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Rapid Visco Analyser (rapid + visco_analyser)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Effect of different starches on rheological and microstructural properties of (II) commercial processed cheese

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2008
Darshan Trivedi
Summary A range of commercial processed cheese samples containing starch were prepared on a Rapid Visco Analyser (RVA) and on a pilot plant scale. This work clearly demonstrated that it was possible to manufacture processed cheese with part of the protein replaced with potato starch, while maintaining similar rheological attributes (firmness) to those of the control and an acceptable melt index. Sensory evaluation showed that, although the reduced-protein cheese samples had a good, clean, fresh flavour that was comparable with that of the control, at high starch concentrations the starch-containing processed cheese had a pasty texture and tended to stick to the wrapper. [source]

Influence of amylases on the rheological and molecular properties of partially damaged wheat starch

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 11 2006
Pedro Leman
Abstract The effects of Bacillus subtilis, porcine pancreatic and Aspergillus oryzae ,-amylases, sweet potato ,-amylase and Bacillus stearothermophilus maltogenic amylase (BStA) on the rheological properties (measured with a Rapid Visco Analyser) of partially damaged wheat starch were studied and the accompanying changes in starch molecular properties were analysed by high-performance size exclusion chromatography. Pasting and gelation of starch slurries (with an increased level of damaged starch) were significantly affected by the supplemented amylases and greatly depended on the mode of action and properties of the enzymes added. In general, at low endo-amylase concentrations, peak, hot paste and cold paste viscosities were more reduced for enzyme-supplemented partially damaged starch than for enzyme-supplemented native wheat starch, demonstrating the significance of damaged starch levels in determining amylase functionality. Higher dosages of thermostable amylases ruled out most of the differences between amylase-supplemented native starch and partially damaged starches, except for BStA. Furthermore, the (limited) endo-action of BStA determines to a great extent the rheological properties of the starch paste. These results contribute to a better understanding of (maltogenic) amylase functionality in processing (damaged) starch-containing foods. Copyright © 2006 Society of Chemical Industry [source]

Evaluation of the influence of different species and cultivars of lupin kernel meal on the extrusion process, pellet properties and viscosity parameters of salmonid feeds

AQUACULTURE NUTRITION, Issue 1 2010
B. GLENCROSS
Abstract This study examined the influence of different lupin species and cultivars and their inclusion levels on the physical properties of an extruded diet. Lupin kernel meals were included into a fish diet formulation at 0%, 10%, 20% and 30%. Soybean meal was also included in a series of diets on a similar basis as a reference. The diet mashes were extruded using a laboratory-scale APV19:45 twin-screw extruder. The pellets were examined for radial expansion, bulk density, vacuum oil uptakes, sink rate, shear and crush strengths. Inclusion of lupin kernel meal significantly increased bulk density, sink rate, shear and crush strength of the pellets. With the increase in lupin kernel meal inclusion level, a concomitant decline in vacuum oil uptake and radial expansion was also observed. An assessment of the diet mashes using a Rapid Visco Analyser showed that the inclusion of lupin kernel meals increased the rate and degree of gelatinization of the mash starch content compared with that with a similar inclusion level of soybean meal. The inclusion of lupin kernel meals in the diet mash also improved the water-holding capacity of the extrudate, which has important implications for the reduction in extruder wear. [source]

Study of the retrogradation behaviour of rice cake using rapid visco analyser, Fourier transform infrared spectroscopy and X-ray analysis

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2010
Ying Ji
Summary Retrogradation of gelatinised starch is the main phenomenon that influences the texture of MiGao (rice cake). The hardness of the MiGao increased during stored at 25 °C for 5 days. Rapid visco analyser (RVA), Fourier transform infrared (FT-IR) spectroscopy and X-ray were quantified to analysis the retrogradation behaviour of MiGao. The most significant change in the pasting curve was the increase in peak viscosity over time measured with an RVA. FT-IR indicated changes in crystallinity of the MiGao crumb. The X-ray diffraction patterns could be classified as typical of A-type starch for the fresh MiGao. With aging, the B-type structure increases, while the A-type structure remains virtually unchanged. All the results suggested that the main mechanism underlying the changes in properties is suggested to be slow amylopectin crystallisation. [source]