Extraction of sunflower seed oil (Helianthus annuus) by supercritical fluid and pressurized ethanol for enrichment of highly digestible dairy product

• Ano de defesa: 2022
• Autor(a) principal: Vicentini-Polette, Carolina Medeiros
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Dióxido de carbono supercrítico; Extração com líquido pressurizado; Goat milk; Leite de cabra; Óleo de girassol; Pressurized liquid extraction; Sunflower oil; Supercritical carbon dioxide; Tocoferol; Tocopherol
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/74/74132/tde-16082022-150357/

We identified the best conditions for extraction of sunflower seed oil (Helianthus annuus) enriched with tocopherols, using the technologies of supercritical extraction with supercritical carbon dioxide (SFE-scCO2) and pressurized liquid extraction (PLE) with ethanol as solvent. Altis 99 sunflower seed was chosen because of its oil and α-tocopherol content, which is considered of high nutritional quality. The raw material was characterized by classical bromatological analyses. Experimental planning was applied to evaluate the influence of process variables on total yield and tocopherol content (α, β, γ, and δ) for obtaining oil by both SFE and PLE. Central Compound Rotated Design [CCRD] was used for both SFE and PLE. SFE design was performed two independent variables (temperature, °C; pressure, MPa), and two axial points (-α, + α). PLE design considered the static purging time of the solvent (min), the temperature (°C) and the rinse volume of solvent (ethanol, %), number of cycles = 4, and P = 10.34 MPa. For yield, the variables that influenced SFE and PLE were pressure and temperature, respectively. Among the material obtained by SFE and PLE, oil and extract, respectively, we analyzed, in addition to yield and tocopherol content, the profile of total and free fatty acids (FAs), estimated composition in triacylglycerols acidity and oxidative stability. In the application study, the tocopherol-rich sunflower oil was incorporated into goat milk yogurt sweetened with xylitol, a viable and inclusive option for low-calorie and highly digestible dairy consumption. After conducting an interest survey with 204 consumers, the enriched yogurt was sensorially described by the free profile technique, with 9 evaluators. A product acceptance test was also applied to 36 evaluators. The mean results obtained in the characterization of dehulled sunflower seeds were 98.76 ± 0.21 % dry matter; 2.70 ± 0.05 % mineral matter; 23.50 ± 0.26 % crude protein; and 12.88 ± 0.27 % crude fiber. As for the ethereal extract, the average obtained was 55.07 ± 0.30 %. The highest oil recovery obtained by SFE was 87.6 % of the total oil in the seed (55 %), where pressure proved significant (p ≤ 0.05) in the process. In PLE, the statistical analysis of the experimental planning indicated that only the temperature had an effect on the responses, adjusted to a linear model that proved significant (p ≤ 0.05) and predictive. In this process the highest oil recovery was 93.9%. When comparing the products from the different processes, the highest concentration of tocopherols was observed in the oil obtained via SFE-scCO2 at 60 °C and 18 MPa, where 91.17 mg of tocopherols / 100 g of oil were obtained. Of these, 88 mg are related to α-tocopherol. In the analysis of the process variables in this response, a significant (and negative) influence of temperature was observed. Although smaller, the extract obtained via PLE also showed a high amount of tocopherols, up to 83.16 mg / 100 g (77 % of which were α-tocopherols) under the conditions of 56 °C and 110 % of the extraction cell volume (34 mL) of solvent volume used in the rinse. However, in the statistical analysis of the influence of the process variables on this response, none proved significant at the 5% level. As for the profile of total AGs, there was no difference between the oils obtained by PLE, the one optimized by SFE-scCO2 and the commercial one, suggesting that both processes do not interfere in the quality of the product obtained. Under the optimized extraction conditions, the oils obtained by SFE-scCO2 and PLE presented total titratable acidity of 3.59 and 3.17 g oleic acid/100 g of oil, respectively. The acidity of the commercial oil and the oil obtained via soxhlet using hexane or petroleum ether in the same raw material showed an acidity of 0.36 and 2.52 g oleic acid / 100 g oil, respectively, indicating that the pressurized extractions resulted in more acidic oils than the non-pressurized (soxhlet). The methodology used for free fatty acids analysis proved to be feasible for its qualitative determination, and suggests similarity between the main total and free fatty acids (such as linoleic, oleic, and palmitic) observed regardless of the process, although minority fatty acids may vary. There was interest from the consumer public in yogurt made with sunflower oil. Sensory analysis showed that the main attributes described were: fatty appearance, characteristic aroma, milky flavor, homogeneity and consistency. There was no statistical difference for acceptance between the natural or oiled yogurts (p ≥ 0.05), both scored on the positive part of the scale: using a 7-point scale, the natural yogurt showed an average of 5.03 ± 1.6, while the enriched yogurt was scored as 4.61 ± 1.2.