Ilkay Koca

Changes in the physicochemical and antioxidant characteristics of watermelon during pekmez production

Watermelon is a health-promoting fruit in terms of being an excellent source of lycopene and gastronomically pleasing. However, its consumption is restricted to a certain season because it is usually consumed as fresh. Therefore, utilisation of watermelon by processing into a more stable product that is available throughout the year would be beneficial. In this research, watermelon was utilised by processing into pekmez (concentrated juice) by concentrating the juice in open boilers until 68°Brix, and changes in some physicochemical properties, colour and antioxidant characteristics that occur during pekmez production were determined. Sensory evaluations for pekmez products were also carried out. It was determined that the redness, yellowness, pH, titratable acidity and formol number values increase, whereas brightness, total sugar and invert sugar values decrease during processing the fruit into pekmez. Hydroxymethyl furfural was produced slightly during processing. Lycopene, total phenolic content and a...

The Physical, Chemical and Antioxidant Properties of the Leafs of Chaerophyllum byzantinum Boiss. Plants

Objective: Chaerophyllum byzantinum Boiss. is a plant which is popularly consumed in the Black Sea Region/Turkey. In spring, the leafs of the plant are mainly used for soup making. This study was carried out in order to determine the physical, chemical and antioxidant properties of the leafs of the plants consumed by people. Material and Methods: The plants were obtained from 8 different locations in Samsun/Turkey. The color, pH, dry matter, ash, crude protein, cellulose, crude fat, total phenolics and antioxidant activity (FRAP and DPPH) analysis were performed to the samples. Results: The results of analysis performed to the leafs of the plants were found as; Lightness (L) 36.99±2.84, greenness (a) -12.56±1.60, yellowness (b) 15.79±2.14, dry matter 16.43±0.41%, ash 2.03±0.20%, crude cellulose 1.95±0.23%, crude protein 4.36±0.31%, crude fat 0.57±0.16%, total phenolics 2890.15±945.33 mg/kg, FRAP 7406.68±4728.03 μmol/g and EC50 value 1.00±0.61 mg/ml, respectively. Conclusion: It has been observed that the plant, which is a good dietary fiber and mineral source, also has high phenolic compounds and antioxidant activity. However, the changes in phenolic compounds and antioxidant activity were found to be quite wide. Growing conditions seem to have a significant effect on the bioactive compounds than the physical and chemical properties.

Physical, rheological and sensory properties of tarhana prepared with two wild edible plants (Trachystemon orientalis (L.) G. Don) and (Portulaca oleracea L.).

Tarhana is a traditional Turkish fermented soup. It is prepared with yoghurt, wheat flour, yeast, some vegetables and spices. In this study, two wild edible plants, kaldirayak (Trachystemon orientalis (L.) G. Don) and purslane (Portulaca oleracea L.) were used to increase the dietary fiber content of tarhana, while keeping the viscosity and sensory properties in acceptable levels. Wheat flour was replaced with plants in 3 proportions (10, 20 and 30%). The fermentation activity, color, rheological and sensory properties of the tarhana products were determined. Soluble, insoluble and total dietary fiber values were determined to be 15.36, 23.04 and 38.40 g/100 g in dry weight for kaldirayak and 7.56, 23.11 and 30.67 g/100 g in dry weight for purslane, respectively. It was determined that addition of these plants in high amounts increase the dietary fiber content but decrease the viscosity. The lightness, redness and yellowness values decreased as the concentration of added plant increased. Also, as the enrichment ratio increased, the sensory evaluation points decreased.