| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 107 === Nitrite salt has been used as a curing agent mainly to contribute cured color and flavor, maintain microbial quality and to prevent lipid oxidation in cured meat products. Thus, nitrite plays an important role in meat curing, and artificially synthesized sodium nitrite has the most utilization rate. However, in recent years, consumers have healthy concerns, and also induce stronger negative response to chemical or artificial additives. Hence, finding a suitable nitrite substitute as natural curing agent is very potential and important research topic. White amaranth (Amaranthus mangostanus cv.) is common leaf vegetable in Taiwan. It can be cultivated throughout the year and the price is cheap. In addition, there are many studies evidenced that white amaranth is rich in nitrate. Therefore, the purposes of this study was to investigate (1) the nitrate contents of white amaranth extract (WAE) treated by ultrasonic extraction with different solvents (RO water and 50% ethanol) and temperatures (20 and 30℃), (2) the optimal nitrate reduction time of WAE inoculated at 37℃ with Staphylococcus carnosus ATCC 51365 as a starter culture, and (3) the effect of adding different levels of pre-converted WAE as a natural curing agent on the quality of frankfurter sausages during refrigerated at 4℃.
In experiment 1, WAE had the significantly highest nitrate content by ultrasonic extraction with RO water at 20℃ for 60min. In experiment 2, the nitrite content of WAE was increased up the highest point at 48 hr then decreased with incubation time. In experiment 3, a total of 4 treatments was designed in this study and as the following: 150 ppm sodium nitrite (control), 1% pre-converted WAE (T1), 3% pre-converted WAE (T2), and 5% pre-converted WAE (T3). No significant differences were found in analyses of proximate composition, cooking yield, pH values, hardness and gel strength among all treatments during storage. In change of color and chemical, a* values, nitrosohemochrome and residual nitrite content of control maintained significantly higher than all treatments during storage. In addition, among treatments T2 and T3 had the most similar a* values and nitrosohemochrome content to those of control but significantly higher than those of T1. Although TBARS values of all samples were increased with storage time but both T3 and control hold significantly lower than T1 and T2. In total plate count, all treatments kept lower value than that of control during storage. Moreover, the color in sensory of control exhibited the highest value but the lowest value was found in T1. However, the flavor, texture and overall acceptability of T2 and T3 were similar to those of the control and also higher than those of T1.
Overall, the pre-converted white amaranth could be used as a potential natural curing agent to produce natural cured meat products that met the healthy and quality demands of consumers. Furthermore, 3 and 5% pre-converted white amaranth extract in a natural curing frankfurter sausage was suggested in this study.
|
|---|
