Pulse Pressure Treatment Research Articles

Changes in the germination and content of protein and gluten in the caryopses of hard and soft wheat under pulse pressure and prolonged storage conditions

The study aims to identify the aging characteristics of hard and soft wheat caryopses without treatment and following treatment with pulse pressure created by a shock wave. The grain was treated with pulse pressures of 11 and 29 MPa. After one month and after three years, the caryopses were sorted into vitreous and floury types. The germination of control soft wheat caryopses decreased after storage, while after pulse pressure treatment and storage, it exceeded that of the control. The germination of control hard wheat caryopses with floury endosperm decreased after storage to a greater extent than that of caryopses with vitreous endosperm. Pulse pressure treatment reduced the germination of caryopses with vitreous endosperm. No change was observed in the protein content of control hard wheat caryopses following prolonged storage. In this case, pulse pressure contributed to the reduction in protein content during storage. The protein content of soft wheat caryopses with floury endosperm decreased after storage. In these caryopses, pulse pressure treatment contributed to better protein retention. Thus, the caryopses of hard wheat and soft wheat with vitreous endosperm were less susceptible to aging as compared to the caryopses of soft wheat and caryopses with floury endosperm, respectively. Pulse pressure damaged the vitreous endosperm, accelerating seed aging. It also contributed to the long-term storage of soft wheat caryopses without a significant loss of viability. Thus, it is possible to treat soft wheat grain to extend its shelf life.

Transformation of non-metallic inclusions in steel under explosive loading and heating

Purpose. The goal of the work was to study phase and structural transformations in nonmetallic inclusions under pulsed loading and subsequent heating.Methodology. Dynamic loading of the samples of steels was carried out according to the scheme of throwing a thin plate (ihe pressure 80...90 GPa, the deformation rate was 100 sec-1, the exposure time was 1,5 · 10-6 sec). After pulsed loading, some of the samples were annealed or thermal cycling. The studies were carried out by methods: metallographic ("Neophot-21"), electron microscopic (JSM-35), petrographic, quantitative metallography ("Quantimet"). Findings. The features of the phase and structural transformations in nonmetallic inclusions under pulsed loading and subsequent heating (high-temperature annealing, thermal cycling) were investigated. It has been found that the explosive action, which creates stresses near the inclusions, influence on the nature of phase transformations during subsequent heating. Originality. The main phase and structural transformations in nonmetallic inclusions that occur at the moment of pulsed loading (polymorphic transformations, transition to an unstable state, amorphization, decomposition of solid solutions) have been determined. The effect of explosive action on transformations in inclusions during subsequent high-temperature annealing and thermal cycling (transition to a more stable state, "devitrification", diffusion crushing, separation of "satellite" particles) was shown.Practical value. The use of the results obtained will make it possible to develop modes of pulsed pressure treatment, as well as complex treatment (explosion + high-temperature annealing, thermal cycling), which allow influencing the mechanical and operational properties of steels for various purposes.

Influence of non-metallic inclusions on the formation of the structure of the steel matrix in explosive loading

Purpose . The goal of this work was to study the localization of deformation near inclusions in steels with various types of metal matrix and the behavior of the inclusions themselves under pulsed loading. Methodology . Dynamic loading of the samples of steels E3 and 08H18N10T was carried out according to the scheme of throwing a thin plate. The calculated pressure was 80...90 GPa, strain rate 100 s -1 , exposure time 1.5 · 10 -6 s. The studies were carried out by several methods: metallographic (Neophot-21), electron microscopic (JSM-35). Findings . The features of local changes in the structure of the steel matrix near non-metallic inclusions under pulsed loading were studied. The processes of localization of deformation near inclusions in steels with various types of metal matrix and the behavior of the inclusions themselves under pulsed loading are discussed. The influence of the physical features of high-speed deformation on the formation of the structure of steels and the processes of its localization near inclusions were analyzed. It was established that stresses localized in a steel matrix near the inclusions cause their destruction. Scientific novelty . The analysis of plastic relaxation zones in a steel matrix was carried out, which made it possible to confirm the formation of regions with various orientations, which indicates a shear-rotational reorientation of these stress relaxation zones near inclusions as a result of plastic deformation having a wave nature. The general patterns of structure formation were determined and the influence of the crystal lattice type of the matrix of steels E3 and 08H18N10T on the development of localization of deformation processes near inclusions was shown. Practical relevance . Using the results obtained will allow us to develop pulsed pressure treatment regimes that allow you to influence the formation of the structure near non-metallic inclusions in various steels.

Theoretical and experimental studies of a gas stamping device with a piston pressure multiplier

In many industries, the share of small-scale production plants is significant. In these conditions, compared with traditional methods of pressure treatment, pulse pressure treatment methods, one of the varieties of which is gas stamping, are more efficient. However, the known devices of gas stamping provide mainly stamping of thin-walled parts. To expand the technological capabilities of gas stamping, the authors developed a gas stamping device with a piston pressure multiplier, in which heating and deformation of the stamping workpiece is carried out using the energy of combustion of fuel mixtures in the combustion chamber, in the working cylinder and in the cavity of the matrix. This article is devoted to the study of the workflow of this device. Theoretical analysis of the workflow was carried out, and, as a result, a pattern was determined for the variation of the pressure that performs the stamping process in the working cylinder. In particular, it was found that at the final stage of the stamping process, due to the energy of combustion of the fuel mixture, the pressure in the working cylinder increases 1.5...2 times, which allows a significant increase in the thickness of the parts to be stamped. An experimental gas stamping device with a piston pressure multiplier was developed, and experimental studies were carried out. The studies confirmed the main results of the theoretical analysis: the discrepancy between the theoretical and experimental values of the degree of pressure multiplication in the working cylinder does not exceed 11%.

Effect of pulsed pressure-assisted brining on lipid oxidation and volatiles development in pork bacon during salting and drying-ripening

In this study, the pulsed pressure-assisted brining technology was used for bacon brining, and its effect on the moisture and lipid oxidation changes during drying-ripening period as well as the flavor composition of final products was investigated by determining the moisture content, acid value, peroxide value, TBARS value and volatile flavor compounds in meat samples during brining and drying-ripening. The results indicated that pulsed pressure-assisted brining could effectively increase the muscle water-holding capacity and decreased the sodium nitrite residues in final cured bacons. After drying-ripening (48 h) the moisture and sodium nitrite content in pulsed pressure-assisted brined samples and control samples were 32.84%, 14.56 mg/kg dry basis and 29.81%, 18.59 mg/kg dry basis, respectively. In addition, the lipid oxidation was promoted by pulsed pressure treatment (P < 0.05), and thus forming more lipid oxidation originated flavor compounds (esters, alcohols and aldehydes) in the pulsed pressure-assisted brined bacons than in control bacons. These suggested that pulsed pressure-assisted brining could effectively improve the sensory quality of cured bacon.

Effect of Pulse Pressure Treatment on Content of Protein and Some Sugars in Wheat Seeds

Seeds of hard wheat (Triticum durum) were treated by pulse pressure (PP), generated by shock wave. Protein content was determined by spectroscopy in the nearest infrared point of the spectrum (NIR). HPLC was used for determining glucose level in samples. Moisture of control seeds was 14.2%. It was not changed in PP 11 MPa samples and was decreased by PP 29 MPa (12.8%); that indicated the damage of seeds. Protein content in control sample was 16.5%. The index was not changed by PP 11 MPa (16.9%), but it increased under PP 29 MPa (17.2%) due to the degradation of starch and relative elevation of protein level. Glucose content in PP 11 MPa samples was less than the control level, probably, due to the acceleration of amino-carbonyl reaction. PP 29 MPa promoted the increase of glucose content due to non-enzymatic starch hydrolysis activation. Thus PP 11 MPa made minor damages without the accumulation of glucose, but PP 29 MPa promoted the ageing due to the accumulation of glucose.

Efficiency of pulse pressure treatment for inactivation of Escherichia coli and Listeria innocua in whole milk

Escherichia coli ATCC 11775 and Listeria innocua ATCC 33090 in whole milk were inactivated by single- and multi-pulsed (up to 10 pulses) high hydrostatic pressure (HHP) treatments. Both bacteria showed similar resistance to single- and multi-pulsed HHP. The efficiency of pulsed pressure treatment depends on the combination of holding time of each pulse and number of pulses. It was observed that multi-pulsed pressure treatment instead of traditional single-pulsed HHP could be used to pasteurize milk at a lower pressure level. Nevertheless, an optimization is necessary between the pulse holding time, number of pulses, and pressure levels to reach the desirable log-reduction of microorganisms compatible with industrial application.

Pulsed pressure treatment for inactivation of escherichia coli and listeria innocua in whole milk

E. coli and L. innocua in whole milk were subjected to continuous pressure treatments (300, 350, 400, 450, 500, 550 and 600 MPa) at ambient temperature for 5, 10, 15 and 20 min. These treatments underlined that at moderate pressure values (300, 350 and 400 MPa), increasing the pressurization time from 5 to 20 min did not improve cell death to a great extent. Therefore, pulsed pressure treatments (at 300, 350 and 400 MPa) for 5 min (2.5 min × 2 pulses, 1 min × 5 pulses and 0.5 min × 10 pulses), 10 min (5 min × 2 pulses, 2 min × 5 pulses and 1 min × 10 pulses), 15 min (5 min × 3 pulses, 3 min × 5 pulses and 1.5 min × 10 pulses) and 20 min (10 min × 2 pulses, 5 min × 4 pulses, 4 min × 5 pulses and 2 min × 10 pulses) were applied. As already observed in continuous pressure experiments, in pulsed pressure treatments the inactivation level is improved with increasing pressure level and in addition with the number of applied pulses; however, the effect of pulse number is not additive. Results obtained in this study indicated that pulsed pressure treatments could be used to pasteurize the whole milk at lower pressure values than the continuous pressure treatments. Nevertheless, an optimization appears definetely necessary between the number of pulses and pressure levels to reach the desirable number of log-reduction of microorganisms.

Inactivation of Escherichia coli and Listeria innocua in kiwifruit and pineapple juices by high hydrostatic pressure

Escherichia coli and Listeria innocua in kiwifruit and pineapple juices were exposed to high hydrostatic pressure (HHP) at 300 MPa for 5 min. Both bacteria showed equal resistance to HHP. Using low (0 °C) or sub-zero (− 10 °C) temperatures instead of room temperature (20 °C) during pressurization did not change the effectiveness of HHP treatment on both bacteria in studied juices. Pulse pressure treatment (multiple pulses for a total holding time of 5 min at 300 MPa) instead of continuous (single pulse) treatment had no significant ( p > 0.05) effect on the microbial inactivation in kiwifruit juice; however, in pineapple juice pulse treatment, especially after 5 pulses, increased the inactivation significantly ( p < 0.05) for both bacteria. Following storage of pressure-treated (350 MPa, 20 °C for 60 s × 5 pulses) juices at 4, 20 and 37 °C up to 3 weeks, the level of microbial inactivation further increased and no injury recovery of the bacteria were detected. This work has shown that HHP treatment can be used to inactivate E. coli and L. innocua in kiwifruit and pineapple juices at lower pressure values at room temperature than the conditions used in commercial applications (> 400 MPa). However, storage period and temperature should carefully be optimized to increase the safety of HHP treated fruit juices.

A novel approach to predicting microbial inactivation kinetics during high pressure processing

The inactivation kinetics of Escherichia coli (ATCC 25922) during high pressure processing (HPP) was examined from 200 to 400 MPa in 50 MPa increments at 15 °C. Although the time course of HPP-induced E. coli inactivation in 0.1% peptone water successfully fitted the Weibull function, this procedure involved curve fitting, and not prediction. The objective of this study was to develop a novel HPP-induced microbial inactivation model to simulate the inactivation kinetics under various pressure conditions. The maximum inactivation rate during HPP was calculated from the inactivation curves at different pressure conditions on a semi-log plot. The relationship between the square root of the absolute value of the inactivation rate ( k max ) and treatment pressure was linear ( R 2 = 0.99). The linear relationship between k max and treatment pressure also successfully described independent data from other studies in the literature. Overall, the newly developed differential equation model, into which was substituted the square root function of the inactivation rate, was capable of simulating the inactivation kinetics during HPP at constant pressure. Additionally, the model could successfully describe the inactivation kinetics during HPP using other researchers’ data. The accuracy of prediction of the new model was comparable to that derived from Weibull or modified Gompertz fitting to the observed data. Furthermore, the new model could successfully simulate the inactivation kinetics during dynamic pressure conditions, which included come-up time, changes in holding pressure during treatment, and pressure-release time. Moreover, the effect of pulsed pressure treatment was also simulated successfully using this model. Therefore, the modeling procedure presented in this study will contribute to the advancement of predictive modeling for HPP-induced microbial inactivation.

Aortic Pulse Wave Velocity and Albuminuria in Patients with Type 2 Diabetes

Development of microalbuminuria increases the risk for cardiovascular disease (CVD) in type 2 diabetes. The nature of this relationship is unclear but may involve arterial stiffness, an independent risk marker for CVD mortality. Aortic pulse wave velocity (Ao-PWV) and albumin creatinine ratio (ACR) were measured in 134 consecutive patients with type 2 diabetes without overt renal impairment (serum creatinine <150 micromol/L). ACR ranged from 0.2 to 153 mg/mmol. Patients with raised ACR (>/=3 mg/mmol) had higher Ao-PWV, poorer diabetic control, and higher pulse pressure (PP) and systolic BP (SBP) (all P < 0.05) than those with normal ACR. The closest univariate associations of Ao-PWV were positively with age, duration of diabetes, SBP, PP, ACR, and insulin treatment and negatively with GFR and weight (all P < 0.01). In a multiple linear step-down regression analysis, the significant predictors of Ao-PWV were age, SBP or PP, duration of diabetes, gender, number of antihypertensive medications, and use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, which together explained 55% of the variance of Ao-PWV. When ACR was offered in place of arterial pressure to a separate model, ACR emerged as a significant predictor of Ao-PWV. After age adjustment, patients with lower, below median GFR had higher Ao-PWV than those with GFR above the median (P = 0.043). In patients with type 2 diabetes without overt renal impairment, raised ACR is associated with higher Ao-PWV, a relationship most likely mediated by raised BP. The association of Ao-PWV with reduced GFR suggests that even modest renal dysfunction may affect the viscoelastic properties of large arteries.

Starches and fibers treated by dynamic pulsed pressure

The effect of dynamic pulsed pressure treatment on water activity, moisture content, water holding capacity (WHC), thermal and rheological properties of corn starch, modified corn starch, microcrystalline cellulose and wheat bran were investigated. Substantial changes in moisture content, water holding capacity, water activity, density, shifts in melting patterns, and reordering of molecules resulted from the pressure treatment. The starches and fibers were made into slurries (starches 200 g/kg; fibers 120 g/kg), fed by gravity into the pressure chamber, and pulsed pressure treated at 120 cycles/min; within chamber residence time for pressure treatment was 1.0 s. Dynamic pulsed pressure of 414 or 620 MPa was generated in the chamber. Slurry flow rate through the pressure chamber ranged from 57 to 100 l/h. 13C NMR analysis of pressure treated starch showed evidence of pressure induced degradation and loss of long range molecular ordering for modified corn starch. Pressure treatment resulted in increases in density and reduction in water holding capacity of cellulose. A 35% reduction in water holding capacity of cellulose was observed, a significant change ( P<0.05) that may potentially increase the amount of cellulose fiber incorporated into foods. Peak melting points of the starches were reduced 10°C at 414 and 620 MPa, and increased with subsequent pressure treatment cycles. The effect of pressure treatment on starches and fibers depend on their source, the degree of pressure treatment, and the number of cycles.