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The effect of high pressure processing (300 and 600 MPa) combined with mild heat treatment (55 and 75 °C) on the colour parameters, anthocyanin content, and sensory characteristics of strawberry puree were examined after the treatments and 2 weeks of cold storage at 2 and 15 °C. As on an industrial scale the simultaneous implementation of these treatments remains a challenge, the HHP and heat treatments were carried out consecutively in different sequences. The colour parameters and the anthocyanin content did not change significantly due to the treatments, but decreased during cold storage, at 15 °C storage the changes were more intensive than at 2 °C. Regarding the sensory test results, the different sequence of the 600 MPa-75 °C combined treatments is not detectable even after 2 weeks of storage at 15 °C, but in case of 300 MPa-55 °C, the enzyme inactivation is probably not sufficient enough as differences between the samples were detected.
Bovine blood samples were treated with high hydrostatic pressure (HHP) to examine the changes that may occur in the blood related to its colour, microbiological characteristics, protein denaturation, and dynamic viscosity. Pressure treatments were carried out from 100 to 600 MPa in 100 MPa scale up, with 5 min holding time. The blood samples were treated with anticoagulant (EDTA) to eliminate the possible measurement distorting effects. We found that 2 log reduction in the microbial load could be achieved with a pressure treatment above 400 MPa. According to the protein denaturation measurements (DSC), blood proteins were resistant to pressure treatment, even at 300–400 MPa a substantial part of proteins remained in native state. The colour of the samples got darker with the rising pressure, however, visible colour change was observed only above 400 MPa. It can be established, that the HHP treatment was suitable to increase the microbiological stability of blood, without significantly changing its techno-functional properties.
Animal blood is a by-product, which can be utilized in a value-adding way instead of being wasted. Allergen substitution is a good possibility especially for a substance that is difficult to substitute, such as milk. Blood plasma is a fluid with high protein content without blood (iron) taste and colour, so it is similar to milk in several ways. While investigating the substitution of milk, it is advisable to investigate the substitution of sugar as well because a lot of consumers who exclude milk from their diet find the glycaemic index and energy content of foods important. The investigated model food is a simple, homogeneous matrix: vanilla custard with milk and with and without sugar and vanilla custard with blood plasma and with and without sugar. Colour, pH and rheological attributes of custard sample groups were measured. According to the results the used protein source as well as sweetener significantly determine the colour, pH and texture of the final product. However, colour and pH are easy to change with other components (food colours, acidity regulators) and the effect of milk and sugar substitution on rheological attributes might not be possible to detect without instrumental analysis.
Animal blood is a by-product, which can be utilized in a value-adding way instead of being wasted. Allergen substitution is an obvious possibility because many properties of blood plasma are similar to egg white. Techno-functional and sensory attributes (water activity, moisture content, colour and texture related properties) were measured by instrumental methods. The allergenic egg powder can be substituted by non-allergenic blood plasma powder in sponge cakes, but the change in the ingredient has an effect on hardness and tolerating compressive stress until the breaking. In the case of water activity and moisture content, sponge cakes with blood plasma were as desirable as sponge cakes with egg.