CHANGES IN MAJOR ANTIOXIDANT COMPOUNDS DURING AGING OF TRADITIONAL BALSAMIC VINEGAR

Traditional balsamic vinegar (TBV) shows antioxidant capacity that increases passing from cask 5, containing the youngest vinegar, to cask 1 containing the oldest vinegar. This increase in antioxidant capacity is a consequence of both the concentration of compounds already present and of new antioxidants formation and is positively related to the increase in the polyphenolic content and in the Maillard reaction/caramellization products. During TBV aging, some reactions involving flavonoids and tannins take place. Tannins can undergo acid-catalyzed cleavage of their interflavonoid bonds with subsequent condensation of other flavonoid molecules. In addition, the low pH, the decrease of the water content and the presence of aldehydes, may promote flavonoids polycondensation. These reactions explain the observed increase in polymeric phenolic compounds and the decrease in monomeric flavonoids. During TBV aging an increase in the browning index is observed as a consequence of the polycondensation reactions of flavonoids and of brown melanoidins accumulation.

PRACTICAL APPLICATIONS

Traditional balsamic vinegar is a potentially healthy seasoning with high antioxidant capacity that increases during the aging resulting in a product with a strong antioxidant capacity and rich in phenolic compounds such as phenolic acids, monomeric catechins, flavonols and tannins. It also contains other antioxidants such as melanoidins derived from the Maillard and caramelization reaction that occur during must boiling and traditional balsamic vinegar aging. Independently of their bioavailability, traditional balsamic vinegar can contribute to supply antioxidant molecules that play an important role in protecting the gastrointestinal tract itself against peroxidation, thereby limiting the formation of detrimental lipid degradation products.     

Miniaturized fibre‐top cantilevers on etched fibres

Fibre‐top probes are self‐aligned, all optical devices obtained by carving a cantilever on top of a 125‐m diameter single‐mode optical fibre. In this paper, we show that this design can be adapted to smaller fibres as well. We evaluated the performance of a 20‐m diameter probe in contact mode atomic force microscopy (AFM) and that of a 50‐m diameter probe in nanoindentation measurements. AFM images proved to be accurate both in air and water, although some distortion was observed because of the mechanical bending of the fibre during scanning. Indentation curves resembled those obtained with larger devices. The maximum indentation depth, however, is limited by the small dimensions of the cantilever.     

The DNA Sequence of Cosmid 14–13b from Chromosome XIV of Saccharomyces cerevisiae Reveals an Unusually High Number of Overlapping Open Reading Frames

This work is part of the effort for sequencing chromosome XIV of Saccharomyces cerevisiae. Cosmid 14–13b contains a 37·8 kb insert derived from a partial Sau3A digestion of the genome, cloned into the BamHI site of the vector Pou6. The strategy used for sequencing is based on the fragmentation of the whole cosmid by sonication, followed by shotgun sequencing on an Applied Biosystem DNA sequencer. The clones with inserts corresponding to the vector were identified by dot-blot hybridization, without the need of sequencing. The analysis of the DNA sequence reveals 29 open reading frames (ORFs) longer than 300 bases. Nine ORFs are internal to some other ORFs. Similarity searches against DNA and protein data banks show that six ORFs correspond to already known yeast genes (OMP1, PSU1, MLS1, RPC19, DBP2, CYB5) and one ORF matches the sequence of a putative yeast gene (ESBP6). The cosmid sequence has been submitted to the EMBL data bank under Accession Number Z69382.©1997 John Wiley & Sons, Ltd.