in a grinding unit where they are crushed till they achieve a soup-like consistency. This aloe vera liquid is then transferred into cleaned and sanitized stainless steel tanks. After this, the large pieces of pulp present in the liquid are removed with the help of a de-pulping extractor.

Filtration

The liquid that is obtained in the end goes through the filtration process. This is important to separate the aloin or latex from the liquid, along with the microscopic remains of sand, leaves, and other such particles. The filtration process is done with the help of a press filter that possesses various carbon-coated plates. These plates have the ability to absorb the latex from the aloe vera liquid. This process is repeated until the whole liquid is free from almost 99% of aloin. After this, the liquid goes through a press filter that contains 5-micron filter paper several times, until it is completely devoid of latex. Finally, the aloe vera liquid is purified through the cold filtration process.

Stabilization

The stabilization of the aloe vera liquid or gel that is obtained after processing is extremely important. This is because processed aloe vera is bound to get oxidized, thus making it unusable. Stabilization of aloe vera gel or liquid can be done through various techniques including cold processing as well as heat treatment processing.

Cold processing is done by using enzymes like catalase and glucose oxidase in the aloe vera gel to stop the production of aerobic organisms. Another cold processing method is to expose the aloe vera gel to ultraviolet rays. On the other hand, heat treatment processing involves the pasteurization of the liquid at a high temperature. Another aloe vera gel stabilizing method is by adding preservatives and additives like potassium sorbate, sodium benzoate, vitamin E, citric acid, etc. to the gel.

Needless to say, aloe vera processing is definitely complex. However, it is quite essential to make the aloe vera gel or juice effective and safe for topical application as well as internal consumption.

Article By:

C.S. Raghav - Senior Scientist-cum-Head, ICAR-Krishi Vigyan Kendra, West Siang, Basar, Arunachal Pradesh

R.K. Singh ^- Senior Scientist-cum-Head, Krishi Vigyan Kendra Hazaribagh, Jharkhand

M.S. Baruah - Asst Chief Technical officer, ICAR-KVK West Siang, Basar, Arunachal Pradesh

Prashant Raghav - M. Tech Scholar (Industrial & Production Engineering), Amity University, Gurgaon, Delhi NCR