Study On The Properties Of Plasma-Soybean Oil Concentrated Emulsions And Application In Emulsified Sausages

Fat substitutes are important additives in food processing. Recently, concentrated emulsions made from oil, protein and water have been researched extensively as fat substitute in meat processing. With good physical stability, water holding capacity and solubility, concentrated emulsions have been used in frankfurt and fermented sausage in order to reduce the fat content and improve fatty acid profile. Concentrated emulsions stabilized with soy protein isolate, sodium caseinate and whey protein isolate have been studied a lot, while concentrated emulsions stabilized with plasma protein have not been reported.In this study, firstly, the optimal parameters for separation and spray drying process of chicken plasma protein were investigated in order to provide some fundamental data for the industrial production of chicken plasma protein. Secondly, emulsions containing different fraction of oil and protein were analyzed in order to provide guide for the development of new fat substitutes. Finally, concentrated emulsions made from oil, chicken plasma protein and water were used as pork backfat replacers in low-fat emulsified sausages. Composition and technological properties were analyzed. The contents and results were as follows:1. Optimization of spray drying technology in processing chicken plasma proteinFirst, the effects of centrifugal speed and time on the separation process were studied. Second, different inlet air temperatures and feeding rates on the physicochemical properties of chicken plasma protein powder were determined, including yield, moisture content, protein content, nitrogen solution index(NSI) and the color. Results indicated that the plasma yield, plasma protein concentration, hemoglobin concentration were 55.20%,48.89 mg/mL and 2.39 mg/mL under the optimal centrifugal operation parameters of 986 × g for 15 min. The yield, moisture content, protein content and NSI of chicken plasma protein powder were respectively 64.29%,4.51%,72.64% and 97.30% under the optimal processing parameters of the airflow pressure 0.3 MPa, introduction temperature 25℃, inlet air temperature 150℃ and feeding rate 0.167 mL/s. The results are expected to provide some fundamental data for the industrial production of chicken plasma protein.2. Study on the properties of plasma protein concentrated emulsionsConcentrated emulsions were made from chicken plasma protein, water and soybean oil. Emulsions with different oil mass fraction(38.00%、42.75%、47.50%、52.25%、57.00%) and protein concentrations (3%、4%、5%、6%、7%) were charactered by emulsion stability, viscosity, rheological property and Water Holding Capicity(WHC). Results indicated that emulsion stability, viscosity, storage modulus and WHC became higher with the increase of oil or protein content in the emulsion. The emulsion present smooth cream, good storage stability of 48h at 4℃, WHC of 77.42% at the ratio of 1.00:7.05:8.62 (chicken plasma protein:water:soybean oil) and is suitable as fat replacers.3. Concentrated emulsion stabilized with plasma protein as pork backfat substitute in low-fat emulsified sausagesConcentrated emulsions stabilized with chicken plasma protein were used as pork backfat replacers in low-fat emulsified sausages. Composition (proximate analysis and fatty acid profile) and technological properties (processing loss,WHC, colour and texture) were analyzed as affected by the percentage of fat replacer(25%,50%,75%,100%).Results indicated that moisture, protein, ash content of emulsified sausages became larger and fat content became smaller with the increase of replacing level. Compared to control sample, sausages produced with emulsions had lower levels of saturated fatty acids (SFA), monounsaturated fatty acid (MUFA) and higher levels of polyunsaturated fatty acid (PUFA) Also, sausages produced with emulsions had higher cooking loss, lower WHC and higher L*, a*, b* values. Sausages with the fat replacing level of 25%,50% and 75% had higher hardness, springiness, chewiness, resilience and lower adhesiveness. Emulsified sausages had unpleased flavor when all pork backfat was replaced by the emulsions and it was not accepted by customers. The suggested percentage of fat substitution was 75%.