Physico‐chemical Characterization of Floridean Starch of Red Algae

The current work reports on isolation and physico‐chemical characterization of floridean starch from three species of agarophytic macro red algae. As determined by ¹H‐NMR spectroscopy, the average chain length and degree of branching frequency of this starch were 18 and 4.8, respectively. According to its amylopectin chain length distribution obtained by Dionex analysis, the crystalline polymorph of floridean starch from the red alga Gracilariopsis lemaneiformis was deduced to be C‐type and this was further supported from its X‐ray crystallographic pattern. Enzymatic analysis of its glucose 6‐phosphate content showed that floridean starch had a low level of covalently linked phosphate (1 nmol per milligram starch) and this was further confirmed by ³¹P‐NMR. The absorbance peak of floridean starch with iodine occurred at 527—530 nm and the blue value was low (0.1), indicating the absence of amylose, which was confirmed by differential scanning calorimetry (DSC). Floridean starch exhibited low gelatinization temperature, low viscosity, high clarity and little or no retrogradation upon repetitive freeze‐thaw cycles, as studied by DSC and rapid viscosity analysis (RVA). These results are discussed in light of the functional properties and the structure of floridean starch.     

Prevalence, distribution, and diversity of Listeria monocytogenes in retail environments, focusing on small establishments and establishments with a history of failed inspections

Despite growing concerns about cross-contamination of ready-to-eat foods with Listeria monocytogenes, our knowledge about the ecology and transmission of L. monocytogenes in retail establishments has remained limited. We conducted a cross-sectional study to characterize the prevalence, distribution, and subtype diversity of L. monocytogenes in 120 New York State retail deli establishments that were hypothesized to present an increased risk for environmental L. monocytogenes contamination (i.e., small establishments and establishments with a history of failed New York State Agriculture and Markets inspections). Analysis of these data along with previously reported data for 121 predominantly larger retail establishments in New York State identified establishment size, geographic location, and inspection history as significant predictors of L. monocytogenes presence and prevalence. The odds of an establishment being L. monocytogenes positive were approximately twice as high for large establishments, establishments located in New York City, or establishments with poor inspection history (as compared with establishments without these attributes), even though correlation between location and inspection history complicated interpretation of results. Within an establishment, L. monocytogenes was significantly more prevalent on nonfood contact surfaces than on food contact surfaces; prevalence was particularly high for floors and in floor drains, sinks, the dairy case, and milk crates. L. monocytogenes subtype diversity differed between sites, with lineage I isolates significantly associated with nonfood contact surfaces and lineage II isolates significantly associated with food contact surfaces. Isolates belonging to the same ribotype were often found dispersed across multiple sites within an operation.     

Apple,Carrot, and Hibiscus Edible Films Containing the Plant Antimicrobials Carvacrol and Cinnamaldehyde Inactivate Salmonella Newport on Organic Leafy Greens in Sealed Plastic Bags

The objective of this study was to investigate the antimicrobial effects of carvacrol and cinnamaldehyde incorporated into apple, carrot, and hibiscus‐based edible films against Salmonella Newport in bagged organic leafy greens. The leafy greens tested included organic Romaine and Iceberg lettuce, and mature and baby spinach. Each leafy green sample was washed, dip inoculated with S. Newport (10⁷ CFU/mL), and dried. Each sample was put into a Ziploc® bag. Edible films pieces were put into the Ziploc bag and mixed well. The bags were sealed and stored at 4 °C. Samples were taken at days 0, 3, and 7 for enumeration of survivors. On all leafy greens, 3% carvacrol films showed the best bactericidal effects against Salmonella. All 3 types of 3% carvacrol films reduced the Salmonella population by 5 log₁₀ CFU/g at day 0 and 1.5% carvacrol films reduced Salmonella by 1 to 4 log₁₀ CFU/g at day 7. The films with 3% cinnamaldehyde showed 0.5 to 3 log reductions on different leafy greens at day 7. The films with 0.5% and 1.5% cinnamaldehyde and 0.5% carvacrol also showed varied reductions on different types of leafy greens. Edible films were the most effective against Salmonella on Iceberg lettuce. This study demonstrates the potential of edible films incorporated with carvacrol and cinnamaldehyde to inactivate S. Newport on organic leafy greens.     

Effects of Allspice, Cinnamon, and Clove Bud Essential Oils in Edible Apple Films on Physical Properties and Antimicrobial Activities

ABSTRACT:  Essential oils (EOs) derived from plants are rich sources of volatile terpenoids and phenolic compounds. Such compounds have the potential to inactivate pathogenic bacteria on contact and in the vapor phase. Edible films made from fruits or vegetables containing EOs can be used commercially to protect food against contamination by pathogenic bacteria. EOs from cinnamon, allspice, and clove bud plants are compatible with the sensory characteristics of apple-based edible films. These films could extend product shelf life and reduce risk of pathogen growth on food surfaces. This study evaluated physical properties (water vapor permeability, color, tensile properties) and antimicrobial activities against  Escherichia coli  O157:H7,  Salmonella enterica,  and  Listeria monocytogenes  of allspice, cinnamon, and clove bud oils in apple puree film-forming solutions formulated into edible films at 0.5% to 3% (w/w) concentrations. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor phase diffusion of the antimicrobial from the film to the bacteria. The antimicrobial activities against the 3 pathogens were in the following order: cinnamon oil > clove bud oil > allspice oil. The antimicrobial films were more effective against  L. monocytogenes  than against the  S. enterica . The oils reduced the viscosity of the apple solutions and increased elongation and darkened the colors of the films. They did not affect water vapor permeability. The results show that apple-based films with allspice, cinnamon, or clove bud oils were active against 3 foodborne pathogens by both direct contact with the bacteria and indirectly by vapors emanating from the films.     

Estrogen-induced alterations in amh and dmrt1 expression signal for disruption in male sexual development in the zebrafish

Dmrt1 and amh are genes involved in vertebrate sex differentiation. In this study, we cloned dmrt1 and amh cDNAs in zebrafish (Danio rerio) and investigated the effects of exposure to 17a-ethinylestradiol (EE2), during early life on their patterns of expression and impact on the subsequent gonadal phenotype. Expression of both amh and dmrt1 in embryos was detected as early as at 1 day post fertilization (dpf) and enhanced expression of amh from 25 dpf was associated with the period of early gonadal differentiation. Sex-dependent differences in enhanced green fluorescent protein transgene expression driven by the promoter of the germ cell-specific vas gene were exploited to show that at 28dpf and 56dpf both amh and dmrt1 mRNA were overexpressed in males compared with females. Exposure during early life to environmentally relevant concentrations of EE2 had a suppressive effect on the expression of both amh and dmrt1 mRNAs and this was associated with a cessation/retardation in male gonadal sex development. Our findings indicate that estrogen-induced suppression in expression of dmrt1 and amh during early life correlate with subsequent disruptive effects on the sexual phenotype in males.     

Spatial distribution of light-induced lipid oxidation in semi-hard yellow cheese as detected by confocal microscopy

The migration of oxidative damage in semi-hard yellow cheese resulting from surface exposure to 436 nm monochromatic light with an intensity of 2.5 × 10¹⁷ quanta min⁻¹ cm⁻² for 0, 5, 10, and 15 min was followed by confocal laser scanning microscopy using labelling with the lipophilic fluorescence ratio probe C₁₁-Bodipy (581/591). From 5 × 5 × 5 mm cubes of cheese exposed to light on one plane 35 μm was sliced off and fluorescence of oxidised and non-oxidised probe recorded simultaneously on the surface of the slice reaching 250 μm inwards from the exposed surface. From the emission of the fluorescence ratio probe light-induced lipid oxidation could be followed with time of exposure to light. The penetration of light inwards in the cheese with time expressed as quanta cm⁻², as calculated from light transmittance at 436 nm determined spectrophotometrically for cheese slices of up to 300 μm thickness, together with light intensity as determined by actinometry, could alone account for the inwards migration of oxidation. Diffusion of radicals seems of less importance for spatial dispersion of light-induced oxidation in semi-hard cheese.     

Mathematical modeling of the freezing process of concrete and aggregates

A two dimensional finite element computer model for predicting frost penetration in saturated porous materials is presented. Based on available second order parabolic differential equations for predicting temperature and moisture content, and equations relating freezing temperature and water potential, the finite element model predicts temperature, water and ice content, frost penetration, and generated pore water pressures as a function of freezing time and given boundary conditions, Comparison of models results with available experimental data for mature cement pastes rendered reasonable agreement between the model and data.     

Liquid Loss as Effected by Post mortem Ultrastructural Changes in Fish Muscle: Cod (Gadus morhuaL) and Salmon (Salmo salar)

This study was performed in order to assess the effect of early post mortem structural changes in the muscle upon the liquid-holding capacity of wild cod, net-pen-fed cod (fed cod) and farmed salmon. The liquid-holding capacity was measured by a low speed centrifugation test. Transmission electron microscopy was used to discover ultrastructural changes both in the connective tissue and in the myofibrils. Differential scanning calorimetric thermograms of the muscle proteins were recorded to elucidate whether fundamental differences did exist between the proteins of the raw material tested. Multivariate statistics were used to explicate the main tendencies of variations in the thermograms. The salmon muscle possessed much better liquid-holding properties than the cod muscle, and wild cod better than fed cod regardless of the storage time. Both fed cod and farmed salmon, underwent the most severe structural alterations, probably caused by the low muscle pH values. The higher liquid-holding capacity of the salmon muscle was related to species specific structural features and better stability of the muscle proteins. The myofibrils of the salmon muscle were denser and intra- and extracellular spaces were filled by fat and a granulated material. The differences in thermograms of muscle from wild and fed cod were largely explained by the variations in pH. The severe liquid loss of fed cod is due to a low pH induced denaturation and shrinkage of the myofibrils. Post mortem degradation of the endomysial layer and the sarcolemma may have further facilitated the release of liquid.