Engineering students require an education which facilitates the development not just of functional design of technological artefacts and processes, but they also need to be equipped to understand and engage with their wider implications and context. Consequently, as part of the formation of sustainability informed engineers, there is a clear necessity to integrate the socio-economic aspects of sustainability in order to posit technology in appropriate contextualised settings. The chemical engineering degree programme at University College Cork incorporates a strong emphasis on integrating the socio-economic dimension of sustainability within the programme. This paper focuses on ecological economics, and how it can connect with engineering and why it is important that engineering students receive a grounding in ecological economics. It outlines the content of a five-lecture series on ecological economics given to fifth-year chemical engineering students. This includes environmental aspects, such ecological limits analysis and the use of strategies, including economic, to move unsustainable natural resource use and emissions discharges to within their ecological limits. It explores social aspects and the critical barriers to transitioning to a sustainable economy, as well as the impact of ecological economics on engineering. Finally, three consecutive final year classes were surveyed to elicit their feedback on being taught ecological economics and to test the hypothesis that the inclusion of ecological economics appreciably enhances students’ ability to engage productively with sustainability and the UN Sustainable Development Goals (SDGs); a key accreditation and professional requirement for contemporary engineering graduates. Overall, most students enjoyed the material, stating that is of value to engineering students, and they provided a useful qualitative assessment of the content.

This paper focusses on comparing carbon footprints of supplying process plant steam and electricity using boiler/ grid, gas turbine and steam turbine CHP systems, and grid heat & power (grid-HP), and investigating the effect of key parameters on the carbon footprints. These parameters include fuel type, grid carbon intensity, plant heat to electric power ratio, plant steam pressure, and operational parameters particular to the CHP systems. The analysis highlights the critical importance of the grid carbon intensity. There exist grid carbon intensity transition values, whereby below a certain value the grid-HP provides the lowest footprint, and above a certain value one of the CHP systems provides the lowest footprint. These transition values are independent of the plant heat to electricity ratio. However, they are influenced by other factors outlined in the paper. Consequently, many fossil fuel boiler/grid and CHP systems may become obsolete due to decreasing grid carbon intensity.

Despite steam sterilisation in autoclaves being a common industrial method of sterilisation, very little research has been conducted into quantifying the resources these processes demand and their associated environmental impacts. This paper aims to investigate industrial steam sterilisation in autoclaves with particular application to the biopharmaceutical industry. A mathematical model of a steam autoclave was developed to examine relationships between load size, load material properties and autoclave capacity with energy consumption, environmental impact and cost of sterilisation. The two main energy requirements are thermal energy to produce the clean steam for sterilising, and electrical energy for the vacuum pump. The study showed that thermal energy is dominant, particularly as load increases. The percentage of the maximum load at which the autoclave is operated has a major impact on the specific energy requirement or the energy required to sterilise per unit mass of load. For a given autoclave, the energy requirement increases with increased load but the specific energy requirement decreases. This in turn impacts on the emissions and the energy cost. It is thus shown that it is much more energy efficient to operate at higher loads, making the autoclave much more energy and cost effective, and with less environmental impact. There is potential for applying the analysis presented in this work for conducting optimisation studies for determining the sizes of autoclaves that could minimise the energy requirement, environmental impact and economic cost (3E) of investments for specified load versus time profiles.

Micellar casein (MC) is usually spray-dried into powder form for transportation and storage. However, the micellar structure maintained by colloidal calcium phosphate (CCP) and hydrophobic forces leads to poor rehydration ability of MC powders, which limits its potential applications. Here, spray freeze drying (SFD) with controlled droplet size was used to produce MC powders. Their effects on the structure of MC and the subsequent rehydration characteristics including wetting, dispersion and dissolution were investigated. The results showed SFD powders obtained from smaller droplet size caused more than 50% of serum Ca2+ and PO43- to release from the micellar structure. These powder particles exhibited extremely high porosity (92%) and spherical morphology, which thus greatly shortened their wetting time. Furthermore, the smallest droplets during SFD were believed to produce the MC powders with the quickest dispersion and best solubility, as over 80% of the solids could be completely dissolved in just 15 min.

This study explored the effect of protein content (whey protein and casein) and carbohydrate content (lactose, sucrose, and maltodextrin) on the breakage behaviour and its influence on spray-dried agglomerated model infant milk formula. Whey protein powders were bigger in particle size, weaker in structural strength, and marginally more irregular in shape, which resulted in better rehydration properties but more breakage than pure casein powders. Similarly, sucrose samples had better rehydration properties and higher glass transition temperatures but suffered more breakage than maltodextrin and pure lactose powders because of their bigger particle size. The influence of proteins on breakage was greater than that of carbohydrates. Breakage changed the physical and structural properties of powders, especially for whey protein and sucrose samples, which caused the deterioration of rehydration properties and the decrease in crystallization temperatures. From the perspective of particle breakage, unwanted dairy powder breakage could be controlled by changing powder formulations.

Particle breakage of dairy powders occurs easily during many processes, reducing the powder functionality. The characteristics of particles and the applied stress from processing conditions on the particles are 2 main factors that can be manipulated to reduce breakage. In this study, we explored the effect of whey protein and lactose contents on dynamic breakage in agglomerated whey protein-lactose powders to provide useful information, in terms of particle characteristics, for controlling unwanted dairy powder breakage. A series of model agglomerates with different whey protein:lactose ratios were produced under the same spray-drying conditions, through a pilot plant trial. We evaluated physical characteristics, composition, and structure of samples; analyzed dynamic breakage under different mechanical stresses; and investigated the rehydration and water adsorption properties of model powders before and after breakage. The particle size and irregularity of agglomerates with more lactose was significantly higher than of samples that contained more protein. This resulted in higher particle breakage during dynamic breakage for samples with more lactose. The breakage of agglomerates was affected by the moisture content of powders and fatigue, where particle breakage happens when mechanical loads, lower than the strength of particles, occur multiple times. Breakage changed the morphology and surface composition of particles and decreased particle size. It also decreased the dispersibility of powders and increased the wetting time of wettable samples but decreased the wetting time of powders with poor wettability. Breakage accelerated time-dependent crystallization and decreased the crystallization temperature but did not affect the glass transition temperature of samples. Thus, under the same drying conditions, composition of powders significantly affected breakage, mainly by altering the physical properties of their particles, which resulted in deteriorated functionality.

Two main breakage mechanisms, surface breakage and body breakage, were both found during laboratory dilute-phase pneumatic conveying and high-speed mixing of infant milk formula, respectively. Body breakage had a greater influence on powder physical properties, particle shapes, and surface compositions than surface breakage. In particular, the particle size of samples decreased by only 10% after surface breakage but by 60% after body breakage. For samples where body breakage predominated, significant changes to both water sorption and mechanical properties of the powder were seen while surface breakage had very little effect on them. Body breakage significantly increased the water sorption rate of samples, at around 10%-126% higher than the other samples for the first 3 h, which accelerated the time-dependent crystallization. Moreover, at aW 0.11 to 0.33, the final water contents of body breakage samples were 3.5%-22% higher than control samples. This decreased the crystallization temperature, by between 2 ?& nbsp;and 10 ?, and the overall molecular mobility of samples. These changes were due to the increase in the number of adsorbed monolayers, sorption surface area, and monolayer value of samples after body breakage.

Dairy-based powder had considerable development in the recent decade. Meanwhile, the increased variety of dairy-based powder led to the complex difficulties of rehydrating dairy-based powder, which could be the poor wetting or dissolution of powder. To solve these various difficulties, previous studies investigated the rehydration of powder by mechanical and chemical methods on facilitating rehydration, while strategies were designed to improve the rate-limiting rehydration steps of different powder. In this review, special emphasis is paid to the surface and structure of the dairy-based powder, which was accountable for understanding rehydration and the rate-limiting step. Besides, the advantage and disadvantage of methods employed in rehydration were described and compared. The achievement of the powder functionality was finally discussed and correlated with the rehydration methods. It was found that the surface and structure of dairy-based powder were decided by the components and production of powder. Post-drying methods like agglomeration and coating can tailor the surface and structure of powder afterwards to obtain better rehydration. The merit of the mechanical method is that it can be applied to rehydrate dairy-based powder without any addition of chemicals. Regarding chemical methods, calcium chelation is proved to be an effective chemical in rehydration casein-based powder.

As a powder wets and dissolves in a liquid, trapped gas bubbles are released and the measurement of the evolution of gas volume versus time can be used to quantify the ease with which powder wets and dissolves in the liquid. This phenomenon forms the basis of the BARDS analytical measurement technique. To complement this experimental approach, a model of the evolution of gas bubbles from a powder into a liquid during powder dispersion and solubilisation is presented. The model is validated against experimental data from the rehydration of Milk Protein Isolate (MPI) powder; both in its original state, and in the agglomerated state and is shown to match the experimental data with good accuracy. Use of the model facilitates a fuller interpretation of the experimental BARDS data and the values of dispersion and solubilisation rate constants can be applied for quantitatively comparing the behaviour of powders. It also permits development of robust rehydration parameters from the experimental BARDS signal.

Rehydration of milk protein isolate (MPI) powder in water is poor which requires more than 24 h, however it is greatly influenced by solution pH. This study analysed the rehydration of MPI powder in acidic solution followed by neutralization (CN), and in alkalized solution followed by neutralization (NC), and how these pH adjustments impact the dissolution ability and functionality of the MPI. Besides, C'N' and N'C' are prepared by the above neutralization sequence with increasing rehydration time. Acid gelation was chosen as an example of critical functional properties. The results showed that applying alkalization (performed by Na-carbonate) as the first step prior to neutralization was superior to acidification (using citric acid) in terms of both dissolution and gelation. MPI powder rehydrated in distilled water gelled very poorly, and this was due to slow dissolution, while neutralized MPI (CN, C'N', NC and N'C') produced much stronger gels, in-part due to rapid dissolution and disrupted casein micelle. NC and N'C' exhibited better gelation characteristics than CN and C'N' overall, showing much higher elasticity values and earlier gelation point. These were also compared with the rehydration of sodium caseinate, which displayed more rapid dissolution and consequently faster gelation; however, the gelation characteristics became similar to NC over time. N'C' with longer rehydration time could display further improved gelation characteristics owning higher elasticity than that of SC and SC'. In addition, the neutralized MPI was able to tolerate over-acidification during the acid gelation process.

Background: Particle breakage deteriorates dairy powder properties and it easily takes place in many processes. However, there currently is a lack of research on dairy powder breakage for understanding and controlling it. The research on particle breakage in other industries is very extensive and thorough, and could act as good reference knowledge for dairy powder breakage research, but at this time there is no review of this useful information. Scope and approach: Based on the research done in dairy powder breakage and findings of particle breakage studies of other industries relevant to dairy powder particle properties, this review includes the breakage mechanisms of dairy powders, methods suitable for studying dairy powder breakage, the influence of breakage on powder properties, and influencing factors of dairy powder breakage which also can be considered as controlling factors. Key findings and conclusions: Powder breakage significantly affects dairy powder physical properties which inturn influence powder functionalities, especially the rehydration properties. The extent of agglomerates breakage corresponds to different breakage mechanisms which result in different final particle sizes and particle size distributions. The processing conditions (such as the parameters during dry-mixing, vibration, and pneumatic conveying) and the characteristics of particles (including physical properties and composition) are two main influencing factors that can be considered to control dairy powder breakage. However, there is currently not enough study showing which factors are more effective in controlling breakage. Some single-particle or multi-particle tests can be used to investigate dairy powder breakage and further research on the effectiveness of those controlling factors should be done.

The engineering graduate of today will engage in a career which will span the middle of the twenty-first century, and beyond. They will work in a world which is increasingly more complex and uncertain than at any time before. This will require an integrated combination of technical knowledge and transferable skills and values, to a greater extent than ever before. This paper highlights the need for the contemporary engineering graduate to develop capacity to deal with increased uncertainty and complexity. It seeks to demonstrate how this can be achieved through developing key graduate attributes. These attributes may be promoted through suitable exposure to progressively more open-ended problems and activities across the programme. A number of exemplars are provided from two European chemical engineering programmes.

Dairy powder breakage occurs in many processes and deteriorates powder properties and functionalities. This study investigated the influence of powder and particle characteristics on the dynamic breakage of dairy powders during the dispersion and conveying in a powder venturi feeder to provide information on assessing and reducing powder breakage during production and transportation. Four kinds of dairy powders (fifteen samples) were analysed: lactose crystals, agglomerates, commercial and lab-scale non-agglomerates. During the dispersion and conveying, breakage degree increased with increasing particle size and decreasing particle structural strength. Considering particle structure, the strength of crystals was the highest, followed by the continuum solids, followed by particles with numerous small holes throughout the particle, followed by particles with a small number of randomly distributed internal holes, followed by the hollow sphere particle with a very thin shell. The breakage behaviour of crystals during conveying was different from the other powders due to the difference in particle structures. Besides, the fat in particles might decrease the breakage of powders.

Natural micellar casein is generally dried into powdered forms for commercial transportation and storage. However, the poor rehydration ability of micellar casein powder critically limited the potential applications due to its dense cross-linked structures caused by colloidal calcium phosphate (CCP). In this study, micellar casein solutions were exposed to a high hydrostatic pressure (HHP) ranging from 100 to 500 MPa and were then freeze dried to produce powders. The effects on the casein micelle structures and the rehydration characteristics including wetting, dispersion and dissolving were comprehensively investigated. The results showed that HHP could induce smaller micelle sizes and significantly increase the free calcium in the reconstituted solution. It demonstrated that the majority of CCP bridges in casein micelles were dissociated, which produced porous powders with loose structures and thus significantly improved rehydration behaviors. 300 MPa was the pressure level that caused the quickest dispersion process and best solubility. Consequently, HHP has potential to be a novel physical technique to potentially modify the protein higher-order structures as well as improve the corresponding functionalities.

Dairy powder breakage has always occurred during production and transportation though few studies on it have been published. This paper examines the breakage of infant formula using three different processing methods (laboratory high-speed mixing, lab-scale pneumatic conveying, and factory-scale blending) and the effect of breakage on powder properties. In both mixing and high-velocity pneumatic conveying, particles were broken into smaller entities and the particle size of samples significantly decreased. Particle breakage was accompanied by a significant decrease in porosity and increase in density and surface free fat. This in-turn decreased the rehydration properties of samples, especially for high-speed mixing, while breakage had only a small influence on powder flowability. By contrast, some agglomeration occurred during blending for short time in the blender and the particle size did not decrease (P > 0.05) even for blending at longer time, thus, there were only minor impacts on physical and functional properties of powders.

Dairy powder breakage occurs in many processes and causes deterioration in powder properties but there is currently no research presented in the literature on dairy powder breakage behaviour. The breakage behaviour and the effect of powder properties of an infant milk formula and its sieved size fractions were investigated during three processing methods (powder venturi feeder, lab-scale dilute phase pneumatic conveyor, and laboratory high-speed mixer) based on the changes of particle size distributions (PSD) before and after breakage. Particle size influenced other properties and the breakage behaviour of powders. Four breakage mechanisms were found, dispersion, chipping, disintegration, and splitting, corresponding to the increasing degree of breakage. More intense processing conditions were needed to cause the same breakage mechanism for smaller-sized particles because of their higher powder strength. The breakage of samples with wide PSD often displayed a combination of breakage mechanisms due to the influence of particle size on breakage behaviour.

Many powders are produced in spray-drying processes from liquid concentrates. Self-agglomeration can be performed in a fluidised bed where the spray-dried powder is agglomerated using the liquid concentrate as the binder material. This has advantages over traditional wet agglomeration in fluid beds using liquid binders (such as water or sugar solutions). These include thermal energy savings and no additional non-aqueous binder components added. The work presented has two parts. The first part is experimental, which investigated the self-agglomeration of whey protein isolate (WPI) powder as a case-study. It showed that satisfactory agglomeration was achieved with a great improvement in the wettability of the powder. The second part of the work performed thermal energy analysis to estimate the energy saving potential of self-agglomeration, and how this is influenced by binder to powder ratio and binder solids concentration. For the WPI case-study, the analysis showed there is potential for a 19% saving in thermal energy requirement for self-agglomeration in comparison to traditional agglomeration using a water binder.

Rehydration in an alkaline solution has been shown to improve the rehydration behaviour of milk protein isolate (MPI). In this study, the focus is on citric acid neutralization of MPI powder dissolved in alkaline solution. The results showed that alkalization induced more negative zeta-potential compared to MPI control, reducing it from -22.4 mV to -32.6 mV. Neutralization had a relatively similar zeta-potential value as alkalized sample. Sodium carbonate addition increased pH and caused a consequential reduction of ionic calcium in aqueous phase and, neutralization caused a small increase in ionic calcium. Soluble aggregate of K-casein protein and whey protein was suggested in alkalization and neutralization process by non-reducing SDS-PAGE. In addition, neutralization kept a stable colloidal particle size for pHs decreased to pH 9,8 and 7; however, alkalization and neutralization created casein aggregates of larger colloidal particle size than primary casein micelle in control MPI.

Milk protein isolate (MN) powder is a difficult to rehydrate powder displaying poor wettability and slow dissolution. In this study, MPI powder was top-sprayed with surfactants (Tween 80 and lecithin) in a fluidised bed to investigate the effect of surfactants on the rehydration behaviour. The wetting behaviour of MPI covered by the surfactants was greatly improved except for 4% lecithin. The wetting time of lecithinated MPI decreased to 42 s compared with MPI of 36 min. The Tween coated powders and larger size fractions displayed faster wetting attaining a minimum wetting time of 15 s. The rate of dissolution was not influenced by the presence of the surfactants as the particles continued to slowly dissolve. Broadband acoustic resonance dissolution spectroscopy (BARDS) showed that the gas release behaviour of surfactant covered MPI was totally altered and accelerated in comparison to the MPI powder, especially for Tween 80.