AGRICULTURAL RESEARCH COUNCIL GRANT
FINAL REPORT
Type of Report:Final Report
Period Covered:September 1, 1998 – September 30, 2001
Title of Project:Production and Processing of Pumpkin Seeds
Contract Number:Class (Klasa): 320-1/98-1/90,
Reference number (Ur. Broj): 525-02-98-51
Project Start Date:July 31, 1998
Principal Investigator:Josip Barčić, Ph.D., Assistant Professor
Participating Institution:Faculty of Agriculture, University of Zagreb,
Agricultural Engineering Department
In Zagreb, October 30, 2001.
______
date
Ph.D., Josip Barčić
Signature of Principal Investigator
Research Topic
Research was done at the following three family farms (FF):
- FF Hrvoje Hrvojčec, Ždralovo (Bjelovar)
- FF Drago Sito, Budrovci (Đakovo)
- FF Franjo Kovačić, Prhovec (Čakovec)
In line with the contemporary nutritional trends, modern dietary trends involve a pronounced interest in natural, wholesome food, rich in valuable ingredients, which gives a chance to increased consumption of good quality, unrefined pumpkin oil both in this country (in tourist trade) and as an important export article.
Introduction of pumpkin growing on arable areas extends the crop rotation while the economic effect of selling pumpkin products (seeds and pumpkin oil) raises the standard of living in agricultural regions where agriculture is the principal source of employment and income.
Application of combined tillage systems may appreciably reduce anthropogenic soil compaction and thereby conserve and improve soil properties, notably the rhizosphere, as the substrate for growing field and vegetable crops.
Seed loss and damage during mechanical harvest , as well as high drying costs, are the main cause of unprofitable production and processing of seeds, and consequently the high price of pumpkin oil. Besides the high purchase price, another problem is the machine mass, as well as frequent machine stoppages when working on moist soil. Research results enabled much better and more efficient seed harvesting with the existing machinery. Construction and application of a machine prototype (made in Croatia), which will be substantially lighter and obtainable at a lower price, can result in a higher efficiency and better quality of seed harvesting.
Technological drying is the continuation and completion of natural ripening of pumpkin seeds, which could not be accomplished in the natural way because of adverse climatic conditions. To enable long-term seed storage, the drying process should be aimed at preserving seed quality. The purpose of drying is to leave the seeds only as much water as that they need for latent life, which is so little that it also reduces to a minimum the biological activity of the present microorganisms.
Pumpkin seed itself has a complex geometrical shape, while the seed layer is not an uninterrupted whole but rather a heterogeneous system with different properties. Constant alternation of geometrical and aerodynamic seed layer factors as well as operating factors of the dryer cause problems in running the optimal drying process, that is, designing the drying technology.Seed, especially huskless seed, is delicate, sensitive not only to high temperature during drying but also to mechanical damage from harvesting to storage. The dark-green seed chlorophyll membrane should be fully preserved both during harvesting and the subsequent manipulation in processing, since it has a direct influence on oil colour and taste.
As huskless seeds have a different structure from that of common seeds with husks, their moisture immediately after seed separation from pumpkin fruits is also different. Thus, huskless seeds contained about 38% water, which rose to about 52% after seed washing. Common seeds with husks contained on average 47% water after harvesting, which then rose to 65% after washing. These differences in initial moisture had a different reflection, besides other factors (temperature and speed of drying air), also on the duration of the drying process.
Thus, about 650 kg water has to be separated in drying very moist huskless seeds after washing (moisture ca. 52%) of the initial mass of 1,350 kg to the final moisture of about 7%. Accordingly, the drying process requires high energy consumption and it represents a bottleneck during seed harvesting and processing. For this reason, large quantities of moist seeds have to be dried in driers in as short a time as possible, and therefore high drying air temperatures, even over 100 ºC, are applied.
Increase of the drying air temperature to 80 or 100 ºC leads to a further shortening of the process, but also causes a considerable thermal stress of seeds, which can break more easily and their quality gets directly impaired. Huskless seeds (Gleissdorf and Slovenska) are in a large part burnt, broken and almost unusable for storage and processing, since they give a bad taste and colour to oil. In contrast, there is practically no thermal damage to common seeds, which can be attributed to the protective role of husks (detailed data are provided in the enclosed papers).
Technology
1. At the family farm of Hrvoje Hrvojčec in Ždralov, the possibility was investigated of applying alternative methods and techniques in pumpkin seed production and processing. Four soil tillage systems were investigated in the production of the Austrian pumpkin cultivar Gleissdorf.
Following different tillage systems was applied:
- conventional system (plough + disc harrow + combined tools)
- conservation system (rotary harrow)
- no-till system (no-till seed drill)
- reduced system (plough + combined tools)
Silage made from pumpkin pulp, which is otherwise a by-product and is left on the field after seed harvest, was applied at this farm for the first time in Croatia in pig fattening (boar-Pietren, sow-German Landras).
2. At the family farm of Drago Sito, the main elements of seed loss and damage during mechanical seed harvesting were analyzed. It was confirmed at this farm that pumpkin can be grown as intercrop in a young plum orchard for the first few years, so as to make use of the growing space between the fruit trees and achieve a considerable financial effect. In such a case, the orchard must be supplied with a dripping irrigation system because fruit trees as well as pumpkins have high water requirements during the growing period.
3. At the family farm of Franjo Kovačić, a detailed analysis was made of the main factors of the seed drying process (cultivars Maik, Gleissdorf and the common husked seed).
Samples of three high-moisture seeds after washing were dried at drying air temperatures of 40, 60, 80 and 100 ºC, as well as at three drying air speeds, 0.8; 1.2 and 1.6 m/s, and the optimal drying regime was determined.
Economic analysis (profitability)
Standard agricultural machinery (tractor, plough, disc harrow, drag, attachments, etc.) is used for the production of pumpkin seeds. Harvesting and processing machines are also mentioned, the acquisition of which is justified if pumpkins are sown on 40-50 ha.
The presented calculation includes all services (soil tillage, treatment with protective agents, distribution of mineral and organic fertilizers) production material (seed, fertilizer, protection), and land lease. Naturally, if the farmer owns land and at least basic machinery (tractor + main tractor attachments), and pays only for the harvesting and drying services, the costs of seed production and processing are much lower.
Calculation of the huskless pumpkin seed production and processing is given in the table below.
Work operation andProduction material / Expenses and profit
Per 1 cadastre acre (kn)
(5754,64 m2)
Ploughing (autumn) / 400,00
Seedbed preparation / 200,00
Fertilizer distribution service / 70,00
Protection – treatment (2x) / 140,00
Cultivation – topdressing / 120,00
Sowing / 120,00
Fertilizer NPK (400 kg) / 800,00
Fertilizer KAN (100 kg) / 140,00
Seed (approx. 4 kg) / 480,00
Proctective agents / 270,00
Mechanical harvest (approx.
1050 kg * 0,70 kn/kg seeds) / 735,00
Drying (1350kg * 1,20 kn/kg seeds) / 1.620,00
Land lease / 250,00
Total costs (kn) / 5.345,00
Yield of dry and impurit-freed seeds (700-50 kg) (650 kg *
16 kn/kg) / 10.400,00
Profit (kn) / 5.055,00
Harvest costs
The average yield of fresh huskless seeds per 1 cadastre acre (ca. 5,700 m2) is about 1,050 kg, harvesting price about 0.7 kn/kg, which makes a total of 735 kn/acre.
Drying costs of washed seeds
Freshly harvested seeds contain about 38% water; after washing, the water content rises to about 50-55%. Thus, the mass of freshly harvested seeds from 1 acre of 1,050 kg increases after washing to about 1,350 kg. Harvested and washed seeds are then submitted to drying to the final moisture of about 7%. The mass of thus dried seeds amounts to ca. 700 kg. To dry 1,350 kg of huskless seeds (after washing) from 52 to 7% water content, almost 650 kg water has to be separated during the drying process. In such a case, the drying costs and drier depreciation amount to about 1.20 kn per 1 kg of fresh (washed) seeds multiplied by 1.350 kg, which makes a total
of 1,620 kn.
Sale of only dry seeds produced on 1 cadastre acre can bring an income of over 5,000.00 kn. Well organized production and processing of pumpkin seeds could constitute an important export product for the demanding Western-European market.
Applicability
Trials conducted at the mentioned family farms are almost fully applicable in the practice. It is noteworthy that no research in the pumpkin seed production and processing has been previously done in Croatia.
Evaluation of farmers
The trials attracted great interest among farmers at locations where they were conducted and the research itself was very interesting, which prompted some farmers to start intensive production and processing of pumpkin seeds, notably in Međimurje, Podravina and Slavonija.
Quantitative and qualitative data
It should be mentioned that the years 2000 and 2001 were expressly droughty, which resulted in 30 to 40% lower seed yields compared to average years.
Energy consumption can be greatly reduced by combined tillage systems. The lowest consumption of energy and time required for the operation was recorded in the no-tillage trial variant (453 MJ/ha), then in conservation (1,550 MJ/ha), conventional (1,919 MJ/ha), and the highest in reduced tillage (1,998 MJ/ha). Unexpectedly low seed yields in no-tillage and conservation tillage systems were caused by an extensive crust formed immediately after seed sowing. It is realistic to expect that seeds will achieve much better results in structurally better and less compacted soils in the conditions of no-tillage and conservation tillage systems.
In pig fattening (boar-Pietren, sow-German Landras), a direct saving in feed price by 12% can be achieved, and the quality of fattening can be substantially increased. A 19% higher cost-effectiveness of fattening was achieved by the application of pumpkin silage. The average income of a family member of 2,791 kuna in standard feeding of 100 fattening pigs increased to 4,310 kuna if pumpkin silage was applied (detailed data are provided in the enclosed papers).
During the harvesting of Gleissdorf seeds, at a peripheral rotation speed of the separating drum of 1.57 m/s, average seed losses of 4.4% were recorded, for Slovenska 5.21%, while the loss of Common husked seed amounted to 7.9%. The best results of pumpkin seed harvesting for all the three cultivars were achieved at the separating drum peripheral speed of 1.57 m/s (or 30 r/min).
Research results point to significantly higher harvesting losses of "Common seeds", which is attributed to the stronger bond of the placenta connecting tissue and the seed, and higher seed friction against the separating drum parts. To facilitate seed separation from the pumpkin placenta, shoots should be separated (torn off) from the stems on the fruit 3-4 weeks before the harvest, which is the so-called placenta saturation time.
Application of the drying air temperature of 60 ºC and the speed of 0.8 m/s shortens the drying time by almost three times as compared to the temperature of
40 ºC, whereby the highest quality of dried seeds is preserved.
The factors analyzed are necessary to set the algorithm for the management and control of the drier during seed drying, and the application of the smart controller (PLC), in order to attain the optimal drier operation with respect to high quality of dried seeds, process duration, and energy consumption.
Conclusions
The following effects may be achieved by applaying the research results:
- growing pumpkins in a young fruit plantation enables rational use of the area between fruit trees and brings in income before fruit trees reach fruition.
- introduction of pumpkin into field production extends the crop rotation and thereby reduces the action of pests and weeds for the next crop (e.g. wheat)
- after pumpkin crop is removed, the soil is fit for sowing e.g. wheat (deep pumpkin roots biologically drain soil, the area is free and weedless at the end of September)
- application of different tillage systems to pumpkin sowing has a direct influence on reduction of production costs,
- optimal setting of the pumpkin seed harvester influences not only the quality and harvest losses but also the harvesting results,
- during the drying process to preserve the quality of dried seeds, temperature of seed should not surpaas 60 ºC,
- speed of airflow through seeds should not exceed 0.8 m/s, otherwise the drying costs are substantially higher,
- use of pulp for animal feed enables rational utilization of the whole fruit and reduces the cost in fattening pigs,
Collaboration and Publications
Seven scientific and two technical articles from this area have been published to date:
1. Sito, S., J. Barčić, J i S. Ivančan, (1998): Utjecaj različitih temperatura radnog medija na trajanja procesa sušenja visoko vlažnih sjemenki buće nakon pranja. Poljoprivredna znanstvena smotra, Vol. 63, No 4, str. 285-290.
Sito, S., J. Barčić, J i S. Ivančan, (1998): EFFECT OF DIFFERENT AIR TEMPERATURES UPON THE DURATION OF THE DRYING PROCESS OF HIGH MOISTURE PUMPKIN SEEDS AFTER WASHING (Cucurbita pepo L.). Agriculturae Conspectus Scientificus, Vol 63, No. 4, pp. 285-290, CAB ACCESSION No. 992400843.
2. Sito, S., J. Barčić, J i S. Ivančan, (1999): Utjecaj različitih strujanja radnog medija (zraka) na trajanje procesa sušenja visoko vlažnih sjemenki buće nakon pranja. Poljoprivredna znanstvena smotra, Vol. 64, No 2, str. 131-136.
Sito, S., J. Barčić, J i S. Ivančan, (1999): EFFECT OF DIFFERENT AIRFLOW SPEEDS UPON THE DURATION OF THE DRYING PROCESS OF HIGH MOISTURE PUMPKIN SEEDS AFTER WASHING. Agriculturae Conspectus Scientificus, Vol 64, No. 2, pp. 131-136.
3. Sito, S., J. Barčić, J i G. Fabijanić, (2000): Optimalizacija procesa sušenja sjemenki bundeve. Zbornik radova, XVI Hrvatsko savjetovanje tehnologa sušenja i skladištenja s međunarodnim učešćem, Stubičke Toplice.
Sito, S., J. Barčić, J i G. Fabijanić, (2000): OPTIMIZATION OF THE PUMPKIN SEED DRYING PROCESS. Proceedings of the 16th Croatian Symposium of the Drying and Storage Technologists with international participation, Stubičke Toplice.
4. Sito, S., J. Barčić, J i G. Fabijanić, (2000): Gubici sjemenki različitih sorti bundeva tijekom strojnog ubiranja. Zbornik radova. Aktualni zadaci mehanizacije poljoprivrede, Opatija, str. 259-265.
Sito, S., J. Barčić, J i G. Fabijanić, (2000): THE LOSSES OF PUMPKIN SEED OF DIFFERENT PUMPKIN SPECIES DURING MECHANIZED HARVESTING. Proceedings of the conference Actual Tasks on Agricultural Engineering, Opatija, pp. 259-265.
5.Sito, S., Z. Grgić, J. Barčić, J i G. Fabijanić, (2000): Ekonomska učinkovitost proizvodnje i prerade bundeve u obiteljskom gospodarstvu. Zbornik radova, XVI Hrvatsko savjetovanje tehnologa sušenja i skladištenja s međunarodnim učešćem, Stubičke Toplice, str. 139-144.
Sito, S., Z. Grgić, J. Barčić, J i G. Fabijanić, (2000): COST-EFFECTIVENESS OF PUMPKIN PRODUCTION AND PROCESSING AT FAMILY FARMS. Proceedings of the 16th Croatian Symposium of the Drying and Storage Technologists with international participation, Stubičke Toplice.
6. Sito i sur., (2000): Bundevine sjemenke i delikatesno ulje. I Dio, Gospodarski list br. 9, Zagreb, str. 49-50.
Sito et al., (2000): Pumpkin Seeds and Fine Oil I, Gospodarski list No. 9, Zagreb, pp. 49-50.
7. Sito i sur., (2000): Bundevine sjemenke i delikatesno ulje. II Dio, Gospodarski list br. 10, Zagreb, str. 51.
Sito et al., (2000): (Pumpkin Seeds and Fine Oil II), Gospodarski list No. 10, Zagreb, p. 51.
8. Sito S., Barčić J., Fabijanić G. i H. Hrvojčec, (2001): Utjecaj različitih sustava obrade tla na prinos i utrošak energije u proizvodnji sjemenki bundeve. Zbornik radova, Aktualni zadaci mehanizacije poljoprivrede, Opatija. str. 179-186.
Sito S., Barčić J., Fabijanić G. i H. Hrvojčec, (2001): INFLUENCE OF DIFFERENT TILLAGE SYSTEMS ON YIELD AND ENERGY REQUIREMENT IN PUMPKIN SEED PRODUCTION.Proceedings of the conference Actual Tasks on Agricultural Engineering, Opatija, pp. 179-186.
9. Sito S., Grgić Z., Barčić J.i G. Fabijanić, (2001): Ekonomska opravdanost primjene pulpe u tovu svinja. Zbornik radova, 17. Hrvatsko savjetovanje tehnologa sušenja i skladištenja s međunarodnim učešćem, Trakošćan.
Sito S., Grgić Z., Barčić J.i G. Fabijanić, (2001): COST-EFFECTIVENESS OF PULP APPLICATION IN FATTENING PIGS. Proceedings of the 17th Croatian Symposium of the Drying and Storage Technologists with international participation, Stubičke Toplice.
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