Effect of Three Types of Drying on the Viability of Lactic Acid Bacteria in Foam-Mat Dried Yogurt

In this research, foaming technology was applied to obtain powdered yogurt from commercial yogurt at lower temperatures than the typical temperatures used during the dehydration process; the viability of lactic acid bacteria (LAB) was evaluated after the application of different drying techniques (conventional drying, freeze drying, and vacuum drying). Three different formulas (F1, F2, and F3) based on a foaming agent (albumen), stabilizers (guar gum), and prebiotics sources (inulin and agave syrup) were developed. Foam stability was evaluated at different pH values through optimum time of foam (OTF), medium drainage time (MDT), and drainage volume (DV). Foam expansion (FE) and foam density (FD) were measured. The OTF ranged from 6 to 10 min. The MDT ranged from 4.3 to 27.3 min, depending on pH, while the DV varied from 14.1 to 16.2 mL only in F1. No drainage was evidenced in F2 and F3, showing the best stability. The F2 and F3 produced the best FE and FD values. The dried yogurt with different techniques showed a survival rate (SR) of up to 85% Log-CFU/mL, even with the conventional drying method. Sensorial trials were carried out in reconstituted product, with the freeze-dried yogurt showing higher scores. The foam formulas developed demonstrate the efficacy of both the dehydration of yogurt and the preservation of LAB.

On the question of the required foam expansion ratio for sublayer extinguishing of oil and oil products fires in vertical steel tanks

Возможность эффективного тушения резервуаров подслойным способом во многом зависит от подъема пены на поверхность горючей жидкости. Критически рассмотрены существующие методики испытаний высоконапорных пеногенераторов для подслойного пожаротушения. Предложены расчетные формулы для определения величины минимальной кратности пены, способной к подъему, в зависимости от состава и плотности горючей жидкости, высоты столба горючей жидкости, типа используемого пенообразователя. Обоснованы условия применения существующих систем подслойного пожаротушения для резервуаров с различной высотой стенки. During the certification tests of high-pressure foam generators for sublayer oil and oil products fire extinguishing in the tanks there is created a conditional back pressure at the generator output, and the foam expansion ratio is measured when this back pressure is no longer present. In accordance with the standardized methodology the foam expansion ratio is measured in the measuring container by weight. The derived foam after passing throughout the pipeline is supplied to the measuring container where the foam expansion ratio is measured under the atmospheric pressure. In practice, during fire extinguishing the flammable liquid exerts a constant excess pressure on the formed foam. The expansion ratio of the foam decreases in proportion to the pressure value of the column. As a result, the foam expansion ratio can reduce to a value when the Archimedean buoyant force no longer occurs. In this case, the foam cannot be supplied to the surface of the flammable liquid and the fire cannot be extinguished. The back pressure created at the tank base depends on the height of the tank wall (level of the liquid fuel filling) and on its density. Foam rise is possible if the foam density is lower than the fuel density. Light oil products extinguishing requires greater expansion ratio foam than heavy oil products extinguishing. At the same time, heavy oil products cause greater back pressure and a decrease in the foam expansion ratio. Alcohols in the composition of modern high-octane gasolines produce an additional defoaming effect on the foam, which questions the feasibility of using a sublayer fire extinguishing system of modern high-octane gasolines. The article evaluates a set of parameters that affect the required foam expansion ratio for sublayer extinguishing of oil and oil products fires in tanks and justifies the minimum value of its expansion ratio.

Experimental effectiveness studies of the technology for cleaning the inner cavity of gas gathering pipelines

Purpose: The purposes of the article are to determine the hydraulic efficiency of two gas gathering pipelines of the Yuliivskyi oil and gas condensate production facility (OGCPF) and develop a set of measures to increase it; to experimentally determine the efficiency of using foams to increase the hydraulic characteristics of the gas gathering pipelines in the Yuliivskyi OGCPF; to develop a set of measures that will help to improve the hydraulic characteristics of gas gathering pipelines. Design/methodology/approach: The research methodology consists in determining the hydraulic efficiency of gas gathering pipelines before and after cleaning their inner cavity with foams with different expansion ratios and comparing the obtained values, which allows to objectively assess the efficiency of this cleaning method. The studies were performed within the framework of research and development work by the specialists of the Ukrainian Scientific Research Institute of Natural Gases. Findings: The pilot testing was carried out to determine the efficiency of cleaning the inner cavity of gas gathering pipelines with foams with different expansion ratios. It showed positive results. It was determined that cleaning the inner cavity of gas gathering pipelines with foams with the expansion ratio from 80 to 90 led to an increase in the hydraulic efficiency coefficient by 10.5%, and with foams with the expansion ratio from 50 to 60 – by 5.7%. The measures taken to clean the inner cavity of gas gathering pipelines from liquid contaminations have proven their efficiency and can be recommended for other fields. Research limitations/implications: The obtained results show that it is reasonable to conduct the experimental studies on the efficiency of cleaning the inner cavity of gas gathering pipelines with the foams with higher expansion ratios. To achieve the maximum quality of cleaning the gas gathering pipelines, it is necessary to develop a new method that will combine the use of foam and gel piston.Practical implications: The performed experimental studies help to take a more reasonable approach to cleaning the inner cavity of gas gathering pipelines with foams and to predict in advance the effect of the foam expansion ratio on the hydraulic efficiency of gas gathering pipelines. Originality/value: The experimental studies on the effect of foam expansion ratios on the hydraulic efficiency of gas gathering pipelines are original.

Ambient Temperature Self-Blowing Tannin-Humins Biofoams

Ambient temperature self-blowing tannin–furanic foams have been prepared by substituting a great part—even a majority—of furfuryl alcohol with humins, a polyfuranic material derived from the acid treatment at high temperature of fructose. Closed-cell foams were prepared at room temperature and curing, while interconnected-cell foams were prepared at 80 °C and curing, this being due to the more vigorous evaporation of the solvent. These foams appear to present similar characteristics as other tannin–furanic foams based only on furfuryl alcohol. A series of tannin–humins–furfuryl alcohol oligomer structures have been defined indicating that all three reagents co-react. Humins appeared to react well with condensed tannins, even higher molecular weight humins species, and even at ambient temperature, but they react slower than furfuryl alcohol. This is due to their high average molecular weight and high viscosity, causing their reaction with other species to be diffusion controlled. Thus, small increases in solvent led to foams with less cracks and open structures. It showed that furfuryl alcohol appears to also have a role as a humins solvent, and not just as a co-reagent and self-polymerization heat generator for foam expansion and hardening. Stress-strain for the different foams showed a higher compressive strength for both the foam with the lowest and the highest proportion of humins, thus in the dominant proportions of either furfuryl alcohol or the humins. Thus, due to their slower reactivity as their proportion increases to a certain critical level, more of them do proportionally participate within the expansion/curing time of the foam to the reaction.

Carbon particulate and controlled-hydrolysis assisted extrusion foaming of semi-crystalline polyethylene terephthalate for the enhanced thermal insulation property

This work presents a facile method to produce low-density PET foams using pristine semi-crystalline resin by moisture-induced controlled-hydrolysis in a tight processing window (moisture content ∼ 0.12 wt.%). We investigated the effect of moisture and moisture containing activated carbon (AC) on the foam expansion ratio, cell morphology, and PET resin degradation and crystallization properties. Controlled-hydrolysis increased the melt-flow rate of PET resin (intrinsic viscosity: 0.52 to 0.54 dL/g) without losing crystallinity, and thus the PET foams possess better tensile properties (∼2 MPa stress and ∼100% strain) and higher thermal stability (>200°C) than chemically modified PET foams. The foam density could be made as low as ∼ 0.15 g/cm3 using a lab scale twin-screw extruder. A strand array die was also designed to produce plate-shaped foam samples. AC allowed easier control of the moisture content and delayed resin degradation in extrusion. Both AC and micrographite (mGr) could stabilize the PET foam morphology in extrusion and serve as good infrared attenuation agents (IAAs) in a simulated housing thermal insulation experiment.

Microcellular foaming behavior of ether- and ester-based TPUs blown with supercritical CO2

The bead foaming behavior of ether- and an ester-based Tensor Processing Unit (TPU) resins were investigated in a lab-scale reactor using supercritical CO2 as the blowing agent. The samples were saturated at various saturation temperatures and the effects of hard segment crystallization during the saturation on the foaming behavior of the TPU samples were explored. The results revealed that the different HS crystallization tendencies and possible CO2 solubility differences in two TPU grades led to their different foaming behaviors. The ester-based TPU could be foamed within a wider saturation temperature range and revealed an easier cell growth and foam expansion while the ether-based TPU showed a more limited cell growth behavior and hence processing window. The effect of pre-annealing and hence the isothermally induced HS crystallization on the foaming behavior of the ether-based TPU and the influence of depressurization rate on the foaming behavior of ester-based TPU was also explored.

Study of the thermal stability of foam of different expansion ratio

Introduction. Currently, the industry produces a wide range of foam generators to produce fire-extinguishing foams, and the foams they produce differ significantly in their expansion ratio and, consequently, fire resistance. Since heat fluxes have the main destructive effect on the foam, the purpose of this paper is to establish the patterns of destruction of foam of different expansion ratio when heated.Methods of research. The foam with expansion ratio from 7.5 to 80 was used for the tests. It was obtained by mechanical beating of 6 % solution of foaming agent PO-6RZ. The thermal stability of the foam was studied when the heat flow from the gas burner flame affects the foam layer. During the experiment, the change in the height of the foam column in time was recorded.Results and Discussion. The results of measurements, presented in the form of dependence of foam layer destruction rate on time, quantity of released liquid phase on 1 m2·s, dependence of foam layer destruction rate on its density allowed revealing a number of patterns. The destruction rate of foam with an expansion ratio of up to 30 remains constant throughout the entire duration of thermal exposure. As the foam expansion ratio increases, the rate of destruction at the initial stage of heat flux exposure increases. With a foam expansion ratio of more than 50, there is initially a sharp increase in the rate of destruction, which subsequently decreases as the foam column decreases. In the conditions of the experiment, the best characteristics were shown by the foam with an expansion ratio of 50, because in the foam with a smaller expansion ratio the syneresis makes a significant contribution to its destruction, and the foams with a larger expansion ratio are destroyed by the mechanical effect of convective flame flows.Conclusion. The study of the foam destruction patterns under thermal impact allowed establishing the fact that its destruction is limited by the rate of impoverishment of the upper layers with liquid.

Influence of MWCNT Coated Nickel on the Foaming Behavior of MWCNT Coated Nickel Reinforced AlMg4Si8 Foam by Powder Metallurgy Process

This research studies the effect of multi-wall carbon nanotube (MWCNT) coated nickel to foaming time on the foam expansion and the distribution of pore sizes MWCNT reinforced AlMg4Si8 foam composite by powder metallurgy process. To control interface reactivity and wettability between MWCNT and the metal matrix, nickel coating is carried out on the MWCNT surface. Significantly, different foaming behavior of the MWCNT coated nickel reinforced AlMg4Si8 was studied with a foaming time variation of 8 and 9 min. Digital images generated by the imaging system are used with the MATLAB R2017a algorithm to determine the porosity of the surface and the pore area of aluminum foam efficiently. The results can have important implications for processing MWCNT coated nickel reinforced aluminum alloy composites.