Effects Of Freeze-thaw Treatment Research Articles

Network structure of response to freeze-thaw cycles in egg white protein gels filled with emulsion: Digestive kinetics regulated by the state of water and embedded oil

In this paper, we focused on the effects of freeze-thaw treatment on the network structure of egg white protein (EWP) emulsion-filled gel (EFG). The freeze-thaw stability of EFG based on egg white protein was analyzed in terms of microstructure, digestive dynamics and processing properties in this work. The results showed that the initial spatial distribution of oil droplets and fine network of gel were damaged during freeze-thaw cycles observed by confocal laser scanning microscopy (CLSM). These phenomena led to the rising of swelling ratio (from 9.882% ± 0.535%–34.985% ± 1.843%) and the change of acid uptake process, which affected the pH value and pepsin activity inside gel. The effect of freeze-thaw cycles on amino acids release during digestion was evaluated by the model of digestive kinetics. Meanwhile, the characteristics of emulsion and gel matrix were detected, illustrating the effect of the ions and percentage of oil on gel subjected to freezing. With the repeats of freeze-thaw treatment, the initial gel network was reorganized for the thicker chain-like structure with higher cohesiveness (from 0.44 ± 0.014 to 0.75 ± 0.041), while ions could be used as stabilizer in frozen. Furthermore, the lower relaxation time proved the improved stability caused by ions, which resulted from the enhanced limitation of network structure to fillings. These findings provided valuable information on the relationship between the freeze-thaw stability of emulsion-filled gel and in vitro digestion, with a view to broader application in the direction of future fat replacement. • The well-distributed emulsion in gel would flocculate after freeze-thaw cycles. • Oil phase in gel promoted the structural changes of EFG during freeze-thaw cycles. • Freeze-thaw treatment slowed release of amino acid during the digestion of EFG. • LF-NMR proved the damage of bond between water and gel matrix due to freezing. • The properties of EFG after freezing were maintained by ions-induced firm structure.

Transport of plastic particles in natural porous media under freeze-thaw treatment: Effects of porous media property.

Freeze-thaw (FT) cycles would alter physical and chemical properties of soil and thus influence the transport of plastic particles (one type of emerging contaminant with great concerns). This study was designed to investigate the effects of FT treatment on the mobility of plastic particles (nanoplastics as representative) in columns packed with natural soils (i.e. loamy sand and sandy soil, quartz sand employed as comparison). We found that FT treatment of different types of porous media would induce different transport behaviors of plastic particles. Specifically, FT treatment of quartz sand did not affect plastic particles mobility. While FT treatment of loamy sand and sandy soil increased plastic particles transport. The increased pore sizes and disintegration of small soil particles from soils (the detached soil would serve as mobile vehicle for the transport of plastic particle) led to the facilitated mobility of plastic particles in two types of soils after FT treatment. The presence of preferential flow paths induced by FT treatment also drove to the enhanced mobility of plastic particles in sandy soil with FT treatment. This study clearly showed that the mobility of model plastic particles in two types of natural soils was greatly enhanced by FT treatment.

Analysis of Mechanical Properties of Sandstone under Freeze-Thaw Cycles Based on Digital Image Correlation (DIC)

This paper studies the change of physical and mechanical properties of sandstone after freeze-thaw (F-T) cycle treatment. Firstly, the effects of the freeze-thaw treatment on the P-wave velocity of sandstone specimens are analyzed. It is found that the P-wave velocity decreases with the increase of the number of freeze-thaw cycles. Secondly, the effect of freeze-thaw treatment on the mechanical properties of sandstone is analyzed. The results show that the tensile strength and compressive strength of sandstone samples decrease with the increase of the number of freeze-thaw cycles. Finally, the digital image correlation (DIC) technique was used to collect the full-field deformation data of the samples, and the influence of freeze-thaw cycles on the deformation characteristics and fracture process of sandstone was analyzed. Based on the standard deviation of the principal strain in the field deformation data, the damage variables were proposed to characterize the damage process of sandstone samples in the Brazilian splitting test and the uniaxial compression test. The results show that the proposed damage variables can reflect the damage evolution process of the sample effectively. According to the variation of damage variables, the damage evolution process of sandstone specimens during the Brazilian splitting test and the uniaxial compression test can be divided into three stages: slow or negative growth stage, stable growth stage, and rapid growth stage. The research results are of great significance for predicting the failure mode and damage evolution of rock mass engineering by using digital image correlation technology.

Effect of freeze-thaw treatment on the quality and flavor of Nang

Freezing processing has been used widely to improve the sensory quality and solve the problems induced by fungi. In this study, the effects of frozen temperature (−20, −30, −40, −50, −60°C), frozen time (30, 40, 50, 60, 70 min), thawing temperature (25, 30, 35, 40, 45°C) and thawing time (10, 15, 20, 25, 30 min) on sensory quality, texture characteristics and flavor of Nang were studied. The results showed that the order of the factors affecting the sensory quality of Nang was frozen temperature > thawing time > frozen time > thawing temperature. The optimum processing conditions were to freeze at −50°C for 50 min and thaw at 40°C for 20 min. The correlation analysis between sensory quality and texture profile analysis (TPA) showed that the highest or the lowest TPA values of the core and edge of Nang did not correspond to the best sensory quality. Frozen treatment affected the characteristic flavor of Nang obviously. There were 15 of flavor substances with a significant increase or decrease among the 41 characteristic ones identified. This study is of great significance for the production and promotion of traditional staple food in Xinjiang.

Effects of freeze-thaw treatment and pullulanase debranching on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes

The effects of multiple cycles of freeze-thaw treatment, combined with pullulanase debranching, on the structural properties and digestibility of lotus seed starch-glycerin monostearin complexes were investigated. The formation and melting of ice crystals during freeze-thaw treatment disrupted the crystalline structure of the starch granules, creating pores which facilitated access of pullulanase to the interior of the granules. Pullulanase debranching increased the free amylose content of the starch, which promoted the formation of starch-lipid complexes, which, in turn, increased the proportion of resistant starch and the overall resistance of the starch to digestive enzyme action. These effects increased with the number of freeze-thaw cycles, because more cycles increased both the disruption of the granule structure and the extent of pullulanase debranching. These findings provide a basis for the preparation of functional foods with low glycemic indices, which have strong potential for management of type II diabetes.

Effects of freeze-thaw treatment on the dynamic tensile strength of granite using the Brazilian test

The deterioration mechanism and dynamic tensile properties of rock subjected to the effects of freeze-thaw cycles are investigated in this study. Brazilian disc granite specimens are treated by 0, 30, 60, 90 and 120 freeze-thaw cycles. Freezing and thawing temperatures are −20 °C and 20 °C respectively. The microscopic damage in the rock samples induced by freeze-thaw treatment is detected by the nuclear magnetic resonance (NMR) technique. T2 spectrum and magnetic resonance imaging (MRI) are used to analyze the effect of freeze-thaw cycles on the pore structure of rock samples. Brazilian splitting tests are performed by a split Hopkinson pressure bar (SHPB) system to measure the dynamic tensile strength of granite and to investigate the effect of freeze-thaw cycles on the dynamic tensile strength and the dynamic mechanical behavior. A formula for dynamic tensile strength prediction considering loading rates and freeze-thaw cycles is presented to quantify the results. The dynamic failure process of specimen is observed by a high-speed camera, it was found that the rock materials were more susceptible to damage and deteriorate after freeze-thaw treatment compared with the untreated rock.

Effect of freeze-thaw treatment on the structure and texture of soft and firm tofu

The effects of freeze-thaw treatments on the microstructural and textural properties in two kinds of commercial tofu were studied. Tofu samples obtained from a commercial supplier were placed in a freezer at −16 °C for various times, then removed and thawed at 20 °C for 20 min. Subsequently, the samples were examined by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) to assess the structural changes during the freeze-thaw treatment. Static compression tests and texture profile analysis were conducted on both freeze-thawed and fresh tofu samples. An analysis of the tofu structure based on the Gibson-Ashby model indicated that freeze-thawed tofu exhibits a reduction in water content compared to fresh tofu. The texture profile analysis results indicated that tofu was harder, springer, gummier and more cohesive after the freeze-thaw treatment. This increase in textural properties of tofu may satisfy consumer preferences for a harder and springier tofu.

Effects of Freeze-thaw Treatment on the Characteristics of Soymilk and Formulated Tofu Curd

Effects of Freeze-thaw Treatment on the Characteristics of Soymilk and Formulated Tofu Curd

Formulation Optimization of Cryoprotectant for Crisp Grass Carp by Response Surface Methodology

The composite cryoprotectants was created using trehalose, polydextrose and sodium lactate. Response surface methodology based on the single-factor investigation was applied to explore optimal cryoprotectant solution formulation on salt soluble protein content of crisp grass carp, and compared to the traditional commercial cryoprotectants, then studied the optimal immersion time and effect of freeze-thaw treatment on crisp grass carp. The results indicate that the optimal formula of composite cryoprotectants is 4% trehalose, 6% polydextrose and 5% sodium lactate. Salt soluble protein content of the optimal cryoprotectants is higher than that traditional commercial cryoprotectants (4% sucrose +4% sorbitol) in crisp grass carp, and the optimal immersion time is 30min. The optimal composite cryoprotectants with low sweetness and low heat can prevent effectively protein from frozen denaturation. Thus the composite cryoprotectants of trehalose, polydextrose and sodium lactate can replace sucrose and sorbitol.

Production of Functional Gametes from Cryopreserved Primordial Germ Cells of the Japanese Quail

The Japanese quail (Coturnix japonica) is a valuable bird as both an experimental animal, for a wide range of scientific disciplines, and an agricultural animal, for the production of eggs and meat. Cryopreservation of PGCs would be a feasible strategy for the conservation of both male and female fertility cells in Japanese quail. However, the effects of freeze-thaw treatment on viability, migration ability and germline transmission ability of quail PGCs still remain unclear. In the present study, male and female PGCs were isolated from the blood of 2-day-old embryos, which were cooled by slow freezing and then cryopreserved at –196 C for 77–185 days, respectively. The average recovery rate of PGCs after freeze-thawing was 47.0%. The viability of PGCs in the frozen group was significantly lower than that of the control group (P<0.05) (85.5% vs. 95.1%). Both fresh and Frozen-thawed PGCs that were intravascularly transplanted into recipient embryos migrated toward and were incorporated into recipient gonads, although the number of PGCs settled in the gonads was 48.5% lower in the frozen group than in the unfrozen control group (P<0.05). Genetic cross analysis revealed that one female and two male recipients produced live progeny derived from the frozen-thawed PGCs. The frequency of donor-derived offspring was slightly lower than that of unfrozen controls, but the difference was not significant (4.0 vs. 14.0%). These results revealed that freeze-thaw treatment causes a decrease in viability, migration ability and germline transmission ability of PGCs in quail.

P94 The effects of freeze-thaw treatment and pre-analytical storage temperature on the stability of insulin-like growth factor-I and pro-collagen type III N-terminal peptide concentrations

P94 The effects of freeze-thaw treatment and pre-analytical storage temperature on the stability of insulin-like growth factor-I and pro-collagen type III N-terminal peptide concentrations

Rheological Properties of Cooking Creams: Effect of Freeze-Thaw Treatment

Rheological characteristics of commercial creams were investigated at different freeze-thaw conditions. This study was carried out to determine the effect of the freeze-thaw treatment on rheological behaviour and the activation energy in different commercial creams. Freeze-thaw treatment was made at different times of frozen storage within a range from 0 to 6 weeks. For each freezing cycle, the sample was submitted to rheological measurements within range of temperature between 20 and 40° C. A rotational, concentric cylinder viscosimeter Viscotester VT550 (Germany) type Searle was used in this work. The apparent viscosity is defined as the ratio of shear stress and shear rate, which was varied between 17.8 and 445 s-1. The Power Law or Oswaltd Waele model describes well the rheological behaviour of the analyzed samples. Furthermore, in all cases sample viscosity increased when was exposed to freeze-thaw treatment with respect to the not treated sample. And other hand, the activation energy has high values; hence there is clear evidence that the rheological behaviour presents a high dependence with the temperature.