Saturday, September 26, 1998
Solution to bitterness in citrus
Solution to bitterness in citrus juices
By B.R. Premi and R.N. Hegde
India holds third rank in respect of production of citrus fruits in the world. The citrus group include sweet orange, mandarin, lemon, acid lime, pumello, grapefruit etc. Though we produce nearly four million MT of citrus fruits, due to our poor post-harvest infrastructure facilities, the wastage of citrus fruits amount to nearly one million MT per annum. There is a need to utilise this wastage to improve the nutritional and health status of people so also to provide remunerative prices to the farmers during seasonal glut.
The commercial cultivation of citrus is concentrated in the northern, eastern and western parts of India. Maharashtra is very famous for its mausami and Nagpuri santra. Punjab is known for its kinnow, mandarin and malta. Citrus fruits are considered as one of the nutritious fruits because these are the rich source of B-carotene (vitamin A source), ascorbic acid (vitamin C) and folic acid. All these vitamins provide protection against fatal diseases like cancer, heart ailments, and neutral tube defects. Doctors recommend orange juice for infants as a supplementary source of vitamin C.
While the fresh fruit juice is a common menu in British, American, and continental breakfasts, in India the fruit juice is still a luxury. The European Community, the USA and Japan are the largest consumers of fruit juice in the world. Brazil and Argentina have large citrus orchards and where citrus juice concentrates are directly loaded on the ships from the fruit processing factories for export. The Australian citrus industry is one of the world famous and highly commercialised where the various operations right from raising nurseries, planting, production techniques and harvesting is fully mechanised. Further processing and packaging of citrus fruit products are done through computer-aided, automated systems.
Commercially manufactured citrus products abroad are juice, frozen citrus juice, squash, marmalade, cordial, concentrate, etc. However, in India only fresh citrus juice is very common. During most part of the year fresh citrus juice stalls and rehris are found in every nook and corner. At present orange, lemon and lime squash containing only 25 per cent of fruit juice, which is further diluted to nearly 10 per cent while serving, is available in our country.
While the Wes-terners like the citrus juices with slight bitter taste, the Indians are very sensitive to bitterness. Hence, the major impediment for the increased consumption of fresh citrus juices and their products is the development of bitter taste. Further, despite of high volume of production waste for want of suitable preservation methods to produce non-bitter citrus juice, the Indian citrus industry has not yet developed. Although a good amount of research has been conducted by the CFTRI, Mysore, the IARI, New Delhi, and other state agricultural universities, not a single commercial unit has been established so far in the country. However, it has been learnt that the National Horticultural Board (NHB) has sanctioned one research project to the Dr Y.S. Parmar University of Horticulture and Forestry, Solan (HP), to establish a pilot scale debittering plant. This project was conceived with the aim of promoting debittering technology in the country.
Potential areas for expansion of citrus fruits such as kinnow, orange, etc. in North India is associated with several other problems like lack of pre-cooling and cold storage infrastructure facilities, low prices due to seasonal glut, stem and puncturing followed by penicillium rotting, etc. The preservation of citrus juices is also very difficult because the citrus juice go highly bitter within four hours of extraction.
Scienti-fic mention of bitterness in literature was first made during 1857 in Java. Later two classes of chemical compounds namely flavonoids and limonoids were found responsible for bitterness in citrus juices. However, there is a difference between flavonoid and limonoid bitterness. The fruits containing high flavonoids are bitter even when consumed as fresh. The peel (rind) of the citrus fruit contain very high amount of flavo-noides like naringin, neohesperidine, etc. making it highly bitter. The limonoids are present in the form of non-bitter compound (limonoate-A-ring lactone) which is converted to bitter limonin and other bitter limonoids in the presence of enzyme limonoate-D-ring lactone hydrolase on storage. Hence, the fresh citrus juice does not taste bitter but turns highly bitter on storage. Several other factors like storage temperature, acidic medium of the juice, etc. also play a vital role in the development of bitterness. This is known as "delayed bitterness".
Several efforts have been made abroad to process citrus juice free from bitterness. The developed countries have well-developed methods of debittering citrus juices. But India lacks all these methods and processes. Research round-up in this direction reveals that efforts were made.
To use root stocks like trifoliate orange, tangello, cleopatra mandarins which are low in limonin.
Pre-harvest sprays of 250 ppm each of 2(4-ethyl phenoxy)triethyl amine and 2(3,4-dimethyl phenoxy) triethyl amine.
Exposure of harvested fruit to 20 ppm of ethylene gas for four hour. The ethylene gas is easily available nowadays either in form of ethylene ampule or ethrel formulations.
Juice extraction without damaging citrus fruit tissues help in lower limonin content in the juice.
Masking bitterness by addition of sweeteners like sucrose to juice.
Carbonation of juice immediately after extraction under chilling temperatures.
Enzymatic debittering by using immobilised enzymes or micro-organisms in bioreactors.
Debittering using membrane technology by using cellulose estate polymers.
Debittering of juice in columns packed with polymer absorbents.
Among all these methods, the technology of debittering by columns packed with absorbents like amberlite XAD-16 andB-cyclodextrin polymers have been exploited for commercial debittering of citrus juice abroad. A view of pilot plant used to debitter citrus juices at commercial scale has been shown in the figure.
The juice is fed from the bottom with the help of feed pump at specific speed through a column packed with polymer. As the juice passes through the polymer, the polymer gets mixed with the juice and the bitter compounds are fixed on the active sites of the polymer. The non-bitter juice is collected from the top out let. However, the original taste and nutritional status of the citrus juice remain intact. The polymer can be reused several times by washing it with light alkali solution (caustic soda). The capacity of the pilot plant can be increased as per the requirement either by using bigger-sized (dia) columns or by installing a series of debittering columns. The juice is either treated first and then concentrated to make citrus concentrate or concentrate is prepared first and treated after proper dilution to single strength.
The plants can be fabricated indigenously with the help of any food processing machinery manufacturer. The amberlite XAD-16 polymer has to be imported from abroad. The reputed chemical companies of the USA, Australia, etc. are the world suppliers of these polymers. The entrepreneurs interested in establishing commercial debittering units for citrus may contact the agencies like the National Horticulture Board, Gurgaon (Haryana), the IARI, New Delhi, the CFTRI, Mysore, and state agricultural universities for further details.
Crop diversification: easier said than done
By A.S. Prashar
DIVERSIFICATION. This has become the new buzzword in the farmer-friendly Government of Punjab. The Chief Minister, Mr Parkash Singh Badal, and the Minister for Agriculture, Mr Gurdev Singh Badal seldom miss an opportunity at most of their rural public meetings to exhort the farmers to get out of the wheat-rice rotation and go in for other, more paying crops.
"Farming is no longer a paying proposition," says the Chief Minister. The increasing population pressure, shrinkage of land holdings and rising cost of inputs and the inability of the government to keep pace with it by fixing higher support prices for the farm produce have made farming an unremunerative profession. Hence, the need for going in for crops which ensure better returns for the farmers.
Punjabs rice, one of the mainstays of agriculture in the border state, is no longer as much sought-after in the country as it was until a few years ago. "For one thing, most other states of India have begun to grow enough to meet their own food requirements," says Mr Badal. Another factor is the sharp increase in the number of complaints about the quality of rice procured in the state, especially during the last year. Farmers brought to the mandis the paddy which did not meet the quality norms set by the Government of India. The produce was purchased by the official procurement agencies under pressure from the government. The quality specifications were later relaxed by the Government of India on a representation by the Punjab Government, but the rice it yielded has no takers.
"I have had a talk with the Union Minister for Food, Mr Surjit Singh Barnala," says Mr Badal. "He says that there is just no demand for Punjab rice because most of the consuming states entertain serious doubts about the quality of Punjab rice and are, therefore, meeting their requirements from elsewhere".
Mr Badal is of the view that coming days may witness a further decline in demand for Punjab rice, not so such because of its quality, but due to the fact that most states will be able to meet their requirements on their own. Hence, the need for the farmers to go in for some other crops.
For this, Mr Badal feels, the cultivation of basmati instead of ordinary rice may offer a much higher return to the farmers. The basmati rice not only fetches a much higher price in the domestic market but is also in great demand abroad. But this is easier said than done, feel the farm scientists at Punjab Agricultual University, Ludhiana. One reason why the Punjab farmer has taken to cultivating rice is the assured return on it by way of the minimum support price fixed by the Government of India. This support price is not available for the basmati rice or for that matter, most other agricultural commodities. In the absence of a support price, the farmer will be exposed to the vagaries of an open market economy. This is a risk he is not willing to take at present.
What prevents the Government of India from fixing a support price for the basmati rice is the wide variation in quality in this variety of rice. Any deviation from the standards set by the Government of India may lead to the rejection of basmati stocks which in turn will lead to widespread discontentment among the farmers. No Indian Government is as yet ready for this. Consequently, the Punjab farmer remains entangled in the wheat-rice rotation.
Dr Jaspinder Singh Kolar, Director, Extension Education, PAU, feels that the solution to the problem lies in introducing contract farming of different crops by private sector companies. Experiments in this regard in the past have been a resounding success. He points out that many multinationals and private individuals have made inroads into selected areas and specialised fields through a system of contract farming as for tomato (Brook Bond Pvt. Ltd. and Nijjar Agro), chillies in the case of Pepsi Foods Limited, and mentha in the case of Indo-US Mint Pvt Ltd.
The philosophy of this system is an integrated approach ie laboratory-land-factory market. The objective is to organise production of adequate quantities of produce for the processing unit. Farmers are identified in compact blocks assigned contracts for areas and quantities at an agreed price and served for cirtical inputs such as seed or nursery. Experience had proved a grand success in the tomato, chillies and mentha crops. Earlier experience of Nestle India Ltd. at Moga in milk production, processing and marketing has also been a magnificent success.
This experience can be repeated in sugarcane as well. Contractual flower seed production by multinationals is another area which can offer high returns to farmers. All this requires industrialisation of the agricultural sector and establishment of more and more agro-processing units in the state, besides creation of an infrastructure for storage, transportation and marketing of the agricultural produce. This in turn requires a huge investment and time. This is where the government comes in. Mere exhortations to the farmers to diversify will not do. "It will have to be a joint effort. The government must help them diversify by facilitating establishment of more and more agro-industries which in turn will help the farmer to venture into cultivating new crops," says Dr Kolar.
Plantation and care of fruit plants
By S.S. Cheema
FRUIT plants occupy an area of about 81,766 hectares in Punjab with a production of approximately 7.36 lakh tonnes of fruit. Keeping in view the minimum per capita requirement of 125 gm fruit per day as advocated by nutritionists our production of fruits is short by 25 per cent. Punjab being the most prosperous state of India and keeping in view the importance of fruits in human health the state should strive to produce much more fruits. This needs a two-pronged strategy to bring more area under fruit and to increase the per unit production. Planting of fruit plants is a long time investment and needs careful planning and implementation. Any mistake made in the beginning is very difficult to rectify later.
There is a popular saying that either you select a fruit which suits your area or plant in an area which suits the fruit you intend to plant. Keeping this in view Punjab has been divided into different fruit zones the Submontane zone for mango, litchi, mandarin, pear, guava, peach and loquat; the central zone for pear, guava, grape, peach, plum, ber, mandarin and baramasi lemon; the arid-irrigated zone for sweet orange, mandarin, grape fruit, sweet lime, baramasi lemon, grape peach and ber; the kandi area for mandarin, galgal, baramasi lemon, ber, guava and mango; and the bet area for pear, phalsa, plum and ber.
The soil for an orchard should be deep, well drained, loamy and fertile. Waterlogged, marshy and salt-affected soil should be avoided. Since the nutritional status and other conditions of sub-soil affect the deep-rooted fruit plants, land for orchard plants should be sampled for its suitability to the depth of 2 metres.
There are two planting times for evergreen fruit plants February-March and September-October. Fruit trees such as citrus, mango and litchi should preferably be planted during September-October.
Deciduous fruit plants are planted during winter when dormant. Their planting must be completed before mid-January in the case of peach and plum and up to middle of February for pear and grapes.
The plot where fruit plants are to be planted should be properly laid out marking the position of fruit plants, pollinisers, if any, roads, shed, etc. Experts help can be sought, if required.
Pits of I metre deep and I metre in diameter should be dug at least one month before planting, and filled 4 inches higher than the ground level with a mixture of top soil and well-rotten farm yard manure in equal parts. To each pit add 30 gm of 10 per cent BHC dust to avoid attack of white ants.
Arrangements for procuring healthy plants of known pedigree and free from insect or pests and diseases should be made from a reliable nursery, preferably one near to the orchard.
Evergreen fruit plants should be lifted with well-sized earth balls while the deciduous fruit plants should have good part of the root system intact.
Every young plant needs to be personally visited once a week. If need be, provide stakes or support to the young plants. Diseased and dead wood should be carefully pruned. Adequate protection against vagaries of weather is to be provided.
One irrigation should be applied immediately after planting. Young fruit plants require frequent light irrigation. Excessive irrigation should be avoided.
The young plants should be protected from insects, pests and diseases by giving protection and spray of insecticides and fungicides.
Weeds should be kept under check by hoeing. Weedicides should be avoided in young plants.
A tendency with many people, especially when planting in the backyard, is to plant saplings too closely. Thus the fruit plants do not get proper space for growth and spread. Litchi and mango needs to be planted 7.5 to 9 metres apart. Guava, peach, plum, mandarin, soft pear, pomegranate, sweet orange and grape fruit require space of 6 metres and papaya and phalsa can be planted 1.5 metres apart. Purchase 10 to 20 per cent more plants than the number of pits. These plants should be kept in the nursery for filling gaps which may develop due to death of plants.
Farm operations for September
Sow small-sized bulbs at 30 cmx30 cm distance to produce bunch onions for table use or seed production. Apply 50 kg of CAN, 155kg of superphosphate and 50 kg of muriate of potash per acre. Irrigate regularly. Plant large close neck true to type 3-4 bulbs of onion on 45 cm apart ridges. Keep plants at 30 cm to produce seed.
In the second fortnight of this month, apply 20 tonnes of well-rotten farmyard manure per acre and mix it into the soil. Apply 50 kg of CAN, 155 kg of superphosphate and 50 kg of muriate of potash per acre. Dibble or drill 225 to 250 kg healthy cloves of garlic. Keep lines 15 cm and plants 10 cm apart. Irrigate immediately thereafter. Repeat watering once a week during this month.
Start sowing "desi" varieties of radish (Punjab Pasand and Punjab Safed), turnip (L-1, 4-white) and carrot (Selection 21, No. 29) using a 4-5 kg seed rate of radish and carrot and 2-3 kg seed rate of turnip per acre. Keep ridges 45 cm and plants 7 to 8 cm apart. Cultivation of root crops on ridges helps in better growth and development of roots and easy harvest.
It is optimum time for the planting of evergreen fruit plants like mango, sweet orange, mandarin, lemon, litchi, guava, loquat and papya as the atmospheric temperature cools down considerably and there is enough moisture in the soil.
The newly planted fruit plants are very tender and, therefore, operations like irrigation, removal of stock sprouts, training, staking and plant protection measures should be undertaken with extreme care.