Xanthan Gum: A Unique Food Hydrocolloid

The classical thermal diffusivity tube method was modified with respect to equipment design and data analysis to generate thermal diffusivity values as a function of temperature in the range of interest in thermal processing operations. The major change in the design was the fabrication of an end insulated cylindrical pressure cell capable of withstanding thermal processing temperatures. A multi-stage regression technique was employed to obtain thermal diffusivity at different temperatures. The temperature range for the regression analysis was expanded by utilizing a significant portion of the lag period through an iterative computer programming technique. UNSTEADY TEMPERATURE IN SHORT TIME HEATED REGULAR THERMALLY CONDUCTIVE SOLIDS. Ramaswamy, H.S. and M.A. Tung, Department of Food Science and K. V. Lo, Department of Bio-Resource Engineering, University of British Columbia, Vancouver, British Columbia V6T 2A2. The infinite summation series describing the heat transfer into regular conductive solids is usually approximated by the first term of the series when the heating time is relatively long. For short time heating (Fo<0.2), the errors involved because of the first term approximation are significant (up to 25% for an infinite slab at Fo = 0.02). This is because of the curvilinear relationship between the temperature and time at Fo<0.2. Simplified relationships for estimating the curved portion of the heating or cooling curve at 0.001
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ALKALINE EXTRACTION OF PROTEIN FROM SPENT HONEY BEES. Ryan, J.K. and P. Jelen, Department of Food Science and W.e. Sauer, Department of Animal Science, University of Alberta, Edmonton, Alberta TOO 2N2. Adult honey bees were evaluated as a potential source of human food grade protein. Bees collected at honey harvest were 49.9% protein, 7.54% lipid (including wax) and 27.1 % reducing sugar (moisture free basis). Bees were homogenized and body proteins solubilized in alkali, chitin removed by filtration, and protein recovered by acid precipitation. Amount of protein solubilized varied with treatment, from negligible without alkali (pH 6.1) to 93% of theoretical maximum with severest treatment at pH 11.2. Precipitate was 66.3% protein, 9.4% lipid and 7.9% ash. Heads, thoraces and abdomens were separated and treated. Head precipitate was purple, odourous and contained 19.3% of whole body precipitate, which was 70.1 % protein. Thorax protein was white and odourless. Abdomen precipitate was brown, sweet, 44.9% of body precipitate and only 36.6% protein. Amino acid composition of these proteins was analyzed. CONSUMER PREFERENCES AND HANDLING PRACTICES OF POTATOES. Ryland, D. and R. Diamant, Department of Foods and Nutrition, University of Manitoba, Winnipeg, Manitoba R3T 2N2. To provide a basis for the evaluation of table stock varieties of potatoes, a survey of Manitoba consumers was conducted regarding their criteria for the selection and assessment of potato quality. Also determined was their behaviour regarding consumption, handling and cooking methods. The survey, done by telephone, utilized a questionnaire based on information from focus group interviews. Random telephone numbers (chosen by the plus one method) were called by professional interviewers. In each household reached, the major food preparer was interviewed, 200 in Winnipeg and 200 in other Manitoba locations. Frequencies of responses were related to certain characteristics of the samples. ATTACHMENT OF SALMONELLA TYPHlMURIUM TO TWO TYPES OF CHICKEN SKIN. Sahasrabudhe, J.M. and B.J. Skura, Department of Food Science, University of British Columbia, Vancouver, British Columbia V6T 2A2. Attachment of Salmonella typhimurium to lean (Type I) and fatty (Type 11) chicken broiler leg skin was evaluated. Representative legs, after dipping in attachment medium containing 10" S. typhimuriuml mL, were subjected to the following procedures 0, 5, 10 and 15 min after inoculation: (I) no washing (inoculated), (2) washing with sterile attachment medium (inoculated-washed), and (3) washing with sterile attachment medium containing 1% Tween 80 (inoculated-surfactant washed). More S. typhimurium attached to Type 11 skin than to Type I skin (PO.05). XANTHAN GUM: A UNIQUE FOOD HYDROCOLLOID. Sanderson, G.R., Kelco, 8355 Aero Drive, San Diego, California 92123. Aqueous solutions of xanthan gum, the extracellular polysaccharide from Xanlhomonas campeslris, possess a number of extremely useful rheological properties. They exhibit a yield value, are highly pseudoplastic and have high viscosities at low gum concentrations. In addition, viscosity is not significantly reduced by large changes in pH, temperature and ionic strength. These properties make xanthan gum a unique thickener and stabilizer for a wide range of food products. The widespread use of xanthan gum in the food industry is also partly the result of its good compatibility and, in some cases, favourable interactions with other food ingredients. N-NITROSODIMETHYLAMINE (NDMA) AND N-NITROSOPROLINE (NPRO) IN MALT AND BEER. Sen., N.P., S. Seaman and L. Tessier, Food Research Division, Food Directorate, Health Protection Branch, Ottawa, Ontario KIA OL2. The average levels of NDMA in both the domestic and imported beers seemed to have decreased significantly during the last 3 years thus confirming the efficacy of the improved malt drying techniques introduced recently in various countries. The details will be presented at the meeting. The development of a rapid method (based on GLC-TEA@ analysis of the methyl-ester) for determining NPRO in malt and beer, and some recent data on the NPRO levels in these products, will also be reported. Both mall (5-113 ppb) and beer (0.5-3.9 ppb) were found to contain traces of NPRO.

J. Inst. Can. Sci. Technol. Aliment. Vo!. 15, No. 3, 1982