Uticaj kvaliteta semenki grožđa na bioaktivne komponente i održivost hladno presovanog ulja

Abstract

Podizanje novih zasada i povećanje kapaciteta prerade grožđa povećava količinu otpada sa kojim se suočava industrija proizvodnje vina i rakije. Najbolji i najodgovorniji način upravljanja otpadom je njegovo dalje iskorišćenje kao nusproizvoda. U ovoj disertaciji sagledavana je mogućnost iskorišćenja nusproizvoda iz različitih faza proizvodnje u vinarijama i destilerijama za dobijanje semenki grožđa koje su korišćene za proizvodnju hladno presovanog ulja. Hipoteza se zasniva na činjenici da semenke grožđa raznih sorti iz različitih faza proizvodnje vina (bela, roze ili crvena vina), odnosno, rakije mogu imati sasvim različit hemijski sastav i kvalitet koji svakako može da se reflektuje na kvalitet, bioaktivne komponente i održivost hladno presovanog ulja. Ovakav proizvod, obzirom da je dobijen hladnim presovanjem, može biti veoma atraktivan za potrošače, zbog svojih specifičnih senzorskih i nutritivnih karakteristika. Za potrebe izrade disertacije prikupljeni su nusproizvodi i pripremljeni su uzorci iz vinarija i destilerija fruškogorskog vinogorja. Dobijene su semenke i proizvedeno hladno presovano ulje od semenki crnog grožđa sorte Merlot, belog grožđa sorte Italijanski rizling i belog grožđa sorte Sila, kao autohtone sorte vinove loze. Hladno presovana ulja su proizvedena od semenki grožđa koje nisu prošle nikakav tretman, odnosno dobijene su nakon presovanja, prilikom proizvodnje belih (Italijanski rizling i Sila) i roze (Merlot) vina, zatim od semenki koje su prošle proces fermentacije prilikom proizvodnje crvenih vina (Merlot) i od semenki koje su prošle proces fermentacije i destilacije prilikom proizvodnje rakije (Merlot, Italijanski rizling i Sila). Pored navedenih semenki i ulja, pripremljen je i prosečan proizvodni uzorak koji predstavlja uzorak dobijen od svih prikupljenih semenki. Kao uporedni uzorci korišćeno je nerafinisano i rafinisano ulje od semenki grožđa nabavljeno na tržištu. Za realizaciju postavljenog cilja, rad na izvođenju ove disertacije obuhvatio je različite faze. U prvoj fazi prikupljene su semenke grožđa i ispitivane su njihove tehničko-tehnološke karakteristika i kvalitet. Zatim su od navedenih semenki proizvedena hladno presovana ulja. U sledećim fazama, ovako dobijena uja, zajedno sa uzorkom nerafinisanog i rafinisanog ulja od semenki grožđa sa tržišta ispitivana su sa aspekta senzorskog i nutritivnog kvaliteta i praćene su razlike u održivosti ulja. Izvršena je senzorska analiza, određivane su frakcije pigmenata, karotenoidi i hlorofili, merena je transparencija, a parametri boje ulja određivani su i instrumentalno. Nutritivni kvalitet ulja sagledavan je na osnovu sadržaja i sastava bioaktivnih komponenti, pre svega tokoferola i tokotrienola, fenola i sterola. Budući da ova jedinjenja ispoljavaju značajne antioksidativne aktivnosti izvršeno je i ispitivanje antiradikalske aktivnosti uzoraka. Odživost ulja od semenki grožđa sagledana je na osnovu početnog kvaliteta i oksidativnog stanja, kao i rezultata ubrzanih testova, kao što je Rancimat test, Schaal-oven test i fluorescentni test. Na osnovu dobijenih rezultata, može se konstatovati da su svi dobijeni uzorci semenki imali dobru skladišnu vlagu, koja, obzirom na mali sadržaj ulja u semenkama, može da osigura čuvanje semenki u dužem periodu. Sadržaj ulja u semenkama, pored uticaja sorte vinove loze, zavisi i od uticaja procesa kome su podvrgnute semenke pre presovanja (fermentacija, destilacija). Senzorska analiza ulja od semenki grožđa pokazala je značajne razlike u karakteristikama koje su posledica ne samo načina dobijanja ulja (hladno presovano ili rafinisano), sorte vinove loze, već i postupka dobijanja, porekla i kvaliteta semenki grožđa. Uslovi kojima su semenke grožđa izložene u toku alkoholne fermentacije i posebno destilacije utiču na formiranje specifične arome hladno presovanog ulja. I pored toga što se pojavljuje izuzetno širok spektar različitih aroma, mirisa i ukusa u ulju i što postoje značajne razlike u aromi ulja u zavisnosti od sorte grožđa, moguće je prepoznati da li je hladno presovano ulje dobijeno od semenki grožđa bez fermentacije, posle fermentacije ili posle destilacije. Takođe, sa aspekta boje ulja može se kazati da rafinisano ulje od semenki grožđa ima svetlo žutu boju sa zelenkastom nijansom, dok su hladno presovana ulja intenzivnijih boja i kreću se od žuto-zelenkaste, preko zelenkasto žute i svetlo zelenkaste do tamno zelene. Veći udeo zelene boje imaju hladno presovana ulja od semenki grožđa dobijenih posle destilacije. U radu je pokazano da sadržaj pigmenata (karotenoida i hlorofila) u velikoj meri zavisi od porekla semenki. Postupak fermentacije doprinosi povećanju sadržaja pigmenata, dok postupak destilacije, zbog visokih temperatura ima negativan efekat. Transparencija uzoraka hladno presovanih ulja od semenki grožđa proizvedenih za potrebe disertacije kretala se od 32,8% do 53,8%. Sadržaj nezasićenih masnih kiselina u svim uzorcima ulja od semenki grožđa veći je od 90%, pri čemu dominantnu masnu kiselinu čini linolna, omega-6, masna kiselina. Sadržaj tokotrienola je veći od sadržaja tokoferola u uljima od semenki grožđa, a dominantni tokoferol je alfatokoferol. Njegov sadržaj je veći u uzorcima ulja dobijenim iz semenki nakon fermentacije i destilacije. Sadržaj fenolnih jedinjenja, u zavisnosti od sorte, u proseku je nešto viši u hladno presovanim uljima dobijenim od crvene sorte grožđa, ali uočava se i značajan porast (akumulacija) fenola u hladno presovanim uljima dobijenim iz semenki grožđa nakon procesa fermentacije i destilacije. Najveći pojedinačni sadržaju u ulju od semenki grožđa ima ursolna kiselina, a pored nje značajniji sadržaj, mada mnogo manji, pokazuju rezveratrol, kemferol i vanilinska kiselina. Najzastupljeniji steroli ulja semenki grožđa su β- sitosterol sa udelom od 62,59-69,74%, stigmasterol sa udelom od 12,13-15,00% i kampesterol sa udelom od 6,59- 11,94% u ukupnim sterolima. Na sadržaj fitosterola u uljima od semenki grožđa nemaju uticaja procesi fermentacije i destilacije kojima su podvrgnute semenke pre preosvanja. U radu je dokazan negativan uticaj procesa fermentacije i destilacije kojima su povrgnute semenke grožđa na antiradikalski potencijal dobijenih ulja. Antiradikalski potencijal ulja od semenki grožđa zavisi i od sorte vinove loze, kao i od načina dobijanja ulja (hladno presovano ili rafinisano). Procesi fermentacije i destilacije utiču i na osnovni hemijski kvalitet dobijenih hladno presovanih ulja na način da dovode do povećanja kiselinskog i peroksidnog broja. Hladno presovana ulja od semenki grožđa pokazuju dobru oksidativnu stabilnost. Rancimat test je pokazao razlike u indukcionom periodu hladno presovanih ulja od semenki grožđa kao posledicu razlike u sorti, kao i u načinu dobijanja semenki. Proces fermentacije utiče na povećanje, a proces destilacije na smanjenje indukcionog perioda. Na osnovu svih dobijenih rezultata istraživanja može se konstatovati da su hladno presovana ulja od semenki grožđa pokazala različit nutritivni kvalitet i oksidativnu stabilnost, zbog specifičnih razlika koje su posledica razlika u sorti i poreklu semenki, tj. zbog specifičnog efekta fermentacije i destilacije na semenke od kojih je ulje proizvedeno, čime je i potvrđena hipoteza.

Raising new plantations and increasing the grape processing capacity increases the amount of waste faced by the wine and brandy industry. The best and most responsible way of waste management is its further exploitation as by-products. In this dissertation, the possibility of using by-products from different stages of production in wineries and distilleries for obtaining grape seeds, which were used for the production of cold pressed oil, was examined. The hypothesis is based on the fact that grape seeds of various varieties from different stages of wine production (white, rose or red wine), that is, brandy can have a completely different chemical composition and quality that can certainly be reflected on the quality, bioactive components and stability of cold pressed oil. Such a product, as it is obtained by cold pressing, can be very attractive to consumers, due to its specific sensory and nutritional characteristics. For the needs of the dissertation, the by-products were collected and samples were prepared from the wineries and distilleries of the Fruška Gora vineyard. Seeds were obtained and cold pressed oil produced from Merlot grape seed, as representatives of red grape varieties, Italian Riesling, as representatives of white grape varieties and Sila, as new white grape varieties. Cold pressed oils were produced from grape seeds that did not undergo any treatment, that is, they were obtained after pressing, during the production of white (Italian Riesling and Sila) and rose (Merlot) wines, then from the seeds that were fermented during the production of red wines (Merlot ) and seeds that have undergone fermentation and distillation process during the production of brandy (Merlot, Italian Riesling and Sila). In addition to the mentioned seeds and oils, an average production sample was prepared, which is a sample obtained from all collected seeds. Unrefined and refined grape seed oil purchased on the market was used as comparative samples. For realization of the set goal, the work on the performance of this dissertation encompassed different phases. In the first phase, grape seed were collected and their technical and technological characteristics and quality were examined. Then cold-pressed oils were produced from these seeds. In the following phases, the resulting ear, together with a sample of unrefined and refined grape seed oil from the market, were examined from the aspect of sensory and nutritional quality and differences in oil stability were observed. Sensory analysis was performed, pigmentate fractions, carotenoids and chlorophylls were determined, transparency was measured, and oil color parameters were also determined instrumentally. The nutritive oil quality was examined based on the content and composition of bioactive components, primarily tocopherols and tocotrienols, phenols and sterols. Since these compounds exhibit significant antioxidant activities, the antiradical activity of the samples was also tested. The stability of grape seed oils was examined based on the initial quality and the oxidative state, as well as the results of accelerated tests, such as Rancimat test, Schaal-oven and fluorescence test. On the basis of the obtained results, it can be concluded that all the obtained seed samples had good storage moisture, which, given the small content of oil in the seeds, can ensure the storage of seeds for a longer period. The content of oil in the seed, in addition to the influence of the grape variety, depends on the influence of the process to which the seeds are subjected to pressing (fermentation, distillation). Sensory analysis grape seed oils showed significant differences in characteristics that are due not only to the method of obtaining oil (cold pressed or refined), grape varieties, but also the method of obtaining, the origin and quality of grape seed. The conditions for grape seeds exposed during fermentation and especially distillation affect the formation of a specific cold pressed oil. Although an extremely wide range of different flavors, odors and flavors in oil appear, and there are significant differences in the aroma of the oil, depending on the grape variety, it is possible to recognize whether the cold-pressed oil is derived from the grape seed without fermentation, after fermentation or after distillation. Also, from the aspect of oil color it can be said that refined grape seed oil has a light yellow color with a greenish shade, while cold pressed grape seed oils have more intense colors range from yellowish-greenish, over greenish yellow and light greenish to dark green. A higher proportion of green color has cold pressed grape seed oils obtained after distillation. The thesis has shown that the content of pigments (carotenoids and chlorophyll) depends to a great extent on the origin of the seed. The fermentation process contributes to increasing the content of pigments, while the distillation process has a negative effect due to high temperatures. Transparency of cold pressed grape seed oils produced for the dissertation ranged from 32.8% to 53.8%. The content of unsaturated fatty acids in all samples of grape seed oil is greater than 90%, with the dominant fatty acid being linoleic, omega-6, fatty acid. The content of tocotrienols is higher than the content of tocopherols in grape seed oils, and the dominant tocopherol is alpha-tocopherol. Its content is higher in oil samples obtained from the seed after fermentation and distillation. The content of phenol compounds, depending on the variety, is somewhat higher in cold pressed oils obtained from red grape varieties, but there is also a significant increase in accumulation of phenol in cold pressed oils obtained from the grape seed after the fermentation and distillation process. The largest individual oil content of grape seeds has ursolic acid, and besides it, significant content, although much smaller, shows rezveratrol, kemferol and vanillinic acid. The most prevalent sterols of grape seed oils are β- sitosterol with a share of 62.59-69.74%, stigmasterol with a share of 12.13-15.00% and campesterol with a share of 6.59-11.94% in total sterols. Fermentation and distilation processes, to which the seeds have been exposed, have no effect on the content of phytosterols in grape seed oils. The paper has shown the negative influence of the fermentation and distillation process, to which the seeds have been exposed, onto the antiradical potential of the obtained oils. The antiradical potential of grape seed oils depends on grape varietes, as well as on the way oil is obtained (cold pressed or refined). Processes of fermentation and distillation also affect the basic chemical quality of obtained cold pressed oils in such a way as to increase the acid and peroxide values. Cold pressed grape seed oils show good oxidative stability. The Rancimat test showed differences in the induction period of cold pressed grape seed oils as a result of the variation in the variety, as well as in the method of obtaining the seed. The fermentation process affects the increase, and the process of distillation decreases the induction period. Based on all the obtained results, it can be concluded that cold pressed grape seed oils showed different nutritional quality and oxidative stability due to specific differences resulting from differences in variety and seed origin, i.e. due to the specific effect of fermentation and distillation processes on the seeds from which the oil was produced, thus confirming the hypothesis.