Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/24552
標題: 冷卻及被覆處理對水煮蛋貯存品質之影響
Effect of cooling and coating treatments on storage qualities of hard-cooked eggs
作者: 徐志忠
Shyu, Ji-Jung
關鍵字: cooling
冷卻
coating treatment
hard-cooked egg
storage quality
被覆處理
水煮蛋
貯存品質
出版社: 畜產學系
摘要: 本研究目的為嘗試以不同的材料與方式進行水煮殼蛋被覆處理,以維持良好的水煮蛋品質,並延長水煮蛋於室溫下之存放時間。選擇被覆及被覆後貯存較方便之石蠟、玉米蛋白、乙基纖維素及聚乙烯乙酸酯作為水煮蛋貯存試驗之被覆材料。 水煮蛋水煮後的冷卻方式對產品品質和貯存期間品質變化有直接影響,水冷之水煮蛋蛋黃綠環化較氣冷者輕微。在25℃貯存,微生物侵入水冷之水煮蛋速度較氣冷水煮蛋為快,因而使水冷之水煮蛋保存期限較短。本實驗中發現,降低殼蛋水煮後與被覆前微生物的污染,對水煮蛋的貯存影響很大。殼蛋水煮後以氣冷方式冷卻,可大幅延長水煮蛋在25℃的貯存天數。因此,本實驗採用氣冷處理之水煮蛋做被覆處理之貯存試驗。 各被覆處理組之外觀以玉米蛋白處理組之外觀差異較大,且其蛋表為淡黃色。由掃瞄式電子顯微鏡觀察發現,殼蛋水煮後,蛋殼表面裂縫增加且裂縫加大,被覆處理後,蛋殼表面之裂縫幾乎完全被覆蓋。各被覆材料僅覆蓋於蛋殼表面,並未由氣孔滲入蛋內容物。 氣冷水煮蛋,在25℃貯存12天,生菌數及揮發性鹽基態氮皆在合格範圍內。貯存期間,各處理組之蛋白pH在貯存期間,呈先下降再漸漸上升的趨勢,蛋黃pH值隨貯存時間增加而升高;蛋白水分下降情形以未被覆組和玉米蛋白處理組最嚴重,乙基纖維素、石蠟及聚乙烯乙酸酯處理組降低情形較緩和,蛋黃水分含量則都有增加之趨勢;水活性的變化並不大,大多介於0.967-0.975之間;各處理組失重情形隨貯存時間皆有增加之趨勢,唯石蠟處理失重情形顯著(p<0.05)比其它各被覆處理為低。 各被覆材料僅覆蓋於蛋殼表面,對剝殼性並無影響。被覆處理會影響貯存期間水煮蛋蛋黃色澤。石蠟被覆處理對水煮蛋貯存期間之蛋白、蛋黃色澤評分皆有影響。在本實驗中,石蠟被覆處理為保持水煮蛋味道最佳的被覆材料。而由外觀、色澤、風味及質地等官能品評之結果,顯示聚乙烯乙酸酯可作為貯存水煮蛋之良好被覆材料。
The purpose of this study was to maintain the storage quality and extend the shelf life of hard-cooked eggs at room temperature using various coating materials. Paraffin wax, zein, ethyl cellulose and polyvinyl acetate were selected as coating materials in this experiment. The cooling methods of hard-cooked eggs directly affect both the production and storage quality. The degree of yolk discoloration of water cooling hard-cooked eggs was lighter than that of air cooling ones. As storage at 25℃, microbial penetration rate of water cooling hard-cooked eggs was more rapid than air cooling hard-cooked eggs, that made the former had the shorter shelf life of water cooling hard-cooked eggs. This experiment showed that reducing the microbial contamination during processes of hard-cooked and coating had marked effect on the storage quality of hard-cooked eggs. The shelf life of hard-cooked eggs stored at 25℃ was greatly extended by air cooling treatment after being cooked. Therefore, air cooling hard-cooked egg was used in coated hard-cooked storage test. The appearance of zein treated hard-cooked egg was much yellow and was significantly different from others. Scanning electron micrographs showed that both the number and the size of cracks on the eggshell surfaces increased after cooking. After coating, cracks on the eggshell surfaces were almost covered by coating materials. The bonding of coating materials was only on the eggshell surface, and there was no penetration of the coating materials below the surface. Both total plate counts and volatile basic nitrogen value of air cooling hard-cooked eggs stored at 25℃ for 12 days did not reached spoilage standard. During storage at 25℃, the pH values of albumen of all treatments tended to decline at early stage and then rise slowly. The pH values of yolk in all treated samples increased with storage time. The moisture loss of albumen of the uncoated and zein treated samples declined most seriously. The moisture content of yolk increased with storage time. The water activity in all treatments was between 0.967 and 0.975, which did not change markedly. The weight loss of all treatments increased with storage time, but of paraffin wax treatment significantly (p<0.05) lighter than other treatments. All the coating materials were only covered on eggshell surfaces and had no effect on the shell peelability of hard-cooked eggs. Coating treatment had effect on yolk color of hard-cooked eggs during storage. Paraffin wax treatment had effect on the scores of albumen and yolk color. Paraffin wax was the best coating material for holding hard-cooked egg flavor in this experiment. Results of sensory evaluation of appearance, color, flavor and texture showed that polyvinyl acetate was a good coating material for storage of the hard-cooked eggs.
URI: http://hdl.handle.net/11455/24552
Appears in Collections:動物科學系

文件中的檔案:

取得全文請前往華藝線上圖書館



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.