Reduction of trimethylamine oxide by <i>Shewanella</i> spp. under modified atmospheres in vitro

Two strains of Shewanella spp. were isolated from cod fillets packed in modified atmosphere (60% CO2, 30% O2, 10% N2). One of the strains was identified asShewanella putrefaciens. The other strain could not be fully identified but was determined as a Shewanella spp. different from S. putrefaciens. The effect of modified atmosphere (CO2, O2) on the growth of the two strains and on the reduction of TMAO to TMA was studied using solid medium from fish extract packed under variable mixtures of CO2, O2 and N2. All the samples were incubated at 7°C for 7 days. The Shewanella-like strain was shown to be a stronger TMAO reducer and was more resistant to CO2 than S. putrefaciens per se. Modified atmosphere packaging of marine fish can inhibit the growth and TMAO-reducing activity of S. putrefaciens when 50% of CO2 together with 10% of O2 are introduced into the packaging atmosphere. The growth and TMAO-reducing activity of the Shewanella-like strain can be inhibited when higher proportions of CO2 together with as high as possible proportions of O2 are introduced into the packaging atmosphere. It is suggested that a combination of 60-70% CO2 and 30-40% O2 is introduced into the packaging atmosphere in order to prevent TMA production by Shewanella spp

Effect of modified atmosphere packaging on the TVB/TMA-producing microflora of cod fillets

Cod fillets (Gadus morhua) were packed under modified atmospheres, with four different gas compositions (60% CO2-10% O2-30% N2, 60% CO2-20% O2-20% N2, 60% CO2-30% O2-10% N2, 60% CO2-40% O2), and stored at 6 degrees C. Plate counts were carried out after 3, 4, 5, 6 and 7 days, to follow the growth of aerobic and anaerobic bacteria, lactic acid bacteria, H2S-producing bacteria and Enterobacteriaceae. The production of total volatile bases (TVB) and trimethylamine (TMA), and the changes in pH of the fillets were measured. Modified atmosphere packaging (MAP) had in general an inhibitory effect on the growth of the microflora but limited inhibition of the production of TVB and TMA. Despite the fact that increased oxygen proportions in the atmosphere contributed in a slightly lower production of TMA, all the samples had a TVB and TMA content high enough to be considered as spoiled after 4 days' storage at 6 degrees C. A total aerobic plate count at 25 degrees C of a 10(6) cfu/g, combined with the presence of only a 10(3) cfu/g of H2S-producing bacteria, which are normally considered as TMAO-reducing organisms in fish, cannot explain the strong increase in TMA. A high cell concentration of more than 10(8) cfu/g of Shewanella putrefaciens is required for production of a TMA level normally found in spoiled fish. This suggests that there could be another type of bacterium in fish, not involved in the spoilage of unpacked fish, which is resistant to 60% CO2, is not H2S-producing, and shows a high TMAO-reducing capacity. This bacterium could be Photobacterium phosphoreum

Assessment of table olives' organoleptic defect intensities based on the potentiometric fingerprint recorded by an electronic tongue

Table olives are prone to the appearance of sensory defects that decrease their quality and in some cases result in olives unsuitable for consumption. The evaluation of the type and intensity of the sensory negative attributes of table olives is recommended by the International Olive Council, although not being legally required for commercialization. However, the accomplishment of this task requires the training and implementation of sensory panels according to strict directives, turning out in a time-consuming and expensive procedure that involves a degree of subjectivity. In this work, an electronic tongue is proposed as a taste sensor device for evaluating the intensity of sensory defects of table olives. The potentiometric signal profiles gathered allowed establishing multiple linear regression models, based on the most informative subsets of signals (from 24 to 29 recorded during the analysis of olive aqueous pastes and brine solutions) selected using a simulated annealing meta-heuristic algorithm. The models enabled the prediction of the median intensities (R2 ≥ 0.942 and RMSE ≤ 0.356, for leave-one-out or repeated K-fold cross-validation procedures) of butyric, musty, putrid, winey-vinegary, and zapateria negative sensations being, in general, the predicted intensities within the range of intensities perceived by the sensory panel. Indeed, based on the predicted mean intensities of the sensory defects, the electrochemical-chemometric approach developed could correctly classify 86.4% of the table olive samples according to their trade category based on a sensory panel evaluation and following the International Olive Council regulations (i.e., extra, 1st choice, 2nd choice, and olives that may not be sold as table olives). So, the satisfactory overall predictions achieved demonstrate that the electronic tongue could be a complementary tool for assessing table olive defects, reducing the effort of trained panelists and minimizing the risk of subjective evaluations.This work was financially supported by Project POCI-01-0145-FEDER-006984—Associate Laboratory LSRE-LCM, by Project UID/QUI/00616/2013 —CQ-VR, and UID/AGR/00690/ 2013—CIMO, all funded by Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI) and by national funds through Fundação para a Ciência e a Tecnologia (FCT), Portugal. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN, and FSE for the Ph.D. Grant (SFRH/BD/104038/2014).info:eu-repo/semantics/publishedVersio

The Mediterranean diet for Polish infants: a losing struggle or a battle still worth fighting?

The Mediterranean diet is well known for its health-promoting effects. Among its key ingredients, olive oil is the most characteristic. Processing industries have been successfully manufacturing and marketing jarred baby foods with the use of vegetable oils, including olive oil, as well as other sources of visible fat. We aimed to survey manufacturer claims concerning added fat in jarred infant foods supplied to the Polish market. A total of 124 kinds of infant foods from six suppliers were analyzed. Corn, canola, and soybean oil occupied the first three positions, respectively, in rank order of vegetable oils used in jarred baby foods. In our sample, only one type of ready-to-eat jars with vegetables contained olive oil. 11% of products contained cow milk butter or cream. 61% of jarred “dinners” contained poultry or fish, which are typical sources of animal protein in the Mediterranean diet. Given that commercial baby foods currently available in the Polish market contain no olive oil, we advocate considering home preparation of infant foods with the use of visible fat. Medical professionals should encourage food manufacturers to return to the concepts of the Mediterranean diet for young consumers, aimed at long-term health