Conjugated Triene Oxidation Products of α-Farnesene Induce Symptoms of Superficial Scald on Stored Apples

Abstract

The sesquiterpene alpha-farnesene (1) and its conjugated triene oxidation products accumulate in the skin of apples after harvest and are implicated as the causal agents of superficial scald. Conjugated triene oxidation products and analogues were synthesized and applied to the surface of Granny Smith apples either as vapors or in squalane. Farnesyl hydroperoxide (2a), trienol (2b), endoperoxide (3a), dehydronerolidol (5), and cumyl hydroperoxide (4) all produced the symptoms of superficial scald when applied at nanomolar doses. Scald-inducing activity was dependent on the mode of application. Farnesyl hydroperoxide (2a) was the most active conjugated triene when applied directly to the apple skin. Trienol (2b) also induced scald symptoms and partially reversed the inhibition of scald caused by diphenylamine.

Effect of the Cooling System and 1-MCP on the Incidence of Superficial Scald in ‘Granny Smith’ Apples

“…TC are generated as a product of the oxidation of AF during the storage of apples and have been identified as the direct cause of cellular damage that leads to the expression of scalding symptoms (Whitaker et al, 1997;Rowan et al, 2001). The application of 1-MCP to fruit with normal and step-wise cooling resulted in significantly lower levels of TC 258; 269 and 281 in comparison to fruit without treatment, throughout all the evaluations ( Figure 3A, 3B and 3C).…”

“…Given that this alteration is induced by the low-temperature storage, it is accepted as a manifestation of chilling injury (Watkins et al, 1995). It has been demonstrated that superficial scald is associated with oxidation of α-farnesene to conjugated trienes (Anet, 1972;Rowan et al, 2001;Arquiza et al, 2005;Isidoro and Almeida, 2006), which appear in greater concentrations, than just the accumulation of α-farnesene at the end of the storage period (Huelin and Coggiola, 1968;Meir and Bramlage, 1988;Whitaker et al, 2000).…”

Fruit quality of Granny Smith apples picked at different harvest times and treated with 1-MCP

“…Superficial scald usually appears during shelf life of fruits removed from cold storage, but with highly susceptible cultivars the scald can appear even during storage [1]. Scald has been associated with oxidation of α-farnesene and the consequent accumulation of conjugated trienes [2].…”

Mouldy, musty earthy off-odour of apple fruits - Short communication

“…Golden Delicious associated with a mouldy, musty and earthy off-odour in this research were two endoperoxides with molecular weights 236 and 252, respectively, as described previously (Rowan et al 1995(Rowan et al , 2001. These compounds were eluted after 27.5 and 30.5 min and encompassed 0.5% and 0.7% of the peak area, respectively.…”

“…α-Farnesene autooxidises easily at 1°C to 2,6, 10-trimethyldodeca-2,7(E),9(E),11-tetraen-6-ol, 6-hydroperoxy-2,6,10-trimethyldodeca-2,7(E),9(E)-11-tetraene, its 7E,9Z isomers and 6-methyl-5-hepten-2-one (Anet 1969; Rowan et al 1995Rowan et al , 2001). On this basis it was concluded that the mouldy, musty and earthy off-odour of cv.…”