Rheological Issues on Oropharyngeal Dysphagia.

There is an increasing proof of the relevance of rheology on the design of fluids for the diagnosis and management of dysphagia. In this sense, different authors have reported clinical evidence that support the conclusion that an increase in bolus viscosity reduces the risks of airway penetration during swallowing. However, this clinical evidence has not been associated yet to the definition of objective viscosity levels that may help to predict a safe swallowing process. In addition, more recent reports highlight the potential contribution of bolus extensional viscosity, as elongational flows also develops during the swallowing process. Based on this background, the aim of this review paper is to introduce the lecturer (experts in Dysphagia) into the relevance of Rheology for the diagnosis and management of oropharyngeal dysphagia (OD). In this sense, this paper starts with the definition of some basic concepts on Rheology, complemented by a more extended vision on the concepts of shear viscosity and elongational viscosity. This is followed by a short overview of shear and elongational rheometrical techniques relevant for the characterization of dysphagia-oriented fluids, and, finally, an in-depth analysis of the current knowledge concerning the role of shear and elongational viscosities in the diagnosis and management of OD (shear and elongational behaviors of different categories of dysphagia-oriented products and contrast fluids for dysphagia assessment, as well as the relevance of saliva influence on bolus rheological behavior during the swallowing process).

Advances in 3D printing of food and nutritional products.

The main advantage of both 3D printing (3DP) and 3D food printing (3DFP) over other technologies is the enormous capacity of both techniques for customization. Its use makes it possible to obtain products without planning and implementing a complex and costly manufacturing process. This makes 3DFP a technology of choice for the preparation of food products that meet specific needs, such as controlled nutritional or rheological properties. However, further technological developments are still needed before 3DFP can be considered fully useful for innovative and demanding applications. If both preparation and post-processing of materials based on 3D printing are optimized, aiming to reduce production time and/or complication for non-expert users, this would open a whole new range of possibilities. It is in this sense that the development of advanced 3DFP systems becomes a must. This chapter reviews current advances in extrusion-based 3D food printing systems, with in situ gelation and mixing as key aspects to better exploit the potential of 3DFP. On one hand, 3DFP systems based on in situ gelation (G3DFP) provide greater control over the final properties of the printed products, as the selection of adequate printing parameters gives the possibility of influencing the gelation process. On the other hand, mixing is indispensable for true 3DFP automation, so that the formulations do not have to be prepared by the user. Different innovative 3DFP systems based on gelling and/or mixing are presented in this chapter. Finally, the status and future of extrusion-based 3DFP, and its application in the production of customized foods for specific needs, are also overviewed.

Combination of supercritical CO2 and high-power ultrasound for the inactivation of fungal and bacterial spores in lipid emulsions.

For the first time, this study addresses the intensification of supercritical carbon dioxide (SC-CO2) treatments using high-power ultrasound (HPU) for the inactivation of fungal (Aspergillus niger) and bacterial (Clostridium butyricum) spores in oil-in-water emulsions. The inactivation kinetics were analyzed at different pressures (100, 350 and 550 bar) and temperatures (50, 60, 70, 80, 85 °C), depending on the microorganism, and compared to the conventional thermal treatment. The inactivation kinetics were satisfactorily described using the Weibull model. Experimental results showed that SC-CO2 enhanced the inactivation level of both spores when compared to thermal treatments. Bacterial spores (C.butyricum) were found to be more resistant to SC-CO2 + HPU, than fungal (A.niger) ones, as also observed in the thermal and SC-CO2 treatments. The application of HPU intensified the SC-CO2 inactivation of C.butyricum spores, e.g. shortening the total inactivation time from 10 to 3 min at 85 °C. However, HPU did not affect the SC-CO2 inactivation of A.niger spores. The study into the effect of a combined SC-CO2 + HPU treatment has to be necessarily extended to other fungal and bacterial spores, and future studies should elucidate the impact of HPU application on the emulsion's stability.

Freeze-drying: A relevant unit operation in the manufacture of foods, nutritional products, and pharmaceuticals.

Freeze-drying, a drying unit operation frequently used in food, pharmaceutical, and biopharmaceutical industries to prolong the shelf life of labile products, is an energy-intensive, time-consuming, and expensive process. Although all three steps (freezing, primary drying, and secondary drying) of freeze-drying are important, primary drying is the longest and most critical one. As sublimation during primary drying is mainly described in terms of heat and mass transfer, the present work provides extensive theoretical and experimental analyses of these processes. First, a detailed review of the current state-of-the art of freeze-drying, focusing on the drying stage, is given, which contributes to a fundamental understanding of the drying process. Second, a detailed experimental study of the drying section of the freeze-drying process is discussed, furnishing information on the relationship between input and output process parameters during the primary drying stage and thus aiding freeze-drying process design and optimization. In this regard, the influence of primary drying input parameters (i.e., shelf temperature and chamber pressure) and vial position on output parameters such as product temperature, sublimation rate, overall vial heat transfer coefficient, and resistance to mass transfer of the dried product are extensively discussed. For all combinations of shelf temperature and chamber pressure studied herein, the highest product temperature, sublimation rate, and overall vial heat transfer coefficient are observed in front edge vials, whereas the lowest values are observed in center vials. In general, the highest sublimation rate, at a given product temperature, is observed for low chamber pressure-high shelf temperature combinations.

Therapeutic Effect, Rheological Properties and α-Amylase Resistance of a New Mixed Starch and Xanthan Gum Thickener on Four Different Phenotypes of Patients with Oropharyngeal Dysphagia.

Thickened fluids are a therapeutic strategy for oropharyngeal dysphagia (OD). However, its therapeutic effect among different phenotypes of OD patients has not yet been compared. We aimed to assess the therapeutic effect and α-amylase resistance of a mixed gum/starch thickener [Fresubin Clear Thickener® (FCT)] on four phenotypes of OD patients: G1) 36 older; G2) 31 head/neck cancer (HNC); G3) 30 Parkinson's disease; and G4) 31 chronic post-stroke. Therapeutic effect of FCT was assessed during videofluoroscopy using the Penetration-Aspiration Scale (PAS), for 5/20 mL boluses, at four levels of shear-viscosity (<50, 250, 1000 and 2000 mPa·s). The effect of α-amylase was assessed after 30 s of oral incubation. Patients had high prevalence of VFS signs of impaired efficacy (98.44%) and safety (70.31%) of swallow with a severe PAS score (4.44 ± 0.20). Most severe OD was in HNC (80.6% unsafe swallows). FCT showed a strong therapeutic effect on the safety of swallow at a range between 250-1000 mPa·s (74.19-96.67%, safe swallows in G1, G3, G4, and 58.06% in G2), without increasing pharyngeal residue. Viscosity was unaffected by α-amylase. Increasing shear-viscosity with FCT causes a strong viscosity-dependent therapeutic effect on the safety of swallow. This effect depends on the phenotype and is similar among older, Parkinson's and post-stroke patients.

Non-thermal pasteurization of lipid emulsions by combined supercritical carbon dioxide and high-power ultrasound treatment.

Supercritical carbon dioxide (SC-CO2) is a novel method for food pasteurization, but there is still room for improvement in terms of the process shortening and its use in products with high oil content. This study addressed the effect of high power ultrasound (HPU) on the intensification of the SC-CO2 inactivation of E. coli and B. diminuta in soybean oil-in-water emulsions. Inactivation kinetics were obtained at different pressures (100 and 350 bar), temperatures (35 and 50 °C) and oil contents (0, 10, 20 and 30%) and were satisfactorily described using the Weibull model. The experimental results showed that for SC-CO2 treatments, the higher the pressure or the temperature, the higher the level of inactivation. Ultrasound greatly intensified the inactivation capacity of SC-CO2, shortening the process time by approximately 1 order of magnitude (from 50 to 90 min to 5-10 min depending on the microorganism and process conditions). Pressure and temperature also had a significant (p < 0.05) effect on SC-CO2 + HPU inactivation for both bacteria, although the effect was less intense than in the SC-CO2 treatments. E. coli was found to be more resistant than B. diminuta in SC-CO2 treatments, while no differences were found when HPU was applied. HPU decreased the protective effect of oil in the inactivation and similar microbial reductions were obtained regardless of the oil content in the emulsion. Therefore, HPU intensification of SC-CO2 treatments is a promising alternative to the thermal pasteurization of lipid emulsions with heat sensitive compounds.

Use of a temperature ramp approach (TRA) to design an optimum and robust freeze-drying process for pharmaceutical formulations.

Freeze-drying, until now, has been a process that was designed using a trial and error experimental approach. This approach is often material and time consuming, and the resulting freeze-drying processes are neither optimum nor robust. Accordingly, the objective of this study was to develop a simple-to-use and experimental-based approach to design an optimum and robust freeze-drying process for any given formulation. The temperature ramp approach (TRA) detailed in this study involves the implementation of a customized design of experiments (DoE) to perform few (three or four) experiments using a given drug formulation. The DoE results are analyzed to define optimum processing conditions (i.e., shelf temperature and chamber pressure) based on a predefined range of target product temperature for primary drying, which could be defined from formulation characterization at its frozen state. In this study, a successful freeze-drying process of two model formulations using the TRA was designed. Verification experiments at the optimum processing conditions showed excellent agreement in both product temperature and sublimation rate with the values obtained using the TRA. Thus, the TRA detailed in this study offers a significant advantage to reduce development time and material, and enhance the efficiency and robustness of the resulting freeze-drying process.

An Experimental-Based Approach to Construct the Process Design Space of a Freeze-Drying Process: An Effective Tool to Design an Optimum and Robust Freeze-Drying Process for Pharmaceuticals.

The application of quality by design (QbD) is becoming an integral part of the formulation and process development for pharmaceutical products. An essential feature of the QbD philosophy is the design space. In this sense, a new approach to construct a process design space (PDS) for the primary drying section of a freeze-drying process is addressed in this paper. An effective customized design of experiments (DoE) is developed for freeze-drying experiments. The results obtained from the DoE are then used to construct the product-based PDS. The proposed product-based PDS construction approach has several advantages, including (1) eliminating assumptions on the heat transfer coefficient and dried product resistance, as it is constructed from experimental results specifically obtained from a given formulation, yielding more realistic and reliable results and (2) PDS construction based on a narrow range of product temperatures and considering the variations in product temperature and sublimation rate of vials across a shelf. This guarantees the effectiveness and robustness of the process and facilitates the process scale-up and transfer. The PDS developed herein was experimentally verified. The PDS predicted parameters were in excellent agreement with the experimentally obtained parameters.

The Importance of Understanding the Freezing Step and Its Impact on Freeze-Drying Process Performance.

The freeze-drying process is a combination of 2 equally important processes, freezing, and drying. In the past, the effort was mainly focused on optimizing the drying process without considering the possible effects of the freezing step. During freezing, a solution undergoes several physical changes, including a supercooling state. The degree of supercooling of a solution dictates the ice habit (size, number, and morphology) during freezing, which impacts the subsequent drying process, such as the resistance to water vapor flow. Therefore, heterogeneous degree of supercooling leads to heterogeneous ice habits and, in turn, to heterogeneous drying behavior. This poses significant challenges during freeze-drying process development, optimization, and scale up. Hence, controlling the degree of supercooling significantly improves freeze-drying process design. The aim of the current review is to gather existing information on the physicochemical phenomena involved in the freezing process and how these phenomena impact the subsequent drying step of the freeze-drying process. In addition, modification of the freezing process and different techniques used to actively control the degree of supercooling during freezing will be reviewed and discussed. Their impact on freeze-drying process performance will be also addressed.

Development of antimicrobial active packaging materials based on gluten proteins.

BACKGROUND: The incorporation of natural biocide agents into protein-based bioplastics, a source of biodegradable polymeric materials, manufactured by a thermo-mechanical method is a way to contribute to a sustainable food packaging industry. This study assesses the antimicrobial activity of 10 different biocides incorporated into wheat gluten-based bioplastics. The effect that formulation, processing, and further thermal treatments exert on the thermo-mechanical properties, water absorption characteristics and rheological behaviour of these materials is also studied. RESULTS: Bioplastics containing six of the 10 examined bioactive agents have demonstrated suitable antimicrobial activity at 37 °C after their incorporation into the bioplastic. Moreover, the essential oils are able to create an antimicrobial atmosphere within a Petri dish. CONCLUSION: Depending on the selected biocide, its addition may alter the bioplastics protein network in a different extent, which leads to materials exhibiting less water uptake and different rheological and thermo-mechanical behaviours. © 2015 Society of Chemical Industry.

Droplet-size distribution and stability of commercial injectable lipid emulsions containing fish oil.

PURPOSE: The droplet size of commercial fish oil-containing injectable lipid emulsions, including conformance to United States Pharmacopeia (USP) standards on fat-globule size, was investigated. METHODS: A total of 18 batches of three multichamber parenteral products containing the emulsion SMOFlipid as a component were analyzed. Samples from multiple lots of the products were evaluated to determine compliance with standards on the volume-weighted percentage of fat exceeding 0.05% (PFAT(5)) specified in USP chapter 729 to ensure the physical stability of i.v. lipid emulsions. The products were also analyzed to determine the effects of various storage times (3, 6, 9, and 12 months) and storage temperatures (25, 30, and 40 °C) on product stability. Larger-size lipid particles were quantified via single-particle optical sensing (SPOS). The emulsion's droplet-size distribution was determined via laser light scattering. RESULTS: SPOS and light-scattering analysis demonstrated mean PFAT(5) values well below USP-specified globule-size limits for all the tested products under all study conditions. In addition, emulsion aging at any storage temperature in the range studied did not result in a significant increase of PFAT(5) values, and mean droplet-size values did not change significantly during storage of up to 12 months at temperatures of 25-40 °C. CONCLUSION: PFAT(5) values were below the USP upper limits in SMOFlipid samples from multiple lots of three multichamber products after up to 12 months of storage at 25 or 30 °C or 6 months of storage at 40 °C.

Natural and synthetic antioxidant additives for improving the performance of new biolubricant formulations.

Knowledge of the oxidative stability of vegetable oils for lubricant applications is a key point, because vegetable oil oxidation potential is the main disadvantage for its use as a lubricant. Oil degradation after an oxidation process can seriously affect its lubricating function and increase wear. In this work, two different methods for evaluating the oxidation stability of lubricating vegetable oils, the oxidation onset temperature, characterized through DSC measurements (ASTM E 2009-08), and the pressure drop in the oxygen pressure vessel (ASTM D 942-02), have been used. Additionally, thermogravimetric analysis and FTIR studies have also been carried out. High-oleic sunflower (HOSO) and castor (CO) oils were selected and blended with natural ((+)-α-tocopherol (TCP), propyl gallate (PG), l-ascorbic acid 6-palmitate (AP)) or synthetic antioxidants (4,4'-methylenebis(2,6-di-tert-butylphenol) (MBP)), with the aim of formulating biodegradable vegetable-based lubricants according to REACH regulation. (1) The results showed that the most effective biodegradable antioxidant is PG, comparable to MBP, whereas lower effectiveness was obtained for TCP and AP. In relation to the methods tested, DSC measurements achieve accurate data more quickly for evaluating the oxidation stability of these basestocks, showing a linear correlation with the traditional method based on the oxygen bomb test. The empirical equation obtained depends on the mechanism involved in the antioxidant activity.

Droplet-size distribution and stability of lipid injectable emulsions.

PURPOSE: The droplet-size distribution (DSD) and stability of multiple lots of lipid injectable emulsions were studied. METHODS: A total of 234 commercial batches of Intralipid (Fresenius Kabi, Uppsala, Sweden) were characterized, and the influence of the emulsions' oil content on samples packaged in single- and three-chamber bags was tested. Larger-sized lipid particles were quantified using a single-particle optical sensing device. For this test, a 1-mL sample of each product was analyzed using a dilution factor of 90-400, depending on oil concentration. Analyses were performed in triplicate. Measurements were also performed in single-bag products after up to six months of storage at 23-27 degrees C and 40 degrees C. DSD measurements were determined by laser light scattering. Droplet sizes were determined using laser diffraction, with aliquots of emulsions carefully dispersed step by step applying gentle agitation. Standard deviation analyses were performed using analysis of variance. RESULTS: The volume-weighted percentage of fat droplets greater than 5 mum (PFAT(5)) values of all samples were below the large-globule size limit (0.05%) established by the United States Pharmacopeia for lipid injectable emulsions. Container volume did not significantly influence globule size, though a slight tendency for larger bag volumes to have larger PFAT(5) values was apparent. PFAT(5) and mean volume diameter values increased with oil concentration in the emulsion. Storage time and temperature had no significant effect on PFAT(5) and mean droplet-size values. CONCLUSION: Multiple lots of a lipid emulsion were found to have acceptable PFAT(5) and mean droplet-size values, regardless of oil content, container size, or storage time and tempearture.