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This thesis aims to improve the understanding of the factors that determine the performance of baghouses used for milk powder collection. The research focuses specifically on the similarities and differences between milk powder collection and other common baghouse applications. The thesis also aims to demonstrate the value of recent developments in computational fluid dynamics in developing predictive models of baghouse performance. It is hoped that the findings of the thesis may find application in the New Zealand dairy industry, where such baghouses are commonly used to collect milk powder after spray drying. The effect of operating temperature and humidity on the performance of baghouses was investigated by examining both the forward filtration process and pulse cleaning process. Forward filtration was examined in a series of bench scale experiments, then scaled up to the pilot scale to confirm the findings. The effect of humidity on the pulsing performance was then investigated at the pilot scale. The importance of pulse system design was investigated at the pilot scale in a separate set of experiments. Pulse nozzle position, pulse pressure, and pulse duration were varied and the effect on the baghouse pressure differentials was measured. A computational fluid dynamics (CFD) filter model designed for membrane filtration was adapted with some success to simulate a milk powder baghouse. The model was successful in predicting the length of the low pressure zone at the top of the bag, and the general trends in overpressure associated with changes to the pulse system geometry. The model was not successful in predicting the acceleration of the filter bag during the pulse. The model was used to simulate both forward filtration and pulsing, to extend the results of the experimental investigation. The effects of changes in the pulse nozzle height, pulse nozzle diameter, and pulse pressure were simulated, as well as the effect of gravitational settling during forward filtration, to extend the results of the previous experiments. There is a clear opportunity remaining for further work to extend the basic model developed here and to adapt the model to simulate large industrial baghouses. Experiments on the bench scale and pilot scale indicated that increased cohesive forces between particles improve the performance of milk powder baghouses by lowering the resistance of the filter cake during forward filtration and aiding cake removal during pulse cleaning. Under the conditions typical of industrial milk powder baghouses, cohesive forces are governed primarily by liquid bridging between particles, due to melted fat (particularly at high temperatures) and softened lactose (at high humidity levels). As a range of milk powders with different compositions are produced commercially, the relative importance of lactose-based and fat-based cohesion differs between powder types. Cohesion promotes the formation of porous structures in the filter cake, improving the cake permeability. In skim milk powder (SMP), particle cohesion is dominated by softened lactose, and is highly moisture dependent. In the bench scale experiments conducted here, increasing the relative humidity from 6% to 17% decreased the specific cake resistance from 1.69x10⁹ m.kg¯¹ to 8.23X10⁸ m.kg¯¹, and decreased the proportion of powder adhering to the filter from 14% of the total supplied powder to 3%. The combination of these effects decreased the total resistance over the filter from 1.09X10⁹m¯¹ to 1.89X10⁸; m¯¹, an 83% reduction. The low deposition at high humidity suggested that the porous cake structure formed at high humidity levels was fragile, so that deposited particles were prone to subsequent dislodgement, especially in areas where the shear velocity near the filter surface was high. In pilot scale experiments, the porous cake structure formed at high humidity was more easily removed from the filter bag, resulting in more effective pulse cleaning. It was concluded that particle cohesion promoted cake filtration over depth filtration, as particles tended to adhere to the cake surface immediately upon contact. As depth filtered particles are more difficult to remove, the shift toward cake filtration at high humidity improved the pulse cleaning performance. A high-fat milk protein concentrate (MPC) powder was also filtered on the bench scale apparatus. Particle cohesion in the MPC powder was dominated by liquid fat, and showed a clear dependence on temperature but not on humidity. Increasing the temperature from 30°C to 90°C caused the specific cake resistance of the MPC to decrease from 1.06x10⁸ m⁻¹ to 3.94x10⁷m⁻¹, a 63% decrease. The deposition of MPC powder was unaffected by either temperature or humidity. Gravitational settling of particles in large baghouses was found to produce significant variations in the properties of the filter cake throughout the baghouse. Experimental results with the pilot scale baghouse found a strong decreasing trend in the particle size with increasing height in the baghouse, with the mean particle size decreasing from 117 μm at the bottom of the baghouse to only 31 μm near the top of the filter bag. The filter cake thickness also decreased sharply with height. Results from the CFD simulations indicated that in the pilot scale baghouse particles larger than 120 μm in diameter tend to fall out of the air flow and collect in the bottom of the baghouse, instead of depositing on the filter. While industrial baghouses tend to have a higher elutriation velocity than the pilot scale baghouse used in this study, the large size of industrial baghouses provides ample opportunity for particles to segregate on the basis of size. In addition, bench scale results indicated that high air velocities near the filter surface may cause particles to rebound from the filter. This may occur in industrial baghouses in the region near the inlet, where the air velocity is highest. The reverse pressure differential induced in the filter bag by a cleaning pulse was found to increase with distance from the cell plate. Positioning the nozzle too close to the bag opening created a low pressure zone just beneath the cell plate, where the pressure remained lower inside the bag than outside throughout the pulse. This may lead to poor cleaning at the top of the bag. In the pilot scale baghouse, positioning the nozzle at least 0.7 m from the bag opening eliminated the low pressure zone. The optimum distance of 0.7 m is is dependent on the nozzle type and bag diameter, but can be directly applied to recent industrial baghouse designs in the NZ dairy industry, which have the same nozzle type and bag diameter as the pilot scale baghouse. The design of the pulse cleaning system is important in achieving good baghouse performance. Increasing the pulse tank pressure on the pilot scale baghouse from 3.5 bar to 6.5 bar caused a 30% reduction in the forward pressure differential after the pulse, while decreasing the pulse pressure below 3.5 bar caused the pressure differentials to increase indefinitely. Altering the nozzle position had no effect on the overall pressure differentials, but did alter the local acceleration at different points on the filter bag during a pulse. CFD simulations indicated that decreasing the distance between the nozzle and the bag opening from 0.7 m to 0.1 m increased the overpressure at the bottom of the bag from 770 Pa to 3500 Pa, but this was offset by the appearance of the low pressure zone at the top of the bag as mentioned above. CFD simulations indicated that the diameter of the pulse nozzle altered both the mean bag overpressure generated by the pulse, and the distribution of the overpressure over the bag surface, with the low pressure zone at the top of the bag becoming longer at large nozzle diameters. The pulse duration was found to be unimportant, with experiments on the pilot scale baghouse finding that this had no effect on either the overall baghouse pressure differentials or the length of the low pressure zone at the top of the bag. The project has extended the understanding of milk powder baghouse performance by relating the moisture-dependent properties of lactose and the temperature-dependent melting of dairy fats to baghouse performance. The project has also provided a useful design tool in the form of the CFD model. The project demonstrates an opportunity for further CFD research into baghouse design, as the basic model developed here could now be modified to directly simulate large industrial baghouses. It is hoped that the results from this thesis will find application in the New Zealand Dairy Industry.

It is the extreme essential that the functions of the modernizing pharmacy stores integrate into the entire community and medical care system. Due to the environment alternation and the constant epoch evolution, however, pharmacy stores have not only been impacted by the national health insurance and the medicine profession categorization, but also affected by the logistic development and the business modernization. Under the circumstances, pharmacy stores have to confront transformation, and pursue the much better solutions in assuring the persistent business management in future. This research focuses on pharmacy stores around the middle of Taiwan, and proceeds with the questionnaire investigations without signature, aiming at four hundreds of their consumers in Taichung, Nantao, Chang Hua and adjacent districts. The contents of questionnaire include four sections: 1) The comparison of both modernizing and traditional pharmacies; 2) Personal daily custom of healthy life style; 3) Perceiving of import infant Milk powder serving by pharmacy stores; 4) Individual base information. Based on the analysis of the questionnaire investigation findings, the purport is to realize whether or not the purchasing custom of ordinary consumers would be changed in the existence of import infant milk powder serving by the modern pharmacy chain stores. This research discovered that: Since infant milk powder is the sole principal food of baby, parents are very much concerned about it. The manufacturers have the respective features for milk powder of their own brands, and babies have quite different physiques. The certain brand of infant milk powder might be suitable for some babies, but against another ones on the other hands. For such instances, more than 80% of consumers are in favor of milk powder serving by pharmacy stores, according to the findings of the research, and agree that they would go there for consults if they need to make a decision about milk powder. Besides, the more often milk powder they purchased from pharmacy stores, the more frequency that they interacted with medicine chemists.

Poor rehydration properties of skim milk powder (SMP) can impact processing efficiency and functionality in finished product applications. Rehydration can be split into four stages: wettability, sinkability, dispersibility, and solubility. Previous work has suggested that chelator addition during SMP manufacture leads to higher solubility compared to SMP without chelators. This study focuses on the addition of ethylene diamine tetraacetic acid (EDTA) or sodium citrate dihydrate (SCD) at concentrations of 5, 10, and 15 mM to skim milk prior to evaporating and spray drying. The objective of this investigation was to determine the effects of the chelator additions on each SMP rehydration property (wettability, sinkability, dispersibility, and solubility) during reconstitution to 10% total solids. SCD 15 mM, SCD 10 mM, and SCD 5 mM did not have a significant effect on wettability as measured by IDF method (p-value 0.3234, 0.6376, and 1.0000, respectively). However, SCD 15 mM, SCD 10 mM, and SCD 5 mM had higher levels of solubility as measured by particle size analysis of reconstituted 10%TS samples (p-value

The use of washable baghouses for fines collection in milk powder plants has been investigated. The main aim of this study was to increase the fundamental understanding of both operation and design of washable baghouses for application in milk powder plants. This work has focussed on the industrial scale. Industrial plant operating data has been collected, plant designs compared and analyses conducted on powder produced at the industrial scale. The amount of powder that becomes fines, the small size fraction of powder entrained in spray dryer outlet air streams, has been shown to be significantly greater than the traditionally vague estimate of 10 % to 20 %. The ratio of fines flows to total powder flows ranged from 49 ± 8 % to 86 ± 2 % depending on the powder type and plant operating conditions. A simple yet reliable method was developed to quantify fines flows based on measured powder size distributions of samples taken from around the plant. These estimates were supported by readings from an online optical scintillation instrument, which was shown to be capable of measuring fines flows at concentrations approximately four times the supposed maximum stated by the instrument’s manufacturer. Observations in another part of this work supported previous Fonterra observations showing that the amount of bulk fat in skim milk powder (SMP) has a large influence on the baghouse differential pressure. Fines flows measured by the optical scintillation instrument and analysis of other plant operating data showed that a change in bulk fat in SMP does not appear to cause any change in fines concentration. Observations of the surface of SMP by scanning electron microscopy, and electron spectroscopy for chemical analysis, both showed that fat is over-represented on the surface of the particles, and that only small increases in the bulk fat content are required to cause large increases in the surface fat coverage. It is hypothesised that increased fat on the surface of particles increases the clumping of SMP before deposition on the bags. Consequently, the powder forms more porous cakes and is less likely to penetrate into the interior of the filter bags, which also makes it easier to pulse clean powder from the filter bags. Therefore, the baghouse differential pressure is reduced. The design of pulse-jet baghouses from the literature was found to rely heavily on the authors past experience and approach, giving rise to large variation in recommended values of the key design parameters. A procedure for determining the optimal combination of these parameters was developed. This procedure showed that the main Fonterra washable baghouses are far from optimal because of their high air-to-cloth ratios, long bags and high elutriation and annular velocities. This procedure also showed that the Fonterra vibrating fluid bed washable baghouses are much closer to the optimum, which is the probable reason these washable baghouses have had almost no operational issues. Observations of the movement of the bags from below showed significant movement for bags near the inlet of the baghouse, indicating that this was the probable cause of the high bag damage in this zone. It is suggested that increasing the outer gap (distance between the baghouse wall and the bag on the edge of the bag bundle) be investigated further in an attempt to slow the annular velocity around the edge of the bag bundle and reduce bag movement. It is also recommended that stainless steel inspection hatches installed in the wall of a baghouse for this research, be included in all current and future washable baghouses because use of these hatches reduced the overall clean-in-place turn around time by 20 %. Computational fluid dynamics simulations of the air flow patterns within the Clandeboye Dryer 2 chamber were carried out using a commercial code CFX10.0. These simulations are possibly the first to include the influence of a spray dryer’s internal fluid bed airflow on the flow patterns within a spray dryer. As expected, the simulations showed the main air jet oscillated and precessed about the central axis with no apparent distinct frequency. In turn, the recirculation zones between the main jet and the chamber walls fluctuated in size. Different fluid bed flows within the industrial range had only a local influence on the air only flow field by reducing the length of the main jet. A different outlet boundary condition (including a flow resistance representing the baghouse) also appeared to have little influence on the overall flow field. Good agreement was found between the movements of the main jet via simulations and from telltale tufts installed in the plant dryer. This supported other indications that the simulations were an accurate representation of the actual flows. It was concluded that this project achieved its main aim of improving the fundamental understanding of washable baghouse operation and design, especially for application in milk powder plants. Also this project, as well as a change in production schedules, has helped to reduce downtime associated with the washable baghouses in the Fonterra Clandeboye Dryer 2 plant by an estimated 50 hours per annum.

O leite é classificado quimicamente como uma dispersão mista de aspecto branco com sabor levemente adocicado. Além da elevada concentração de cálcio, contém micronutrientes, aminoácidos e ácidos graxos em proporções adequadas à nutrição humana. Segundo a FAO, até o final de 2016, a produção mundial de leite bovino atingirá 817 milhões de toneladas. No Brasil, o setor lácteo apresenta-se como uma atividade de impacto socioeconômico significativo. Para atender o anseio de uma sociedade cada vez mais preocupada com a qualidade dos produtos que consome, assim como exigências internacionais, a Rede Brasileira de Laboratórios Centralizados da Qualidade de Leite (RBQL) através do Programa Nacional de Melhoria da Qualidade do Leite (PNMQL), criado pelo Ministério da Agricultura, Pecuária e Abastecimento, aprovou a Instrução Normativa nº 51 - IN51, contendo os regulamentos técnicos de produção, identidade e qualidade do leite. Milhares de medições químicas são realizadas com o propósito de tomada de decisões e regulamentações da qualidade dos alimentos oferecidos à população mundial, sendo essencial existir confiabilidade nos resultados das análises químicas. Recomenda-se que os laboratórios analíticos utilizem materiais de referência certificados (MRC), provenientes de um fornecedor reconhecido e competente, que propiciem caracterização química inequívoca do material. Neste contexto, este trabalho objetivou a caracterização química de leite em pó bovino de diferentes tipos comercialmente disponíveis, com o propósito de fornecer subsídios para a produção de MRC dessa matriz alimentar. Foram adquiridas 72 amostras de leite em pó no comércio varejista, englobando os tipos integral, semidesnatado, desnatado, instantâneo e enriquecido. O método de análise por ativação neutrônica instrumental empregado permitiu a determinação dos elementos químicos essenciais Ca, Fe, K, Na e Zn, além de Br, Co, Cs e Rb. O emprego de materiais de referência certificados como controle da qualidade analítica corroborou a exatidão e a precisão dos resultados. Dentre as amostras estudadas, algumas são enriquecidas com os elementos químicos Ca e Fe. A hipótese de igualdade dos leites enriquecidos com Ca e Fe foi rejeitada para ambos, visto que observou-se a existência de diferenças estatísticas (p < 0,001) para esses elementos. A média aritmética dos leites enriquecidos com Fe foi de 167,7 mg/kg (n = 15), enquanto a média aritmética dos leites não-enriquecidos foi de 13,6 mg/kg (n = 57). A média aritmética dos leites enriquecidos com Ca foi de 22.822 mg/kg (n = 3), enquanto a média aritmética dos leites não-enriquecidos foi de 10.049 mg/kg (n = 69). De maneira geral, os leites em pó com menores quantidades de gordura (desnatado e semidesnatado) apresentaram maiores quantidades dos elementos químicos. Pela análise de agrupamento, verificou-se que a distância multivariada entre os leites em pó integrais foi menor, o que indica similaridade. Assim, entende-se como estratégica e viável a seleção deste tipo de leite em pó como candidato para a produção de material de referência certificado / Milk is chemically classified as a mixed white appearance dispersion with a slightly sweet taste. Besides the high calcium concentration, the milk contains micronutrients, amino acids and fatty acids in proportions suitable for human nutrition. According to FAO, by the end of 2016, the world production of bovine milk will reach 817 million tons. In Brazil, the dairy sector is an activity with a significant socioeconomic impact. To meet the longing of a society increasingly concerned with the quality of the products it consumes, as well as the international requirements, the Brazilian Network of Centralized Milk Quality Laboratories (RBQL) through the National Program for the Improvement of Milk Quality (PNMQL), created by the Ministry of Agriculture, Livestock and Supply, approved the Normative Instruction No. 51 - IN51, containing the technical regulations for milk production, identity and quality. Thousands of chemical measurements are performed for the purpose of making decisions and regulations of the quality of food offered to the world population, and it is essential to have reliability in the results of chemical analyses. It is recommended that analytical laboratories use certified reference materials (CRM) from a recognized and competent supplier that provides unequivocal chemical characterization of the material. In this context, this work aimed at the chemical characterization of bovine milk powder of different types commercially available, with the purpose of providing subsidies for the production of CRM of this food matrix. Seventy-two samples of milk powder were purchased in the retail market, including the integral, semi-skimmed, skimmed, instant and enriched types. Instrumental neutron activation allowed the determination of the essential chemical elements Ca, Fe, K, Na and Zn, as well Br, Co, Cs and Rb. The analytical quality control with certified reference materials corroborated the accuracy and precision of the results. Among the samples studied, some are enriched with the chemical elements Ca and Fe. The hypothesis of equality of Ca- and Fe-enriched milks was rejected for both, since there were statistical differences (p < 0.001) for these elements. The arithmetic mean of Fe-enriched milks was 167.7 mg/kg (n = 15), while the arithmetic mean of non-enriched milks was 13.6 mg/kg (n = 57). The arithmetic mean of Ca-enriched milks was 22,822 mg/kg (n = 3), while the arithmetic mean of non-enriched milks was 10,049 mg/kg (n = 69). In general, milk powder with lower amounts of fat (skimmed and semi-skimmed) had higher amounts of the chemical elements. The cluster analysis evidenced that the multivariate distance for the whole milk powder was smaller, which indicates the similarity. Thus, it is understood as strategic and viable the selection of this type of milk powder as candidate for production of certified reference material

The effects of thermosonication (high intensity ultrasound coupled with thermal treatment), on the reduction of thermophilic spore-forming microorganisms and its effects on the solubility index in reconstituted skim milk powder (RSMP) were evaluated. Thermosonication was applied to RSMP at various solids concentrations, temperatures, and lengths of time based on commercial milk powder processing conditions. Microbial counts were determined prior to and after treatments to determine the log reduction of Geobacillus stearothermophilusvegetative cells and spores. Log reductions were recorded, and data were analyzed by response surface analysis. The log reductions induced by temperature and time without high intensity ultrasound (HIU) were compared to reductions observed with HIU. Thermosonication was also applied to RSMP to determine effects on solubility using a continuous flow cell system. Thermosonication yielded a significantly higher level of microbial destruction for both vegetative cells and spores than heat treatment alone. For experiments involving vegetative cells, the interaction of treatment time and temperature proved to have the greatest influence on microbial inactivation. In comparison, the interaction of total solids content and length of HIU treatment demonstrated the greatest effect on the increased log reductions for spores. The solubility of RSMP treated with HIU did not significantly differ from the solubility of RSMP not treated with HIU. Further data showed the implementation of HIU, or thermosonication, during milk powder processing would be most effective before and after the evaporation stage when the total solids content of product is 9.2% and 50% at 75°C and 60°C, respectively. Based on preliminary data, it is assumed HIU applied for 10 s at these two locations would produce an additive effect, thereby reducing overall microbial counts by 5.76 log and 0.51 log for G. stearothermophilus vegetative cells and spores, respectively, in the product prior to entering the drying stage. All research findings and observations suggest HIU, or thermosonication, to be a successful method for reducing microbial populations during milk powder processing without sacrificing skim milk powder solubility

The aim of this work is to research various pasteurization regimes and albuminous milk products influence on the quality of kefir. The research was made in the Food Institute of Kaunas Technology University, 8 aliquots of kefir were made and evaluated in laboratory conditions. These raw milk pasteurization regimes were applied- instantaneous pasteurization (in 87-90°C temperature), pasteurization maintaining to 30 min. (in 87-90°C temperature), pasteurization maintaining to 60 min. (in 87-90°C temperature). The raw milk of these aliquots was enriched with 1%, 2%, 3% fat-free milk powder and with 1%, 2%, 3% whey powder ripening the mixture to 60 min. in 87- 90°C pasteurization temperature. Physical and chemical, microbiological indicators and sensual qualities were determinated by standard methods. It is determinated that the long-lasting milk pasteurization (maintaining to 30-60 min. in 87- 90° C pasteurization temperature), compared with the instantaneous pasteurization, increases viscosity of the product and enriches sensual qualities. Enriching of milk with whey powder in production of kefir stimulates the activity of milk acid bacteria. In comparison, aliquots enriched with 1%, 2%, 3% whey powder, it is determinated that the best is aliquot of kefir among which production it is interspersed 3% whey powder; physical-chemical and sensual qualities of the product signally better then. In comparison all the data of the experiment, the kefir characterized with the best... [to full text]

This research investigates possible monitoring methods to non-invasively detect blockages in the cyclone of milk powder spray driers to avoid costly production shutdowns. Two possible solutions have been identified. These are guided wave and vibration analysis. This research focuses on vibration analysis method, based on variation in the natural frequencies and/or damping ratios caused by blockages. Experimental simulation studies the performance to assess the viability of the vibration analysis method in identifying blockage in the cyclone. To test this method, a 1.87m long vertical cylindrical steel tube with both ends simply supported was setup as a prototype and flour was used as the powder conveyed by the tube. Analytical, numerical and experimental methods were implemented on the prototype using vibration analysis techniques. Experimental resonant frequencies of the empty shell from the impact hammer excitation were compared with analytical and numerical solutions to analyse the modal shapes. The first bending mode was determined as 79 Hz, which decreased with the amount of added mass and location closer to the middle point. This was validated by the simulated mass experiment, which also matched with the beam-mass theory. Flour induced experiment further validated the variation of the first bending mode. Experimental 270Hz, 380Hz and 398Hz resonant frequencies increased with the amount of added mass, which was validated by the simulated mass and flour induced experiment. Besides the variation of the natural frequencies, the damping ratio was also studied and quantified using the Hilbert transform envelope curve method. Onsite monitoring of the vibration of the cyclone in a spray dryer was done at Fonterra Te Rapa and clear resonant frequencies were obtained. The research results from the prototype demonstrate that vibration analysis as a non-destructive method to detect the milk powder deposition or blockage in the cyclone is possible and promising. However, more work is required before industry application.