肉および肉製品の風味成分に関する研究II. : 豚の皮下脂肪および赤肉の低沸点成分

A study on the flavor components of meat and meat products II. : Low-boiling compounds in barrow's subcutaneous fat depot and fresh lean pork

Kami Takayasu

Otaishi Satoru

Hayashi Shuichi

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

　生後7カ月の中ヨークシャ一種の去勢牡豚(生体重100 kg) から，右背ロース部(Back and Loin) 5. 65kg を採取し，皮下脂肪部と赤肉部に分けて実験に供した.
　(1)皮下脂肪2. 64kg は等量の蒸留水と共に，攪拌しながら2時間半煮沸蒸留した.水冷却トラップに捕集された低沸点化合物を含む留出水は， 2N ‐燐酸でpH3に調整したあとイソベンタンで抽出して，イソベンタン可溶部と不溶部に分けた.イソベンタン可溶部は，貯蔵容器の上部気相をとって水素炎型ガスクロマトグラフィーで分析した.一方不溶部は5部に分けてそれぞれ誘導体に導き，カルボニル化合物，アルコール，塩基性，酸性および硫黄化合物を分析した.イソオクタン， n-オクタン，アセトアルデヒト，プロピオンアルデヒド， n-プチルアルデヒド， イソバレルアルデヒド， イソヘプチルアルデヒド， グリオキザール，アセトン， メチルイソプロピルケトン， メチルイソプチルケトン， ジアセチル，メタノール， イソプロパノール，第二ブタノール，第三プタノール， nーベンタノール，第三ベンタノール， イソノナノール， イソデカノール， nープロピルメルカプタン， イソアミルメルカプタン， アンモニア，ギ酸イソプロピル，酢酸エチル，酢酸n プロピル，酢酸，プロピオン酸， n- 酪酸，イソ酪酸， n-吉草酸およびイソヘプタノイック酸の存在を確認した.
　(2) 赤肉1.84 kg も皮下脂肪と全く同様にして水蒸気蒸留，イソベンタン抽出を行なって分析した.GCでは2個の小ピークを検出したのみであったが， 誘導体分析においてはn- ブチルアルデヒドおよびイソプロパノールを検出しなかった以外は，成分的にほとんど差異を認めなかった.
　(3) イソベンタン可溶部のTLCにおいて，赤肉はトリグザセライドおよびコレステロールエステルに富み，皮下脂肪は不飽和脂肪酸に富んだ.窒素含量は皮下脂肪の方が約5倍多かった.

Roast meat (Back and loin), 5.65 kg, was obtained from the right side of a Middle Yorkshire barrow of seven-month-old, weighing 100 kg. This was separated into the subcutaneous fat depot and fresh lean pork to examine the low-boiling compounds.

(1) A portion of the subcutaneous fat depot weighing 2.64 kg was heated with an equal volume of distilled water at lOO"C for 2% hours under constant stirring. The distillate collected in the watercooled trap was adjusted to pH 3 with 2N-phosphoric acid and was extracted with isopentane. The head space vapor of the isopentane soluble fraction, was taken out from the material-storing tube, and was examined in FID-equipped gas chromatograph. From the isopentane insoluble fraction, 2,4-dinitrophenylhydrazone. 3,5-dinitrobenzoate, phenylthiourea, methyl ester and mercury cyanide complex were prepared, which were analyzed by the gas chromatography, TLC and IR etc. The following compounds were thus identified as: isooctane, n-octane, acetaldehyde, propionaldehyde, n-butyraldehyde, isovaleraldehyde, isoheptyraldehyde, glyoxal, acetone, methyl isopropyl ketone, methyl isobutyl ketone, diacetyl, methanol, isopropanol, sec-butanol, tert-butanol, n-pentanol, lerl-pentanol, isononanol, isodecanol, n-propyl mercaptane, isoamyl mercaptane, ammonia, isopropyl formate, ethyl acetate, n-propyl acetate, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid and isoheptanoic acid.

(2) Fresh lean pork, 1.84 kg, was distilled by steam and analyzed in the same manner as mentioned above. Only two small peaks were detected by the gas chromatography from the head space vapor of the isopentane soluble fraction, but the result obtained by the analysis of derivatives from the isopentane insoluble fraction was the same as that of the subcutaneous fat, lacking only n-butyraldehyde and isopropanol. Thus, the difference between the low-boiling compounds of the subcutaneous fat and the lean pork is not qualitative but only quantitative.

(3) It was observed by thin layer chromatography of isopentane extracts that lean pork is rich in triglycerides and cholesterol esters, while subcutaneous fat is rich in unsaturated fatty acids. The nitrogen content of the subcutaneous fat was about five times higher than that of the lean pork.

Animal husbandry [ 640 ]

jpn

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563