Naslov
Parametri compositivi per la valutazione dell’ olio extra vergine di oliva prodotto in Istria – Croazia
(Compositional parameters in evaluation of extra virgin olive oil produced in Istria - Croatia)

Autori
Sponza, Silvia

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, diplomski rad

Fakultet
Agronomski fakultet

Mjesto
Udine (Italija)

Datum
13.03

Godina
2006

Stranica
94

Mentor
Koprivnjak, Olivera

Neposredni voditelj
Conte, Lanfranco

Ključne riječi
olio extra vergine di oliva; composizione; Istria
(extra virgin olive oil; composition; Istria)

Sažetak
The region Istria is placed on the northern limit of the distribution area of the olive. The Istrian olive oil production is the 7% of the total production in Croatia. In the Istrian region, there are fifteen oil mills with a total work capacity of 11850 Kg olives/h. This work deals with the olive oil made from five olive sorts: Bjelica, Buža, Karbonaca, Rosinjola and Leccino that grow in Istria. The olive oil of this thesis has been made from olives with the same maturation index. Half of the olives have been destoned. The centrifugation method of extraction has been used. All the samples of olive oil have been put in vials in a dark place during the storage. The evaluation of olive oils quality has been carried out analysing the parameters fixed by international laws (COI) and using also parameters “ not law fix” but useful for the evaluation of the quality (amount of tocopherols and phenolic compounds, composition of volatile fraction). The analysis are: composition of fat acids and rancimat test once ; free acidity, peroxide value, poliphenols with Folin Ciocalteau method and panel test every three months ; tocopherols, poliphenols with HPLC and volatile fraction with SPME-GC-MS every six months. The most part of the samples has a lower value of free acidity than the one for the extra virgin class. This shows a good process of manufacture. The peroxide values are also low. There is no important difference between the samples made from destoned olive and the “ classic” one. During the storage, these two parameters have not changed. A statistic analysis has not been made because of the low number of samples. The composition of fat acids has shown high concentrations of oleic acid (>74%) independent of the olive sort or of the destoned olive. About the tocopherols, the sort Leccino has the highest concentration of tocopherols, independent of the presence of the stone ; Karbonaca and Buža have similar values ; Bjelica has the lowest value. During the storage, the concentration of tocopherols has decreased in all the samples. About the poliphenols, the sort Bjelica has the highest values (300-460 mg/Kg), Leccino has the lowest values (5-40 mg/Kg) ; as before, Buža e Karbonaca have similar values. All the sorts show higher concentrations of poliphenols in the samples of oil made from destoned olive. This shows that, being the activity of the poliphenol-oxidize enzyme in the seed high, in the oil made of destoned olive is reduced the degradation of the poliphenols. The evaluation of the stability of the oil has been determined with the rancimat test: the sorts Bjelica and Rosinjola have the stablest oil. The panel test shows: the oil of the sort Bjelica has high sensorial qualities of fruit, of bitter and sharp, and absence of sweet ; the oil of the sort Leccino has the highest sensorial quality of sweet. In both cases these sensorial qualities are independent of the presence of the stone in the olive. SPME-GC-MS has been applied to evaluate the volatile fraction of the samples. About sixty compounds have been found, whose distribution is very articulated in relation with the sort, destoned olive and time storage.

Izvorni jezik
Ita

Znanstvena područja
Prehrambena tehnologija

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