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

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

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

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

Development of a Novel Gluten-Free Egg Pie Product: Effects of Sensory Attributes and Storage

In the last few decades, convenience has become one of the most important factors for consumers. Therefore, food products that take a short time to prepare are gaining in popularity. The aim of this study was to develop a gluten-free egg-pie product which is quick-frozen in pre-baked form and remains usable for a long time. Besides, it satisfies various consumer needs while remaining sustainable by not having a great impact on the environment. A dough containing rice, millet, and buckwheat flour was developed. The fillings also appeared in unflavored and flavored form (spinach onion, cheese) with and without increased egg white content. Acceptance of the product was measured by sensory test. Texture and dry matter content measurement, triangular test, and color measurement were performed to track changes through six months of frozen storage. The stored pies’ hardness declined for three months, then doubled the original value at the end of the frozen storage. The stored pies hardness declined for three months (from 10.76 ± 1.78 and 11.22 ± 1.47 N to 8.52 ± 1.74 and 9.91 ± 1.16 N), then doubled the original value at the end of the frozen storage (21.69 ± 2.55 and 19.62 ± 1.67 N). The dry matter content showed increasing tendency. Results of the triangular tests showed that the stored flavored pies were less distinguishable from freshly baked ones than the unflavored egg-pies. Color measurement showed that the fillings of the pies were darkening during the frozen storage. Consumer liking test showed values between 6.52 ± 1.76 and 7.56 ± 1.2 on a 9-point hedonic scale. Color measurement showed that the fillings of the pies were darkening during the frozen storage, and the lightness values decreased from 90.17 ± 0.06 and 90.53 ± 0.11 to 81.43 ± 0.41 and 83.22 ± 0.87 in six months. Results generated in this study suggest that consumers’ acceptance was high, though results of penalty analysis showed that more flavorings would increase the overall acceptability