Applications of ultrasound in food technology: Processing, preservation and extraction

Chemical studies of anthocyanins: A review

While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) to maintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safety has motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/or interrupt propagation of autoxidation. Fat-soluble vitamin E (α-tocopherol) and water-soluble vitamin C (L-ascorbic acid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, often have strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is most often due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), phenolic diterpenes (carnosol, carnosic acid, rosmanol, and rosmadial), flavonoids (quercetin, catechin, naringenin, and kaempferol), and volatile oils (eugenol, carvacrol, thymol, and menthol). Some plant pigments (anthocyanin and anthocyanidin) can chelate metals and donate H to oxygen radicals thus slowing oxidation via 2 mechanisms. Tea and extracts of grape seeds and skins contain catechins, epicatechins, phenolic acids, proanthocyanidins, and resveratrol, all of which contribute to their antioxidative activity. The objective of this article is to provide an overview of natural antioxidants, their mechanisms of action, and potential applications.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1541-4337.2011.00156.x

Natural antioxidants: sources, compounds, mechanisms of action, and potential applications

A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables.

http://www.ipb.pt/~htgomes/FCT115275/Ref23.pdf

Sub- and supercritical fluid extraction of functional ingredients from different natural sources: Plants, food-by-products, algae and microalgae: A review

1 Preliminary Operations of the Analytical Process.- 1.1 Analytical Chemistry Today.- 1.2 The Analytical Process.- 1.3 Preliminary Operations of the Analytical Process.- 1.3.1 Basic Features.- 1.3.2 Most Common Steps.- 1.3.3 Recent Developments.- 1.4 Analytical Separation Techniques.- 1.4.1 Objectives.- 1.4.2 Classifications.- 1.4.3 Continuous Separation Techniques.- 1.5 Extraction Systems in Analytical Chemistry.- 1.6 Analytical Leaching Methodologies.- 1.7 Ideal Features of an Analytical Leaching System.- 1.8 Supercritical Fluids and Analytical Chemistry.- References.- 2 Physico - Chemical Properties of Supercritical Fluids.- 2.1 Definition of Supercritical Fluid.- 2.2 Physical Properties of Supercritical Fluids.- 2.2.1 Properties at or near the Critical Point.- 2.2.2 Properties of the Supercritical Region.- 2.2.2.1 Density.- 2.2.22 Diffusivity.- 2.2.2.3 Viscosity.- 2.2.2.4 Dielectric Constant.- 2.3 Binary Systems.- 2.4 Polarity.- 2.4.1 The ?* Polarizability/Polarity Scale.- 2.5 Reactions in or with Supercritical Fluids.- 2.5.1 Reactions in Supercritical Fluids.- 2.5.1.1 Influence of Pressure on the Reaction Rate.- 2.5.1.2 Catalytic Effects.- 2.5.1.3 Supercritical Water as an Exceptional Reaction Medium.- 2.5.1.4 Enzymatic Reactions in Supercritical Fluids.- 2.5.2 Reactions with Supercritical Fluids.- 2.6 Other Properties of Supercritical Fluids.- 2.7 General Applications of Supercritical Fluids.- 2.7.1 Industrial Processes.- 2.7.1.1 Supercritical Fluids in the Food Industry.- 2.7.1.2 Polymer Processing with Supercritical Fluids.- 2.7.2 Processing of Heavy Hydrocarbons.- 2.7.3 Analytical Applications of Supercritical Fluids.- 2.7.4 Waste Detoxification with Supercritical Fluids.- 2.7.5 Other Applications of Supercritical Fluids.- References.- 3 Theoretical and Practical Aspects of Supercritical Fluid Extraction.- 3.1 Introduction.- 3.2 Foundation of Leaching.- 3.3 Purity of Supercritical Fluids.- 3.4 Solubility in Supercritical Fluids.- 3.4.1 Solubility Measurements in Supercritical Fluids.- 3.4.2 Solubility and Chemical Structure.- 3.4.2.1 Hydrocarbons.- 3.4.2.2 Hydroxyl Compounds.- 3.4.2.3 Carboxylic Acids.- 3.4.2.4 Ethers.- 3.4.2.5 Esters.- 3.4.2.6 Aldehydes.- 3.4.2.7 Nitrogen-Containing Compounds.- 3.4.3 The Solubility Parameter.- 3.4.4 Theoretical Models.- 3.4.5 Influence of Cosolvents on Solubility: the Entrainer Effect.- 3.4.5.1 Clustering.- 3.4.5.2 Effect of the Cosolvent on Selectivity.- 3.4.6 Entrainer Effect of a Second Solute.- 3.4.7 Solubility near a UCEP.- 3.5 Transport Phenomena.- 3.5.1 Desorption of Adsorbed Species.- 3.5.2 Diffusion in the Solid.- 3.5.2.1 The Spherical Model.- 3.5.2.2 The Infinite Slab Model.- 3.6 Factors Influencing Supercritical Leaching.- 3.6.1 Properties of the Supercritical Fluid.- 3.6.2 Properties of the Solid.- 3.6.3 Properties of the Solute.- 3.6.4 Presence of a Modifier.- 3.6.5 Additives.- 3.6.6 Derivatization.- 3.6.7 Temperature.- 3.6.8 Dynamic Factors.- References.- 4 The Analytical-Scale Supercritical Fluid Extractor.- 4.1 Introduction.- 4.2 The Supercritical Fluid Extractor: A Broad View.- 4.3 Basic Elements of a Supercritical Fluid Extractor.- 4.3.1 The Fluid Reservoir.- 4.3.1.1 Description.- 4.3.1.2 Connection to the Extractor.- 4.3.1.3 Functioning, Cautions.- 4.3.1.4 Measurement of the Cylinder Contents.- 4.3.2 The propulsion system.- 4.3.2.1 Single Systems.- 4.3.2.2 The Need for a Dual Propulsion System: Use of Modifiers.- 4.3.3 The Extraction Chamber.- 4.3.3.1 General Features.- 4.3.3.2 Cell Size.- 4.3.3.3 Sample Size to Cell Volume Ratio.- 4.3.3.4 Cell Geometry.- 4.3.3.5 Special Cells.- 4.3.3.6 Multi-Extraction Systems.- 4.3.3.7 Performance of Extraction Chambers.- 4.3.4 The Depressurization System.- 4.3.4.1 Types of Restrictors.- 4.3.4.2 Problems Arising from Depressurization.- 4.3.5 Collection Systems.- 4.3.5.1 Types.- 4.3.5.2 Special Collection Systems.- 4.3.6 Thermostating.- 4.3.7 Ancillary Components.- 4.4 Extraction Modes.- 4.5 Off-Line Coupled SF Extraction/Detection.- 4.6 On-Line Coupled SF Extraction/Detection.- 4.6.1 Types of Interfaces Used.- 4.6.2 Coupled SFE/Gas Chromatography.- 4.6.3 Coupled SFE/SFC.- 4.6.4 Coupled SFE/HPLC.- 4.6.5 Comparison of SFE Hyphenated Techniques with GC, SFC and HPLC.- 4.6.6 Other Hyphenated Techniques.- 4.7 Comparison of the Off-Line and On-Line Modes.- 4.8 Commercially Available Supercritical Fluid Extractors.- References.- 5 Analytical Applications of Supercritical Fluid Extraction.- 5.1 Introduction.- 5.2 Variables Affecting Extraction Quality.- 5.2.1 Nature and Composition of the Extractant.- 5.2.2 Pressure.- 5.2.3 Temperature.- 5.2.4 Flow-Rate.- 5.2.5 Extraction Time.- 5.2.6 Sample and Analyte Properties.- 5.2.7 Collection Systems.- 5.2.8 In-situ Derivatization.- 5.2.9 Other Factors.- 5.2.10 Quality Parameters.- 5.3 Sequential Extractions.- 5.4 General Applications of SFE.- 5.4.1 Types of Samples.- 5.4.1.1 Solid Samples.- 5.4.1.2 Liquid Samples.- 5.4.1.3 Gaseous Samples.- 5.4.1.4 Sample Size.- 5.4.2 Types of Analytes.- 5.4.3 Scope of Application of SFE.- 5.5 SFE and Other Extraction Techniques.- 5.5.1 Advantages of Supercritical Fluid Extraction.- 5.5.2 Disadvantages of Supercritical Fluid Extraction.- 5.6 Trends in SFE.- References.

Analytical Supercritical Fluid Extraction

Supercritical fluid extraction of phenol compounds from olive leaves.

Determination of benzene, toluene, ethylbenzene and xylenes in soils by multiple headspace solid-phase microextraction

Multiple headspace solid-phase microextraction for the quantitative determination of volatile organic compounds in multilayer packagings.

Supercritical fluid extraction (SFE) and liquid solvent sonication, in combination with two different sample treatments, were compared for the extraction of natural antioxidants from rosemary leaves. Dried, ground, and sieved rosemary leaves (20 mg) were subjected to SFE with CO2 at 355 bar at 100 °C (CO2 density 0.72 g/mL) for 20 min at a liquid flow rate of 4 mL/min. The analytes were concentrated on an ODS trap and subsequently eluted with acetone. Antioxidants in the SF and liquid solvent extract were analyzed by HPLC. Compounds of known antioxidant activity such as carnosol, carnosic acid, and methyl carnosate were identified by mass spectrometry of the HPLC fractions collected. Freezing and grinding the samples in liquid nitrogen resulted in decreased carnosic acid recoveries. Supercritical CO2 extraction provided the highest recovery of carnosic acid from rosemary leaves (35.7 mg/g), the lowest relative standard deviation (4.4%), and the cleanest extractno cleanup prior to HPLC was required. Among ...

María Teresa Tena

Papers

Analytical Supercritical Fluid Extraction

Supercritical fluid extraction of phenol compounds from olive leaves.

Determination of benzene, toluene, ethylbenzene and xylenes in soils by multiple headspace solid-phase microextraction

Multiple headspace solid-phase microextraction for the quantitative determination of volatile organic compounds in multilayer packagings.

Supercritical fluid extraction of natural antioxidants from rosemary: comparison with liquid solvent sonication.