The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Essential oils are aromatic and volatile liquids extracted from plants. The chemicals in essential oils are secondary metabolites, which play an important role in plant defense as they often possess antimicrobial properties. The interest in essential oils and their application in food preservation has been amplified in recent years by an increasingly negative consumer perception of synthetic preservatives. Furthermore, food-borne diseases are a growing public health problem worldwide, calling for more effective preservation strategies. The antibacterial properties of essential oils and their constituents have been documented extensively. Pioneering work has also elucidated the mode of action of a few essential oil constituents, but detailed knowledge about most of the compounds’ mode of action is still lacking. This knowledge is particularly important to predict their effect on different microorganisms, how they interact with food matrix components, and how they work in combination with other antimicrobial compounds. The main obstacle for using essential oil constituents as food preservatives is that they are most often not potent enough as single components, and they cause negative organoleptic effects when added in sufficient amounts to provide an antimicrobial effect. Exploiting synergies between several compounds has been suggested as a solution to this problem. However, little is known about which interactions lead to synergistic, additive, or antagonistic effects. Such knowledge could contribute to design of new and more potent antimicrobial blends, and to understand the interplay between the constituents of crude essential oils. The purpose of this review is to provide an overview of current knowledge about the antibacterial properties and antibacterial mode of action of essential oils and their constituents, and to identify research avenues that can facilitate implementation of essential oils as natural preservatives in foods.

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Essential oils in food preservation: mode of action, synergies, and interactions with food matrix components.

Perspectives for chitosan based antimicrobial films in food applications

Statistical Databases

Release and antibacterial action of phenolic acids incorporated into PHBV films

Selección de recubrimientos comestibles para extender la vida útil de manzana y pera

Chitosan (CH) is a cationic biopolymer used as a matrix to develop edible films and coatings for food applications. When developing chitosan-based film-forming dispersions and films, CH is usually dissolved in aqueous acetic acid solutions (pH = 3.8); sodium hydroxide is often added to increase the pH of the solvent, thus preventing film solubilization at high relative humidity conditions, which can cause changes in the solvent properties (pH and ionic strength) affecting the structure and properties of the obtained films. This is particularly significant for chitosan, since its conformation in solution greatly depends not only on structural parameters like the degree of acetylation and chain length, but also on solution parameters such as ionic strength, solvent, temperature, and pH (Sorlier et al. 2002). During film drying, changes in solvent properties occur in line with water evaporation: increase in ionic strength, change in pH, and conformational modifications in the polymer chain. Moreover, when sodium hydroxide is added to chitosan-based film-forming dispersions, sodium-acetate tri-hydrate salts can crystallize, since these are oversaturated when the film reaches determined water content, depending on molecular mobility, which in turn is greatly affected by film moisture content.

Amparo Chiralt

Papers

Release and antibacterial action of phenolic acids incorporated into PHBV films

Selección de recubrimientos comestibles para extender la vida útil de manzana y pera

Salt Crystallization in Chitosan Films as Affected by Solvent pH and Moisture Content

Influence of the cellulose purification process on the properties of aerogels obtained from rice straw.

Applications to Food Processing