Ildikó Zeke - Academia.edu (original) (raw)

Papers by Ildikó Zeke

Progress in Agricultural Engineering Sciences, Feb 20, 2021

Eggs are commonly used in the food industry because of their excellent nutrient value and also fo... more Eggs 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 À18 8C. 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 8C, 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.

World Academy of Science, Engineering and Technology, International Journal of Nutrition and Food Engineering, 2020

ETP International Journal of Food Engineering, 2021

In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by... more In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by preparing lemon curd samples. Therefore, LEY frozen at-18°C was used to make lemon curd samples. LEY was stored for 90 days at -18°C and it was thawed with two different methods (in 2 hours, 35°C and in 24 hours, 5°C) on measurement days (day 1, 7, 14, 30, 60 and 90). After thawing of LEY samples, lemon curd samples were made by adding liquid egg white, butter, lemon juice and sugar. Ingredients were mixed by constant whisking over the steam of hot water. After that, butter was also added to the cream and it was cooled to 20°C. Rheological parameters of the lemon curd samples were examined with rotational rheometer. Shear stress data were recorded by increasing, than by decreasing shear rate values in the range of 10-1000 1/s. Herschel-Bulkley model was fitted to the flow curves of decreasing shear rate. Based on our measurements, we found that the thawing method of frozen liquid egg yo...

Review on Agriculture and Rural Development, 2016

Samples prepared from liquid egg yolk (LEY), liquid egg white (LEW) and liquid whole egg (LWE) we... more Samples prepared from liquid egg yolk (LEY), liquid egg white (LEW) and liquid whole egg (LWE) were processed by high hydrostatic pressure (HHP) using different holding times (60, 180, 300, 420 and 600 s). The aim of our experiment was to examine how different holding times influences technofunctional attributes of liquid egg products. The color of samples changed after 60 s HHP treatment, but visible changes were evaluated just after 180­ 300 s. The pH of samples was stable, there were no significant changes caused by HHP (one-way ANOVA, a=0,05). The apparent viscosity was measured by a rotational viscometer as a function of shear rate. The shearthinning behavior of LEY and pseudopastic behavior of LEW and LWE were fitted well into HerschelBulkley model (with a satisfying correlation of R2 > 0.96). For the selected shearing rate, viscosity was measured in relation to shearing time. Thixotropic behavior of samples was increased by longer holding time of HHP treatments.

Review on Agriculture and Rural Development, Nov 1, 2019

Quick frozen food are becoming increasingly popular among consumers in the last decades. During t... more Quick frozen food are becoming increasingly popular among consumers in the last decades. During the development of a quick frozen gluten-free pie crust dough product, the aim was to develop a dough that does not suffer any harmful changes after the freeze-thaw process. The texture is one of the most important sensorial properties, and has a great influence on consumer acceptance. Texture Analyser was used to measure the hardness and the brittleness of various doughs. A quick frozen pie crust dough should be easily cut, but non-crumbling after baking. The results showed that the hardness of a dough with 10% more rice flour was bigger than the other dough's hardness and it became harder after the freeze-thaw process, while the other dough's hardness have not changed during the process. The first dough was less brittle than the second dough, also before and after the freeze-thaw. In conclusion, the 1st dough is harder, so it is not more easy to cut than the 2nd dough. However, the first dough being less brittle allows cutting with less crumbs. Considering the expectations, in the future the first recipe should be used to make a fast-frozen pie crust dough product.

Abstract book of the 18th Alps-Adria Scientific Workshop, 2019

Eggs are used for a wide variety of purposes in the food industry. Mostly ready for use egg produ... more Eggs are used for a wide variety of purposes in the food industry. Mostly ready for use egg products are used in the technology, for example, liquid whole egg. However, this product has limited shelf life (10 11 days) and there is a market need for products with longer shelf life. In our study, we worked on the prolongation of pasteurized salted liquid whole egg’s shelf life. We used different plant extracts and allyl isothiocyanate because there is an emerging trend of using natural preservatives. Among the used plant extracts were lavender, rosemary, ginger and sage extracts. First, we determined the appropriate concentrations of plant extracts with sensory tests. We prepared solutions in 10 different concentrations of the extracts in the range of 10 10 mg/L. An expert panel identified the maximal concentration of each extract based on the samples sensory properties. After that, a 4-week long storage experiment was performed. We defined total plate count and the number of Enteroba...

Minimal processing technologies, like High Hydrostatic Pressure (HHP), heat treatments on law tem... more Minimal processing technologies, like High Hydrostatic Pressure (HHP), heat treatments on law temperatures, ultra-sonication have an increasing tendency in food industry. Eggs are considered as functional foods, but for high retention of biological active compounds adequate minimal processing technologies are needed during preservation procedure. In our study liquid egg yolk was examined to meet consumer’s expectations. Several combinations of law temperature pasteurization (57 63 C, 5 7 min.) and High Hydrostatic Pressure (350 400 MPa, 5 min.) were used to provide microbiological stability of liquid egg yolk. After treatments samples were examined for mesophyll aerobes and Enterobacteriaceae cell counts (using Nutrient agar and usual incubation of 30 C for 48 hours) and viscosity attributes. Viscosity attributes (measured with Anton Paar MCR 92) analyzed by Hershel-Bulkley models. Our results show that microbiological stability is significant influenced by the different parameters ...

Review on Agriculture and Rural Development, 2016

In food preservation technologies there are pursuits to apply minimal processing technologies whi... more In food preservation technologies there are pursuits to apply minimal processing technologies which don’t influence product quality attributes like protein structure. High hydrostatic pressure (HHP) is one of the minimal processing technologies. The effect of high hydrostatic pressure (HHP) was studied at 400 MPa 600 s on proteins of liquid egg products (egg yolk, LEY and whole egg, LWE). Thermo-physical, calorimetrical properties were examined on Micro DSC III (differential scanning calorimeter). Our result show that whole egg’s proteins are not desaturated by HHP, but 40% of egg yolk’s proteins had denaturation caused by processing. Aggregation and separation of protein groups can be observed by both products. Changes in protein structures caused texture modifications.

The aim of this work was to evaluate the effect of perforation modified atmosphere packaging on q... more The aim of this work was to evaluate the effect of perforation modified atmosphere packaging on quality of carrot slices during 12 days of storage at 5 °C. Polyethylene bags with different number of perforations (3, 4 and 6) were used in this experiment. Headspace oxygen concentration, respiration, weight loss, surface color, firmness, pH, and soluble solid content were examined throughout storage. It was observed, that all the investigated packages were equally effective in maintaining the quality of carrot slices. There was no symptom of decay till the end of the experiment. In addition, pH, soluble solid content and firmness showed only minor change. Moreover, weight loss of carrot slices was below 2 % after 12 days of storage. Thus, perforation modified atmosphere packaging (MAP) has been proved to be efficient in maintaining the quality of slice carrot.

Acta Universitatis Sapientiae, Alimentaria, 2015

There are numerous new technologies whose implementation in food industry is hampered by the fact... more There are numerous new technologies whose implementation in food industry is hampered by the fact that people hesitate to invest in expensive systems which they cannot be sure will work or at least are questionable in terms of a given product. Until recently, preservation by HHP, high hydrostatic pressure, was such a technology, and still is today in some branches of the food industry. Investigations were conducted to answer the question of whether the literature, the laboratory, and the industrial (or at least pilot plant) measurements and results agree with one another. We compared the literature data with two HHP systems which were significantly different in terms of treatment capacity, but their efficiency in killing microbes was studied under the same treatment parameters. Our results show that in nearly all cases only minimal differences exist between the data in the literature and the measurements taken on the two appliances.

Common Norwegian dairy products involving mysost were tested by oscillation technique in amplitud... more Common Norwegian dairy products involving mysost were tested by oscillation technique in amplitude sweep mode. Viscoelastic properties of dairy products were evaluated based on eight parameters defined from the rheograms.

Acta Alimentaria, 2013

The aim of the present study was to examine the infuence of hydrolyzed, nanofltered concentrate o... more The aim of the present study was to examine the infuence of hydrolyzed, nanofltered concentrate of the ultrafltered permeate (HNF concentrate) of acid whey on the quality characteristics of milk-based ice cream. Thermophysical properties were determined by differential scanning calorimeter, consistency was measured by oscillatory rheometer, and sensorial quality was evaluated by scoring method. It was concluded that the acid whey did not increase the melting of the product, and reduced the freezing point. Cryoscopic temperature, onset point, and glass transition temperature (Tg) gradually decreased as the quantity and proportion of acid whey increased in the ice-cream. Rheological results indicated that using HNF, acid whey produced more creamy and smooth ice-cream. However, because of its characteristic taste, maximum 20% of milk could be replaced by HNF acid whey in milk-based ice-creams.

Agriculture, 2021

Egg yolk undergoes an irreversible gelation process at temperatures below −6 °C, which greatly im... more 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. More...

Flow properties of a selection of common Norwegian dairy products were tested by a rheological ro... more Flow properties of a selection of common Norwegian dairy products were tested by a rheological rotational method, changing the shear rate up and down between 0.01 and 200 s -1 . Herschel-Bulkley model fitted well to the downward curve. Samples proved to be plastic as indicated by high yield stress values. A marked hysteresis loop was observed on flow curves indicating strong time-dependent behavior of all the samples tested.

Czech Journal of Food Sciences

The egg yolk undergoes an irreversible gelation process when freezing to –6 °C or lower. In this ... more 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.

Progress in Agricultural Engineering Sciences

Freezing can enhance the storage time of liquid egg products, but egg yolk undergoes an irreversi... more Freezing can enhance the storage time of liquid egg products, but egg yolk undergoes an irreversible textural and structural change when it is cooled to –6 °C. In this study, the effects of different salt concentrations on the physical properties of frozen-thawed egg yolk were investigated.The pasteurised liquid egg yolk (LEY) was treated with 4, 5, and 6% of NaCl before freezing and it was stored at –18 °C for 4 weeks. The colour, pH, and rheological characteristics (firmness, consistency, cohesiveness, and index of viscosity) of yolk samples were evaluated before and after freezing.Salt treatment resulted in preventing gelation, with decreasing firmness, consistency and viscosity compared to control samples. The pH of all yolk samples increased during frozen storage. The lightness value decreased in treated samples and increased in the control sample after freezing.The results indicated that the applied salt concentrations could inhibit protein aggregation of LEY induced by freezi...

Progress in Agricultural Engineering Sciences, Feb 20, 2021

Eggs are commonly used in the food industry because of their excellent nutrient value and also fo... more Eggs 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 À18 8C. 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 8C, 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.

World Academy of Science, Engineering and Technology, International Journal of Nutrition and Food Engineering, 2020

ETP International Journal of Food Engineering, 2021

In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by... more In this study, we examined the industrial usability of frozen and thawed liquid egg yolk (LEY) by preparing lemon curd samples. Therefore, LEY frozen at-18°C was used to make lemon curd samples. LEY was stored for 90 days at -18°C and it was thawed with two different methods (in 2 hours, 35°C and in 24 hours, 5°C) on measurement days (day 1, 7, 14, 30, 60 and 90). After thawing of LEY samples, lemon curd samples were made by adding liquid egg white, butter, lemon juice and sugar. Ingredients were mixed by constant whisking over the steam of hot water. After that, butter was also added to the cream and it was cooled to 20°C. Rheological parameters of the lemon curd samples were examined with rotational rheometer. Shear stress data were recorded by increasing, than by decreasing shear rate values in the range of 10-1000 1/s. Herschel-Bulkley model was fitted to the flow curves of decreasing shear rate. Based on our measurements, we found that the thawing method of frozen liquid egg yo...

Review on Agriculture and Rural Development, 2016

Samples prepared from liquid egg yolk (LEY), liquid egg white (LEW) and liquid whole egg (LWE) we... more Samples prepared from liquid egg yolk (LEY), liquid egg white (LEW) and liquid whole egg (LWE) were processed by high hydrostatic pressure (HHP) using different holding times (60, 180, 300, 420 and 600 s). The aim of our experiment was to examine how different holding times influences technofunctional attributes of liquid egg products. The color of samples changed after 60 s HHP treatment, but visible changes were evaluated just after 180­ 300 s. The pH of samples was stable, there were no significant changes caused by HHP (one-way ANOVA, a=0,05). The apparent viscosity was measured by a rotational viscometer as a function of shear rate. The shearthinning behavior of LEY and pseudopastic behavior of LEW and LWE were fitted well into HerschelBulkley model (with a satisfying correlation of R2 > 0.96). For the selected shearing rate, viscosity was measured in relation to shearing time. Thixotropic behavior of samples was increased by longer holding time of HHP treatments.

Review on Agriculture and Rural Development, Nov 1, 2019

Quick frozen food are becoming increasingly popular among consumers in the last decades. During t... more Quick frozen food are becoming increasingly popular among consumers in the last decades. During the development of a quick frozen gluten-free pie crust dough product, the aim was to develop a dough that does not suffer any harmful changes after the freeze-thaw process. The texture is one of the most important sensorial properties, and has a great influence on consumer acceptance. Texture Analyser was used to measure the hardness and the brittleness of various doughs. A quick frozen pie crust dough should be easily cut, but non-crumbling after baking. The results showed that the hardness of a dough with 10% more rice flour was bigger than the other dough's hardness and it became harder after the freeze-thaw process, while the other dough's hardness have not changed during the process. The first dough was less brittle than the second dough, also before and after the freeze-thaw. In conclusion, the 1st dough is harder, so it is not more easy to cut than the 2nd dough. However, the first dough being less brittle allows cutting with less crumbs. Considering the expectations, in the future the first recipe should be used to make a fast-frozen pie crust dough product.

Abstract book of the 18th Alps-Adria Scientific Workshop, 2019

Eggs are used for a wide variety of purposes in the food industry. Mostly ready for use egg produ... more Eggs are used for a wide variety of purposes in the food industry. Mostly ready for use egg products are used in the technology, for example, liquid whole egg. However, this product has limited shelf life (10 11 days) and there is a market need for products with longer shelf life. In our study, we worked on the prolongation of pasteurized salted liquid whole egg’s shelf life. We used different plant extracts and allyl isothiocyanate because there is an emerging trend of using natural preservatives. Among the used plant extracts were lavender, rosemary, ginger and sage extracts. First, we determined the appropriate concentrations of plant extracts with sensory tests. We prepared solutions in 10 different concentrations of the extracts in the range of 10 10 mg/L. An expert panel identified the maximal concentration of each extract based on the samples sensory properties. After that, a 4-week long storage experiment was performed. We defined total plate count and the number of Enteroba...

Minimal processing technologies, like High Hydrostatic Pressure (HHP), heat treatments on law tem... more Minimal processing technologies, like High Hydrostatic Pressure (HHP), heat treatments on law temperatures, ultra-sonication have an increasing tendency in food industry. Eggs are considered as functional foods, but for high retention of biological active compounds adequate minimal processing technologies are needed during preservation procedure. In our study liquid egg yolk was examined to meet consumer’s expectations. Several combinations of law temperature pasteurization (57 63 C, 5 7 min.) and High Hydrostatic Pressure (350 400 MPa, 5 min.) were used to provide microbiological stability of liquid egg yolk. After treatments samples were examined for mesophyll aerobes and Enterobacteriaceae cell counts (using Nutrient agar and usual incubation of 30 C for 48 hours) and viscosity attributes. Viscosity attributes (measured with Anton Paar MCR 92) analyzed by Hershel-Bulkley models. Our results show that microbiological stability is significant influenced by the different parameters ...

Review on Agriculture and Rural Development, 2016

In food preservation technologies there are pursuits to apply minimal processing technologies whi... more In food preservation technologies there are pursuits to apply minimal processing technologies which don’t influence product quality attributes like protein structure. High hydrostatic pressure (HHP) is one of the minimal processing technologies. The effect of high hydrostatic pressure (HHP) was studied at 400 MPa 600 s on proteins of liquid egg products (egg yolk, LEY and whole egg, LWE). Thermo-physical, calorimetrical properties were examined on Micro DSC III (differential scanning calorimeter). Our result show that whole egg’s proteins are not desaturated by HHP, but 40% of egg yolk’s proteins had denaturation caused by processing. Aggregation and separation of protein groups can be observed by both products. Changes in protein structures caused texture modifications.

The aim of this work was to evaluate the effect of perforation modified atmosphere packaging on q... more The aim of this work was to evaluate the effect of perforation modified atmosphere packaging on quality of carrot slices during 12 days of storage at 5 °C. Polyethylene bags with different number of perforations (3, 4 and 6) were used in this experiment. Headspace oxygen concentration, respiration, weight loss, surface color, firmness, pH, and soluble solid content were examined throughout storage. It was observed, that all the investigated packages were equally effective in maintaining the quality of carrot slices. There was no symptom of decay till the end of the experiment. In addition, pH, soluble solid content and firmness showed only minor change. Moreover, weight loss of carrot slices was below 2 % after 12 days of storage. Thus, perforation modified atmosphere packaging (MAP) has been proved to be efficient in maintaining the quality of slice carrot.

Acta Universitatis Sapientiae, Alimentaria, 2015

There are numerous new technologies whose implementation in food industry is hampered by the fact... more There are numerous new technologies whose implementation in food industry is hampered by the fact that people hesitate to invest in expensive systems which they cannot be sure will work or at least are questionable in terms of a given product. Until recently, preservation by HHP, high hydrostatic pressure, was such a technology, and still is today in some branches of the food industry. Investigations were conducted to answer the question of whether the literature, the laboratory, and the industrial (or at least pilot plant) measurements and results agree with one another. We compared the literature data with two HHP systems which were significantly different in terms of treatment capacity, but their efficiency in killing microbes was studied under the same treatment parameters. Our results show that in nearly all cases only minimal differences exist between the data in the literature and the measurements taken on the two appliances.

Common Norwegian dairy products involving mysost were tested by oscillation technique in amplitud... more Common Norwegian dairy products involving mysost were tested by oscillation technique in amplitude sweep mode. Viscoelastic properties of dairy products were evaluated based on eight parameters defined from the rheograms.

Acta Alimentaria, 2013

The aim of the present study was to examine the infuence of hydrolyzed, nanofltered concentrate o... more The aim of the present study was to examine the infuence of hydrolyzed, nanofltered concentrate of the ultrafltered permeate (HNF concentrate) of acid whey on the quality characteristics of milk-based ice cream. Thermophysical properties were determined by differential scanning calorimeter, consistency was measured by oscillatory rheometer, and sensorial quality was evaluated by scoring method. It was concluded that the acid whey did not increase the melting of the product, and reduced the freezing point. Cryoscopic temperature, onset point, and glass transition temperature (Tg) gradually decreased as the quantity and proportion of acid whey increased in the ice-cream. Rheological results indicated that using HNF, acid whey produced more creamy and smooth ice-cream. However, because of its characteristic taste, maximum 20% of milk could be replaced by HNF acid whey in milk-based ice-creams.

Agriculture, 2021

Egg yolk undergoes an irreversible gelation process at temperatures below −6 °C, which greatly im... more 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. More...

Flow properties of a selection of common Norwegian dairy products were tested by a rheological ro... more Flow properties of a selection of common Norwegian dairy products were tested by a rheological rotational method, changing the shear rate up and down between 0.01 and 200 s -1 . Herschel-Bulkley model fitted well to the downward curve. Samples proved to be plastic as indicated by high yield stress values. A marked hysteresis loop was observed on flow curves indicating strong time-dependent behavior of all the samples tested.

Czech Journal of Food Sciences

The egg yolk undergoes an irreversible gelation process when freezing to –6 °C or lower. In this ... more 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.

Progress in Agricultural Engineering Sciences

Freezing can enhance the storage time of liquid egg products, but egg yolk undergoes an irreversi... more Freezing can enhance the storage time of liquid egg products, but egg yolk undergoes an irreversible textural and structural change when it is cooled to –6 °C. In this study, the effects of different salt concentrations on the physical properties of frozen-thawed egg yolk were investigated.The pasteurised liquid egg yolk (LEY) was treated with 4, 5, and 6% of NaCl before freezing and it was stored at –18 °C for 4 weeks. The colour, pH, and rheological characteristics (firmness, consistency, cohesiveness, and index of viscosity) of yolk samples were evaluated before and after freezing.Salt treatment resulted in preventing gelation, with decreasing firmness, consistency and viscosity compared to control samples. The pH of all yolk samples increased during frozen storage. The lightness value decreased in treated samples and increased in the control sample after freezing.The results indicated that the applied salt concentrations could inhibit protein aggregation of LEY induced by freezi...