Development of Technologies for Separation and Functional Improvement of Individual Milk Protein Fractions

End of Project ReportMilk proteins can be hydrolysed (i.e. fragmented) using proteolytic enzymes to give enhanced functional and nutritional properties. There is an increasing demand for hydrolysed protein ingredients with specific properties for nutrition of individuals with specialised dietary requirements including infants, the critically ill, the immuno-compromised and athletes. Such hydrolysed proteins can be specifically designed to provide distinctive tailor-made solutions to meet customer needs in these areas. This project explored the technologies for the production of two types of hydrolysates i.e. acid-soluble and glutamine-rich. Acid-soluble protein hydrolysates have potential in the fortification of acidic beverages, including soft drinks. Glutamine-rich hydrolysates are suggested as an optimal glutamine source for administration during periods of stress, such as recovery from strenuous exercise, or from surgery. Casein was selected as the protein for development of acid-soluble product and cereal protein for the glutamine-rich product. The main conclusions were as follows: A number of protein hydrolysate products with value added properties and the processes required for their manufacture have been developed and are available for uptake by the food industry. Laboratory investigations identified conditions for the generation of two casein hydrolysates with desirable functional properties. Scale-up conditions for the manufacture of these hydrolysates in the pilot plant were successfully developed. Both hydrolystates were 100% soluble at pH 4.6, exhibited clarity in solution at low pH in clear soft drinks and in caramelised beverages and were stable in solution over a wide temperature range (from 4 to 30ºC) for extended periods. Solutions containing these hydrolysates exhibited no foaming properties and had acceptable sensory properties, being considered as weakly bitter compared to unsupplemented solutions. These performance characteristics make the acid-soluble hydrolysates useful supplements for caramelised beverages, such as colas, and clear soft drinks. Six glutamine-enriched peptide products were produced at laboratory scale using two commercially available enzyme preparations. These products had desirable characteristics such as increased levels of peptide bound glutamine, low free amino acid and free pyroglutamate levels. Pilot plant processes were developed for manufacture of the two glutamine-rich hydrolysates with most suitable compositional properties and these were fully characterised chemically. The manufacturing process was modified to enable industrial scale batches (5,000 litres) to be produced.Department of Agriculture, Food and the Marin

A Quantum-Mechanical Equivalent-Photon Spectrum for Heavy-Ion Physics

In a previous paper, we calculated the fully quantum-mechanical cross section for electromagnetic excitation during peripheral heavy-ion collisions. Here, we examine the sensitivity of that cross section to the detailed structure of the projectile and target nuclei. At the transition energies relevant to nuclear physics, we find the cross section to be weakly dependent on the projectile charge radius, and to be sensitive to only the leading momentum-transfer dependence of the target transition form factors. We exploit these facts to derive a quantum-mechanical ``equivalent-photon spectrum'' valid in the long-wavelength limit. This improved spectrum includes the effects of projectile size, the finite longitudinal momentum transfer required by kinematics, and the response of the target nucleus to the off-shell photon.Comment: 19 pages, 5 figure

Electromagnetic Dissociation of Nuclei in Heavy-Ion Collisions

Large discrepancies have been observed between measured Electromagnetic Dissociation(ED) cross sections and the predictions of the semiclassical Weiz\"acker-Williams-Fermi(WWF) method. In this paper, the validity of the semiclassical approximation is examined. The total cross section for electromagnetic excitation of a nuclear target by a spinless projectile is calculated in first Born approximation, neglecting recoil. The final result is expressed in terms of correlation functions and convoluted densities in configuration space. The result agrees with the WWF approximation to leading order(unretarded electric dipole approximation), but the method allows an analytic evaluation of the cutoff, which is determined by the details of the electric dipole transition charge density. Using the Goldhaber-Teller model of that density, and uniform charge densities for both projectile and target, the cutoff is determined for the total cross section in the nonrelativistic limit, and found to be smaller than values currently used for ED calculations. In addition, cross sections are calculated using a phenomenological momentum space cutoff designed to model final state interactions. For moderate projectile energies, the calculated ED cross section is found to be smaller than the semiclassical result, in qualitative agreement with experiment.Comment: 28 page

Combinatorial Markov chains on linear extensions

We consider generalizations of Schuetzenberger's promotion operator on the set L of linear extensions of a finite poset of size n. This gives rise to a strongly connected graph on L. By assigning weights to the edges of the graph in two different ways, we study two Markov chains, both of which are irreducible. The stationary state of one gives rise to the uniform distribution, whereas the weights of the stationary state of the other has a nice product formula. This generalizes results by Hendricks on the Tsetlin library, which corresponds to the case when the poset is the anti-chain and hence L=S_n is the full symmetric group. We also provide explicit eigenvalues of the transition matrix in general when the poset is a rooted forest. This is shown by proving that the associated monoid is R-trivial and then using Steinberg's extension of Brown's theory for Markov chains on left regular bands to R-trivial monoids.Comment: 35 pages, more examples of promotion, rephrased the main theorems in terms of discrete time Markov chain

High Pressure Processing of Dairy Foods

End of Project ReportThe term High Pressure Processing (HPP) is used to describe the technology whereby products are exposed to very high pressures in the region of 50 - 800 MPa (500 - 8000 Atmospheres). The potential application of HPP in the food industry has gained popularity in recent years, due to developments in the construction of HPP equipment which makes the technology more affordable. Applying HPP to food products results in modifications to interactions between individual components, rates of enzymatic reactions and inactivation of micro-organisms. The first commercial HPP products appeared on the market in 1991 in Japan, where HPP is now being used commercially for products such as jams, sauces, fruit juices, rice cakes and desserts. The pioneering research into the application of HPP to milk dates back to the end of the 19th century. Application of HPP to milk has been shown to modify its gel forming characteristics as well as reducing its microbial load. HPP offers the potential to induce similar effects to those generated by heat on milk protein. Recent reports have also indicated that HPP could accelerate the ripening of cheese. Much of the Irish cheese industry is based on the production of Cheddar cheese, the ripening time for which can vary from 4 - 12 months or more, depending on grade. A substantial portion of the cost associated with Cheddar manufacture is therefore attributed to storage under controlled conditions during ripening. Thus, any technology which may accelerate the ripening of Cheddar cheese while maintaining a balanced flavour and texture is of major economic significance. While food safety is a dominant concern, consumers are increasingly demanding foods that maintain their natural appearance and flavour, while free of chemical preservatives. HPP offers the food industry the possibility of achieving these twin goals as this technology can lead to reduced microbial loads without detrimentally effecting the nutritional or sensory qualities of the product. The development of food ingredients with novel functional properties offers the dairy industry an opportunity to revitalise existing markets and develop new ones. HPP can lead to modifications in the structure of milk components, in particular protein, which may provide interesting possibilities for the development of high value nutritional and functional ingredients. Hence these projects set out to investigate the potential of HPP in the dairy industry and to identify products and processes to which it could be applied.Department of Agriculture, Food and the Marin

Parity Violating Measurements of Neutron Densities

Parity violating electron nucleus scattering is a clean and powerful tool for measuring the spatial distributions of neutrons in nuclei with unprecedented accuracy. Parity violation arises from the interference of electromagnetic and weak neutral amplitudes, and the $Z^0$ of the Standard Model couples primarily to neutrons at low $Q^2$. The data can be interpreted with as much confidence as electromagnetic scattering. After briefly reviewing the present theoretical and experimental knowledge of neutron densities, we discuss possible parity violation measurements, their theoretical interpretation, and applications. The experiments are feasible at existing facilities. We show that theoretical corrections are either small or well understood, which makes the interpretation clean. The quantitative relationship to atomic parity nonconservation observables is examined, and we show that the electron scattering asymmetries can be directly applied to atomic PNC because the observables have approximately the same dependence on nuclear shape.Comment: 38 pages, 7 ps figures, very minor changes, submitted to Phys. Rev.

A Bayesian analysis of pentaquark signals from CLAS data

We examine the results of two measurements by the CLAS collaboration, one of which claimed evidence for a $\Theta^{+}$ pentaquark, whilst the other found no such evidence. The unique feature of these two experiments was that they were performed with the same experimental setup. Using a Bayesian analysis we find that the results of the two experiments are in fact compatible with each other, but that the first measurement did not contain sufficient information to determine unambiguously the existence of a $\Theta^{+}$. Further, we suggest a means by which the existence of a new candidate particle can be tested in a rigorous manner.Comment: 5 pages, 3 figure

eta-prime photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

Differential cross sections for the reaction gamma p -> eta-prime p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data indicate for the first time the coupling of the etaprime N channel to both the S_11(1535) and P_11(1710) resonances, known to couple strongly to the eta N channel in photoproduction on the proton, and the importance of j=3/2 resonances in the process.Comment: 6 pages, 3 figure

Measurement of the Deuteron Structure Function F2 in the Resonance Region and Evaluation of Its Moments

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasi-elastic peak up to the invariant mass of the final-state hadronic system W~2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c)^2. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasi-elastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behaviour of the higher twist contribution suggests a partial cancellation of different higher twists entering into the expansion with opposite signs. This cancellation, found also in the proton moments, is a manifestation of the "duality" phenomenon in the F2 structure function

First measurement of direct f0(980)f_0(980) photoproduction on the proton

We report on the results of the first measurement of exclusive $f_0(980)$ meson photoproduction on protons for $E_\gamma=3.0 - 3.8$ GeV and $-t = 0.4-1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the $\pi^+ \pi^-$ channel by performing a partial wave analysis of the reaction $\gamma p \to p \pi^+ \pi^-$. Clear evidence of the $f_0(980)$ meson was found in the interference between $P$ and $S$ waves at $M_{\pi^+ \pi^-}\sim 1$ GeV. The $S$-wave differential cross section integrated in the mass range of the $f_0(980)$ was found to be a factor of 50 smaller than the cross section for the $\rho$ meson. This is the first time the $f_0(980)$ meson has been measured in a photoproduction experiment