Effects of spoilage on nitrogen and carbon stable isotopes signatures of the clam Ruditapes decussatus

Fish and seafood products are highly susceptible to post-mortem spoilage due to autolytic reactions at start, then microbiological activity and eventually oxidative reactions. Chemical and microbiological parameters are usually used to assess quality and make decisions for protecting public health, but they lack precision in defining which spoilage pathway is occurring at each moment. The objective of this work was to assess the effects of spoilage reactions on nitrogen and carbon stable isotopes in the grooved carpet shell clam, Ruditapes decussatus, and compare them to biochemical indicators of seafood deterioration, in order to better understand the relations between the different spoilage pathways during commercial storage conditions. Clams were kept in a refrigerator at 5 ºC, to simulate normal commercial storage conditions, and sampled in the beginning of the experiment, and after eight, ten and twelve days. Moisture, condition index, percentage edibility, total volatile basic nitrogen (TVB-N), pH, nitrogen and carbon percentages and stable isotopes were determined for each sampling moment. Stable isotope analyses were performed using a Costech Elemental Analyzer (ECS 4010) coupled to a ThermoFinnigan Delta V Advantage. Stable isotopes analysis, especially for nitrogen, proved to be a good tool for the study of clam deterioration. Nitrogen stable isotopes results showed a relation with other spoilage indicators, such as pH and TVB-N, and allowed identifying spoilage specific pathways, such as amino acids decarboxylation and production of volatile nitrogen compounds.info:eu-repo/semantics/publishedVersio

Geographical differentiation of saffron by GC-MS/FID and chemometrics

The volatile compounds of saffron of different origins were investigated to check their suitability as markers of geographic differentiation. A total of 247 saffron samples from Greece (40 samples), Iran (84 samples), Italy (60 samples) and Spain (63 samples) which were harvested in 2006 were analysed using ultrasound-assisted extraction, gas chromatography followed by mass spectrometry and flame ionisation. All regions were easily differentiated by canonical discriminant analysis. The percentages of correct classification and validation were 96.4 and 94.3%, respectively. These investigations showed the potential of saffron volatiles to discriminate saffron samples with different geographical origins