臭豆腐油炸油總極性物質測定及油炸臭豆腐成分之變化

Determination of Total Polar Materials in Frying Oil and Changes in Compositions of Frying Stinky Soybean Curd (Chou-Tofu) after Frying

李元豐(Yung-Feng Lee) ； 駱錫能(Shyi-Neng Lou)

《宜蘭大學生物資源學刊》 12卷 (2016/12) Pp. 39-50

https://doi.org/10.6175/job.2016.12.13

摘要

本研究比較臭豆腐油炸油總極性物質之測定方法，並分析油炸後臭豆腐的組成變化，以為油炸臭豆腐品質的參考資料。實驗結果顯示以Testo 快速檢測法測定總極性物質，所得數值顯著高於公告方法之測定值，因此，Testo 測定儀使用於臭豆腐油炸油脂測定時需做校正。油炸臭豆腐五和八分鐘後，臭豆腐的水分含量大幅下降約32%，因而造成灰分、粗蛋白、粗脂肪和碳水化合物的增加。換算乾物基礎時，發現灰分(0.08 g/g dry weight)減少約二分之一，粗蛋白亦由0.45 g/g dry weight 下降至0.28 g 左右，顯示部分礦物質和蛋白質於油炸過程中流失進入炸油中。然而，粗脂肪含量則增加兩倍之多，由0.21 g/gdry weight 增加至0.40g 之範圍，應係油炸過程中臭豆腐吸收炸油所致。同時，臭豆腐的不飽和脂肪酸總量下降，相對飽和脂肪酸的總量則增加，主要減少之不飽和脂肪酸為C18:2 及C18:3，增加之飽和脂肪酸為C16:0，但是不飽和之C18:1 也有增加。碳水化合物的含量則 無明顯之變化。

關鍵字

臭豆腐 ； 油炸 ； 總極性物質測定 ； 組成分變化

並列摘要

The purpose of this study was to investigate the change in compositions of frying stinky soybean curd (Chou-Tofu). The determination of total polar materials by Testo and standard methods was also evaluated. The results indicated that the total polar materials of frying oil determined by Testo method were significantly higher than by standard method. Process of calibration should be carried out before testing by Testo method. The moisture content of stinky soybean curd decreased about 32% after frying in 5 and 8 minute. The content of total ash, crude protein, crude lipid and carbohydrate increased consequently. In dry weight basis, it was found that the total ash (0.08 g/g dry weight) decreased about 50%, while crude protein also decreased from 0.45 g/g dry weight to about 0.28 g. This hinted that some of mineral materials and protein released from stinky soybean curd into frying oil. However, the content of crude lipid increased about two times during frying, which was from 0.21 g/g dry weight to 0.40 g. Obviously, stinky soybean curd absorbed frying oil during frying. Changes in fatty acid of frying stinky soybean curd were found. Total content of unsaturated fatty acid decreased after frying, while total saturated fatty acid increased. The major reduced unsaturated fatty acid was C18:2 and C18:3, while the main increased saturated fatty acid was C16:0 and C18:0. Besides, C18:1 increased also after frying. However, no significantly change of carbohydrate (in dry weight basis) was observed.

並列關鍵字

stinky soybean curd ； frying ； determination of total polar materials ； change of composition