Showing papers by "University of Bedfordshire published in 1975"

Chemistry and Interactions of Seed Galactomannans

Abstract: Publisher Summary This chapter discusses the interaction of galactomannans with other polysaccharides. The general chemistry of the galactomannans has been reviewed by Whistler and Smart and others. The chapter discusses the uses of guar and locust-bean gums in various industrial applications and investigates the structural chemistry of galactomannans, especially as revealed by enzymic studies. Mixtures of locust-bean gum with the non-gelling polysaccharide from Xanthomonas campestris have been shown to interact synergistically to give firm, rubbery gels, whereas the use of the galactomannan from C yamopsis tetragonolobus (guar gum) results only in viscosity enhancement. These interactions are important in many of the industrial applications of galactomannans, and a study of them may also help provide an understanding of the associations among polysaccharide chains, contributing to biological cohesion and texture. The two main groups of galactomannan polysaccharides are those derived from (1) the endosperm of plant seeds, the vast majority of which originate in the Leguminoseae, and (2) microbial sources, in particular, the yeasts and other fungi. D-Mannose and D galactose are also found in numerous other plant polysaccharides—for example, glucomannansm, mannans, and galactans.

Analysis of nitrate and nitrite in foodstuffs: A critical review

Abstract: A general review is presented of published methods for the determination of nitrate and nitrite levels in foodstuffs especially meat. Published methods show wide variations in techniques for extraction, clean-up (clearing) of extracts and final determinative steps and these are critically compared. The effect of interferences due to the presence of ascorbate, sulphite and phosphate together with the formation of a “meat blank” when nitrate is reduced to nitrite with spongy cadmium are discussed. Newer techniques based on the use of ion selective electrodes and automated techniques are outlined and the application of techniques such as amperometry, liquid chromatography, ion exchange and spectrophotometry are listed.

The Search for a Vector Model.

Abstract: Many teachers are apologetic about the definitions of vector which they offer because they believe that any elementary definition must be imperfect compared with the sophisticated definitions of higher mathematics [1]. In a review of many common definitions we show that the one which best stands up to criticism is quite elementary. Moreover, it provides a base for valid criticism of the supposedly superior tensor definition.

Circuits for detecting rapid fluctuations in the phase of an a.c. signal

Abstract: A circuit for detecting rapid fluctuations in the phase of an A.C. signal, comprising a phase detector adapted to receive the A.C. signal at one of its input terminals and at the other of its input terminals an A.C. signal generated by a controlled oscillator and to provide an output signal dependent on the phase difference between the two signals applied to its input terminals, filter means through which the output of the phase detector is supplied to the controlled oscillator in such a manner that the output of the oscillator is held stably by negative feedback at a frequency equal to the means frequency of the A.C. signal, the filter means preventing rapid changes in the output of the phase detector from being applied to the controlled oscillator, and means for comparing the phase of the A.C. signal with that of the oscillator output thereby to provide an output dependent on the rapid fluctuations on phase of the A.C. signal.

A Comparison of Two Methods of Overall Fumigation for the Control of Docking Disorder of Sugar Beet

Abstract: SUMMARY Field experiments in Norfolk in 1969–70 and in Yorkshire and Norfolk in 1970–71 and 1971–72 compared the control of Trichodorus spp. and Longidorus spp. given by different rates of dichloropropene placed by a tine injector and by a sub-surface sprayer. Increasing rates of fumigant up to 410 1./ha improved nematode control; populations recovered only slightly a year later. The larger rates of fumigant increased sugar yield especially when the crop had shown Docking disorder symptoms, but there was no consistent difference between the two methods of application in controlling nematodes or increasing sugar yield.

Thermal transitions relating to gelling processes

Abstract: The usefulness of differential scanning calorimetry (DSC) as a tool for studying thermal transitions in systems of biological origin is illustrated, using examples drawn from DSC studies of the gelation of the carrageenan polysaccharides.