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    In vitro release kinetics of pine bark extract enriched orange juice and the shelf stability
    (2010) Celiktas O.Y.; Isleten M.; Vardar-Sukan F.; Cetin E.O.
    Purpose: This paper seeks to demonstrate a functional beverage incorporating pine bark which is an unutilized forestry waste, determine in vitro release kinetics of enriched beverages, and antioxidant activities, besides assessing their shelf stabilities. Design/methodology/approach: Orange juice was enriched with Pinus brutia, Pinus pinea bark extracts, Pycnogenol ® . In vitro release kinetics was determined in pH 1.2 and pH 7.4. Ascorbic acid content, pH, titratable acidity, and colorimetric analyses were analyzed monthly for eight months to determine shelf life. Additionally, total phenol contents and radical scavenging activities were analyzed. Subsequently a consumer acceptance test was conducted among 200 participants. Findings: The release of all extracts in orange juices in pH 1.2 were slower than pH 7.4. The release results were fitted to Higuchi square root of time kinetic model with high determination coefficients. Although total titratable acidity values were in agreement with the trend of minor pH changes, prominent losses in antioxidant capacities, ascorbic acid contents and color were observed for the last two months suggesting a shelf life of six months. Female participants and young people had a greater tendency to consume such a beverage. Health concerns and flavor were the primary factors affecting their purchasing decisions. Research limitations/implications: Findings of the study demonstrated the effects of fortification with a plant-based extract as a substitute to the present practice of fortifying beverages with vitamins and minerals for a potential future market. Originality/value: The paper shows that juices fortified with pine bark extracts show higher antioxidant capacities and ascorbic acid contents compared to the control, thereby providing improved functionality. © Emerald Group Publishing Limited.
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    Influence of supercritical carbon dioxide and methanolic extracts of rosemary on oxidation and sensory properties of wheat germ oil
    (2009) Yesil-Celiktas O.; Isleten M.; Karagul-Yuceer Y.; Bedir E.; Vardar-Sukan F.
    Both supercritical CO2 and methanolic extracts from the leaves of rosemary (Rosmarinus officinalis) harvested from three different locations of Turkey at four different times of the year were added at a concentration of 100 mg/kg to wheat germ oil. Wheat germ oil samples were stored in an incubator for 10 days at 50C in order to promote oxidation and for the efficacy of the extracts for stabilization purposes to be examined. Degree of oxidation was determined by peroxide and p-anisidine values, which were performed every 2 days. Extracts from Mersin and Canakkale regions performed better results. Additionally, June and September harvests had lower peroxide values. According to the descriptive sensory analysis, both locations and extraction methods were found to effect flavor. Some flavor attributes, such as wheatlike/starchy, fishy and rubbery/metallic changed during storage regardless of locations and extraction methods. Supercritical CO2 extracts performed better results in terms of both oxidation and sensory properties. © 2009 Wiley Periodicals, Inc.