scholarly journals Effects of Radio Frequency Tempering on the Texture of Frozen Tilapia Fillets

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2663
Author(s):  
Jiwei Jiang ◽  
Fen Zhou ◽  
Caining Xian ◽  
Yuyao Shi ◽  
Xichang Wang

Radio frequency (RF) tempering has been proposed as a new alternative method for tempering frozen products because of its advantages of rapid and volumetric heating. In this study, the texture of RF-tempered frozen tilapia fillets was determined under different RF conditions, the effects of related factors on the texture were analyzed, and the mechanisms by which RF tempering affected the texture of the tempered fillets were evaluated. The results show that the springiness (from 0.84 mm to 0.79 mm), cohesiveness (from 0.64 mm to 0.57 mm), and resilience (from 0.33 mm to 0.25 mm) decreased as the electrode gap was increased and the power remained at 600 W, while the shear force increased as the power was increased for the 12 cm electrode gap (from 15.18 N to 16.98 N), and the myofibril fragmentation index (MFI) values were markedly higher at 600 W than at 300 W or 900 W (p < 0.05). In addition, the tempering uniformity had a positive effect on hardness and chewiness. The statistical analysis showed that the texture after RF tempering under different RF conditions correlated relatively strongly with the free water content, cooking loss, and migration of bound water to immobilized water. The decrease in free water and bound water migration to immobilized water resulted in a significant increase in cohesiveness and resilience.

Foods ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 649 ◽  
Author(s):  
Yingwu Shi ◽  
Wangang Zhang ◽  
Guanghong Zhou

The objective of this study was to investigate the effects of six different aging methods (four types of moisture-permeable packaging, wet aging, and dry aging) and aging time (0, 7, and 14 d) on the quality of aging beef, especially physicochemical properties. The weight loss, aerobic bacterial counts, yeast counts, and mold counts increased with the increase of moisture permeability and aging time. However, shear force, hardness, cohesiveness, and chewiness followed an opposite trend with increasing moisture permeability. The values of L* and b* appeared to decrease in the dry-aged samples compared with those of the others. In addition, water content in dry-aged samples for 7 and 14 d showed a significant decrease. The higher myofibril fragmentation index was observed in dry-aged samples for 7 and 14 d compared with groups using moisture-permeable packaging. Meanwhile, the percentage of bound water and free water appeared to decrease with the increase of moisture permeability. Thus, different moisture-permeable packaging was able to control different levels of water loss and effectively reduce microbial contamination compared with dry aging. The changes of both myofibrillar fragmentation index (MFI) and distribution of water indicated that moisture-permeable packaging affected the structure of myofibrils, which influenced the shear force.


2001 ◽  
Vol 44 (10) ◽  
pp. 177-183 ◽  
Author(s):  
J. Kopp ◽  
N. Dichtl

Dewaterabilty of sewage depends on the physical water distribution. The various types of water in sewage sludge are mainly distinguished by type and intensity of their physical bonding to the solids. In a sewage sludge suspension different types of water can be distinguished. These are free water, which is not bound to the particles, interstitial water, which is bound by capillary forces between the sludge flocs, surface water, which is bound by adhesive forces and intracellular water. Only free water can be separated during mechanical dewatering. It can be shown, that thermo-gravimteric measurement of the free water content leads to an exact prediction of full-scale dewatering results. Maximum dewatering results are reached by separating all free water during centrifugation. Furthermore on the basis of the drying curve an estimation of water binding energies can be achieved. The binding energy for free water is less than 0,28 kJ/kg water. The binding energy for bound water (sum of surface and intracellular water) is higher than 5 kJ/kg water.


2016 ◽  
Vol 691 ◽  
pp. 230-238
Author(s):  
Ivan Juríček ◽  
Ľudovít Fillo

In the production of structures made of concrete it is sometimes required to make a completed structure contain a minimum amount of free water. From the point of view of effectiveness of the production process it is also preferred to dry the concrete in a short time and at a reasonable cost. Required for free water content can be limited by various factors (e.g. construction covered by flooring sensitive to humidity, frost resistance, etc.).The moisture characteristic of concrete is verified in civil engineering provided that the concrete is located in the environment with normal atmospheric pressure. By solving the project “Development of methods for structure of thermal vacuum insulated containers” we have met a requirement to produce concrete with extremely low moisture content. It was found out that information about moisture content of concrete obtained by currently used method was unsatisfactory for concrete in the environment with extremely low atmospheric pressure. The research has indicated that usual methods of concrete drying are not sufficient for concrete subjected to vacuum because they don´t eliminate physically bound water.


Holzforschung ◽  
2018 ◽  
Vol 72 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Zhe Wang ◽  
Xi-Ming Wang ◽  
Zhang-Jing Chen

AbstractThe time domain nuclear magnetic resonance (TD-NMR) technique was applied to observe the water states, water migration and theT2cutoffof sapwood (sW) and heartwood (hW) of Xinjiang poplar and Mongolian Scotch pine wood during drying. Three components in theT2spectrum could be observed for poplar and pine at room temperature, and a large, short time component and a small, long time component of free water was visible at the melting point of water. During drying, the long timeT2component diminished rapidly above the fiber saturation point (FSP), and almost disappeared close to or below the FSP. The short time components of theT2distributions slightly enlarged with decreasing moisture content (MC) above the FSP but rapidly diminished and shifted to the left side below the FSP. The bound water content estimated based on theT2cutoffis in agreement with previous findings. Free and bound water have been found to be in two primary states both in poplar and pine. The loss of free water was rapid and profound but the bound water slightly increased with decreasing MC above the FSP, and the free water evaporated completely close to the FSP, where the bound water began to disappear significantly.


2014 ◽  
Vol 665 ◽  
pp. 404-407 ◽  
Author(s):  
Wan Yu ◽  
Pei Sheng Li

Moisture distribution in sewage sludge was considered as the essential of thermal drying. Some methods were given in literatures to test the moisture distribution, but there was no standard method to determine the critical water content between different kinds of water. The municipal sewage sludge was dried by hot air in this work. Based on the drying curve, the derivative of drying rate with respect to dry basis moisture content was brought out to analyze the moisture distribution in sewage sludge. Results show that this method can easily determine the free water, interstitial water, surface water and bound water with a high accuracy. The present work can provide new insight to determine the moisture distribution in sewage sludge, which was still lacking in the literatures.


2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yong Wang ◽  
Aixiang Wu ◽  
Lianfu Zhang ◽  
Fei Jin ◽  
Xiaohui Liu

Cemented paste backfill (CPB) technology has been applied quite popular around the world. Yield stress is a key factor determining whether CPB could be transported. In order to reveal the effect of solid components on yield stress of CPB, a uniform design experimental program (four factors and six levels) was conducted to test the rheological property of a mine’s CPB. The tested four factors including mass fraction, cement versus other solids ratio, coarse tailings, and gravel contents were considered during the experiment design. Likewise, six experimental levels were given to each factor. Results of the test show that yield stress increased with the mass fraction and cement content. However, the trend reversed for the content of coarse tailings and gravel. Contribution of the four factors to yield stress in descending order is mass fraction > content of gravel > content of coarse tailings > cement versus other tailings ration. Effect of solid components on the yield stress of CPB is mainly due to the different flocculation structure inside the CPB. These various flow structures result in the different free-water content of CPB, leading to a different yield stress value.


Solid Earth ◽  
2014 ◽  
Vol 5 (1) ◽  
pp. 537-555 ◽  
Author(s):  
M. E. T. Quinquis ◽  
S. J. H. Buiter

Abstract. Subduction of oceanic lithosphere brings water into the Earth's upper mantle. Previous numerical studies have shown how slab dehydration and mantle hydration can impact the dynamics of a subduction system by allowing a more vigorous mantle flow and promoting localisation of deformation in the lithosphere and mantle. The depths at which dehydration reactions occur in the hydrated portions of the slab are well constrained in these models by thermodynamic calculations. However, computational models use different numerical schemes to simulate the migration of free water. We aim to show the influence of the numerical scheme of free water migration on the dynamics of the upper mantle and more specifically the mantle wedge. We investigate the following three simple migration schemes with a finite-element model: (1) element-wise vertical migration of free water, occurring independent of the flow of the solid phase; (2) an imposed vertical free water velocity; and (3) a Darcy velocity, where the free water velocity is a function of the pressure gradient caused by the difference in density between water and the surrounding rocks. In addition, the flow of the solid material field also moves the free water in the imposed vertical velocity and Darcy schemes. We first test the influence of the water migration scheme using a simple model that simulates the sinking of a cold, hydrated cylinder into a dry, warm mantle. We find that the free water migration scheme has only a limited impact on the water distribution after 1 Myr in these models. We next investigate slab dehydration and mantle hydration with a thermomechanical subduction model that includes brittle behaviour and viscous water-dependent creep flow laws. Our models demonstrate that the bound water distribution is not greatly influenced by the water migration scheme whereas the free water distribution is. We find that a bound water-dependent creep flow law results in a broader area of hydration in the mantle wedge, which feeds back to the dynamics of the system by the associated weakening. This finding underlines the importance of using dynamic time evolution models to investigate the effects of (de)hydration. We also show that hydrated material can be transported down to the base of the upper mantle at 670 km. Although (de)hydration processes influence subduction dynamics, we find that the exact numerical implementation of free water migration is not important in the basic schemes we investigated. A simple implementation of water migration could be sufficient for a first-order impression of the effects of water for studies that focus on large-scale features of subduction dynamics.


Author(s):  
Velumani M ◽  
Sakthivel S ◽  
Yuvaraj K

The main aim of the environmental protection agencies and the government are to seek ways and means to minimize the problems of disposal and health hazards of by products. It is considered as a waste material which could have a promising future in construction industry as substitute of either cement or coarse aggregates or fine aggregates. Copper slag is one of the replacement mechanisms of material in concrete. Use of copper slag as a replacement for fine aggregate in concrete cubes various strength measurements was experimentally investigated in this study. Mainly contents of that M35 conventional concrete and copper slag as a replacement of fine aggregate  in 10%, 20%, 30%, 40%,50%, 60%, 80%, and 100% and also Portland Pozzolana Cement is noted. In this regard, laboratory study including water absorption test, bond strength, and percentage of voids, compressive strength & bulk density were conducted in ppc cement concrete which made by copper slag waste as a replacement of fine aggregate and PPC. A substitution up to 40-50% as a copper slag as a sand replacement yielded comparable strength to that of the conventional concrete. However, addition of more copper slag resulted in strength reduction due to the increase in the free water content in the mix, cured period in a curing tank for later resulting at 28 and 60 days.


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