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.

Effect of cryogenic freezing on the rheological and calorimetric properties of pasteurized liquid egg yolk | Karina Hidas, Csaba Németh, Lien Le Phuong Nguyen, Anna Visy, Adrienn Tóth, Annamária Barkó, László Friedrich, Attila Nagy, Ildikó Csilla Nyulas-Zeke | Agricultural Journals

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.

Currently, there is a growing demand for ready-to-eat, prepared, high-quality, preservative-free products. However, the shelf-life of these products is often so short that a relatively high percentage of these products cannot be sold and end up as food waste. In this study, pork loin with different marinades (paprika and herbs) was treated with different high hydrostatic pressures (0 MPa, 300 MPa, 450 MPa and 600 MPa) and a bioactive component (piperine) and then the quality of the meat was examined after 0, 4, 8, 12 and 14 days of cold storage. Changes were monitored using color, pH, texture and microbiological analyses. Both pressure, piperine enrichment, storage time and the interactions of different factors had a significant effect on the quality of the loin samples with different marinades. Due to the denaturation of myoglobin, meat slices were less red and lighter after HHP treatment. The addition of piperine reduced this lightness. The pH increased with increasing pressure and decreased with storage time. HHP treatment significantly increased meat hardness, with samples treated at 600 MPa being 19% harder than those treated at 450 MPa. Microbiological results indicated that HHP at 450 MPa and 600 MPa effectively reduced anaerobic total live plate counts, ensuring satisfactory sensory and microbiological quality throughout storage. Piperine fortification also resulted in a more favorable microbiological status during storage without any perceptible change in quality properties during storage. These findings underscore the effectiveness of HHP and piperine enrichment in enhancing the safety and quality of marinated meats.

The aim of this study was to investigate the utilization of buttermilk, a by-product of butter production, in ice cream. Butterfly pea flower, which provides natural coloring and antioxidant properties, was added to buttermilk for investigating its improving effect on the techno-functional and sensory attributes of ice cream. Ice cream mixes were prepared with varying buttermilk concentrations (0%, 20%, 40%, 60%, 80%, 100%) as the first factor of the research. In addition, the effect of fermentation was also investigated as the second factor of the experiment. The ingredients included buttermilk, milk, cream, sucrose, dextrose, locust bean gum, butterfly pea flowers, and vanilla extract. The preparation involved the extraction of the butterfly flowers, fermentation in case of the fermented samples, homogenization, pasteurization, freezing, and hardening. Quality attributes such as dry matter content, pH, color, rheological properties of the ice cream mixes, overrun, melting properties, and ice cream hardness were analyzed to determine the maximal substitution level of milk by buttermilk without compromising ice cream quality. Our results explore the impact of buttermilk content and fermentation on the techno-functional properties of ice cream. As buttermilk concentration increased, dry matter content decreased, ranging from 34.4 g/100 g at 0% buttermilk to 31.9 g/100 g at 100% buttermilk. pH levels were lower in the fermented samples, decreasing from 6.5 in the non-fermented to 4.6 in the fermented samples. L* decreased with higher buttermilk content, while a* and b* values increased slightly. The butterfly pea flower provided a blue hue across all samples; the blue hue increased by 20% with a higher buttermilk content. Increasing the buttermilk concentration led to a 40% decrease in the yield stress and consistency coefficient, indicating a less viscous mix. The flow behavior index slightly increased, suggesting a more Newtonian-like flow at higher buttermilk levels. Overrun decreased with a higher buttermilk content, from 45% at 0% buttermilk to 30% at 100% buttermilk, indicating reduced air incorporation. The meltdown rate increased with a higher buttermilk content, meaning the ice cream melted more rapidly. The hardness of the ice cream decreased as buttermilk concentration increased, from 15 N at 0% buttermilk to 10 N at 100% buttermilk. The fermented sample groups were on average 44% harder than the non-fermented sample groups. The findings suggest that up to 100% of buttermilk can effectively replace milk in ice cream formulations without compromising quality, providing a sustainable and health-beneficial use for this dairy by-product.

The consumption of wild red deer (Cervus elaphus) meat is growing due to its nutritional benefits and sustainability. However, challenges like a shorter shelf life and increased microbial load of game meat highlight the need to investigate effective preservation techniques. This study investigated the effects of high hydrostatic pressure (HHP) on the quality parameters of wild red deer meat, including pH, color characteristics, microbial load, texture attributes, and protein stability, assessed on different days. Wild red deer meat was treated with pressures ranging from 150 to 600 MPa, followed by storage at 4 °C for up to 14 days. Results showed that HHP at or above 300 MPa stabilized pH and suppressed microbial growth. On Day 1, the control samples had a microbial count of 4.67 log CFU/g, while treatments at or above 500 MPa reduced microbial levels to below 1 log CFU/g. Texture analysis revealed improved tenderness at lower pressures (150–300 MPa) and enhanced firmness at higher pressures. Color parameters, including lightness and redness, were also influenced by HHP, as lightness increased with pressure, while redness decreased at higher pressure levels. SDS-PAGE analysis indicated protein denaturation, especially at ≥300 MPa, with significant degradation of sarcoplasmic and myofibrillar proteins at ≥500 MPa. These findings suggest that HHP can be an effective method for improving certain quality parameters and extending the shelf life of wild red deer meat up to 14 days of storage, depending on the pressure level applied.