Effect of high acyl gellan gum and pH on the structural and foaming properties of heated whey protein suspensions

Effects of association between high-acyl gellan gum and whey protein on heat-induced aggregation and foaming properties of aggregates were assessed in aqueous suspensions. Associative complexes were identified by turbidity and colloidal charge below pH 6, and a balance of charge in the complexes was achieved at pH 5 with a 5:1 protein:polysaccharide ratio. As gellan gum content increased, size of aggregates formed by heating at pH 5 decreased (>1000 nm to 200-300 nm). Microscopy showed polysaccharide chains adhered to spherical aggregates at pH 5 and 6. Gellan gum added to protein before heating did not increase foam volume yet doubled foam half-life at pH 5 when used at a 2:1 protein-to-polysaccharide ratio. Microscopy showed that protein aggregates with attached gellan gum were present in drained foams. These findings indicate that gellan gum improves foam stability of heated whey protein at pH 5 by reducing aggregate size and adhering to aggregates.

Influence of microwave drying on quality parameters of foamed Nagpur Mandarin (Citrus reticulata) juice

In the world of industrial drying processes, foam mat microwave drying is a significant and valuable approach. Its advantages include increased drying effectiveness, preservation of product quality, energy and cost savings, flexibility in application, and improved safety. Development of Nagpur mandarin juice powder is tedious and time-consuming due to its bitter test and less total soluble solid, therefore the present research carried out with the process parameters for microwave drying include microwave power levels (180, 360, 540, 720, and 900 W) and drying bed thicknesses (2, 4, and 6 mm). Foamed juice is produced using soy protein isolate (2.10 %), GMS (2.75 %), CMC (1.75 %), and sugar (5.10 %), with whipping times of 8 min. Additional foaming agents include guar gum (0.45 %), soy protein isolate (3.30 %), and sugar (10 %) with whipping times of 6 min. The optimal conditions for drying Nagpur mandarin juice were determined through analysis using Design-Expert 11.0.4.1 software. These conditions include 540 W of microwave power, a drying bed thickness of 3 mm, and the use of a foaming agent comprising 2.10 % soy protein isolate, 2.75 % GMS, 1.75 % CMC, and 5.10 % sugar, with an 8-min whipping period. Under these optimized conditions, the resulting powder exhibited the following characteristics: color b value of 19.59, ΔE (change in color) of 6.24, acidity of 0.40 %, ascorbic acid content of 36.64 mg/100 g, water activity of 0.26, drying time (in minutes), and overall acceptability rating of 7.77. These findings highlight the effectiveness of the optimized process parameters in achieving desirable quality attributes for Nagpur mandarin juice powder production.

On recycling earth pressure balance shield muck with residual foaming agent: defoaming and antifoaming investigations

Earth pressure balance (EPB) shield is increasingly employed in metro tunnel construction, and causes a series of environmental, safety, and resource waste problems due to the disposal of a considerable amount of muck. In situ recycling of EPB shield muck is an effective solution, whereas the foam is generated by residual foaming agents used as the muck conditioning material during tunnelling, which often adsorbs clay particles and overflows the flocculation tank. To achieve defoaming and antifoaming during the reuse of muck, this study prepared novel eco-friendly silicone oil-polyether defoamers by condensation, compounding, and shear emulsification. Defoaming and antifoaming performances of different defoamers were tested using a modified Ross-Miles method and a scale model of field flocculation systems. The results indicated that a high efficiency in defoam and antifoam was characterized by chemical grafting of nano-SiO2 from silicone oils, uniform distribution and large size of grains, low viscosity, and surface tension. The defoamer dosage of 0.002-0.004 wt% near critical micelle concentration (CMC) for each defoamer is reasonable. Overall, the prepared hydroxyl silicone oil-glycerol polyoxypropylene ether (H-G) defoamer compared with other silicone oil-polyether defoamers and commercial defoamers presents the highest defoaming and antifoaming efficiency. Considering the effects of EPB shield muck, the H-G defoamer is least affected by the compound materials and increasing concentration of the commercial foaming agent. Nevertheless, the stability of the H-G emulsion system is weaker than that of the dimethyl silicone oil-glycerol polyoxypropylene ether (D-G) emulsion system after 1 month of sealed storage.

Optimization of protein recovery from sewage sludge via controlled and energy-saving ultrasonic-alkali hydrolysis

The abundant protein in excess sludge can be recovered to prepare high value-added products. However, this sustainable treatment method still has large challenges, such as high energy consumption. In this work, the classical batch operation (BO) and semi-batch operation (SBO) modes were adopted and compared for ultrasonic-alkali hydrolysis. The results showed that the reaction time of SBO significantly decreased to half of that of BO with the same efficiency (ca. 70 %), indicating that SBO was much more energy-efficient. Moreover, analysis of the nitrogen solubility index and trichloroacetic acid-soluble nitrogen index demonstrated that the further proteolysis of protein under SBO was limited. Furthermore, the first-order reaction model fitted the hydrolysis data well (R2 ≥ 0.91) for both modes, in which the rate constant of SBO (k = 0.44 min^-1) was 2.3 times that of BO. Finally, the properties of both products met the standards of foaming extinguishers.

Study on the control of high ore pass dust pollution by pre-injection foam dedusting technology in the ore bin

The impact airflow generated by ore unloading in the chute raises the dust carried by the ore itself and the floating dust, and then, the dust raised enters the roadway with the airflow and pollutes the environment. In order to minimize the amount of dust entering the roadway and reduce the pollution of unloading dust, we conducted an experimental study of selection of best foam formula and pre-injection foam dust dedusting technology in ore bin. It was found that the optimal foaming formula was 1.0% sodium dodecyl benzene sulfonate (SDBS) + 0.5% sodium dodecyl sulfate (SDS) + (0.2 ~ 0.4%) sodium carboxymethyl cellulose CMC-Na and coconut oil monoethanolamide (CMEA) by the compound experiment using two evaluation criteria of initial foaming amount and foam defoaming rate. When the air pressure is 0.7 MPa, the foaming rate of the foam generator is proportional to the gas and liquid flow rate and the best foaming gas and liquid flow ratio is 27.8. Under this circumstance, the foaming rate of the foaming formula is 500 l/min. When the height of foam is controlled at 15 cm, the effect of foam dust removal is the best. The dust emission rate from the foam to the fourth level can reach 60%, and the dust fall rate of the third level is 28%, which effectively reduces the dust production and relieves the pressure of the spray hole dust fall at the wellhead.

Fabrication and characterization of thermally-insulating coconut ash-based geopolymer foam

This study aims at synthesizing porous coconut ash (CA)-based geopolymer foam with high thermal insulation property. Sodium hydroxide (NaOH), alumina slag (AS) and water contents as the main parameters, which affect the performance hardened CA, have been studied. The porosity was developed by hydrogen gas resulted from the interaction of Al metal, in AS, with NaOH. The compressive strength, bulk density, porosity and thermal conductivity were evaluated. The results proved that the AS has a potential impact on the reduction of thermal conductivity of CA-based geopolymer foam by creation of high porous system. Open celled hardened CA-based geopolymer with high porosity (∼87%), low thermal conductivity (∼0.045 W/m·K), compressive strength (1.3 MPa) and bulk density (∼0.60 g/cm³) was obtained when 7% AS (by weight of CA powder) and water to CA powder ratio of 0.4 were used.