Obtaining dietary fiber and bioactive components from pomegranate peel waste

In this thesis, the aim was to convert pomegranate peel residues, often regarded as waste in the food industry, into functional food components. For this purpose, the extraction process for obtaining dietary fiber and bioactive compounds from pomegranate peel was optimized using Response Surface Methodology (RSM). The optimum conditions were determined as 48.17 °C, 55.16 min, and a sample/solvent ratio of 0.4980 g/mL. Under these conditions, the dietary fiber obtained showed high yield with 84.30% total fiber content. Of this, 34.87% was soluble and 49.42% was insoluble fraction. In addition, 772.79 mg GAE/100 g DM total phenolic content and 45.76 mg QE/100 g DM total flavonoid content were determined. These properties were supported by functional parameters such as low water activity, high protein content, and strong water-holding capacity. After extraction, bioactive-rich solutions were processed under vacuum to recover solvents, and the remaining fractions were freeze-dried. The bioactive residues were analyzed in terms of phenolic profiles. The acetone fraction contained 178.42 mg GAE/g, while the ethanol fraction contained 132.87 mg GAE/g total phenolics. Flavonoid contents were 166.34 mg QE/g and 110.63 mg QE/g, respectively. Punicalagin-β and gallic acid were dominant in the acetone fraction, whereas ellagic acid was higher in the ethanol fraction. Comparison with a commercial dietary fiber showed superior properties in terms of soluble fiber ratio, phenolic profile, water-holding capacity, and protein content. In conclusion, the utilization of low-cost agricultural by-products through sustainable processing techniques to obtain high-value food components presents significant environmental and industrial potential. Future studies should investigate the functional effects of this fiber in different food systems and explore its industrial-scale applications.