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Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethylformamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7.

The effect of microwave and conventional cooking methods on chlorophyll pigments and colour properties of squash, green beans, peas, leek, broccoli and spinach were studied, by HPLC and colorimetry, respectively. In five of six vegetables, chlorophyll a was found more heat resistant compared with chlorophyll b, except in peas. Chlorophylls in peas were retained to the 80-90%, the highest in all vegetables evaluated. Chlorophylls were retained to 19-100%, depending on the vegetable type and cooking method. Pheophytins increased in all vegetables after cooking. Highest chlorophyll a and chlorophyll b losses were observed in boiled leek while microwaved peas and boiled peas retained the most chlorophyll a and chlorophyll b, respectively. Pheophytin a and pheophytin b formation was highest at boiled squash and boiled green beans, which were fifty-ninefold and twentyonefold compared with fresh ones, respectively. Most of the pheophytin formations occurred in boiled and the least in microwaved vegetables. Surface colour changed depending on the type of vegetable and cooking method.

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Black mate tea was extracted with di#erent /*ῌ solvents (acetone, N,N-dimethyl formamide (DMF), ethanol and methanol) for ,, 2 and +2 h. The extracts were screened for polyphenol content, antioxidant and antibacterial activities. Total polyphenol content of the extracts ranged from 31.*+ to ++3.,2 mg gallic acid equivalent (GAE)/g dry weight (dw) tea depending on the solvent used and extraction time applied. In general, methanol was the least e$cient solvent for polyphenol extraction from black mate tea and the e$ciency of the others was found to be similar. All extracts showed antioxidant activity by ,,,-diphenyl-+-picryhydrazyl (DPPH) radical and reducing power. Di#erent trend was observed for each method with respect to solvents used. The extracts possessed antibacterial activity depending on the solvent used and bacterium tested and the results sowed that black mate tea extracts had strong antimicrobial activity against selected bacteria, except for E. coli O+/1 : H1. While S. aureus was found to be the most sensitive to all extracts, E. coli was the most resistant among bacteria tested.

In this study, the effect of copigmentation with phenolic acids i.e., tannic, gallic, ferulic and caffeic acids that have various pigment : copigment molar ratios (1:10; 1:50; 1:100) on Berberis crataegina anthocyanins at 90C was monitored. Copigmentation increased the stability anthocyanins. The increase in pigment : copigment ratios resulted differently on each phenolic acid compound, i.e., as the molar ratio increases in gallic acid copigmented samples, the anthocyanin degradation reduces, but conversely it increases in all the other acids used. Additionally, the compatibility of the degradation of copigmented anthocyanins to first order and Weibull distribution models were studied. In the result of the validation, Weibull distribution model was found to fit to better explain the anthocyanin change. The Weibull model half‐lives of gallic (1:100) and ferulic acid (1:10) at given molar ratios were calculated as 111.17 and 91.92 min when compared to59.89 min of the control group. Practical Applications Color is an important quality criterion of a food product for consumers. When manufacturing conditions were taken into account, during storage, color bleaching and/or losses in foods might occur. For this reason, food‐coloring additives are used to prevent color losses or enhance color. The most important group involved in natural colorants is anthocyanins. However, relatively low stability of anthocyanins compared to synthetic dyes has restricted their use as natural colorants. Components that form stable and different compounds by complexing with anthocyanins are called copigments. Although they are generally colorless when they are added to solutions containing anthocyanins, their color become stronger; stability of the color increases and their characteristics change.