Calibration powders were developed using combinations of milk ingredients for the purpose of calibration of infrared milk analyzers. They were shown to be capable of producing calibrations very similar to conventional calibration milks available commercially. A subsequent collaborative study was carried out involving nine laboratories to assess the performance of the preformulated powders in industrial quality control, payment and dairy herd analysis laboratories. The calibration powders were shown to produce consistent calibrations within laboratories and between laboratories and met AOAC specifications in terms of accuracy and repeatability. The reconstituted solutions were shown to be stable for up to 6 h at 40$ sp circ$C and could be stored under refrigerated conditions and used for repeated analyses for up to 21 days without apparent deterioration in calibration performance. It was concluded that the calibration powders perform as well as conventional calibrants, were more consistent overall and suitable for any calibration application. The calibration powders have the stability and performance characteristics to serve as reference standards for monitoring instrument performance and would be a useful tool for accrediting payment and dairy herd analysis laboratories.

In 1890, Dr. S. M. Babcock developed a practical method for the determination of butterfat in milk. From that time, fat was regarded as the major milk constituent and indeed, has controlled milk price variations in many countries, even up to the present time. [...]

Polar bears are found in Canada in a region which lies between the 60th and 95th meridians and the 63rd and the 75th parallels. They are particularly abundant in Northern Baffin Island, Southampton Island, Simpson Peninsula, and the small islands near Cornwallis Island. [...]

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Milk, preheated at 82°C for 30 minutes, was heated to 146°C for four seconds (UHT-treated) and cooled to 5°C in a tubular heat exchanger. Immediately after heat treatment, 20 gallons of heated milk were vacuum distilled at 30°C in a semi-continuous, reduced pressure glass apparatus. Twenty gallons of non-heated milk were distilled in a similar manner to serve as a control. Continuous liquid-liquid ethyl ether extractions were employed to recover the compounds from the aqueous distillates. Gas chromatography, mass spectrometry, infrared spectrophotometry and odor confirmation were used to characterize the compounds in the flavor concentrates. A technique for collecting and transferring packed column gas chromatographic fractions to capillary columns for mass spectral analysis was developed. The following compounds were identified in UHT-treated milk (the underlined compounds appeared to result from the heat treatment): the C₃, ₄, ₅, ₇, ₈, ₉, ₁₀, ₁₁, ₁₃ n-methyl ketones, the C₈, ₁₀, ₁₂ delta-lactones, acetaldehyde, hexanal, benzaldehyde, furfural, phenylactaldehyde, vanillin, the C₆, ₈, ₁₀ n-alkanoic acids, ethanol, oct-1-en-3-ol, n-heptanol, 2-butoxyethanol, diacetyl, maltol, acetophenone, ethyl acetate, benzothiazole, toluene, naphthalene, a dichlorobenzene, a trichlorobenzene, methyl iodide, benzonitrile and chloroform. The following compounds were identified in non-heated milk: C₃, ₄, ₅, ₇, ₉ n-methyl ketones, C₁₀, ₁₂ delta-lactones, hexanal, benzaldehyde, C₆, ₈, ₁₀ n-alkanoic acids, ethanol, diacetyl, ethyl acetate, methyl palmitate, diethyl phthalate, a dichlorobenzene, a trichlorobenze and methyl iodide. The concentration of diacetyl in UHT-treated and non-heated milk was determined by a modified gas entrainment, on-column trapping GLC technique. The amount of diacetyl in non-heated milk was 3 ppb while the amount in the UHT-treated was 38 ppb. The diacetyl concentration of UHT-treated milk decreased approximately 40% over 16 days storage at 4°C. The average flavor threshold for diacetyl in milk was found to be 12 ppb. It seems therefore that the UHT-treatment increased the diacetyl concentration from a subthreshold level to above the average flavor threshold. It is suggested that diacetyl contributes to the "rich", "heated" note in the flavor of heated milk. / Graduation date: 1968

Graduation date: 1966

No description available.

No description available.

No description available.

No description available.