Effect of cryogenic freezing on the rheological and calorimetric properties of pasteurized liquid egg yolk

The egg yolk undergoes an irreversible gelation process when freezing to –6 °C or lower. In this experiment, liquid egg yolk (LEY) was frozen in liquid nitrogen and stored at –18 °C for 150 days. The measurement of pH and colour of LEY were performed. The examination of the rheological and calorimetric properties of samples was also carried out. The results indicated that the pH of LEY changed significantly during frozen storage, increasing from 6.37 ± 0.02 to 6.58 ± 0.03 over five months. The colour of the samples also showed a significant change compared to the fresh sample. The rheological properties of the LEY also changed significantly after 1 day of freezing and during frozen storage, with a clear increasing trend of the yield stress. The results of the calorimetric study showed that freezing and frozen storage did not affect the denaturation temperature, however, the denaturation enthalpy was reduced by about half after five months of frozen storage.

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HOW DOES CRYOGENIC FREEZING AFFECT THE CALORIMETRIC PROPERTIES OF LIQUID EGG PRODUCTS?

JOURNAL OF ENGINEERING & PROCESSING MANAGEMENT ◽

10.7251/jepm1901001h ◽

2019 ◽

Vol 11 (1) ◽

Author(s):

Hidas Karina Ilona ◽

Ildikó Csilla Nyulas-Zeke ◽

László Friedrich ◽

Anna Visy ◽

Judit Csonka ◽

...

Keyword(s):

Liquid Nitrogen ◽

Frozen Storage ◽

Colour Change ◽

Egg Yolk ◽

Egg White ◽

Dry Matter Content ◽

Scanning Calorimetry ◽

Egg Products ◽

Liquid Whole Egg ◽

Whole Egg

Eggs are widely utilized because of their high nutrient value, coagulating, foaming, emulsifying and sometimes even colouring or flavouring facilities in food manufacturing. Production of processed egg products shows an increasing trend. Frozen products belong to first processing, their shelf life can increase up to 1 year. By freezing, a large reduction in microbial loss can be achieved. But different undesirable processes can occur. The effect of freezing on animal cells is highly dependent on freezing parameters. It has a different effect on egg subtituents. Egg yolk undergoes a gelation process while proteins can denaturate. In our study pasteurized liquid egg products (liquid egg white, liquid egg yolk and liquid whole egg) were frozen by dripping into liquid nitrogen. After that, a 14-day frozen storage experiment was carried out at -18°C. Before freezing and on the 1th, 7th and 14th days of storage experiment pH, dry matter content, colour and calorimetric properties (denaturation temperatures and enthalpy of denaturation) with differential scanning calorimetry were tested. For statistical analysis, one-way ANOVA (α = 0.05) was employed. In our experiment, we found no significant change in calorimetric properties of liquid egg white after freezing, but significant decreasing of enthalpy and denaturation temperatures of liquid egg yolk and liquid whole egg was identified. In contrast, frozen storage had a decreasing effect in all these products. Freezing caused a clearly visible colour change in LEW, a visible change in colour of LWE and a very clearly visible change in colour of LEY. In case of LEW and LEY changes increased to clearly visible 14 days. In conclusion, our results show that frozen storage had a greater effect on liquid egg products properties than freezing in liquid nitrogen.

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Gelation process in two different squid (Dosidicus gigas) surimis throughout frozen storage as affected by several cryoprotectants: Thermal, mechanical and dynamic rheological properties

Journal of Food Engineering ◽

10.1016/j.jfoodeng.2011.05.037 ◽

2011 ◽

Vol 107 (1) ◽

pp. 107-116 ◽

Cited By ~ 14

Author(s):

Laura Campo-Deaño ◽

Clara A. Tovar ◽

Javier Borderías ◽

Fernando Fernández-Martín

Keyword(s):

Rheological Properties ◽

Frozen Storage ◽

Dosidicus Gigas ◽

Gelation Process ◽

Dynamic Rheological Properties

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Comparison of different thawing methods effect on the calorimetric and rheological properties of frozen liquid egg yolk

Progress in Agricultural Engineering Sciences ◽

10.1556/446.2020.20005 ◽

2020 ◽

Author(s):

Karina Ilona Hidas ◽

Csaba Németh ◽

Anna Visy ◽

Adrienn Tóth ◽

László Ferenc Friedrich ◽

...

Keyword(s):

Rheological Properties ◽

Dry Matter ◽

Frozen Storage ◽

Egg Yolk ◽

Matter Content ◽

Dry Matter Content ◽

Freezing And Thawing ◽

Scanning Calorimetry ◽

Nutrient Value ◽

Analyse Data

AbstractEggs are commonly used in the food industry because of their excellent nutrient value and also for their coagulating, foaming, emulsifying, colouring and flavouring properties. Manufacturers substitute shell eggs with processed egg products, such as liquid whole egg, liquid egg yolk or albumin. They have a shelf life of a few weeks, but freezing can increase it to 1 year. However, freezing causes gelation in case of egg yolk. This process is highly dependent on the conditions of freezing and thawing.In our study, raw liquid egg yolk was frozen and stored for 14 days at −18 °C. On days 1, 7 and 14 samples were thawed by two different methods. Denaturation temperature and enthalpy were investigated by differential scanning calorimetry. Besides, rheological properties were examined at 20 °C, Herschel–Bulkley model was fitted to flow curves of the examined samples. The dry matter content was also recorded during the experiment. Two-way ANOVA was used to analyse data.The results of the study showed that method of thawing had no significant effect on calorimetric and rheological properties and dry matter content. In contrast, freezing and frozen storage had a significant effect on denaturation enthalpy and rheological properties.

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Effect of Combination of Salt and pH on Functional Properties of Frozen-Thawed Egg Yolk

Agriculture ◽

10.3390/agriculture11030257 ◽

2021 ◽

Vol 11 (3) ◽

pp. 257

Author(s):

Karina Ilona Hidas ◽

Ildikó Csilla Nyulas-Zeke ◽

Anna Visy ◽

László Baranyai ◽

Lien Phuong Le Nguyen ◽

...

Keyword(s):

Thermal Properties ◽

Citric Acid ◽

Rheological Properties ◽

Functional Properties ◽

Apparent Viscosity ◽

Frozen Storage ◽

Egg Yolk ◽

Emulsifying Properties ◽

L Value ◽

Different Levels

Egg yolk undergoes an irreversible gelation process at temperatures below −6 °C, which greatly impairs its application and increases its apparent viscosity. This work was aimed to investigate the effect of salt and pH in preventing the gelation of frozen-thawed egg yolk. Before freezing, 5% of salt was added into the pasteurized liquid egg yolk, then pH was adjusted to different levels (5.7, 6.0 and 6.3) with citric acid. After that, the yolk was stored at −18 °C for four weeks. Rheological and thermal properties of the fresh and frozen-thawed egg yolk were measured. In addition, the colour, turbidity and emulsifying properties were also determined. The results showed that pH of all samples increased during frozen storage, but at different rates. The combination of 5% of salt and pH at 6.0 and 6.3 could prevent the gelation, resulting in rheological properties more like the fresh liquid egg yolk. In addition, emulsifying properties also obtained better results for treated yolk. Moreover, L* value of treated egg yolk was higher before freezing and became lower after storage compared to control. The results of this work found that the combination of 5% of salt and adjusted pH could prevent the gelation of frozen-thawed liquid yolk.

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A simulation-based approach to evaluate objective material parameters from concrete rheometer measurements

Applied Rheology ◽

10.1515/arh-2019-0012 ◽

2019 ◽

Vol 29 (1) ◽

pp. 130-140 ◽

Cited By ~ 1

Author(s):

Florian Gerland ◽

Alexander Wetzel ◽

Thomas Schomberg ◽

Olaf Wünsch ◽

Bernhard Middendorf

Keyword(s):

Yield Stress ◽

High Performance ◽

Evaluation Method ◽

High Performance Concrete ◽

Direct Determination ◽

Plastic Viscosity ◽

Flow Properties ◽

Fresh Sample ◽

Material Parameters ◽

Simulation Based

Abstract Modern concretes such as ultra-high performance concrete (UHPC) show excellent strength properties combined with favorable flow properties. However, the flow properties depend strongly on process parameters during production (temperature, humidity etc.), but also change sensitively even with slight variations in the mixture. In order to ensure desired processing of the fluidlike material and consistent process quality, the flow properties of the concrete must be evaluated quantitatively and objectively. The usual evaluation of measurements from concrete rheometers, for example of the ball probe system type, does not allow the direct determination of the objective material parameters yield stress and plastic viscosity of the sample. We developed a simulation-based method for the evaluation of rheometric measurements of fine grained high performance concretes like self-compacting concrete (SCC) and UHPC. The method is based on a dimensional analysis for ball measuring systems. Through numerical parameter studies we were able to describe the identified relationship between measuring quantities and material parameters quantitatively for two devices of this type. The evaluation method is based on the Bingham model. With this method it is possible to measure both the yield stress and the plastic viscosity of the fresh sample simultaneously. Device independence of the evaluation process is proven and an application to fiber-reinforced UHPC is presented.

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Comparison of the Effects of Conching Parameters on the Contents of Three Dominant Flavan3-ols, Rheological Properties and Sensory Quality in Chocolate Milk Mass Based on Liquor from Unroasted Cocoa Beans

Molecules ◽

10.3390/molecules26092502 ◽

2021 ◽

Vol 26 (9) ◽

pp. 2502

Author(s):

Bogumiła Urbańska ◽

Hanna Kowalska ◽

Karolina Szulc ◽

Małgorzata Ziarno ◽

Irina Pochitskaya ◽

...

Keyword(s):

Rheological Properties ◽

Yield Stress ◽

Sensory Quality ◽

Raw Material ◽

Antioxidant Compounds ◽

Chocolate Milk ◽

Cocoa Beans ◽

Variable Parameters ◽

The Relationship ◽

Manufacturing Parameters

The content of polyphenols in chocolate depends on many factors related to the properties of raw material and manufacturing parameters. The trend toward developing chocolates made from unroasted cocoa beans encourages research in this area. In addition, modern customers attach great importance to how the food they consume benefits their bodies. One such benefit that consumers value is the preservation of natural antioxidant compounds in food products (e.g., polyphenols). Therefore, in our study we attempted to determine the relationship between variable parameters at the conching stage (i.e., temperature and time of) and the content of dominant polyphenols (i.e.,catechins, epicatechins, and procyanidin B2) in chocolate milk mass (CMM) obtained from unroasted cocoa beans. Increasing the conching temperature from 50 to 60 °C decreased the content of three basic flavan-3-ols. The highest number of these compounds was determined when the process was carried out at 50 °C. However, the time that caused the least degradation of these compounds differed. For catechin, it was 2 h; for epicatechin it was 1 h; and for procyanidin it was 3 h. The influence of both the temperature and conching time on the rheological properties of chocolate milk mass was demonstrated. At 50 °C, the viscosity and the yield stress of the conched mass showed its highest value.

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Evaluation of long-term frozen storage of plasma for measurement of high-density lipoprotein and its subfractions by precipitation

Clinical Chemistry ◽

10.1093/clinchem/36.5.783 ◽

1990 ◽

Vol 36 (5) ◽

pp. 783-788 ◽

Cited By ~ 16

Author(s):

M N Nanjee ◽

N E Miller

Keyword(s):

High Density Lipoprotein ◽

Liquid Nitrogen ◽

Frozen Storage ◽

Density Lipoprotein ◽

High Density ◽

Long Term Stability ◽

Long Term Storage ◽

Different Temperatures ◽

Edta Plasma

Abstract The concentration of high-density lipoprotein cholesterol (HDL-C) in plasma is now established as an independent risk factor for coronary heart disease, but more data are needed on the relative risk-predictive powers of different HDL subclasses. For epidemiologic and clinical purposes, isolation of HDL from other lipoproteins and separation of its two major subclasses, HDL2 and HDL3, are performed most conveniently by precipitation. Although storage of plasma is commonly necessary, little information is available on the long-term stability of HDL subclasses at different temperatures. Therefore, we quantified HDL-C, HDL2-C, and HDL3-C by dual precipitation with heparin-MnCl2/15-kDa dextran sulfate (H-M/DS) in samples of EDTA-plasma from 93 healthy subjects, after storage for one to 433 days at -20 degrees C, at -70 degrees C, or in liquid nitrogen (-196 degrees C). Fourteen samples (15%) were stored for a year or longer. At -20 degrees C, HDL-C decreased by 4.8% per year and HDL3-C decreased by 6.9% per year (P = 0.002 for both variables) relative to results obtained with samples stored in liquid nitrogen; total cholesterol, HDL2-C, and triglyceride did not change significantly at this temperature. When stored at -70 degrees C, none of the lipids showed any change relative to results obtained with liquid nitrogen. Thus, long-term storage of EDTA-plasma at -20 degrees C is unsuitable for subsequent quantification of HDL-C and its subclasses by H-M/DS dual precipitation. Storage at -70 degrees C is preferable, and is as reliable as storage in liquid nitrogen.

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