Classification of macroalgae as fuel and its thermochemical behaviour.

A preliminary classification of five macroalgae from the British Isles; Fucus vesiculosus, Chorda filum, Laminaria digitata, Fucus serratus, Laminaria hyperborea, and Macrocystis pyrifera from South America, has been presented in terms of a Van Krevelen diagram. The macroalgae have been characterised for proximate and ultimate analysis, inorganic content, and calorific value. The different options for thermal conversion and behaviour under combustion and pyrolysis have been evaluated and compared to several types of terrestrial biomass including Miscanthus, short rotation Willow coppice and Oat straw. Thermal treatment of the macroalgae has been investigated using thermogravimetry (TGA) and pyrolysis-gc-ms. Combustion behaviour is investigated using TGA in an oxidising atmosphere. The suitability of macroalgae for the different thermal processing routes is discussed. Ash chemistry restricts the use of macroalgae for direct combustion and gasification. Pyrolysis produces a range of pentosans and a significant proportion of nitrogen containing compounds. High char yields are produced.

Quantification of toxic Microcystis spp. during the 2003 and 2004 blooms in western Lake Erie using quantitative real-time PCR.

In August of 2003 and August of 2004, blooms of potentially toxic cyanobacteria Microcystis spp. persisted in western Lake Erie. Samples collected from the bloom were analyzed for the cyanobacterial toxin microcystin and the presence of Microcystis spp. cells. Estimates of microcystin toxicity exceeding 1 microg L(-1) (microcystin-LR activity equivalents), the safety limit set by the World Health Organization, were found from the samples in both 2003 and 2004. The presence of Microcystis spp. in water samples was confirmed through standard polymerase chain reaction (PCR) using a combination of four primer sets. Quantification of Microcystis was accomplished by a real-time PCR assay utilizing specific primer-Taq-man probe sets targeted on a conserved, Microcystis-specific 16S rDNA fragment and a microcystin toxin synthetase gene mcyD. This approach allowed us to specifically study the distribution and abundance of toxic Microcystis in the lake in contrast to previous studies that have assessed Microcystis populations with less refined methods. On the basis of quantification by quantitative real-time PCR analysis, the total abundance of Microcystis cells in the bloom area varied from 4 x 10(8) to 2 x 10(3) cells L(-1). The results of this study provide novel insight regarding the distribution and abundance of Microcystis spp. in the western basin of Lake Erie, a region plagued in recent years by large-scale (>20 km2) blooms. Our results suggest that the Maumee River and Bay may serve as a source for Microcystis to western and central Lake Erie.

Flavor enhancement of reduced fat cheddar cheese using an integrated culturing system.

Mild cheese flavor in reduced fat Cheddar cheese was enhanced by using an integrated starter culture system. Three cultures, Lactococcus lactis subsp. cremoris SK11, L. lactis subsp. lactis biovar. diacetylactis JVI, and Lactobacillus casei 7A, were carefully selected to obtain a nonbitter, mildly acid, buttery flavored cheese. Cheeses were produced from all possible combinations of these cultures with the constraint that L. lactis subsp. cremoris SK11 was used as the primary acid-producing culture. Cheeses made with SK11 were compared to cheeses produced using an L. lactis subsp. cremoris commercial starter culture. Cheeses were ripened for 150 days and periodically sampled for chemical, microbiological, and sensory analysis. Cheeses produced with L. lactis subsp. cremorisSK11 had substantially lower bitterness intensity than the cheeses produced with commercial starter culture. L. lactis subsp. lactis biovar. diacetylactis JVI significantly increased diacetylacetoin and acetate concentrations. Sensory results indicate that these cheeses had increased buttery (diacetyl) flavor.

Bacteriocidal activity of sanitizers against Enterococcus faecium attached to stainless steel as determined by plate count and impedance methods.

Enterococcus faecium attached to stainless steel chips (100 mm2) was treated with the following sanitizers: sodium hypochlorite, peracetic acid (PA), peracetic acid plus an organic acid (PAS), quaternary ammonium, organic acid, and anionic acid. The effectiveness of sanitizer solutions on planktonic cells (not attached) was evaluated by the Association of Official Analytical Chemists (AOAC) suspension test. The number of attached cells was determined by impedance measurement and plate count method after vortexing. The decimal reduction (DR) in numbers of the E. faecium population was determined for the three methods and was analyzed by analysis of variance (P < 0.05) using Statview software. The adhered cells were more resistant (P < 0.05) than nonadherent cells. The DR averages for all of the sanitizers for 30 s of exposure were 6.4, 2.2, and 2.5 for the AOAC suspension test, plate count method after vortexing, and impedance measurement, respectively. Plate count and impedance methods showed a difference (P < 0.05) after 30 s of sanitizer exposure but not after 2 min. The impedance measurement was the best method to measure adherent cells. Impedance measurement required the development of a quadratic regression. The equation developed from 82 samples is as follows: log CFU/chip = 0.2385T2-0.96T + 9.35, r2 = 0.92, P < 0.05, T = impedance detection time in hours. This method showed that the sanitizers PAS and PA were more effective against E. faecium than the other sanitizers. At 30 s, the impedance method recovered about 25 times more cells than the plate count method after vortexing. These data suggest that impedance measurement is the method of choice when evaluating the number of bacterial cells adhered to a surface.