Various grape seed samples collected in wineries, as a by‐product before and after the fermentation process of pomace and after fermentation and distillation process of pomace, are used for oil extraction by cold pressing. Fatty acid profile, content and composition of tocopherols, content and composition of phenols, as well as the oxidative stability of oils are investigated. Obtained results show that cold pressed grape seed oils are characterized by different nutritional quality and oxidative stability, due to peculiar effects of the fermentation and distillation processes. Cold pressed oil obtained from cleaned and dried seeds of grapes after fermentation and/or distillation process is richer in bioactive compounds compared to the oil obtained from grape seeds without fermentation. On the other hand, the high temperature in distillation process of pomace has a negative effect on the content of some bioactive compounds and oxidative stability of oil from this waste material. Practical Applications: In this paper, different cold pressed grape seed oils are analyzed for nutritionally important compounds and oxidative stability. The results show that, depending on the source of grape seeds as waste material, the nutritional quality of the obtained oils differs. In the production of high quality cold pressed grape seed oil, seeds from different sources of waste should not be mixed. It is not recommended to use the seeds from the waste material after distillation process in the production of high quality cold pressed grape seed oil. Some chemical characteristics of cold pressed grape seed oils obtained from different winery waste are analyzed. The different waste materials have a pronounced effect on the quali‐quantitative profiles of bioactive compounds and induction period of oils. Obtained results show that cold pressed grape seed oils are characterized by different nutritional quality and oxidative stability, due to peculiar effect of fermentation and distillation processes. For production of high quality cold pressed oil, seeds from different winery waste material should not be mixed.
Izvod U ovom radu ispitivan je uticaj vremena skladištenja, sadržaja nečistoće i ljuske u masi semena na oksidativnu stabilnost hladno presovanog ulja suncokreta. Oksidativna stabilnost ulja je analizirana primenom RSM metodologije (Response Surface Methodology), određivanjem produkata oksidacije izraženih preko vrednosti specifičnih apsorbancija na 232 nm za konjugovane diene i 270 nm za konjugovane triene, u svežem ulju i u ulju nakon temperiranja u uslovima Schaal-Oven testa (96 h pri 63±2 °C). Utvrđeno je da vreme skladištenja semena značajno utiče na sadržaj primarnih (A 1% 232nm) i sekundarnih (A 1% 270nm) produkata oksidacije, kako pre (b 1-p < 0,001; b 1-p = 0,021) tako i nakon zagrevanja (b 1-p = 0,048; b 1-p = 0,033) ulja. Prisustvo različitog sadržaja nečistoće i ljuske semena u materijalu za presovanje takođe utiče na sadržaj konjugovanih diena i triena, ali njihov uticaj nije statistički značajan ni u svežem, ni u temperiranom ulju. Osim toga, izvestan efekat na vrednosti navedenih parametara kvaliteta ulja ispoljava i interakcije vremena skladištenja semena, sadržaja nečistoće i ljuske, kako kod svežeg ulja tako i kod ulja nakon termičke obrade, međutim ni njihov uticaj nije statistički značajan. Dobijeni rezultati su ukazali na činjenicu da hladno presovano ulje suncokreta pri umerenim temperaturama, do 63±2 °C, pokazuje dobru oksidativnu stabilnost.
Six cold-pressed oil samples obtained from the seeds of different grape varieties grown in a Fruška Gora vineyard in the Republic of Serbia were examined for chemical and nutritive quality, as well as antiradical capacity. All the tested samples were of good quality, but the results showed noticeable differences in seed oil properties for red and white grape varieties. The highest content in total tocols, 575.23 ± 4.46 mg/kg, was found in the red grape seed oil of the Merlot variety, but the vitamin E activity of white grape seed oils was significantly higher. Regarding single phenols, the most prevalent fraction in all the oil samples was ursolic acid, up to 336.3 ± 4.8 μg/g in the grape seed oil of the Hamburg variety. The highest content in the total phenolic compounds, 54.92 ± 0.93 μg GAE/g, was detected in the oil of red grape seeds. Although significant differences existed between samples, EC50 values were the lowest for the red grape seed oils, varying from 29.84 ± 1.07 to 65.34 ± 0.32 mg oil/mg DPPH, indicating that these oils had the highest antiradical capacity.
The objective of this study was to investigate the impact of seed storage time on the quality of cold-pressed sunflower oil. The quality and oxidative stability of oil was determined in samples of domestic varieties of sunflower hybrid, linoleic type seeds, obtained from fresh seeds and from seeds stored in silo cell for 6 and 12 months at temperature below 30oC and in good ventilation conditions. It was found that the longer storage time of seeds had a negative impact on many quality aspects of the oil, such as flavor, odor and aroma, primarily on the sensory profile. Chemical characteristics and oxidative stability of oil were also influenced by the storage time, which was confirmed by increased values of the acid value (AV) and peroxide value (PV) of the oil samples. Fresh seed oil had an AV of 0.49?0.01 mgKOH/g, while oils that were obtained from one-year old seeds had an AV of 1.95?0.02 mgKOH/g. Content of the primary oxidation products in the oil obtained by cold-pressing of the fresh seeds was 1.73?0.02 mmol/kg (measured as PV), and 2.22?0.07 mmol/kg in that from the seeds stored for 12 months. The anisidine value for the oil obtained from the seeds stored for 12 months was 0.86?0.04 (100A1% 350nm).[ Projekat Ministarstva nauke Republike Srbije, br. TR 31014]
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