Shedding light on why it is so 'tough' to make healthier hot dogs

Anna M. Herrero and colleagues explain that some brands of sausage (frankfurters) have been reformulated with olive oil-in-water emulsion as a source of more healthful fat. With consumers gobbling up tens of billions of hot dogs annually, and the typical frankfurter packing 80 percent of its calories from fat, hot dogs have become a prime candidate for reformulation. Some hot dogs reformulated with vegetable oil develop an unpleasant chewy texture. Herrero's team set out to uncover the chemistry behind that change with an eye to guiding food companies to optimize low-fat sausage manufacture.

Using a laboratory instrument called an infrared spectrometer (IR spectrometer) they verified that sausages made with heart-healthy olive oil-in-water emulsion stabilized with casein were slightly tougher. However, when frankfurters were elaborated with an emulsion stabilized with a combination of casein and microbial transglutaminase (to help the oil blend in better) the sausage became much tougher. The IR spectrometer revealed that the proteins and fats in low-fat cooked derivates formulated with this stabilizer system as animal fat replacer showed weak lipid-protein interactions, which implies more physical entrapment of the emulsion within the meat matrix. This fact could explain why those sausages are tougher than the others.

More information: Infrared Study of Structural Characteristics of Frankfurters Formulated with Olive Oil-in-Water Emulsions Stabilized with Casein As Pork Backfat Replacer, J. Agric. Food Chem., Article ASAP. DOI: 10.1021/jf203941b

Abstract
This article reports an infrared spectroscopic (FT-IR) study on lipids and protein structural characteristics in frankfurters as affected by an emulsified olive oil stabilizing system used as a pork backfat replacer. The oil-in-water emulsions were stabilized with sodium caseinate, without (F/SC) and with microbial transglutaminase (F/SC+MTG). Proximate composition and textural characteristics were also evaluated. Frankfurters F/SC+MTG showed the highest (P < 0.05) hardness and lowest (P < 0.05) adhesiveness. These products also showed the lowest (P < 0.05) half-bandwidth of the 2922 cm–1 band, which could be related to the fact that the lipid chain was more orderly than that in the frankfurters formulated with animal fat and F/SC. The spectral results revealed modifications in the amide I band profile when the olive oil-in-water emulsion replaced animal fat. This fact is indicative of a greater content of aggregated intermolecular ß-sheets. Structural characteristics in both proteins and lipids could be associated with the specific textural properties of frankfurters.

Provided by American Chemical Society (news : web)

Shedding light on the interaction between DNA and UVA radiation

Ultraviolet A (UVA) radiation is now known to cause skin cancers. The first information on the way in which UVA radiation acts directly on DNA has been revealed by a CNRS team from the Laboratoire Francis Perrin in collaboration with a CEA-Inac laboratory in Grenoble. The interaction between UVA and DNA results from the collective behavior of the bases of the DNA double helix, which causes chemical lesions that can induce carcinogenic mutations. This work is published on-line on 18 March 2011 in the Journal of the American Chemical Society.

Ultraviolet A (UVA) radiation represents over 95% of the solar UV radiation that reaches the Earth's surface. This UVA radiation is now known to cause skin cancers due to carcinogenic mutations brought about by chemical alterations of the four bases of DNA (adenine, cytosine, guanine and thymine). The most important chemical modification is thymine dimerization: two thymines next to each other in the DNA combine to form a new entity, known as “cyclobutane dimer”.

A CNRS team from the Laboratoire Francis Perrin (CNRS/CEA), in collaboration with researchers from the CEA Laboratoire Lésions des Acides Nucléiques, has examined the very first steps of the formation of such chemical lesions. They are publishing the first study describing the physical and chemical effects, prior to any biological effects, of UVA radiation on model DNA. The team of physical chemists examined the behavior of a synthetic DNA double helix (formed solely of adenine-thymine pairs) with regard to UVA photons. They then compared its behavior with that of two complementary single strands (containing only thymines or only adenines).

They found that DNA's capacity to absorb UVA photons results from the collective behavior of its bases. Studied individually, DNA bases (including thymine) are “transparent” to UVA. However, in this study, the scientists have shown that the absorption of UVA radiation substantially increases following the pairing of two single strands to form a double helix. In addition, the probability that a UVA photon absorbed leads to the formation of cyclobutanes is at least ten times higher in the case of a double strand than it is in the case of a single strand. These differences could be explained by changes induced by the UVA photons to the electronic structure of the bases. Following the absorption of a photon, the new electronic configuration adopted by the DNA, known as excited state, persists longer for a double strand than for complementary single strands. The thymines then have more time to undergo permanent alterations.

These experimental studies now need to be extended to more complex DNA sequences, similar to natural DNA. The stakes in terms of public health are high, especially since the quantity of UVA that reaches us is very high compared to UVB radiation (which represents less than 5% of the ultraviolet radiation that reaches the Earth's surface) and also because UVA radiation is still widely used in tanning centers.

More information: Base Pairing Enhances Fluorescence and Favors Cyclobutane Dimer Formation Induced upon Absorption of UVA Radiation by DNA, Akos Banyasz, et al. – Journal of the American Chemical Society, 18 March 2011.

Provided by CNRS (news : web)