LEE- Gıda Mühendisliği Lisansüstü Programı

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http://hdl.handle.net/11527/19292

Gözat

Konu "antioxidants" ile LEE- Gıda Mühendisliği Lisansüstü Programı'a göz atma
  • Öge
    Novel nutritional yeast formulation as a functional ingredient for healthy snacks
    (ITU Graduate School, 2025) Karslı, Ayşe Nur ; Çapanoğlu Güven, Esra ; 506221502 ; Food Engineering
    In recent years, the increasing interest in healthy and sustainable nutrition has accelerated research on alternative protein sources. The environmental impact of animal-based protein production, along with the growing popularity of vegan, vegetarian, and flexitarian diets, has driven the search for more eco-friendly and innovative solutions. In this context, nutritional yeast, a microbial protein source, has attracted attention as a sustainable food ingredient due to its high protein content, richness in B vitamins and minerals, efficient production process, and environmentally conscious nature. This study aimed to evaluate the usability of nutritional yeast enriched with phenolic compound-rich fruit and vegetable powders such as apple, beetroot, and black carrot, as a functional food ingredient. The total phenolic content, total antioxidant capacity, and in vitro bioaccessibility of the prepared samples were analyzed. The samples were freeze-dried by lyophilization. Then, phenolic compounds were extracted using an ultrasound-assisted extraction method. Total phenolic content was measured using the Folin–Ciocalteu method, while antioxidant capacity was evaluated through ABTS and CUPRAC methods. Analysis were carried out after extraction and at the gastric and intestinal phases of the digestion process. All analyses were carried out in laboratory conditions in accordance with an in vitro digestion model. When all the samples in the study were evaluated in terms of their phenolic content and antioxidant capacities, it was observed that although the apple formulations had low initial values, the total antioxidant capacity increased, especially in the ABTS analysis, when applied together with yeast; this can be explained by the components in the yeast protecting the phenolics in the gastric environment and releasing them in the intestine. However, the decrease observed in the CUPRAC analysis suggests that these compounds may have undergone structural transformation or that the CUPRAC method may be less sensitive to the newly formed phenolic forms. In the beetroot-enriched samples, phenolic content and ABTS values were generally preserved or showed an increase in total antioxidant capacity during the digestion process. However, the decrease in CUPRAC capacity suggests that some phenolic compounds may have been released during the early stages of digestion and then broken down by the yeast. In the black carrot samples, although the initial phenolic and antioxidant capacities were very high, a decrease in intestinal phase values was observed when used in combination with yeast; this may be due to the high anthocyanin content forming strong bonds with the yeast cell wall, preventing sufficient release in the digestive environment. Yeast formulations, in general, showed a bioaccessibility-enhancing effect in matrices with low or moderate phenolic content such as apple and beetroot, whereas in complex structures such as black carrot, yeast may have played a binding or limiting role. In this context, the molecular structures of phenolic compounds, their potential binding tendencies with yeast, and the sensitivity of the analytical method used can be considered as key factors determining the outcome. The physical, chemical, sensory, and functional properties of the nutritional yeast formulations enriched with plant powders were assessed through various analytical methods. Textural properties were determined using Texture Profile Analysis (TPA), which measured parameters such as hardness, springiness, and cohesiveness. Textural results showed that beetroot and black carrot formulations had lower hardness and stickiness compared to plain yeast, which may provide an advantage for direct consumption or incorporation into carriers such as yogurt. Sensory analysis was conducted with 10 trained panelists who evaluated yogurt-based samples for attributes including overall liking, color intensity, fruity aroma, sourness, and umami flavor using the Quantitative Descriptive Analysis (QDA) method. Although plain yogurt received the highest overall acceptability score, enriched formulations received positive feedback particularly for umami perception and color. In terms of chemical evaluations, pH values were measured using a 1:10 (w/v) suspension of the samples. The pH values ranged between 5.3 and 6.2, a range considered suitable for both microbial safety and phenolic stability. The fermentation activity of the samples was assessed by monitoring CO₂ production over two hours at 30 °C using a Rizograph device. The freeze-dried samples showed low levels of gas production, suggesting they may be safer for digestive health. In conclusion, nutritional yeast formulations enriched with phenolic compounds can be considered innovative and sustainable alternatives for health-oriented snacks. This study demonstrates that nutritional yeast can function not only as a protein source but also as a carrier and functional agent for phenolic compounds. Apple-enriched formulations stood out as one of the most successful combinations in terms of both phenolic release and antioxidant capacity. Beetroot-enriched samples yielded promising results particularly in terms of phenolic retention and stability throughout digestion. These formulations present strong potential for use in healthy snack products designed for direct consumption. Future studies are recommended to compare different drying methods, enhance sensory properties, and verify the health effects of these formulations through clinical trials. The findings of this study reveal that nutritional yeast formulations enriched with phenolic compounds are not only high-protein options but also functional and sustainable food ingredients. Thanks to their high bioaccessibility, acceptable sensory qualities, stable pH range, and low gas production, these formulations offer a promising foundation for the development of healthy snacks that can be consumed directly or integrated into various food systems. The role of nutritional yeast in carrying and preserving phenolics is supported by this research, emphasizing its broader application potential in next-generation food technologies. Yeast-based formulations thus emerge as forward-looking solutions for developing products that support well-being, respond to consumer expectations, and promote sustainability.