COMPLETION REPORT Type of Report: Completion Report Period Covered: April 17th 1998. – June 17th 2001. Title of Project: Investigation of optimal harvest time for high olive oil quality in Istria. Contract Number: Maslina Project Start Date: April 17th 1998. Principal Investigator: Prof. Dr. sc. Ivo Miljković Participating Institution: ____________________ (date) Faculty of Agriculture University of Zagreb Department of Pomology _____________________________ (Signature of Principal Investigator) COMPLETION REPORT Objectives One of the major factors of olive oil quality is the degree of fruit maturity or choosing the optimal term of harvesting for each single cultivar in specific ecological conditions. The goal of this research was to find optimal harvesting moments of the most important olive cultivars in two significantly different ecological conditions of Istria. For this experiment the following olive orchards were chosen: 1. Barbariga (the property of ‘Agroprodukt’, Pula), plantation near the sea, Cultivars: Leccino on its own root Leccino on the generative root Istarska bjelica on its own root 2. Veli Mlun (near Buzet, a private plantation of Mr. Danilo Cerovac) Plantation is 30 km distant from the sea on the level above sea 250 – 300 m Cultivar: Leccino on its own root. 3. Pračana (near Buzet, a private plantation of Mr. Sirotić) Plantation is 30 km distant from the sea, on the level above sea 250 – 300 m Cultivars: Buža on its own root. Istarska bjelica on its own root. In each year of the three-year lasting research the harvest was performed in three moments of ripeness. Oil extraction using small extracting machine took place immediately after harvesting. The obtained samples were chemically analysed to prove oil quality parameters. Details dealing with setting of the experiment and with experimental results can be found in PhD dissertation of mr.sc. Đani Benčić ‘The Influence of the Degree of Ripeness and Harvesting Term on Quality of Istrian OliveOrchards Oils.’ Description of technology On the basis of results given by this research, we concluded that cultivars Leccino and Bjelica reach the optimal degree of ripeness by November 10th in ecological conditions of Buzet, when on the seaside (Pula) it is up to November 23rd. Higher indexes of ripeness, that is later dates of harvesting decrease the oil quality, and it is most obvious in decrease of the total phenols content. Cultivar Istarska bjelica showed stability in quality of oil in both ecological regions as well as in later moments of harvesting. For this reason Istarska bjelica can be harvested later – in the first half of December – without significant degradation of oil quality. Some of the oils obtained from cultivar Leccino growing by the sea contain up to two times higher quantity of total phenols in comparison to oil from the same cultivar grown in continental Istria (Buzet and its surroundings), which significantly affects sensorial characteristic. On this basis it can be said that these oils would be essentially different in their chemical composition and organoleptical characteristics. It is also possible to consult additional researches that dealt with the influence of different conditions of fruit storage on quality of cultivar’s Istarska bjelica oil, and which were presented in scientific papers: 1. Olivera Koprivnjak, G. Procida, Đ. Benčić, T. Zelinoti (1999) ‘Effect of ‘Bjelica’ Olive Fruits Storage in Sea Water on Olive oil Quality.’ Food Technology and Biotechnology, Volume 37 No. 3 p. 209-214; cited in: CC, 1999, Accession Number 244JH-0010. 2. Olivera Koprivnjak, Lanfranco S. Conte, Đani Benčić, Nicola Totis (2001) ‘Application of solid-phase microextraction of olive oil volatiles on varieties characterization’. In press; American Journal of Oil Chemist Society (JAOCS). Economical analysis (profitability) The profitability of the mentioned technology will be fully expressed when the laws regulating the standardization of olive oil quality are fully applied. Then the price will be regulated by the category to which the oil belongs. For the major Istrian cultivars this technology guarantees harvesting at the right moment. In this way it will be possible to obtain extra quality oils that can achieve up to 100% higher prices in relation to second and third class oils. We will be able to make a definitive economical analysis with the application of given laws. Applicability Applicability of optimal harvest terms for the leading Istrian olive cultivars is very easy and it depends mainly on producers’ good will. The exception is cultivar Istarska bjelica that can be harvested even later (till December 15th). But in some years Istarska bjelica can loose more than 50% of fruits before the right harvest time, and in such cases it is necessary to perform an earlier harvest time – as soon as an intensive fruit fall is observed. Also when temperature below 0 °C are lasting more then 20 hours the fruits could be frozen, which rapidly decreases the quality of oil. In this case it is necessary to perform the harvest immediately and/or to harvest in earlier terms. Evaluation of olive producers Olive producers have used our research in many cases – especially in the northern region of Istria, and in the surroundings of Buje and Buzet, where we organized a series of lectures and evaluation of their olive oil quality. For example, in year 2000, 60% of oil producers from upper Bujština had extra virgin quality olive oil what is very good success if it is known that only 5% of annually world production have extra virgin label. This success highly interested other olive producers for production of extra quality olive oil. Quantitative data Oil obtained from cultivar Istarska bjelica had significantly higher total phenol content in relationship to cultivars Leccino and Buža in all years and harvest times of research. For instance, in third harvest term (23.11.) for all three years of research there was the following content of total phenols: Table 1. 1998. Istarska bjelica Leccino Buža 1999. 284.7 182.3 90.5 2000. 257.4 103.2 90.1 340.1 130.3 143.6 Oil obtained from cultivar Leccino grown near the sea had relatively higher content of total phenols in relationship to oils from the same cultivar grown in the northern Istria. On the basis of these results it is possible to plan further research with the purpose of detail defining of oil quality specific for particular Istrian regions. Table 2. 1998. 1999. 2000. TERMS OF HARVEST TERMS OF HARVEST TERMS OF HARVEST 10.11. Leccino – Barbariga Leccino – Veli Mlun 161.1 86.9 23.11. 182.3 81.3 10.11. 217.5 144.5 23.11. 103.2 32.1 10.11. 211.4 130.0 23.11. 130.9 120.7 Qualitative data The data in this three-year research shown the same regularity in relationship between total phenols content and they can be considered reliable. However, it must be pointed out that relationship between phenols significantly oscillate due to soil water supply. Namely, in extremely dry conditions total phenols amount significantly getting higher, and mentioned regularity can be lost then. With application of irrigation it could be possible to satisfy the main conditions for achieving continued yields and optimum of oil quality. Conclusions For achieving of extra quality olive oil from the main Istrian cultivars it is necessary to perform harvest in such degree of ripeness that for cultivars Leccino and Buža comes (by calendar) up to November 15th in Istrian conditions. Cultivar Istarska bjelica can be harvesting also in later harvest terms, of course, with daily observation of fruits falling.