Critical Review of Norovirus Surrogates in Food Safety Research: Rationale for Considering Volunteer Studies

The inability to propagate human norovirus (NoV) or to clearly differentiate infectious from noninfectious virus particles has led to the use of surrogate viruses, like feline calicivirus (FCV) and murine norovirus-1 (MNV), which are propagatable in cell culture. The use of surrogates is predicated on the assumption that they generally mimic the viruses they represent; however, studies are proving this concept invalid. In direct comparisons between FCV and MNV, their susceptibility to temperatures, environmental and food processing conditions, and disinfectants are dramatically different. Differences have also been noted between the inactivation of NoV and its surrogates, thus questioning the validity of surrogates. Considerable research funding is provided globally each year to conduct surrogate studies on NoVs; however, there is little demonstrated benefit derived from these studies in regard to the development of virus inactivation techniques or food processing strategies. Human challenge studies are needed to determine which processing techniques are effective in reducing NoVs in foods. A major obstacle to clinical trials on NoVs is the perception that such trials are too costly and risky, but in reality, there is far more cost and risk in allowing millions of unsuspecting consumers to contract NoV illness each year, when practical interventions are only a few volunteer studies away. A number of clinical trials have been conducted, providing important insights into NoV inactivation. A shift in research priorities from surrogate research to volunteer studies is essential if we are to identify realistic, practical, and scientifically valid processing approaches to improve food safety

Modification of the structural and rheological properties of whey protein/gelatin mixtures through high pressure processing

High pressure processing (HPP) can induce structure development in macromolecules which are distinct from those of conventional thermal treatments. Gelation properties of whey protein (5-20% w/w) upon 15 min HPP at 600 MPa and 5 or 30 °C (initial sample temperatures) were examined in the presence and absence of 5% w/w gelatin. The values of storage modulus (G')in pressure treated mixed gels were below those of their counterparts thermally treated at 80 °C. Mixed systems subjected to HPP in the solution state possessed higher G' than the mixed systems subjected to HPP in the form of gels. The cooling profile of G' in pressurised mixed solutions was similar to that of the gelatin solution, which indicates that HPP resulted in a high degree of gelatin continuity. Confocal images confirmed that gelatin was the continuous phase whilst whey protein aggregated in discontinuous inclusions within the pressurised mixed systems

Growth of superconducting epitaxial LaNixBi2pnictide thin films with a Bi square net layer by reactive molecular beam epitaxy

We have grown superconducting epitaxial thin films of LaNixBi2 which crystallize in the ZrCuSiAs structure with a peculiar Bi square net layer. This material represents an additional class of pnictide superconductors since superconductivity is assumed to occur in the Bi square net layer. Optimized thin films grown by molecular beam epitaxy have a superconducting transition temperature of around 4 K and are stable in ambient air

Structuring dairy systems through high pressure processing

This review highlights the current knowledge on gelation of hydrocolloids induced by high pressure processing (HPP) of dairy products. Pressure-induced gelation of single systems (casein rich, whey protein rich, gelatin, and polysaccharide solutions) as well as rheological and thermo-mechanical effects of HPP on mixture systems are discussed. The mechanism of dairy protein gelation under pressure, their properties and microstructure, and potential application of HPP to improve physical properties of dairy products (cheese, yoghurt, and ice cream) are included. HPP is a promising tool for future manufacturing of structured dairy products with unique sensorial properties

Search for superconductivity in LaNiP2 (P=Bi, Sb) thin films grown by reactive molecular beam epitaxy

We have explored the possibility of using reactive molecular beam epitaxy (RMBE) as a synthesis technique for the search for arsenic free pnictide superconductors. High quality epitaxial thin films of LaNiBi2 were successfully grown on (1 0 0) MgO substrates by RMBE. The films were (0 0 l) oriented and the epitaxial nature of the films was confirmed by RHEED and X-ray diffraction measurements. The LaNiBi2 thin films grown on (1 0 0) MgO shows that the a-axis of the films were 45° rotated with respect to MgO. The Ni deficient films gave a Tc(0) of 3.1 K. We have successfully substituted Bi by Sb and have grown high quality epitaxial thin films of LaNiSb2. However, the LaNiSb2 thin films did not show any superconductivity down to 1.5 K

MBE growth of LaNiBiO1-x thin films

The discovery of superconductivity in FeAs based compounds has generated tremendous interest in the search for new superconducting materials. The toxic nature of As naturally calls for the search for alternative materials with similar structure which may be superconducting. LaNiBiO1-x has the same structure as FeAs-1111. We have grown LaNiBiO1-x thin films on (100) MgO substrate by reactive molecular beam epitaxy (RMBE). Films were grown by simultaneous evaporation of La, Ni and Bi from elemental sources by electron beam evaporators and the in situ oxidation is achieved by an RF activated oxygen radical source. The reflection high energy electron diffraction and X-ray diffraction analysis revealed that the films were polycrystalline in nature. The LaNiBiO1-x phase forms only in a very narrow growth parameter window and is very sensitive to the oxidation conditions. The polycrystalline films have a Tc (onset) of ∼ 5.5 K

Effect of high pressure processing on rheological and structural properties of milk-gelatin mixtures

There is an increasing demand to tailor the functional properties of mixed biopolymer systems that find application in dairy food products. The effect of static high pressure processing (HPP), up to 600MPa for 15min at room temperature, on milk-gelatin mixtures with different solid concentrations (5%, 10%, 15% and 20% w/w milk solid and 0.6% w/w gelatin) was investigated. The viscosity remarkably increased in mixtures prepared with high milk solid concentration (15% and 20% w/w) following HPP at 300MPa, whereas HPP at 600MPa caused a decline in viscosity. This was due to ruptured aggregates and phase separation as confirmed by confocal laser scanning microscopy. Molecular bonding of the milk-gelatin mixtures due to HPP was shown by Fourier-transform infrared spectra, particularly within the regions of 1610-1690 and 1480-1575cm-1, which reflect the vibrational bands of amide I and amide II, respectively