Armand Boudreau

Distribution of cholesterol in milk fat fractions

Milk fat was fractionated into liquid (m.p. congruent to 12 degrees C), intermediate (m.p. congruent to 21 degrees C) and solid (m.p. congruent to 39 degrees C) fractions by three different processes--melt crystallization, short-path distillation and supercritical CO2 extraction--and the cholesterol content of these fractions determined. Cholesterol was enriched in the liquid fractions from all three processes, in particular about 80% of the cholesterol being found in the liquid fraction obtained by short-path distillation. The basis of migration of cholesterol into various milk fat fractions was explained by its affinity to various triglycerides (melt crystallization) and by vapour pressure and molecular weight (short-path distillation). It was more complex in the supercritical CO2 extraction process; the interplay of cholesterol affinity toward CO2 and its molar volume, and its vapour pressure enhancement under applied pressure play a role.

Fractionation of anhydrous milk fat by short-path distillation

Anhydrous milk fat was fractionated by short-path distillation into four fractions at temperatures of 245 and 265 C and pressures of 220 and 100 μm Hg. Two fractions (LF1 and LF2) were liquid, one fraction (IF) was semi-solid and one fraction (SF) was solid at room temperature. The fractions were characterized by melting temperature profile, solid fat index and triglyceride and fatty acid compositions. The peak melting temperature progressively increased (8.8 to 38.7 C) from liquid to solid fractions. The solid fat content ranged from 0 to 27.5% at 20 C, while native milk fat was 15.4%. The short chain (C24–C34) triglycerides were enriched in the LF1 fraction, long chain (C42–C54) triglycerides were concentrated in the SF fraction, and medium chain (C36–C40) triglycerides in the IF fraction; in the LF2 fraction, though, both short and medium chain triglycerides were enriched. Short chain (C4–C8) fatty acids gradually decreased from liquid to solid fractions and the trend was reverse for long chain (C14–C18) fatty acids, both saturated and unsaturated. The weight average molecular weights and geometric mean-carbon number of milk fat fractions were in the range of 590.7–782.8 and 31.9–46.3, respectively, compared to 729.3 and 41.0, respectively, for native milk fat, suggesting short-path distillation effects a very high degree of molecular weight separation.

Fractionnement de la matière grasse laitière par cristallisation simple et son utilisation dans la fabrication de beurres mous

Abstract Anhydrous milk fat was fractionated into 7 fractions by melt crystallization at temperatures ranging from 26°C to 9°C. The fractions were characterized by fatty acid and triglyceride composition, melting point profile and solid fat index. The process was based on a slow cooling of the melted fat, a short duration of stabilization at the fractionation temperature and the separation of the crystals from liquid phase by vaccum filtration. The liquid fractions were rich in smaller triglycerides as well as short chain and unsaturated fatty acids, whereas the solid fractions had high concentrations of larger triglycerides with long chain saturated fatty acids. The separation of milk fat triglycerides by molecular size is not feasible by melt crystallization as evidenced by the weight average molecular weight of various fractions ranging from 714,8 to 769,7 compared to 727,5 for native milk fat and the geometric mean-carbon number of fractions ranging from 38,4 to 44,9 compared to 41,0 for milk fat. Selected fractions were used for the preparation of spreadable butters which were characterized for their spreadability, melting temperature profile and dilatation. Experimental butters showed a 2 to 4 fold improvement in spreadability at 7°C compared to the regular butter and they approached the spreadability of soft margarine at 15°C. Butter made from a blend of 80% of liquid fraction obtained at 9°C and 20% of solid fraction, obtained at 26°C, was the most spreadable. The limitation in improving spreadability of butter from milk fat triglycerides alone, is discussed.

Regiospecific analysis of fractions of bovine milk fat triacylglycerols with the same partition number

Bovine milk fat was fractionated using preparative reversed-phase high-performance liquid chromatography. The conditions consisted of two successive linear gradients of acetonitrile and tert-butylmethylether, followed by a final isocratic mixture of the two eluants, leading to triacylglycerols grouped by their partition number (PN). Fractions corresponding to partition numbers 32 to 50 were isolated and analyzed for fatty acid distribution between sn-1,3 and sn-2 positions by Grignard degradation. Results showed that the fatty acid distribution in milk fat triacylglycerols is nonrandom. The distribution of short-chain fatty acids, stearic (predominantly at sn-1,3 position) and palmitic (predominantly sn-2 position), did not change with triacylglycerol size. Medium-chain fatty acids were predominantly located at sn-2 position, but their proportion at this position decreased with triacylglycerol size. Oleic acid distribution was also size-dependent in that it was located in high proportions at sn-2 position in smaller triacylglycerols and vice versa. Results also showed that the sn-2 position was more unsaturated than sn-1,3 position in the PN range from 32 to 40, but it was more saturated in triacylglycerols with higher PN.

Effect of Lactobacillus brevis, Saccharomyces uvarum and Grist Composition on Amine Formations in Beers

Abstract The influence of L. brevis and S. uvarum, the type of malt (2- and 6-row) and adjuncts (corn syrup, corn, wheat, barley and rice) on biogenic amine contents in unfermented and fermented worts have been studied. Histamine, putrescine, tyramine and agmatine contents were determined by an ion-exchange chromatographic method. L. brevis produced putrescine and tyramine, but reduced the agmatine content in worts. S. uvarum did not produce amines. The 2-row malts contributed less to amine contents than the 6-row malts. Partial substitution of malt by adjuncts, in particular increasing amounts of rice (20 and 40%), resulted in lower amine contents in fermented worts.

Solubility of milk fat triglycerides in supercritical carbon dioxide

Abstract Five fractions of milk fat triglycerides were obtained by extraction with supercritical carbon dioxide in the pressure range of 12–33 MPa and at temperatures of 50 and 80°C. The results showed that increasing the solubility parameter or density of supercritical CO 2 under these conditions increased the solubility of milk fat triglycerides, but with this increase the supercritical fluid became less selective for the extraction of short-, medium- or long-chain triglycerides. The differences in solubility of individual milk fat triglycerides in supercritical CO 2 can be explained by solute-solvent interactions (extraction) and vapour pressure enhancement (distillation).

Contamination problems with 63Ni electron capture detectors

Abstract A study was performed on two 63Ni electron capture detectors operating in d.c. mode. Several parameters have been examined. It appeared that the temperature difference between the detector and the column is important. Scavenger gas temperature and detector isolation are not less important. Furthermore the detector polarization switch must always be off when no chromatogram is being run. These modifications help to keep the detector sensitivity much longer, with a consequent reduced number of washings.

Utilisation de la féverole dans la fabrication du tofu

Abstract A tofu product was fabricated from faba beans (Vicia Faba L. Minor). Various experimental conditions were modified to optimize product yield and organoleptic properties. Optimum yield (66.8% by weight and 44.8% protein) of the faba bean tofu was obtained with bean to water ratio of 1:10 by the decantation process. Increasing amounts of ascorbic acid increased the protein content and texture firmness and lowered the grey coloration of the product. Colour intensity may further be decreased by removing the cuticle before grinding. Also, increasing amounts of coagulant decreased the protein yield. Glucono-δ-lactone gave a tofu of very pale colour, but the protein yield was less than the other salts. The optimized decantation process gave better yield than the enzymatic process, and the resulting products were of similar texture and firmness as the tofu made from soya.

Mesure de la radioactivité dans des tomates cultivées sur des résidus miniers d'Oka – Communauté minière de niobium

Abstract The radioactivity contained in the tailings of a niobium mine in the Oka region, Quebec, was the object of concern for the population of the area in 1979. To find the impact of these tailings on fruit and vegetables grown in this environment, an investigation of the radioactivity found on tomatoes grown in green houses in niobium tailings and in vermiculites was undertaken. The tailings contained a high level of natural radioactivity and a small amount of 137Cs while the vermiculites has a very low level of natural radioactivity and an appreciable amount of 137Cs. Cesium-137 was the only nuclide detected in tomato ashes in measurable quantity. Absence of natural radioactivity is explained by its presence as insoluble minerals.