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Comparative study of walnut and pumpkin seeds oils biological value and oxidative stability
(2019) Nosenko, Tamara; Korolyuk, Tamara; Usatyuk, Svitlana; Vovk, Hanna O.; Kostinova, Tetiana
The work is devoted to the study of the biologically active components content and the oxidation stability of oils from non-traditional raw materials such as walnuts and pumpkin seeds. The content of phospholipids, carotenoides, chlorophylls, tocopherols and sterols as well as fatty acids and tocopherol homologues composition, acidity and oxidation stability of walnut and pumpkin seeds oils were determined. The walnut and pumpkin oils contain a significant amount of polyunsaturated fatty acids, in particular, the walnut oil contains linolenic acid and has close to the recommended ratio of ω-3: ω-6 polyunsaturated fatty acids. The linoleic (polyunsaturated, ω-6) and oleic (monounsaturated) fatty acids were dominated in fatty acids composition of pumpkin oil, the sum of saturated fatty acids was three times higher than in walnut oil. The important property of walnut oil is very high ratio of ω-3:ω-6 polyunsaturated fatty acids, that was 1:5 almost the same as recommended by dietologists for human diet. The difference of total tocopherols content of two oil samples was slight, but tocopherol homologues composition was very distinctive, that is the β-tocopherol was the main in the walnut oil and α-tocopherol − in the pumpkin seeds oil, respectively. Acidity of investigated samples of oils have increased sufficiently fast, reaching the value close to 4 mg KOH/g of oil during the 63 and 70 days for walnut and pumpkin seeds oils, respectively. Oxidative stability of two oil samples were estimated as peroxide value changes during 98 days of oil storage. It was shown that the induction period of walnut oil oxidation, measured as peroxide value increase initiation, was 56 days, inspite of high content of polyunsaturated fatty acid content and particularly linolenic acid in this oil. Duration of induction period of pumpkin seeds oil oxidation and shelf life were 70 and 98 days, respectively, while shelf life of walnut oil was about 90 days. The higher resistance of pumpkin oil to oxidative damage is primarily due to the fatty acid composition of this oil, namely to the high content of saturated and monounsaturated fatty acids and almost twice lower content of polyunsaturated fatty acids compared to the walnut oil. Both oils can be recomended as a valuable source of polyunsaturated fatty acids, antioxidants and vitamins for human nutrition.
Effect of hydrolytic enzymes pretreatment on the oil extraction from pumpkin seeds
(2019) Nosenko, Tamara; Vovk, Hanna O.; Korolyuk, Tamara
Introduction. Enzyme assisted technologies were proposed for oil seeds processing. Currently there are no reports about pumpkin seeds oil recovering using enzyme assisted pretreatment. The aim of the present study was to evaluate the effect of enzyme mixture on the cell integrity, oil yield of cold-pressing and dynamics of solvent extraction of pumpkin seeds oil. Materials and Methods. Protolad, Alkaline, acid proteases and Cellulad (ENZIME, Ukraine) were used for pumpkin seeds pretreatment. The cells integrity was evaluated by the method of immediate "shaking". The cold pressing was carried out on the laboratory screw press. The solvent oil extraction rate was estimated using a Soxhlet extractor as oil quantity extracted after one extraction cycle. Results and discussion. It was detected that main increase of pumpkin seed cells integrity destruction comparing with a control sample had been happened after 2-hour of enzyme pretreatment. Further incubation of ground seeds with enzymes did not lead to significant increase of "open" cells content in the mixture. It was shown that using of different kind of proteolitic enzymes for pumpkin seeds pretreatment resulted in increase of destroyed cells quantity from 3 to 10.4 %. Using of proteases and cellulase mixture for pumpkin seeds pretreatment had resulted in further increase of level of pumpkin seed cells "revealing" by 10 %. The oil yield of cold pressed pumpkin oil after enzyme pretreatment with protease (70 %) and cellulase (30 %) mixture was increased from 62.3 (control sample) to 70.0 % from total oil content of seeds. The rate of solvent extraction of oil from pumpkin seeds had increased after enzyme pretreatment, that means 25.4 and 17.7 % of oil were extracted after 80 min extraction from mass of enzyme pretreated and control seeds, respectively. There was no difference of peroxide content between enzyme pretreated sample and control. Conclusions. Using of proteases and cellulases mixture for pumpkin seeds pretreatment had resulted in increase of destroyed cells quantity, following by increase of cold pressed pumpkin oil as well as rate of solvent extraction of oil from pumpkin seeds.
Walnut uhf-treatment influence on oil lipid fraction fatty acid composition
(2012) Derbygova, Galina; Usatyuk, Svitlana; Korolyuk, Tamara
The paper presents the investigation results of the microwave processing influence on lipid fraction fatty acid composition of walnut oil.

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