Today approximately 10 % of fermented milk products stick to the packaging material inner surface, and therefore it is not possible to pour all of the dairy product from the package. This is both an economical and environmental issue. The product loss is expensive for consumer and makes recycling of package less effective. As they do not yet exist the development of packaging materials to which fermented milk products stick less, it would make it possible to both save money and protect our environment. The aim of this work was to provide knowledge and understanding of the important factors involved in the phenomenon when fermented milk products adhere to the inner surface of a packaging material. Studies were done on materials having different surface properties, such as polarity and relative oxidation. They were incubated in fermented milk and other dairy products varying in fat concentration and protein type up to 168 h. The systems were investigated gravimetrically, with Fourier Transform Infra Red/Attenuated Total Reflectance Spectroscopy, Scanning Electron Microscopy and Contact Angle measurements. Fermented milk contains amphiphilic components and therefore can interact both with polar and non-polar surfaces, such that the relative oxidation of the surface does not contribute to the adhesion. The adhesion of fermented milk is an equilibrium reaction, which depend on the fat concentration before equilibrium as well as the protein concentration after equilibrium. The adhesion seems to follows the Vroman effect, with smaller molecules associating faster and thereby adhering to the surface initially, but are displaced by larger molecules that associates slower as times passes.

Tez (Yüksek Lisans) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Gıda Mühendisliği Anabilim Dalı, 2009. / Kaynakça var.

This study was designed to measure the prevalence and nutritional impact of dairy product restriction in both pregnant and lactating women. Dairy product (DP) restriction was assessed in 2091 prenatal class attendees. Subsamples of 279 healthy pregnant and 175 exclusively breastfeeding women provided repeat 24-hour dietary recalls which were used to estimate nutrient intake and to assess dietary adequacy using adjusted nutrient distributions. Pregnancy outcome was recorded. Pregnancy. DP restriction was reported by 13.2% (95% CI: 12.7%,14.1%) of pregnant women. Significant differences were found in the proportion of restrictors (Rs, 20.8%) below the calculated EAR for adjusted protein intakes vs. nonrestrictors (NRs, 9.2%, chi 2 = 6.78, p = 0.009). Intake distributions of calcium and vitamin D were compared to their respective Als for descriptive purposes and were lower for Rs vs. NRs but dietary inadequacy could not be assessed. Infants of NRs weighed on average 120 g +/- 468.9 g more than those of Rs but this difference was not statistically significant (p = 0.06). However, in multiple regression analysis where maternal weight gain, age, education and pregravid weight were controlled for, restriction predicted a comparable loss in birthweight of 122.5 g's (p = 0.048) and vitamin D intakes were positively associated with fetal growth. Lactation. Restriction (≤250 ml milk/day) was reported by 23% (95% CI; 16%--29%) of exclusively lactating women. Protein was lower than the EAR for 60% of Rs and 37.8% of NRs (chi 2 = 6.22, p = 0.025). The proportion of Rs and NRs < EAR from diet differed for thiamin (15% vs. 0%, chi2 = 0.97, p < 0.001), riboflavin (15% vs. 1.5%, chi2 = 12.93, p < 0.001) and zinc (65.0% vs. 34.8%, chi2 = 11.6, p < 0.041). From diet and supplement intake vitamin D and calcium remained lower for Rs compared to NRs but inadequacy could not be assessed or compared. DP restriction was not associated with greater weight loss amo

Increasing interest has been shown in the irradiation sterilization and irradiation pasteurization of foods, but problems of off-flavors and odors are still unsolved, especially in the case of dairy products. From the flavor chemistry point of view, milk lipids are very highly susceptible to irradiation effects. Therefore, this investigation was designed to study some irradiation induced reactions involving flavor changes in the milk fat and to identify the volatile components produced in the milk fat upon irradiation. Milk fat, prepared from raw sweet cream and washed free of phospholipids, was first irradiated in the presence of air and under vacuum in glass vials at 4.5 Mrad with gamma rays from cobalt-60. The irradiation resulted in increase in TBA number, peroxide value, total monocarbonyls, bleaching of color, slightly rancid and typical candle-like off-flavors. Free fatty acids were also produced upon irradiation. The changes were more drastic in air along with production of a slight oxidized flavor. The monocarbonyls identified by column and paper chromatographic methods in irradiated milk fat include: C₁ through C₁₂, C₁₄ , and C₁₆ n-alkanals; C₃ through C₉, C₁₁, C₁₃ and C₁₅ alk-2-ones with only traces of C₆ and C₈ alk-2- ones; and C₅, C₆, C₉, and C₁₂ alk-2-enals. Irradiation of milk fat that had been dried over calcium hydride also caused free fatty acid production, especially short chain fatty acids. Methyl octanoate treated with calcium hydride and irradiated at 1.5, 3.0, 4.5, and 6.0 Mrad yielded small quantities of free octanoic acid, confirming that irradiation caused fission of the ester linkage even when traces of water were removed. The quantities of octanoic acid formed increased with increasing dose of irradiation. For identification of volatile components, the milk fat was irradiated in 307x409 'C' enameled cans under vacuum. The headspace analysis showed some air still left in the cans. Irradiation resulted in consumption of oxygen and production of hydrogen, carbon monoxide, carbon dioxide, and methane as identified in the headspace gases. The volatiles were isolated from the irradiated and control milk fats by low temperature, vacuum steam distillation at 40°C and 1-2 mm Hg. The volatile components were then extracted from the aqueous distillate with ethyl ether. The ethyl ether extract exhibited the typical candle-like defect. The ethyl ether concentrate was analyzed by combination of GLC and fast-scan mass spectrometric techniques. Identification of various components was achieved on the basis of mass spectral data and coincidence of gas chromatographic retention times. In the case of the components for which only GLC t[subscript r]/t[subscript r] evidence was available or the mass spectra obtained were not satisfactory, the identity assigned was only tentative. The volatile compounds that were positively identified to be present in irradiated milk fat are given below: n-Alkanes C₅ through C₁₇ 1-Alkenes C₅, C₇ through C₁₇ Fatty acids C₄, C₆, C₈ and C₁₀ n-Alkanals C₅ through C₁₁ Others γ-decalactone, δ-decalactone, 2-heptanone, benzene, ethyl acetate, chloroform, and dichlorobenzene. The tentative identification was obtained for the following compounds: γ-lactones C₆ and C₈ δ-lactones C₆, C₈, C₁₁, and C₁₂ 1, ?-alkadienes C₁₀, C₁₁, C₁₂, C₁₆ and C₁₇ iso-alkanes C₁₀, C₁₁, C₁₂, and C₁₃ Others methyl hexanoate, 2-hexanone, 4-heptanone and n-dodecanal. The compounds present in unirradiated control milk fat included: short chain fatty acids (C₄, C₆, C₈, and C₁₀), C₈, C₁₀, and C₁₂ δ-lactones, 2-heptanone, chloroform, dichlorobenzene, benzene, toluene, and ethyl-benzene. Only tentative identity was established for most of these components in control milk fat. Possible reaction mechanisms are presented for the formation of the compounds in irradiated milk fat. / Graduation date: 1966

Typescript (photocopy) / xv, 210 leaves, [2] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / By using a regression equation relating the difference between dye binding and Kjeldahl values with the total protein concentration of the milk, the accuracy of estimates of casein in milk from individual cows was improved. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Physiology, 1981

The goal of this project was to synthesise potential flavour compounds combinatorially and identify key components for further investigation as flavourants in dairy products. This thesis describes the design and synthesis of libraries of ketones and γ-lactones that will be evaluated for flavour potential. Gas chromatography-mass spectrometry (GCMS), the Fox, and gas chromatography-olfactometry (GC-O) were used throughout this study. Ketones were synthesised individually via a two-step sequence: a Grignard reaction followed by the oxidation of the resulting alcohol in Chapter 2. Some compounds selected from the Fox analysis were assessed by GC-O. The analysis gave promising results for aromatic and cyclopropyl ketones and a library of cyclopropyl ketones was prepared. Individual racemic lactones were synthesised via a two-step sequence: the Linstead modification of the Knoevenagel reaction and subsequent lactonisation in Chapter 3. Libraries of racemic γ-lactones (C8-C12), including α-substituted γ-lactones, were produced combinatorially. Further, synthesis of a library of γ-thionolactones was achieved by treatment of a library of γ-lactones with Lawesson's reagent. The libraries were analysed by GC-O. A (R)-dodecalactone was synthesised from L-glutamic acid and the (S)-enantiomer was synthesised by the same sequence from D-glutamic acid in Chapter 4. Asymmetric syntheses of both enantiomeric series of γ-lactones utilizing the Sharpless asymmetric dihydroxylation reaction was employed to give the libraries in Chapter 5. Libraries of a-substituted and β-substituted γ-lactones were synthesised combinatorially and analysed by GC-O.

Master of Engineering / Spray dryers are the core components of a milk powder production plant, where the basic configuration usually features co-current flow of milk powder and air. Spray dryers have to be cleaned frequently due to powder deposit build-up on the walls. Powder deposit build-up gives rise to lower product yields and poses a potential fire risk. If the powder deposits are scorched (from being overheated) they will contaminate, and thus compromise, the quality and consumer safety of the final product, if the powder deposits fall in and mix with it. With milk powder production rates of most industrial spray dryers ranging from 4-28 tonnes of dry powder an hour, these wall deposition problems are significant. This problem is worth investigating because the outcome of reducing or eliminating wall deposition is that a spray dryer could operate for a longer period of time without having to be cleaned. Reduction in downtime due to cleaning would give rise to increased production time and possibly a reduction in the cost of manufacturing the product. The spray dryer used in this work was a modified short-form co-current Niro unit, fabricated from stainless steel. The spray dryer had an internal diameter of 0.80 m, narrowing down to 0.06 m at the base, and a height of 2 m. A two-fluid nozzle was used to spray the process fluids (water, skim milk and grape skin extract) into the drying chamber. To measure the wall deposition fluxes on the internal walls of the spray dryer, four stainless steel plates (dimensions 110 mm by 120 mm) were inserted in place of the windows that were previously used as sight glasses. A fifth plate (dimensions 110 mm by 120 mm) and a sixth plate (dimensions 110 mm by 110 mm) were also placed on the conical section of the spray dryer at different circumferential locations. Before this work, no quantitative data on the effects of spray dryer operating conditions on the wall deposition fluxes of food material were available. This work investigated the effect on the spray deposition flux of skim milk powder on the walls of the spray dryer of (i) flow patterns in the spray dryer, by changing the degree of swirl imparted to the incoming air by using three swirl vane angles of 0o, 25o and 30o, and (ii) the stickiness of the product, through first changing the temperature of the incoming air by using three inlet air temperatures of 170oC, 200oC and 230oC; and then changing the process fluid flowrate by using three flowrates of 1.4 kg hr-1, 1.6 kg hr-1 and 1.8 kg hr-1. Previous researchers have found that the extent to which water droplets spread out in the drying chamber is affected by the amount of swirl in the inlet air. This is likely to affect wall deposition fluxes because the particles will be closer to the walls if the droplets spread out widely. The results of this work have quantitatively confirmed that the spray deposition flux increases at higher swirl vane angles, where the spray deposition flux increased from 7 g m-2 hr-1 (swirl vane angle 0o) to 12.9 g m-2 hr-1 (swirl vane angle 30o). When a swirl vane angle of 0o was used, it was observed that the cross-sectional area of the spray cloud did not change very significantly with time. However, when a swirl vane angle of 25o was used, the spray cloud was observed to “flutter”, and when the swirl vane angle was increased to 30o, the spray cloud was observed to recirculate rapidly back in the direction of the nozzle. Thus, the chance of the particles being thrown further towards the walls of the chamber is likely to increase at higher swirl vane angles. This result suggests that higher wall deposition arises because more swirl is imparted to the air entering the dryer, which in turn affects the stability of the spray cloud and, therefore, the stability of the flow patterns in the spray dryer. The stickiness of the skim milk powder is related to the temperature and moisture content of the particles. In the past, the sticky-point curve has been suggested as a semi-quantitative concept in selecting operating conditions for spray drying food material containing carbohydrates, where it has been implied that there is no significant wall deposition below the sticky-point curve. This work has quantified the spray deposition in spray dryers with respect to the sticky-point curve, where the highest spray deposition flux of skim milk powder on the walls was 16 g m-2 hr-1, and the operating point corresponding to this spray deposition flux was located at and above the sticky-point curve. Hence, both particle stickiness and flow patterns affect the wall deposition of particles in a spray dryer. This work also investigated the effect of wall properties, namely a non-stick food grade material (nylon), adhesive tape and stainless steel, on the spray deposition flux of skim milk powder on the walls. The effect of electrostatics on wall deposition was studied by grounding the spray dryer and an anti-static agent was added to the skim milk to investigate if altering the properties of the feed material could reduce wall deposition. This work has quantitatively confirmed that cohesion occurs at the same rate as adhesion for skim milk powder in this spray dryer, because firstly, decreasing the adhesion tendency of the v wall by using nylon coating had no significant effect on the spray deposition flux compared with a smooth stainless steel wall and a wall covered with a double-sided adhesive tape; and secondly the powder collected on the walls was a linear function of time with and without adhesive on the plates. Furthermore, using a nylon coated wall did not eliminate wall deposition, and the wall deposition flux was found to be the same as when a stainless steel wall was used. This result further supports the finding here that spray deposition on the walls for skim milk powder is controlled by cohesion rather than adhesion. The spray dryer operating parameters that gave rise to the least spray deposition flux on the walls were a swirl vane angle of 0o, an inlet air temperature of 230oC and a process fluid flowrate of 1.4 kg hr-1. Decreasing the feed flowrate from 1.8 kg hr-1 to 1.4 kg hr-1 (decrease by 24%), with the inlet air temperature and swirl vane angle held constant, decreased the wall deposition flux by 43% from 7 g m-2 hr-1 to 4 g m-2 hr-1. Since the spray deposition flux on the walls decreased by 43% when the feed flowrate was decreased by 24%, it might be considered that the production process is in favour of a decrease in the feed flowrate to 1.4 kg hr-1 in this dryer, and consequently a decrease in the spray deposition flux on the walls per unit production output. Finally, this work investigated if the outlet moisture content from this small spray dryer used here was equilibrium limited or controlled by drying kinetics. The findings in this work confirmed the product moisture locus concept, which implies that the outlet moisture content of the skim milk particles approaches the equilibrium moisture content (in equilibrium with the outlet gas), and that the outlet moisture content of spray-dried food material containing carbohydrates is probably not limited by particle drying kinetics, even though the spray dryer is smaller (diameter 0.8 m, height 2 m) than those used in the dairy industry, typically with a diameter of 30 m and a height of 10 m.

Master of Engineering / Spray dryers are the core components of a milk powder production plant, where the basic configuration usually features co-current flow of milk powder and air. Spray dryers have to be cleaned frequently due to powder deposit build-up on the walls. Powder deposit build-up gives rise to lower product yields and poses a potential fire risk. If the powder deposits are scorched (from being overheated) they will contaminate, and thus compromise, the quality and consumer safety of the final product, if the powder deposits fall in and mix with it. With milk powder production rates of most industrial spray dryers ranging from 4-28 tonnes of dry powder an hour, these wall deposition problems are significant. This problem is worth investigating because the outcome of reducing or eliminating wall deposition is that a spray dryer could operate for a longer period of time without having to be cleaned. Reduction in downtime due to cleaning would give rise to increased production time and possibly a reduction in the cost of manufacturing the product. The spray dryer used in this work was a modified short-form co-current Niro unit, fabricated from stainless steel. The spray dryer had an internal diameter of 0.80 m, narrowing down to 0.06 m at the base, and a height of 2 m. A two-fluid nozzle was used to spray the process fluids (water, skim milk and grape skin extract) into the drying chamber. To measure the wall deposition fluxes on the internal walls of the spray dryer, four stainless steel plates (dimensions 110 mm by 120 mm) were inserted in place of the windows that were previously used as sight glasses. A fifth plate (dimensions 110 mm by 120 mm) and a sixth plate (dimensions 110 mm by 110 mm) were also placed on the conical section of the spray dryer at different circumferential locations. Before this work, no quantitative data on the effects of spray dryer operating conditions on the wall deposition fluxes of food material were available. This work investigated the effect on the spray deposition flux of skim milk powder on the walls of the spray dryer of (i) flow patterns in the spray dryer, by changing the degree of swirl imparted to the incoming air by using three swirl vane angles of 0o, 25o and 30o, and (ii) the stickiness of the product, through first changing the temperature of the incoming air by using three inlet air temperatures of 170oC, 200oC and 230oC; and then changing the process fluid flowrate by using three flowrates of 1.4 kg hr-1, 1.6 kg hr-1 and 1.8 kg hr-1. Previous researchers have found that the extent to which water droplets spread out in the drying chamber is affected by the amount of swirl in the inlet air. This is likely to affect wall deposition fluxes because the particles will be closer to the walls if the droplets spread out widely. The results of this work have quantitatively confirmed that the spray deposition flux increases at higher swirl vane angles, where the spray deposition flux increased from 7 g m-2 hr-1 (swirl vane angle 0o) to 12.9 g m-2 hr-1 (swirl vane angle 30o). When a swirl vane angle of 0o was used, it was observed that the cross-sectional area of the spray cloud did not change very significantly with time. However, when a swirl vane angle of 25o was used, the spray cloud was observed to “flutter”, and when the swirl vane angle was increased to 30o, the spray cloud was observed to recirculate rapidly back in the direction of the nozzle. Thus, the chance of the particles being thrown further towards the walls of the chamber is likely to increase at higher swirl vane angles. This result suggests that higher wall deposition arises because more swirl is imparted to the air entering the dryer, which in turn affects the stability of the spray cloud and, therefore, the stability of the flow patterns in the spray dryer. The stickiness of the skim milk powder is related to the temperature and moisture content of the particles. In the past, the sticky-point curve has been suggested as a semi-quantitative concept in selecting operating conditions for spray drying food material containing carbohydrates, where it has been implied that there is no significant wall deposition below the sticky-point curve. This work has quantified the spray deposition in spray dryers with respect to the sticky-point curve, where the highest spray deposition flux of skim milk powder on the walls was 16 g m-2 hr-1, and the operating point corresponding to this spray deposition flux was located at and above the sticky-point curve. Hence, both particle stickiness and flow patterns affect the wall deposition of particles in a spray dryer. This work also investigated the effect of wall properties, namely a non-stick food grade material (nylon), adhesive tape and stainless steel, on the spray deposition flux of skim milk powder on the walls. The effect of electrostatics on wall deposition was studied by grounding the spray dryer and an anti-static agent was added to the skim milk to investigate if altering the properties of the feed material could reduce wall deposition. This work has quantitatively confirmed that cohesion occurs at the same rate as adhesion for skim milk powder in this spray dryer, because firstly, decreasing the adhesion tendency of the v wall by using nylon coating had no significant effect on the spray deposition flux compared with a smooth stainless steel wall and a wall covered with a double-sided adhesive tape; and secondly the powder collected on the walls was a linear function of time with and without adhesive on the plates. Furthermore, using a nylon coated wall did not eliminate wall deposition, and the wall deposition flux was found to be the same as when a stainless steel wall was used. This result further supports the finding here that spray deposition on the walls for skim milk powder is controlled by cohesion rather than adhesion. The spray dryer operating parameters that gave rise to the least spray deposition flux on the walls were a swirl vane angle of 0o, an inlet air temperature of 230oC and a process fluid flowrate of 1.4 kg hr-1. Decreasing the feed flowrate from 1.8 kg hr-1 to 1.4 kg hr-1 (decrease by 24%), with the inlet air temperature and swirl vane angle held constant, decreased the wall deposition flux by 43% from 7 g m-2 hr-1 to 4 g m-2 hr-1. Since the spray deposition flux on the walls decreased by 43% when the feed flowrate was decreased by 24%, it might be considered that the production process is in favour of a decrease in the feed flowrate to 1.4 kg hr-1 in this dryer, and consequently a decrease in the spray deposition flux on the walls per unit production output. Finally, this work investigated if the outlet moisture content from this small spray dryer used here was equilibrium limited or controlled by drying kinetics. The findings in this work confirmed the product moisture locus concept, which implies that the outlet moisture content of the skim milk particles approaches the equilibrium moisture content (in equilibrium with the outlet gas), and that the outlet moisture content of spray-dried food material containing carbohydrates is probably not limited by particle drying kinetics, even though the spray dryer is smaller (diameter 0.8 m, height 2 m) than those used in the dairy industry, typically with a diameter of 30 m and a height of 10 m.

Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formated into pages; contains 1 v. (various pagings). Includes abstract. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.