15 research outputs found

    Comparison of different methods of antioxidant activity evaluation of green and roast C. Arabica and C. Robusta coffee beans

    Get PDF
    Coffee beans contain a large amount of antioxidants, which are subjected to various changes during roasting. In this study, antioxidant potential of raw and roasted to different degree (light, medium, dark) C. arabica and C. robusta coffee beans was evaluated by the four antioxidant assay methods, TPC, FRAP, TEAC, and DPPH˙. The obtained results revealed significant differences between the coffee types, roasting degree, and antioxidant activity assessment methods. FRAP and TPC appeared to be the most appropriate methods for revealing the differences in antioxidant potential of different coffee types and the effects of roasting. The results obtained by these methods were in good correlation. ABTS and DPPH? methods are not enough sensitive for the determination of roasting degrees. In general, based on statistical data evaluation, antioxidant activity is more dependent on the coffee type than on the degree of roasting, however, the selection of analytical method may also be significant

    Antioxidant activity of extracts obtained by high-pressure extraction procedures from Asparagus stipularis Forssk

    No full text
    Roots and rhizomes of Asparagus stipularis Forssk were separately extracted using supercritical CO2 extraction (SC–CO2) and pressurized liquid extraction (PLE) and their Total Phenols Content and antioxidant potential was investigated. The results indicated that the roots and rhizomes are a potential source of natural antioxidants. The PLE method gave better extraction yields than SFE and its fractions present the highest antioxidant activity. Direct evaluation of antioxidant capacity using the QUENCHER procedure showed that also the solid residue of the plant material remaining after the SC–CO2 and PLE may be of interest as a source of valuable phytochemicals

    A Comprehensive Meta-Analysis of the Comparison Question Polygraph Test

    Get PDF
    We conducted a meta‐analysis on the most commonly used forensic polygraph test, the Comparison Question Test. We captured as many studies as possible by using broad inclusion criteria. Data and potential moderators were coded from 138 datasets. The meta‐analytic effect size including inconclusive outcomes was 0.69 [0.66, 0.79]. We found significant moderator effects. Notably, level of motivation had a positive linear relationship with our outcome measures. Information Gain analysis of CQT outcomes representing the median accuracy showed a significant information increase over interpersonal deception detection across almost the complete range of base rates. Our results suggest that the CQT can be accurate, that experimental studies are generalizable, and no publication bias was detected. We discussed the limitations of the field research literature and problems within polygraph profession that lower field accuracy. We suggest some possible solutions
    corecore