| Abstract: | 固態豬油與液態豬油於150℃下每天加熱8小時,於第0、1、2、3、4、及5 天時,分析豬油之脂肪酸組成、過氧化價、酸價、膽固醇與膽固醇氧化物 之含量。豬肉(里肌肉)切成1cm厚,貯藏在0-2℃、每天光照24小時,於第 0、2及4天時,分析膽固醇及其氧化物含量並分別以固態豬油及液態豬油之 新鮮油與加熱3天油油炸豬排,然後比較生鮮肉與炸熟肉之水分、粗脂肪、 水分總流失率、TBA值、膽固醇與膽固醇氧化物含量。結果發現豬油在加 熱過程中,飽和脂肪酸(C14:0,C16:0,與C18:0)含量百分比會隨加熱時間的 增加而顯著增加,不飽和脂肪酸之C18:2則隨加熱時間的增加而顯著下降; 過氧化價之變化為先上升而後下降,酸價隨加熱時間的增加而顯著上升; 膽固醇及膽固醇氧化物含量皆是以固態豬油之含量較高,隨著加熱時間的 增加,固態或液態豬油中膽固醇含量皆會呈線性式的明顯流失;在二種豬油 中可檢測到之膽固醇氧化物有7-hydroxycholesterol, cholesterol β- epoxide, cholesterol α- epoxide, 7- ketocholes- terol, 20-hydroxycholesterol, 25-hydroxycholesterol與 cholestane triol 。豬肉於貯藏時水分與粗脂肪之含量不會有顯著的改變,但豬肉經油炸 後, 水分會顯著減少而粗脂肪含量則會顯著增加;TBA值會隨光照貯藏時間 的增加而增加, 經油炸後TBA 值更會顯著增加; 於貯藏時間內豬肉之膽固 醇會被氧化而使膽固醇氧化物含量增加, 豬肉經油炸後膽固醇及其氧化物 皆會顯著增加,炸熟肉增加之比例以加熱過3天油較新鮮油為高, 炸熟肉之 膽固醇氧化物種類與含量隨使用豬油之不同而不同, 但以固態豬油處理組 較多。
Lard(solid form and liquid form) were heated at 150℃ for 8hr /day. Fatty acids composition, peroxide value, acid value, cho- lesterol, and COPs of lard were determined after 0, 1, 2, 3, 4, and 5 days of heating. Pork chop with 1cm thickness were cut from pork loin, then stored at 0-2℃ and exposed to light for 24hr/day . Fresh and used lard(heated for 3 days, soild form and liquid form) were used to fry meat after 0, 2, and 4 days of stored. Moisture, crude fat, total moisture loss, TBA value, cholesterol and COPs of fresh and fried meat were determined. The results showed that saturated fatty acids( C14:0, C:16:0, and C18:0) content would increase and unsaturated fatty acids( C18:0) decreased during heating. At the beginning of heating, peroxide value increased but then decreased at latter stage. Acid value kept increasing during heating. Cholesterol content de- creased lineally with the increase of heating time. The kinds of COPs in lard include 7β - hydroxycholesterol, cholesterol β - epoxide, cholesterol α- epoxide, 7-ketocholesterol, 20- hydroxy- cholesterol, 25 - hydroxycholesterol, and cholestane triol. Moi- sture and crude fat of meat were not significantly affected by storage time; however, moisture decreased and crude fat increased significantly after frying. TBA value increased with the increase of storage time. After frying, TBA value would increased more quickly. During storage, cholesterol in meat would be oxidized and the COPs increased. After frying, both cholesterol and COPs in meat increased significantly, and the increasing rate in oil heated 3 days was higher than that in fresh oil. The kinds and and amounts COPs in meat varied depending on the frying oil. Meat fried with lard (solid form) had more varieties and amount of COPSs. |
