Temperature-Dependent Autoxidation of Conjugated Trienols from Apple Peel Yields 6-Methyl-5-hepten-2-one, a Volatile Implicated in Induction of Scald
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- 作者：Bruce D. Whitaker and Robert A. Saftner
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2000
- 出版时间：June 2000
- 年：2000
- 卷：48
- 期：6
- 页码：2040 - 2043
- 全文大小：55K
- 年卷期：v.48,no.6(June 2000)
- ISSN：1520-5118
文摘
Conjugated triene (CT) oxidation products of 
-farnesene have long been thought to be involved indevelopment of superficial scald in apple fruit. Early studies found that CT hydroperoxides and thevolatile 6-methyl-5-hepten-2-one (MHO) are major in vitro autoxidation products of -farnesene.However, it was recently shown that 
99% of the oxidation products of -farnesene that accumulatein apple peel are conjugated trienols (CTols), isomers of 2,6,10-trimethyldodeca-2,7,9,11-tetraene-6-ol. HPLC-purified CTols from fruit of two scald-susceptible cultivars, Granny Smith (GS) andRed Delicious (RD), were used to study autoxidation of these compounds in vitro. Incubation ofCTols in sealed glass vials under air resulted in accumulation of MHO. Oxygen enrichment did notincrease the amount of MHO produced. Regardless of which cultivar CTols were derived from, at 0
deg.gif">C autoxidation yielding MHO was quite slow and linear, whereas at 20 deg.gif">C MHO production wasmuch more rapid, and after several hours the rate increased abruptly. However, CTols isolatedfrom GS and RD fruit differed in the duration of the initial lag phase and the overall level of MHOgenerated at 20 deg.gif">C. The sharp increase in MHO production occurred after 3 h with GS CTols andat about 12 h with RD CTols. Also, the yield of MHO from GS CTols after 6 h at 20 deg.gif">C was nearly6-fold greater than that from RD CTols after 20 h at 20 deg.gif">C. The antioxidants butylatedhydroxytoluene and diphenyamine reduced the yield of MHO by about 97%. Recent work has shownthat MHO can induce scald-like symptoms in apple peel and that tissue sensitivity increases withtime in storage. This may explain the correlation between high CTol levels and scald development,and why symptoms rapidly intensify when fruits are removed from cold storage.Keywords: -Farnesene; conjugated triene; 6-methyl-5-hepten-2-one; autoxidation; apple fruit;superficial scald
-farnesene have long been thought to be involved indevelopment of superficial scald in apple fruit. Early studies found that CT hydroperoxides and thevolatile 6-methyl-5-hepten-2-one (MHO) are major in vitro autoxidation products of -farnesene.However, it was recently shown that 99% of the oxidation products of -farnesene that accumulatein apple peel are conjugated trienols (CTols), isomers of 2,6,10-trimethyldodeca-2,7,9,11-tetraene-6-ol. HPLC-purified CTols from fruit of two scald-susceptible cultivars, Granny Smith (GS) andRed Delicious (RD), were used to study autoxidation of these compounds in vitro. Incubation ofCTols in sealed glass vials under air resulted in accumulation of MHO. Oxygen enrichment did notincrease the amount of MHO produced. Regardless of which cultivar CTols were derived from, at 0deg.gif">C autoxidation yielding MHO was quite slow and linear, whereas at 20 deg.gif">C MHO production wasmuch more rapid, and after several hours the rate increased abruptly. However, CTols isolatedfrom GS and RD fruit differed in the duration of the initial lag phase and the overall level of MHOgenerated at 20 deg.gif">C. The sharp increase in MHO production occurred after 3 h with GS CTols andat about 12 h with RD CTols. Also, the yield of MHO from GS CTols after 6 h at 20 deg.gif">C was nearly6-fold greater than that from RD CTols after 20 h at 20 deg.gif">C. The antioxidants butylatedhydroxytoluene and diphenyamine reduced the yield of MHO by about 97%. Recent work has shownthat MHO can induce scald-like symptoms in apple peel and that tissue sensitivity increases withtime in storage. This may explain the correlation between high CTol levels and scald development,and why symptoms rapidly intensify when fruits are removed from cold storage.Keywords: -Farnesene; conjugated triene; 6-methyl-5-hepten-2-one; autoxidation; apple fruit;superficial scald