Antioksidativni potencijal polifenola i ulja semena koprive (Urtica dioica L.) i karakterizacija proizvoda od pšeničnog brašna sa dodatkom semena koprive
Modern-day humans are facing an increase in the number of diseases resulting from an inappropriate and unbalanced diet as well as from other risk factors. The food industry has, as a result, shifted more focus on the improvement of the quality and the health safety of its products. The use and implementation of plants and their extracts is widespread in the production of functional food, which in addition to satisfactory nutritional values, also has pharmacological and physiological effects on human health. Due to its nutritional and functional wealth, but also due to its value in terms of the viability of all its parts (the stalk, leaves, roots, and seeds), the nettle has been a topic of increased scientific interest and the development of new products. Nettle seeds, as an insufficiently studied part of this traditional, widely used medicinal plant, warrant considerable attention from the scientific public, but also the health community at large. An estimate of the value of nettle seeds as potential functional food and raw food material is one of the more important segments of this study. Equal importance is also ascribed to the characteristics of a potential functional product based on wheat flour enriched by biologically active components from nettle seeds. Therefore, a chemical characterization (the content of macronutrients and mineral matter, the content of free and bound polyphenols and their oxidative and antimicrobial activity) of nettle seeds was provided, and their morphological characteristics studied. The impact of a solvent on the content and antioxidative potential of polyphenol compounds was analyzed. The antioxidative potential was determined using the DPPH and FRAP test as well as reducing power test, and the correlations between the content of the polyphenol compounds and antioxidative potential were determined. Oil was extracted from nettle seeds and its chemical characterization (its saponification, iodine, acid, and ester numbers, acylglycerol and fatty acid composition, as well as antioxidative potential) was given. Nettle seed oil was analyzed for its oxidative stability by means of a non-isothermal and isothermal regime of differential scanning calorimetry (DSC), the kinetic parameters of oxidation were determined, as well as induction time (resistance to oxidation). By substituting a portion of the wheat flour with ground nettle seeds and applying an aqueous extract of nettle seeds to knead the dough, food products were formed, and the impact of the addition of seeds to the macronutrient content, as well as that of mineral matter and polyphenolic compounds and their antioxidative potential, was studied. A special segment is the analysis of the change in the polyphenol content and its antioxidative potential during the thermal processing of the product. The technological parameters (the volume and „expansion“) and sensory attributes (appearance, color, consistency/texture and aroma) of the product were set, and a comparison was made with a product obtained solely from wheat flour. Considering that the oxidative stability of the obtained food products to the greatest extent depends on the oil of the product, the DSC method was used to analyze their stability. The results showed that nettle seeds are a suitable raw material for products with improved functional, nutritional, and sensory attributes. The substitution of wheat flour with ground nettle seeds led to a significant increase in the content of active components (such as polyphenolic compounds) and a significantly improved antioxidative potential of the product, indicating the good potential of this raw plant material for functional food products. An increase in the content of proteins, lipids, fiber, ash, and all essential minerals is evident, whereby calcium is the most prevalent among the macroelements, and iron among the microelements. The indicators of sensory attributes (appearance, texture, smell, and taste) of the product point out that the substitution of wheat flour with grounds seeds in the product results in a final product of improved quality. The DSC analysis determined greater thermo-oxidative stability of the product with added nettle seeds. The results indicate that the product containing nettle seeds can, based on its characteristics, contribute to the expansion of the range of functional products on the market. Thermal processing led to significant changes in the content of free and bound polyphenolic compounds and to various impacts on antioxidative potential, depending on the form of the polyphenol (free or bound), the origin of the polyphenol (from wheat, extract or nettle seeds) and the method used to study the antioxidative potential (DPPH or reducing power). Nettle seed oil belongs to a group of edible oils of the linoleic type, it is of high nutritional quality (linoleic fatty acid content is 86.05%) and is a highly unsaturated oil (iodine value is 117.54 mg J2/g of oil). In terms of its antioxidative potential, the hydrophilic fraction of oil indicates greater potential compared to lipophilic fraction and unfractionated oil. The DSC analysis shows that nettle seed oil has a pronounced thermo-oxidative stability, and the high concentration of polyunsaturated fatty acids presents it as an alternative source of raw materials for the food, cosmetics and other industries.
Biografija autora sa bibliografijom: str. 166-171,Bibliografija: str. 140-165. Datum odbrane: 29.06.2023. Food technology and biotechnology
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