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11. Value addition of NWFPs
P.L. Soni
[15] and V.K. Varshney[16]


ABSTRACT

Managing forests sustainably in order to improve rural economy, NWFPs hold prospects. An important concept in exploitation of NWFPs is adding value locally. Value addition of NWFPs has attracted attention because gathering and processing activities can be managed by the rural people, with a greater portion of the end product revenue accruing to those who manage the forest resources. Local processing includes grading, purifying, storing in congenial conditions to reduce post-harvest losses, and improving thereby the product quality to fetch higher price. NWFPs in India are derived from over 3000 species. These include medicinal plants, edible plants, starches, gums and mucilage, oils and fats, resins and oleo-resins, essential oils, spices, tannins, insecticides, natural dyes, bamboo and canes, fibers and flosses, grasses, bidi leaves, etc., which have been traditionally used for livelihood, and social and cultural purposes. However, processing of NWFPs into value-added products through simple technologies is limited. Research needs for improving the situation include prospecting, screening, evaluation and classifying NWFPs' yielding plant species, and identifying candidate species, and adequate technology for development of value added products.

INTRODUCTION

Realization of the great dependence of the poor on forests is quite recent. Bringing poverty focus into forest management implies more deliberate efforts to link sustainable livelihood for poverty reduction with sustainable forestry. However, increased population pressure, continuing loss and degradation of forest resource, increased market demand or newly found needs make the situation difficult. Non-wood forest products (NWFPs) are goods of biological origin other than wood derived from forests. NWFPs are a group of under-exploited but potentially promising resource for sustainable livelihood of poor people in rural areas. An important concept in understanding these prospects is sustainable exploitation of NWFPs and adding value locally.

In India, most rural people use some forest products and many obtain part of their income from forest-based activities. For instance, collection of tendu leaves provides part-time employment to about 7.5 million people. A further 3 million people are employed in bidi processing; and another 3 million people are involved in lac (resin) production. About 0.75 million earn income from sericulture; about 0.55 million people are employed in bamboo-based craft enterprises and about 0.13 million households are involved in tassar silk cultivation (Jha and Jha 1985, Arnold 1995). At the local level, NWFPs also provide raw materials for large scale industrial processing, including processing of internationally traded commodities such as foods and beverages, confectionery, flavourings, perfumes, medicines, paints and polishes, etc. At present at least 150 NWFPs (e.g. honey, gum arabic, rattan, edible bamboo, cork, forest nuts and mushrooms, essential oils, and plant and animal parts for pharmaceutical products, etc.) are significant in international trade.

Many people living in and near forests are unaware of the potential of the resources for income generation because they lack access to information on processing possibilities. Processing of NWFPs adds value to them. Value addition of NWFPs has attracted international attention because gathering and processing activities can be managed by the rural people, with a great portion of the end product revenue accruing to those who manage the forest resources. Market oriented production often goes through several levels of processing. The higher the level of processing carried out near the source, more of the product value can be retained locally. This offers the prospect for improving local employment, income and livelihood. At the national level this can also support production of consumer goods from NWFPs (e.g. perfumes, cosmetics, fiber extraction, ropes, handicrafts, etc.) and help increase foreign exchange earnings (FAO 1995). Included amongst the value added processing activities are to reduce post-harvest losses through grading, purifying, storing in congenial environment, to reduce the weight and volume of raw products, to increase their standardization and guarantee consistent quality and acceptability in multiple markets (Clay 1995). NWFP- based industries are generally less polluting, less destructive of environment and amenable for vertical and horizontal integration (FAO 1995).

Several reports and studies provided indication of the current and potential importance of NWFPs in the Asia Pacific region. The region is reported to be the richest in terms of product diversity and the volume and value of trade of NWFPs and every country of the region has a long list of species, either used locally or traded in the local or international markets (Nair 1995). China and India are by far the world's largest producers and consumers of NWFPs. China dominates the world trade in NWFPs followed closely by India.

NWFPs of India

India is one of the 12 mega-biodiversity centres and harbours about 50 000 plant species accounting for 7 percent of the world's flora (Dayal et al. 1999). Out of these, about 3000 species yield economically exploitable NWFPs (FAO 2002). These include medicinal plants, edible plants, starches, gums and mucilages, oils and fats, resins and oleo-resins, essential oils, spices, drugs, tannins, insecticides, natural dyes, bamboos and canes, fibres and flosses, grasses, bidi leaves, animal products and edible products. According to the Centre of Minor Forest Products, Dehradun, 325 species producing NWFPs are very common and have a base in major industry, 879 species are used locally, 677 species are potentially useful only locally, and 1343 species can be described as 'other lesser known' (FAO 2002). Most of India's 50 million tribal people receive a substantial proportion of their cash and in-kind income from NWFPs, while about 200 to 300 million village people depend upon products from forests in varying degrees (Shiva 1995).

The estimated total value of the most economically important NWFPs in world trade is about $ 11 billion annually (Wilkinson amd Elevitoh 2003). At the national level over 50 percent of forest revenue and about 70 percent of forest export revenue comes from NWFPs, mostly unprocessed and raw (Prasad 1999). Small-scale forest-based enterprises, many of which rely on NWFPs, provide up to 50 percent of the income for about 25 percent of India's rural labour force (Tewari and Campbell 1995). The forestry sector provides about 2.3 million man-years of employment. Of this about 1.6 million man-years are related to NWFPs. It is estimated that NWFPs are capable of generating 4 million man-years of employment annually, if their full potential is exploited. Most of the NWFPs are collected in a particular season although they are utilized all year round and as much as 50 percent spoil during storage (FAO 2002). Most NWFPs currently provide employment during only part of the year because processing of these NWFPs is still poorly developed. Since these products occupy an integral place in the international market, ample opportunities exist for enhancing export earnings by developing suitable facilities for processing, drying, storage, packaging and marketing. Improved labour intensive technologies for processing NWFPs would increase the employment opportunities for longer periods of the year and ensure high prices for the product(s).

Major constraints in processing of NWFPs

Harvested products reach the market, local or foreign, after primary processing in the form of cleaning and grading. The potential of many NWFPs is not being utilized fully because of insufficient knowledge and experience on appropriate processing techniques and lack of product development. In addition, extracting, processing, production and marketing of most NWFPs are carried out in traditional ways using worn-out equipment or obsolete methods. Development of processing technologies has stagnated at the level of preliminary processing. Most processing of NWFPs for local use is carried out in units which are small, dispersed, financially weak, primitive in technology and poorly managed. They lack infrastructure and employ unskilled persons, often working on part time basis. These constraints restrict immense potential for value addition, especially in the case of pharmaceuticals and cosmetics (Nair 1995). This has also put negative impact on producers/ collectors of NWFPs.

Value added transformation of NWFPs is labour intensive and stresses on quality and reliability of supply. But lack of technology, skilled manpower, management expertise, capital for investment and marketing skills, coupled with inadequate information on resource and resource development, limit sophisticated or refined downstream processing and often export is confined to primary products. The products of comparatively larger establishments carrying out primary processing for export, undergo further processing/refinement in developed countries. These impact adversely on enterprise survival rates (FAO 1995). Significant value addition is done in importing countries, the benefits of which seldom trickle down to the raw material suppliers.

The NWFP scene is still trader dominated where the emphasis is on generating income through trading. Impact of research on resource conservation, management and development of new products has been negligible and research tends to be preoccupied with traditional products with uncertain future. The substantial efforts on taxonomy and chemical characterization are not effectively followed up to develop marketable products. Enhanced awareness on the long term potential is yet to be translated to action and the efforts to take advantage of the widening product market are far from adequate (Nair 1995).

Research efforts are far from adequate and spread too thinly in several aspects, contributing to their ineffectiveness. Impressive achievements with respect to production and processing have occurred mainly for plantation crops cultivated on a large scale. Technological improvements with respect to production and processing especially with regard to a large number of products in the subsistence sector have been negligible. Research is focused on traditional areas and products, with very little efforts to develop new products and uses. Another weakness identified is the lack of linkages between different institutions. Interaction between universities, R&D institutions and industries is poor, resulting in a substantial proportion of the research remaining unused or no research being undertaken on priority concerns of the processing sector (Nair 1995).

To improve the situation, there is an urgent need for a well defined approach to research. One of the specific areas is: prospecting, screening, evaluation and classifying NWFP plant species and identifying candidate species, and adequate technology for development of value added products. New technologies will substantially alter the scope for utilization of NWFPs' new products and usage will emerge while traditional uses will fade out.

STARCHES FROM FOREST TUBERS AND SEEDS

Starch, after cellulose, is the principal carbohydrate photosynthesized by plant. The most important sources of starch are cereal grains (40-90 percent), pulses (30-70 percent) and tubers (65-85 percent). Total world production of starch is estimated to be 18 million tons (Guilbot and Mercier 1985), extracted mainly from maize (10 million) and potatoes (2.5-3 million), and the rest is derived from wheat, rice, manihot, sorgham and sago. About 50 percent of the starch produced in the world is intended for food purposes. Other than as a food stuff, starch can also be used as a coating, sizing and flocculating agents, chemicals and building materials (Guilbot and Mercier 1985). Starch or its derivatives also find industrial applications as an auxiliary material to provide special functions such as binder, thickener, protective colloid, etc.; raw material for production of new products, fillers for polymers to improve their total properties; components of synthetic polymers for synergistic effects; active material for production of pharmaceutical and agro-chemicals. Through simple process technolgies, native starch can be modified into useful products as it is dispersible in cold water and exhibits a higher reactivity than cellulose. In addition, starch is very susceptible to partial or total hydrolytic degradation by acids or enzymes to yield oligomeric or monomeric products which can be further modified.

Realizing the potential of hitherto untapped potential of forest tubers and seeds as alternatives for production of commercial starch and its value added transformation into products, investigations were made in which a number of tubers seeds such as Pueraria tuberosa, Dioscorea ballophylla, Amorphophallus campanulatus, Stephania glabra, Pueraria thomsonii, Canna edulis and seeds of Shorea robusta, Cassimiroa edulis, Careya arborea and Aesculus assamica were screened for their starch contents and evaluated for their physico-chemical properties and compared with those of commerical starches i.e. maize and tapioca starches (Soni and Agarwal 1983, Soni et al. 1985, and others). These studies have shown that starches isolated from forest tubers and seeds have comparable properties with commercial starches. Five starches from tubers of Pueraria tuberosa, Dioscorea ballophylla, Amorphophallus campanulatus, Canna edulis and seeds of Careya arborea have higher water binding capacity then maize and tapioca. Unique feature of the forest origin starches is that their gelation temperature are higher than the maize and tapioca starches. Amylograph studies of most of the starches have shown high peak viscosity and less retrogradation than the maize and tapioca starches. Starch isolated from defatted sal seeds has more N, P, lipids, amylose and water binding capacity than those of other starches studied. Despite its low and seemingly restricted swelling, the sal starch is much more soluble at any particular degree of swelling. Paste viscosity curve showed that it was stable on continued cooking. These unique physico chemical properties of sal starch has generated interest in the starch industry.

Above studies have led to identify following candidate species for their exploitation as alternative source of commercial starches: Canna edulis, Pueraria tuberosa, Amorphophallus campanulatus, Careya arborea, Cassimiroa edulis and defatted sal seeds. Canna edulis is known to have been used for making noodles in China and Viet Nam.

Starch is an abundantly available source for making dextrin. Dextrin as understood commercially are the degradation products obtained by treating starch in a variety of ways. Dextrin is being marketed in several forms such as powders, granulated particles, thick viscous liquids and white paste. Dextrin exhibits greater solubility and a wide range of solution viscosities. Dextrin finds important application in industries like adhesives, cosmetics, electro plating, textile, paper, food and pharmaceuticals, etc. (Bhatt et al. 2000). However, the process used for the transformation is complex involving the use of catalyst or enzyme, time consuming and expensive. A simple process has been developed for conversion of starch into dextrin which completes in a short period of two hours without the use of catalyst/enzyme. Rheological and adhesive properties, and tackiness of dextrin so produced was found better than those of the commercial samples.

SEED GUMS

Galactomannan gum industry is a fast developing industry because of many uses of these gums in food, paper, textile, petroleum, pharmaceuticals, cosmetics, paints, detergents, agriculture and a large number of related industries (Rani et al. 2000). In the past two decades, this biopolymer has provided solution to a large number of industrial problems. Industrial applications of these gums are due to their wide range of solubility and solution viscosities which depend upon their structures, molecular weight, and mannose-galactose ratio.

Source of these gums are in the endosperm of plant seeds of the family Leguminosae. The leguminous crops owing to their capacity to utilize the atmosphere N for their growth generally do not require expensive nitrogenous fertilizers and increase the soil fertility and can be cultivated on marginal land. A great diversity of legumes is found in India, enough potential to cope with the increasing demand of seed gums in national and international markets. Development of seed gums thus would boost the galactomannan gum industry in the country which in turn would not only generate livelihood opportunity to reduce the poverty but also would improve the productivity of soil without costly fertilizers. Development of simple processing methods for value addition of these gums is also seen as a practical proposition for generation of additional employment opportunities for the rural people.

During the past several years, studies on galactomannan gums have been carried out at the Forest Research Institute, Dehradun. Studies have isolated gums from seeds of Leucaena leucocephala (Subabul) in 30 percent yield and Cassia tora in 32 percent yield through simple and cost effective processes (Soni et al. 1984, and others). The gum derived from Leucaena was also found to be suitable as a wet-end additive in paper making (Soni et al. 1984) and as a thickener in textile printing using reactive dyes (Teli et al. 1996).

Physico-chemical studies of Cassia tora gum has revealed its viability in industrial applications. The gum acted as a flocculant when used for mud settling in sulphited sugar cane juice and in treatment of water of paper mill (Soni et al. 2001). In textiles printing, the thickening properties of the gum was found to be comparable with that of sodium alginate (SA), the commercial thickener used in textile printing. However, blending of the SA with the gum in 1: 1 ratio was found to be a suitable alternative (Soni and Teli 1999). It has also been found effective to achieve optimum strength properties of mill pulp consisting mainly of bleached eucalyptus pulp supplemented with bamboo (12 percent) and pine (2 percent) pulps and bleached bagasse pulp mixed with 20 percent softwood pulp (Soni and Pal 1996).

Through chemical derivatization, Cassia tora gum has also been transformed into value-added products such as carboxymethylated, cyanoethylated, carbamoylethylated quarternized and grafted Cassia tora gum for their utilization in various industries (Sharma et al. 2002, and others). Similarily guar gum (Cyamopsis tetragonoloba) the commercial gum, was also modified into derivatives (e.g. carbamoyethylated and grafted guar gum) of industrial importance (Sharma et al. 2003d). These modified products of Cassia tora and guar gum have good potential as effective and ecofriendly substitutes of synthetic flocculants which are expensive and cause environmental and health hazards in their production and use. Flocculation is a process whereby finely divided or dispersed particles are aggregated together to form large particles of such a size so as to cause their settling or agglomeration of tiny particles to form flocs which settle and cause clarification. Materials which are used in fast solid-liquid separation are called flocculants. Flocculants have wide spread applications to treat chemical effluents in various chemical industries. Modified Cassia tora gum was also used as beater additive in paper making. It was found to be effective in improving the dry strength properties of paper (Soni et al. 2000).

Extensive work to find out new sources of seed gums has been carried out at NBRI, Lucknow (Kapoor 1999). It includes the chemical investigation of about 200 species belonging to different genera of Leguminosae. It is found that almost all the species of Cassia, Crotolaria, Sesbania and Indigofera occurring in India are rich in gum content whereas few species of Bauhinia, Caesalpinia and Desmodium contain appreciable amount of gum. Genera like Acacia, Canavalia, Erythrina, Tephrosia, Pterocarpus, etc. are poor in gum. It has been demonstrated (Kapoor 1999) that the seeds of Cassia angustifolia could open new avenue for the production of seed gum. The seeds are bigger in size and contain about 50 percent of endosperm. The gum is characterized by having high range of mannose with useful viscosity properties. The studies have also shown that the seeds of C. alata, C. grandis, C. siamea, C. nodosa, C. didymobotrya, C. occidentals have great potentialities to become the new source of gums. Similarly various species of Crotolaria, Caesalpinia, Mimosa, Gleditsia, Priotropis and Sesbania could also be exploited for the commercial production of seed gums. However, for commercial viability factors like habitat, availability, cost of collection, seed size and endosperm content are required to be considered.

GUM EXUDATES

Exudate gums, also known as natural gums, are the secretions from trees and bushes. Today several of these natural gums are still common articles of commerce. Important gums such as gum karaya (Stercuilla urens), and gum ghatti (Anogeisus latifolia) have got immense use as food additive. These exudates when secreted by the plant are viscous, gummy liquids but when exposed to air and allowed to dry, form hard, glassy masses. The physical appearance and properties of natural gums are of utmost importance in determining their commercial value and their end uses. These vary considerably with botanical sources, climate, soil, age, absorbed impurities, treatment after collection and storage. India produces 20 000 tonnes of exudate gums in which gum karaya alone contributes about 15 000 tonnes. India earns around Rs. 1200 million by the export of gums (Soni and Bhatt 1999). However, the trade suffers a draw back of adulteration of the gums which make them unfavourable for their incorporation into formulation of products.

Gum ghatti is the exudate of Anogeisus latifolia but it is always mixed, sometimes to the extent of 40 percent, with the gums from other sources such as Albizia, Azadirachta, etc. This admixing restricts its acceptability in food applications. A simple process was developed to purify the gum ghatti and shaped to noodle form.

Mesquite gum obtained from Prosopis juliflora contains high content of tannin compounds which inhibits its application as a commercial food additive. A simple process to purify the gum and remove tannin compounds has been developed. The purified gum in tablet formulation by direct compression and wet granulation method was evaluated and compared with commercially used Acacia and Tragacanth gums. Results of binding and suspending properties of mesquite gum showed its suitability to be used in pharmaceutical formulation like other natural gums (Khanna et al. 1997).

ESSENTIAL OILS

Essential oils are highly volatile aromatic oily substances that can be found in many plant parts. Such oils are called essential because they are thought to represent the very essence of odour and flavour. These oils are stored as microdroplets in specific cells, glands or ducts, either in one particular organ of the plant or distributed over many parts, e.g. leaves, barks, roots, flowers or fruits. They are used in many industries for adhesives (e.g. cements, pastes and glues and tapes), pharmaceuticals (e.g. medical and veterinary preparations), cosmetics and toiletries (e.g. perfumes and sprays, creams, deodorants, colognes, shaving preparations, powders, soaps and detergents), paints (e.g. distempers, diluants, paint removers, air fresheners and cleaning fluids), paper and printing (e.g. carbon paper, crayons, ink, labels, wrappers, writing papers and ribbons), insecticides (e.g. sprays, repellants, attractants and disinfectants), foods and beverages (e.g. liquors, convenience foods, flavouring agents, preservatives and sauces), petroleum (e.g. cream deodorant, solvents and lubricating oils/waxes), textiles printing (e.g. deodorants, upholstery materials, finishing materials), rubber and plastics (surgical gloves, rubber toys, water proofing compounds, general plastics), motors (e.g. polishes, cleaners, seat upholstery and other plastic goods) and dental preparation (e.g. tooth pastes, mouth washes, antiseptics and cements) (De Silva and Atal 1995). The important essential oils produced in India come from sandalwood, lemongrass, palmarosa, Eucalyptus spp. and khus.

Apart from the above described applications of the essential oils in various industries they are widely used in aromatherapy. Aromatherapy can help in easing a wide assortment of ailments, aches, pains, and injuries while relieving the discomforts of many health problems. It also helps in restoring both physical and emotional well being by relieving depression and anxiety, reducing stress, relaxing, uplift spirit, sedation or stimulating. It is the active chemical composition and aroma of the essential oils which provide therapeutic benefits. Oils such as eucalyptus, sandalwood, lemon, bergamot, etc. have powerful antibacterial and anti viral properties, which unlike other pharmaceutical drugs do not leave behind dangerous toxins. There are many ways to use essential oils for their therapeutic and balancing properties. These include inhalation, bath, massage or breathing. About 55 essential oils are known for their therapeutic effects (Varshney et al. 2001). Some of the good examples of the essential oils having therapeutic properties and obtained from forest species are sandalwood (from Santalum album), cedar wood (from Cedrus spp., Juniperus spp.), eucalyptus (from Eucalyptus globulus), pine (from Pinus sylvestris), citronella and palmrosa (from Cymbopogon spp.) etc.

Steam distillation is the most common method for isolation of essential oils. This involves generating steam and passing it through the plant material to carry off the volatile constituents. Though the process sounds simple in theory, the actual commercial process for greatest efficiency and quality varies widely, depending upon the characteristics of the raw material and the final product (De Silva and Atal 1995). Other processes such as enfleurage (e.g. oils from flower of jasmine and rose), solvent extraction (e.g. oleoresins from species such as ginger, pepper, cardamom, etc.), cold expression (e.g. citrus oil), etc. are also used.

The world trade in essential oils and their value-added products is vast. World production of essential oils (excluding turpentile oil) is estimated to be about 105 000 tonnes to the tune of US$ 922 million. India stands at third position with a share of about 16 percent. Indian production of the essential oils is estimated to be 17 000 tonnes valued about US$ 195 million (S.C. Varshney, Personal Communication, 2001).

Primary processing of the essential oil in form of post-harvest operation, e.g. drying and storage of the plant material, and down stream processing (e.g. rectification) add value to the oils. The requirement for post-harvest operations are beyond the means of most rural enterprises. However, such processing centres may be operated near the source by the government or cooperative societies to feed national industries improving thereby the local employment and income.

Rectification of the essential oils can produce pure isolates of added value. Depending on their end uses this may consist of one or more of the following:

Rectification of the oils is done by fractionation. As suggested by De Silva and Atal (1995) it could be carried out in some developed rural areas having small scale processing with backup from national research institution to carry out the analysis and develop the fractionation parameters. This needs more training and equipment and may not be possible in certain rural communities or for forest dwellers. Alternatively fractionation of the oils could be carried out at a central facility which can afford to invest the funds and personnel required for this activity. These pure isolates could further be processed to produce high value aromatic chemicals which have an export market. These aromatic chemicals can be used in blending of perfumes and flavours for local industries.

Essential oils produced in India could be divided into the following categories (S.C Varshney, Personal Communication, 2001):

It is evident that most of these oils are meant for processing and therefore, there exist innumerable possibilities for their value addition. This includes isolation of valuable constituent in high purity and their transformation into useful derivatives. For example, processing of eucalyptus oil obtained from Eucalyptus globulol could isolate valuable constituents (e.g. globulol, eudesmol, viridiflorol and farnesol) constituting 5-6 percent of the oil. The residual oil left after separation of these constituents can be sold at lower prices. Isolates of various essential oils such as citral, citronellal, caryophyllene, geraniol, cis-3-hexanol, himachalene, pulegone/ isopulegone, isomenthol, l-limonene, linalool, methones, neomenthol, 3-octanol, a and b-pinenes, terpinolenes, etc. are available with processing units. Many value-added products can be obtained by further processing these isolates.

Besides above, R&D efforts should also be directed to explore new oils having greatest economic potential as flavours, fragrances and therapeutic agents. Efforts should also be extended to locate such oils, which contain valuable minor constituents, e.g. germacrene-D, b-damascenone, b-and g- endesmol, isoeugenol, lavandulol, cis-rose oxide, etc.

Vitex negundo is of medicinal/pesticidal value. The leaf oil of this species is found to contain 66 compounds. The main compounds were viridiflorol (19.55 percent), b-caryoplyllene (16.59 percent), sabinene (12.07 percent) and a-terpineol (9.65 percent) (Singh et al. 1999). The oil also showed 100 percent mortality against the stored grain pest, Sitotroga cereallela, infesting wheat, seeds and thus has potential to be developed into a pesticide (Singh et al. 2002). The oil isolated from flowering twigs shows the presence of 94 compounds of which 28 compounds were identified with viridiflorol as chief constituent (Singh et al. 2000). Both these oils could be a good source of viridiflorol, which has biological acitivity as antiacetylcholinesterase agent, IC 50 = 25µg/ml (Duke 1995).

Needles of Cephalotaxus harringtonia var. harringtonia is of medicinal value. Investigations were made to isolate essential oils from the needles and flowering twigs produced oil with 31 compounds. 17 compounds were identified with b-caryophyllene (27.9 percent, 31.3 percent); a-humulene (11.4 percent, 10.6 percent), germacrene-D (9.5 percent, 13.0 percent), g-cadinene (8.9 percent, 5.5 percent) and b-elenene (8.3 percent, 10.9 percent) as major constituents. (Mehndiratta et al. 2003).

Essential oils from different parts of Shorea robusta were isolated and characterized (Kaur et al. 2001 and others). The oils obtained from leaves, heartwood and resin showed the presence of 20, 24 and 37 compounds of which 8, 9, 17 and 9 compounds, respectively were identified. a and b-caryophyllens (4.55 percent and 28.27 percent, respectively) were the main constituents in the leaf oil while germacrene-D was the chief constituent in resin oil (29.57 percent) and heartwood oil (31.79 percent). Presence of caryophyllenes in leaf oil suggests its possible use as anti carcinogenic as the caryophyllens are reported to be potential anti carcinogenic agents. Heatwood oil can be a good source of germacrene-D as it is a valuable sesquiterpene needed by many perfumers.

Agar oil, obtained by the steam distillation of agar wood, is highly priced in perfumery. Distillation of this oil is very slow, and the odoriferous constituents distill over only towards the end of the distillation. An inexpensive modification was suggested which employs hydrodistillation of the chips in which a solution of common salt is used in the place of water. Water from the distillate is returned to the still in the beginning of the distillation and at the end of distillation. Clear separation of the oil could be achieved by saturating the distillate with common salt. The oil obtained was comparable to that obtained by the indigenous method and the yield (0.54 percent) was higher by about 20 percent.

Bulk of the camphor produced in India is synthetic camphor produced from a-pinene. Investigations have revealed that leaves of Ocimum kilimandscharicum on distillation yield an essential oil (2.5-5.8 percent) which contains more than 50 percent camphor. A cheap method of isolation and purification of camphor from this oil was developed. Production of camphor from Ocimum kilimandscharicum can easily be adapted as cottage industry because of the inexpensive nature of process, and the plant can be cultivated easily using techniques developed by FRI.

Perfumery compounds have also been prepared from pine needles which are plenty in the pine forests. On an average, one ha of well stocked chir pine forest sheds about 10 tonnes of pine needles per annum. Pine needles, by chlorofom extraction, gave 1.08 percent wax which on hydrolysis gave a mixture of hydroxy acids in 62 percent yield. The acid mixture was converted to a mixture of macrocyclic lactones with long lasting musk odour in 61 percent yield (Dayal et al. 1989).

LEAF PROTEIN CONCENTRATES (LPC)

Short supply of good quality protein to meet the requirement of increasing animal and human population has necessitated the search for additional sources. The unconventional sources of protein which include oilseed meals, fish protein concentrate, single cell protein and perhaps algal and leaf protein have tremendous scope for developing of low cost protein foods. Out of all the unconventional sources of protein, leaf protein appears to have better exploitation in the light of excessive photosynthesis and availability of abundant lush green vegetation (Srivastava and Mohan 1989).

Leaf proteins have been found to have greater nutritive value than most of the pulses, resembling skimmed milk in the diet of infants recovering from Kwashiorkor. Leaf protein has been advocated as a potential source for human consumption (Oelschlegel et al. 1969). Trees have also been suggested as a possible source of leaf protein food (Mohan and Srivastava 1981) in addition to already identified weeds, cultivated crops and wild plants. Moreover production of leaf proteins from trees have unique scope as they do not involve recurring cost of cultivation.

Realizing the importance of the leaf protein concentrate (LPC) in poultry and human nutrition, and potential of trees for production of LPC, a number of tree species such as Morus alba, Cassia fistula, Sesbania grandiflora, Gliricidia maculata, Moringa oleifera and Leucaena leucocephala have been studied for leaf protein extractability and chemical composition of recovered LPC to judge their suitability for the bulk production of LPC (Mohan and Srivastava 1981). Cassia, Sesbania, Gliricidia and Morus showed fairly good extracability of protein N (45.1, 45.9, 37.4 and 33.8 percent, respectively). They also yielded crude products having good nitrogen content of 6.58, 6.86, 7.00 and 6.44, respectively. Sesbania leaves showed the highest LPC recovery of 9.44 g/100 g of fresh pulp while Gliricidia LPC showed highest percentages of protein and ether extracts of 43.8 and 15.1, respectively and lowest ash of 3.60 percent.

Studies carried out by Srivastava and Mohan (1989) have demonstrated that LPC from mulberry leaves could be utilized as human food or as nutritious feed for silkworm, poultry and cattle. The importance of leaf protein fractionation which results in chloroplastic and cytoplasmic fraction has been emphasized in poultry and human nutrition (Mohan and Srivasatava 1984). Variability in composition and nutritive value of these fractions from various plant species has been reported (Betschart and Kinsella 1974). The biochemical composition and nutritive value of the leaf protein fraction from Morus alba, Gliricidia maculata and Sesbania grandiflora have been reported by Mohan and Srivasatava (1981). Cytoplasmic leaf protein fraction from Sesbania grandiflora were found to be suitable for human consumption while the choloroplastic fraction for use in poultry feed.

BIBLIOGRAPHY

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[15] Chemistry Division, Forest Research Institute, Dehradun, India; E-mail: sonipl@icfre.org
[16] Chemistry Division, Forest Research Institute, Dehradun, India; E-mail: sonipl@icfre.org

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