| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 104 === The traditional method of pidan production was using alkaline mud and rice bran wrapping on duck eggs. Nowadays, alkaline solution such as NaOH solution with metal ions is using for pidan production. However, using chemical solution presently causes consumer concern. Eggshell is the major waste of egg industry but the powder generated after cineration could produce a highly alkaline solution, which was demonstrated to possess antibacterial ability and has the potential for pidan making. In addition, electrolyzed water (EO water) is a new product in recently years. Acidic EO water was used as an antimicrobial agent and alkaline EO water currently used as a cleaning agent could be used for pidan production. Therefore, the objectives of this study were to eggshell powder and alkaline EO water for pidan production and determine the optimal combination of metal ions to obtain the optimal physiochemical and sensory qualities of pidan.
One, two, three, four, or five % of the eggshell powder solution or alkaline electrolyzed water was used as the basic pickling solution. Different combinations of ZnSO4 (0.175%), MgCl2 (0.08%), and CuSO4 (0.16%) was added. Duck eggs were pickled for 15, 18, 21, 24, 27 or 30 days at 25~27°C with observation intervals at 3 days. Results showed that the optimal characteristics was obtained with EO alkaline water with 5% eggshell powder and pickled for 24~27 days. Because the commercial process usually includes 14 days ripening, the ripening process was added to the 25 days picking for following process with the combinations of ions and eggshell powder or EO water.
The optimal combinations of metal ions was studied to reduce the use of ions. The basic solution containing 4.2% NaOH and 5% NaCl was used and the combinations of ZnSO4, MgCl2, CaCl2 were tested. The basic solution with all four metal ions was used as a positive control. The process of 25 day pickling plus 14 day ripening at 25~27°C was used. Results showed there was no significant difference (p >0.05) for physio-chemical properties between the positive control, 0.65% ZnSO4 only, and the combination of 0.35% ZnSO4 and 0.33% CaCl2. Thus, Zn was determined as the critical ion for pidan production. Therefore, two types of picking solutions were used. The first one was the basic solution containing 1, 2, or 3% eggshell powder with 0.175 % ZnSO4. The second was the basic solution containing 0.175% ZnSO4, 0.165% CaCl2 and 0.5% or 1% eggshell powder. In addition, pickling 25 day with 14 day ripening and 39 day pickling without ripening were also tested. Results showed that adding 3% eggshell power and 0.175 % ZnSO4 has the best physio-chemical characteristics.
For process, the 25 day pickling with 14 day ripening showed the best properties. Five percent eggshell powder as basic solution containing 0.175% ZnSO4 or alkaline EO water containing 3% eggshell powder show no significant difference (p >0.05) between the positive control. Results of sensory evaluation showed that 5% eggshell powder as basic solution containing 0.175% ZnSO4 had the most close characteristics with the commercial pidan. We successfully used the major waste of egg industry, eggshell, to produce high quality pidan. Thus, a new material being useful for pidan production and meanwhile reducing the negative environmental impact.
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