Effects of extraction solvents on concentration and antioxidant activity of black and black mate tea polyphenols determined by ferrous tartrate and Folin–Ciocalteu methods

Flavonoids are major bioactive compounds known to be beneficial against many chronic diseases such as cancer, cardiovascular disorders, and inflammation. Food products obtained from plants are key sources of flavonoids for humans. However, during different food-processing steps, flavonoids are lost in remarkable amounts. Supplementation of flavonoids as a food additive will help in retaining the required health-beneficial amount of flavonoids in the diet, and extraction is an important step in the preparation of food additives. Microwave extraction is one of the most advanced extraction methods, which has the potential of playing a major role in flavonoid extraction and analytical quantification. The present paper reviews the potential application of microwave extraction for flavonoids and the advantage of microwave-assisted process over the other extraction processes generally employed for extraction.

Microwave-Assisted Extraction of Flavonoids: A Review

Box-Behnken design based statistical modeling for ultrasound-assisted extraction of corn silk polysaccharide.

Free-radical scavenging, reducing activity and some phytochemical content (total phenolic, anthocyanin and ferulic acid) of eighteen Mexican maize phenotypes were determined. Total phenolic contents ranged from 215.8 to 3400.1 mg gallic acid/100 g of whole grain flour and total anthocyanins ranged from 1.54 to 850.9 mg cyanidin-glucoside equivalents/100 g of whole grain flour. Most of the phenolics in grain were in the bound form (ca. 85%), while anthocyanins were the major free phenolic compounds. Among the different samples, bound phenolic extracts of corn appeared to have greater anti-radical and reducing activities than free phenolic extracts from the same grain samples when tested at a normalized phenolic concentration. The phenotypes Veracruz 42 and AREQ516540TL exhibited the greatest activities and these purple-colored strains were most enriched in anthocyanins. Extracts from a red-colored phenotype Pinto were also among the most effective at exhibiting anti-radical activities. Differences in free-radical scavenging and reducing activities appeared to be dependent on the unique profile of anthocyanins and other phenolics in each phenotype.

Dorde Malencić

Papers

Polyphenol contents and antioxidant activity of Maydis stigma extracts