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.
Blood coagulation is a process, which is initiated by certain physico-chemical effects. This process results in a change in the blood from the sol state, that is well suited for further processing, to gel state. 13 blood clotting factors take part in the cascade system of blood coagulation. Trisodium-citrate affects factor IV, the calcium, and prevents the change in blood texture. The effect of different concentrations of trisodium-citrate (0, 0.48, 2.4, 4.8, 9.6, 14.4, 19.2, 24 w/w%) on the texture of blood is investigated. Porcine blood was collected in 20 cm3 test tubes in a slaughterhouse directly before trisodium-citrate addition and was stored for one day under refrigerated conditions. The samples without trisodium-citrate coagulated and the samples with high trisodium-citrate (4–5 g) became solid as well because of the protein salting-out. The viscosity of successfully treated samples and the shear stress were measured with a rotational viscometer (Physica MCR 51, Anton-Paar) with concentric cylinders and Couette type method. The flow behavior of all samples could be described by the Herschel-Bulkley model. The yield point, the consistency index and the power of law index, which are determined by the equation of the model, showed that the samples with lower trisodium-citrate content coagulated “better” and the sample with high trisodium-citrate were most similar to Newtonian fluid. The results are trend-likes, but significant differences may be expected in the case of higher sample amount. The yield point of the sample, which contained 14.4 w/w% trisodium-citrate, was by 37.3% less than the sample containing 0.48% trisodium-citrate, and the consistency index of the sample with 3 g trisodium-citrate was by 20.5% higher than that of the sample with 0.48% trisodium-citrate. Thanks to these results a cheaper concentration and drying of porcine blood and blood fractions are available because no surplus water is added to the blood.