Abstract

Headspace solid-phase microextraction has been applied to the analysis of aroma compounds in vinegar. Silica fibre coated with Carboxen–polydimethylsiloxane was found to be more efficient at extracting these compounds than other fibres such as those coated with polydimethylsiloxane, Carbowax–divinylbenzene, and polydimethylsiloxane–divinylbenzene, but its repeatability was low. Different parameters such as extraction time, temperature of the sample during the extraction, ionic strength, and sample volume were optimised using a two-level factorial design expanded further to a central composite design. This chemometric tool is very appropriate in screening experiments where the aim is to investigate several possibly influential and/or interacting factors. The extraction efficiency is inversely affected by the acetic acid content—an increase in the acetic acid concentration decreases the extraction efficiency. No interference is observed with the increase in content of polyphenols.

Keywords

• Headspace analysis;
• Solid-phase microextraction;
• Chemometrics;
• Factorial design;
• Vinegar;
• Food analysis

Keywords

• Alcohols;
• Aldehydes;
• Volatile organic compounds;
• Aroma compounds

Antioxidant properties in vitro and total phenolic contents in methanol extracts from medicinal plants

Abstract
In order to find out new sources of safe and inexpensive antioxidants, the antioxidant capacities of 45 selected medicinal plants were evaluated using ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC) assays, respectively, and the total phenolic contents of these plants were measured by the Folin–Ciocalteu method. Most of these plants were analyzed for the first time for their antioxidant activities. It was found that the plants Sargentodoxa cuneata Rehd. Et Wils, Fraxinus rhynchophylla Hance, Paeonia lactiflora Pall, Paeonia suffruticosa Andr and Scutellaria baicalensis Ceorgi possessed the highest antioxidant capacities and thus could be potential rich sources of natural antioxidants. A strong correlation between TEAC values and those obtained from FRAP assay implied that antioxidants in these plants were capable of scavenging free radicals and reducing oxidants. A high correlation between antioxidant capacities and their total phenolic contents indicated that phenolic compounds were a major contributor of antioxidant activity of these plants.

Keywords
Antioxidant capacity; Natural products; Ferric reducing antioxidant power assay; Trolox equivalent antioxidant capacity assay

Herbal Teas - Tisanes: Remedies, Recipes, How To Make

Herbal Tea - This method is commonly referred to as a standard brew., or herbal infusion.

Herbal tea making is just as much of an art as it is a science. Color, taste, aroma all will signal you when the brew is "just right".

Tools : You don't need anything fancy, the most important tea tool is a non-aluminum pot with a tight fitting lid. Add a strainer and a tea cup and you are good to go.

Average Dose: The average dosage is usually 3 to 4 cups in a day. Bitter medicines need only be taken in small doses, usually 1/2 cup at a time.

Variations : Spices like ginger, cinnamon, cardamom, cloves, and allspice add heat and energy to the infusion. Almond and vanilla extracts, raw honey, fresh lemon, or a pinch of stevia add flavor and zest.

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