Novel carbohydrate blend enhances chemical and sensory properties of lobster (Homarus americanus) after one-year frozen storage.

It has previously been shown that a novel blend of carbohydrates could preserve lobster meat after 6 months of frozen storage. Increased year-round demand for high-quality lobster may make selling to the frozen seafood market an unintended option for some fishermen. Yet, the chemical and sensory changes that occur in lobster meat after one-year frozen storage in this cryoprotectant blend is not known. The objective of this study was to determine the chemical and sensory characteristics of lobster frozen in five different solutions: solution-1 (water); solution-2 (water + NaCl + STPP, sodium tripolyphosphate, 0.5%); solution-3 (water + NaCl + carbohydrate blend); solution-4 (water + NaCl + STPP, 0.25% + carbohydrate blend), and solution-5 (water + NaCl + STPP, 0.5% + carbohydrate blend). No difference (P > 0.05) existed among the treatments with regard to Malondialdehyde levels as a measure of lipid oxidation. Lobster frozen in the cryoprotectant showed increased tenderness, compared to the control which was frozen in water. The lobster meat treated with a combination of the carbohydrate blend and STPP had lower (P < 0.05) moisture content than the control. In addition, consumers preferred (P < 0.05) lobster frozen in the novel cryoprotectant blend and STPP with respect to flavour, texture, and overall acceptability compared to the control. Penalty analysis revealed that overall liking scores were positively associated with the attributes moist and sweet. In conclusion, the combination of the novel carbohydrate blend and STPP enhanced the sensory quality and the chemical properties of frozen lobster, which in turn extended the shelf-life of these products. These findings may have wide implications for the long-term preservation of frozen lobster meat.

Impact of a Novel Cryoprotectant Blend on the Sensory Quality of Frozen Lobster (Homarus americanus).

Frozen storage of lobster meat (Homarus americanus) can result in undesirable quality changes that decrease consumer acceptability of these products. Current seafood industry methods use cryoprotective agents that contain phosphates including sodium tripolyphosphates (STPP). However, recent evidence suggests that cryoprotective mixtures that combine different carbohydrates and STPP can have equal or even greater cryoprotective properties compared to using STPP alone. The objective of this study was to compare the overall consumer acceptability of lobster meat stored for 6 months in different blends of these cryoprotective solutions. One hundred and seven panelists were recruited to score the acceptability of the lobster samples using nine-point hedonic scales. A check-all-that-apply (CATA) question containing 27 literature-informed, sensory descriptors was also used to identify terms frequently used to describe lobster meat. Analysis of variance analysis, indicated a significant increase for overall liking (22.1%, P < 0.0001), liking of flavor (23.6%, P < 0.0001) and texture (15.6%, P = 0.000) scores for samples stored in a novel carbohydrate blend plus sodium chloride (NaCl) and STPP compared to the water control. Subsequent penalty analysis revealed that overall liking scores were most positively associated with the attributes tender, sweet, moist and soft. Moreover, the attributes with the highest positive mean impact were more frequently used to describe lobster samples stored in solutions containing NaCl and the novel carbohydrate blend, as well as NaCl and STPP (Lobster-3 and Lobster-5 samples, respectively). PRACTICAL APPLICATION: The positive impact on the sensory quality of this novel blend of cryoprotective compounds (carbohydrates and NaCl) is proof of concept that this mixture is comparable, if not better than preservatives currently used by the seafood industry. Given the necessary regulatory approval and industry acceptance, lobster processors may consider this novel blend as a suitable alternative to freeze lobster products for up to 6 months.

Mechanisms of heterogeneous crystal growth in atomic systems: insights from computer simulations.

In this paper we analyze the atomic-level structure of solid/liquid interfaces of Lennard-Jones fcc systems. The 001, 011, and 111 faces are examined during steady-state growth and melting of these crystals. The mechanisms of crystallization and melting are explored using averaged configurations generated during these steady-state runs, where subsequent tagging and labeling of particles at the interface provide many insights into the detailed atomic behavior at the freezing and melting interfaces. The interfaces are generally found to be rough and we observe the structure of freezing and melting interfaces to be very similar. Large structural fluctuations with solidlike and liquidlike characteristics are apparent in both the freezing and melting interfaces. The behavior at the interface observed under either growth or melting conditions reflects a competition between ordering and disordering processes. In addition, we observe atom hopping that imparts liquidlike characteristics to the solid side of the interfaces for all three crystal faces. Solid order is observed to extend as rough, three-dimensional protuberances through the interface, particularly for the 001 and 011 faces. We are also able to reconcile our different measures for the interfacial width and address the onset of asymmetry in the growth rates at high rates of crystal growth/melting.

Quantum effects in ice Ih.

Quantum and classical simulations are carried out on ice Ih over a range of temperatures utilizing the TIP4P water model. The rigid-body centroid molecular dynamics method employed allows for the investigation of equilibrium and dynamical properties of the quantum system. The impact of quantization on the local structure, as measured by the radial and spatial distribution functions, as well as the energy is presented. The effects of quantization on the lattice vibrations, associated with the molecular translations and librations, are also reported. Comparison of quantum and classical simulation results indicates that shifts in the average potential energy are equivalent to rising the temperature about 80 K and are therefore non-negligible. The energy shifts due to quantization and the quantum mechanical uncertainties observed in ice are smaller than the values previously reported for liquid water. Additionally, we carry out a comparative study of melting in our classical and quantum simulations and show that there are significant differences between classical and quantum ice.

Impacts of quantization on the properties of liquid water.

The results of classical and quantum simulations of liquid water over a wide range of temperatures are compared to probe the impact of quantization on the properties of liquid water. We show that, when treated quantum mechanically, water molecules have an enhanced probability of accessing nontetrahedral coordination in the local three-dimensional structure. We discuss how this enhanced probability, also called "effective tunneling", is related to the dynamics of the hydrogen-bond breaking and molecular diffusion in the liquid. We explore in detail how local molecular environments affect the manifestation of quantum effects and identify a previously unreported and apparently unique behavior of the quantum mechanical uncertainty of the water molecule as a function of temperature. The nonmonotonic behavior of the quantum mechanical uncertainty with temperature is shown to be due to the notable strength of the water-water interaction in the condensed phase and becomes further evidence of the importance of the water structure in the properties of this ubiquitous liquid.