Adrienn Varga-Tóth

In this investigation, the antioxidant capacity of stirred-type hypoallergenic and lactose-free yogurt was improved using cylindra-type beetroot peel extract. Milk proteins were hydrolyzed with papain at different concentrations (0.008 g·L⁻¹ and 0.012 g·L⁻¹) and, subsequently, milk with papain-hydrolyzed proteins were fermented with yogurt starter culture with or without lactase. Antioxidants and betalains were extracted from beetroot peel using microwave heating-assisted water extraction. Extraction was performed considering different amounts of beetroot peel (10 g·L⁻¹, 30 g·L⁻¹ and 50 g·L⁻¹) and temperature-exposed times (1 min, 3 min, and 5 min) at 450 W power. The extract with highest antioxidant capacity was incorporated into papain-treated and starter culture-fermented yogurt at different amounts (10-, 20-, 30-, and 40-volume%). Papain hydrolysis of milk proteins followed by starter culture fermentation of milk significantly reduced the allergenicity of yogurt (>90% with 0.012 g·L⁻¹ of papain and lactase) than control. Addition of 30% beetroot peel extract after post-fermentation stage significantly enhanced the red colour intensity of yogurt. The antioxidant capacity of yogurts produced by hydrolysed milk proteins by 0.012 g·L⁻¹ of papain and starter culture fermentation with lactase was improved approx. 3.5-fold than control due to the addition of 40% beetroot peel extract after fermentation.

Freeze–thaw cycles lead to undesirable gelation in egg yolk, which negatively affects its functional properties, restricting its application in the food industry. This study aimed to investigate whether enzymatic treatment can prevent the freeze-induced gelation of egg yolk, thereby maintaining its desirable quality attributes. Egg yolk samples were treated with an enzyme preparation (Biocatalysts Flavorpro™ 750MDP) at concentrations of 0.05, 0.3, and 0.5 w/w%, homogenized, and incubated at 40 °C for 120 min, followed by rapid cooling and freezing at −24 ± 1 °C for 60 d. Control samples without enzyme treatment were subjected to the same processing steps as the other samples. After thawing, all samples were analyzed for pH, color, rheological and thermophysical properties, turbidity and visual appearance. The results demonstrated that although enzymatic treatment and its combination with freezing significantly altered color, turbidity, rheological and thermophysical properties of egg yolk, it effectively inhibited freezing-induced gel formation, particularly at 0.3 w/w%. The parameters characterizing rheological behavior—yield stress, consistency coefficient, and flow behavior index—were preserved close to those of fresh yolk after the freeze–thaw process. These findings suggest that exopeptidase treatment is a promising approach for controlling freeze–thaw-induced gelation in egg yolk, supporting its wider use in frozen and processed egg products.

In the present study, egg white suspensions (12 w/v%) were HHP-treated at 300, 400, 450, 500, 550 and 600 MPa for 5 min. The effects of HHP treatment on the colour, rheological properties, microbiological status and digestibility of the samples was investigated. Colorimetric analysis revealed increased lightness (L*) and yellowness (b*), with decreased redness (a*), indicating enhanced visual appeal. The rheological evaluation at 500 MPa and above showed a transition from dilatant to pseudoplastic behaviour, which is favourable for food processing due to improved flow under shear stress. SDS-PAGE and in vitro digestion confirmed extensive protein denaturation and enhanced digestibility—especially the complete hydrolysis of ovotransferrin—potentially reducing allergenicity and increasing nutrient bioavailability. Microbiologically, treatments at 500–600 MPa significantly reduced mesophilic aerobic bacteria and extended shelf-life, maintaining safety over 44 days. Overall, HHP-treated egg white demonstrates promising potential as a functional ingredient in safe, nutritious, and technologically adaptable food products.

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.

In this study, the effects of crust formation were investigated on the quality properties of pork meat, including texture, colour, cooking loss, pH, water-holding capacity (WHC), and sensory attributes. Two cuts of pork, (1) tenderloin (lean) and (2) collar (fatty), were subjected to three treatments as follows: (1) crusting before cooking, (2) crusting after cooking, and (3) cooking without crusting. Texture was analyzed measuring hardness, cohesiveness, springiness, and chewiness. Colour was analyzed measuring lightness, redness–greenness, yellowness–blueness, and hue angle. Cooking loss and pH and WHC were measured using standard methods and a pressing test. Results showed that meat type and treatment significantly impacted texture, with tenderloin exhibiting greater hardness and chewiness than collar (p = 0.05). Crusting after cooking produced the highest values for hardness and chewiness, while cohesiveness and springiness were unaffected by treatment (p = 0.05). Colour measurements revealed significant treatment-induced differences, with samples crusted after cooking being darker and redder, on average 14% and 33%, respectively. Cooking loss varied considerably, with no significant treatment differences, although a trend suggested lower loss in samples crusted before cooking. pH values were slightly higher in crusted samples, while WHC was notably higher for samples crusted after cooking, likely due to oil retention.

In this present study, bovine blood plasma suspensions (12 w/v%) were HHP-treated at 300, 400, 450, 500, 550 and 600 MPa for 5 min. The effect of HHP treatment on the color, rheological properties and digestibility of the samples was investigated. The changes in proteins due to HHP treatment were monitored using SDS-PAGE. Furthermore, the HHP-treated samples were subjected to a 44-day storage experiment and the development of mesophilic aerobic bacterial counts was investigated. Even the application of 300 MPa of pressure induced a significant change in the color of the samples. With the application of a pressure of 300–550 MPa, dilatational rheological behavior was observed, while at 600 MPa, the sample was characterized by pseudoplastic flow properties. The SDS-PAGE study found that there was no significant effect of HHP treatment on the protein fractions in plasma. The application of 450 MPa of pressure improved the digestibility of the plasma suspension. Blood plasma produced in this way has better nutritional value in accordance with consumer needs. The study of mesophilic aerobic bacteria count found that HHP treatments at 550 and 600 MPa improved the shelf life of the samples by 30 days. Additionally, the observed microbial stability improvements suggest that HHP-treated blood plasma could be a viable alternative for extending shelf life in processed food applications, reducing the need for synthetic preservatives. These results suggest that HHP treatment can enhance the functional properties of blood plasma suspensions, enabling their use in food formulations such as protein supplements, emulsifiers and texturizing agents. This approach aligns with the industry’s need for sustainable protein sources and clean-label ingredients.

This study aimed to evaluate the impact of increasing total protein content on the rheological properties of liquid whole eggs. The study fills the gap between fundamental science and industrial application by exploring the potential for developing high-protein, functional egg products for health-conscious consumers and the food industry. Liquid whole egg samples were enriched with different percentages of egg white and whey proteins. Proteins were added either before or after heat treatment, followed by homogenization, to analyze the effects on rheological behavior. Results indicated that whey protein samples exhibit near-Newtonian behavior due to their high solubility and minimal protein interactions, while egg white protein samples, especially at higher concentrations, induce shear thinning behavior and increased viscosity due to their water-binding capacity and partial heat-induced denaturation. Flow behavior index (n) decreased by 62.7 ± 5.7% and 25.2 ± 1.8% for heat treated with 10% added egg white and whey protein samples, respectively; meanwhile, it decreased by 2.64 ± 0.06% for 10% of added egg white protein and increased by 12.0 ± 1.0% for 10% of whey protein when heat treatment was induced prior to protein additions. The findings from this study offer valuable insights for developing functional food enriched with whey and egg white proteins.

Liquid egg products are globally recognized and increasingly used in large-scale industries due to their microbiological stability and ease of handling. A 100 g of liquid whole egg contains 76.15 g of water, 9.5 g of fat, and 12.56 g of protein. Egg proteins are high quality proteins, characterized by an amino acid score of 100 and the highest net protein utilization rate among dietary proteins. Many studies have examined the characteristics and health benefits of egg white proteins, revealing that their consumption can promote muscle mass and strength, reduce visceral fat, and lower blood cholesterol levels. Given these health advantages, this study aimed to enhance the nutritional value of liquid whole egg by fortifying it with powdered egg white protein. The impact of this addition was assessed through the evaluation of the rheological properties of liquid whole egg. Powdered egg white protein was added in varying concentrations (3%, 5%, and 10%) to 200 g of raw, homogenized liquid whole egg. The mixtures were then subjected to heat treatment at 65 °C for 15 minutes in a water bath and subsequently stored at 4 °C for 21 days. Rheological measurements, specifically viscosity, were performed on days 1, 7, 14, and 21 using an MCR 92 rheometer at 15 °C. The results demonstrated that viscosity was influenced by both the concentration of egg white protein and the duration of storage, exhibiting notable changes throughout the experimental period.

Game meat could be considered a good alternative for red meat for human consumption. Meat sourced from wild animals raised under natural environment become increasingly popular with consumers in recent years. This study aimed to assess the effect of high hydrostatic pressure (HHP) on the textural properties of cooked wild red deer (Cervus elaphus) meat. Samples of raw deer meat were treated with different pressures ranging from 150 to 600 MPa for 5 min and stored at 4°C. The samples were cooked on day 1 and 7, and after cooking drip loss and the textural properties were measured. The textural properties were determined using Texture Profile Analysis (TPA) and the Warner–Bratzler (WB) methods. The decision to measure cooked samples is based on the fact that the product will be consumed by the consumers in a cooked form. The results of this study showed that the significant changes in texture attributes, including hardness, springiness, cohesiveness, chewiness, and shear force, in response to HHP treatment and storage duration. These results provide valuable information about the influence of HHP on the textural quality of cooked wild red deer meat, informing food processing practices aimed at increasing consumer satisfaction and product acceptability.

This study investigated the effect of a 2% lactic acid and 2% ascorbic acid mixture, applied via a spray method, on the quality of wild red deer (Cervus elaphus) meat stored under vacuum packaging at 4 ± 1 °C for 21 days. A total of 48 semimembranosus muscle steaks were used, divided into two groups: 24 treated with the acid mixture and 24 non-treated controls. Key parameters, including the pH, instrumental color, bacterial counts, texture profile analysis, and protein degradation (sarcoplasmic and myofibrillar proteins) using sodium dodecyl-sulfate polyacrylamide gel electrophoresis, were assessed on different days. Treated samples exhibited significantly lower aerobic plate counts (p < 0.05) compared to controls. No significant differences in pH were found between the groups, except on day one (p < 0.05). Over time, texture analysis revealed a significant reduction in hardness, cohesiveness, and chewiness in both groups, with treated samples showing greater tenderness. Importantly, the lactic acid and ascorbic acid treatment did not adversely affect the color attributes of the meat. This method shows potential for improving the microbiological safety of venison without compromising its quality, making it a promising preservation technique for the meat industry.