No abstract

Strawberries were sampled a t six different stages of maturity (5-45 days after blooming). A whole strawberry fruit a t each stage was incubated in a flask with 5 FL of pentanal at 30 "C for 1 h. The headspace gas analysis by gas chromatography revealed the following facts: (1) the reduction of pentanal to 1-pentanol by strawberry fruit occurs at every stage of maturity, and the reduction rate is stimulated with progress of maturity; (2) the biosynthesis of 1-pentyl esters of volatile fatty acids via 1-pentanol formation from pentanal occurs not in immature fruit but in mature fruit. The generation of enzyme systems concerning alcohol and ester formation from aldehyde is discussed. It was confirmed that volatile free fatty acids in strawberries played an important role in ester formation. The method of determination of volatile fatty acid in strawberries by gas chromatography is also briefly discussed.Development of flavor in fruits and vegetables is one of the most prominent changes that occurs during maturation before harvest and storage thereafter. Pitsarnitskii et al. (1970) reported the changes in volatile carbonyl compounds in strawberries during the maturization process. Tressl et al. (1969) isolated and identified 214 volatile compounds from ripe strawberries. Among them are esters as the major component, followed by alcohols and carbonyl compounds.Recent evidence indicates that ester formation can be induced by addition of alcohol or aldehyde to ripe strawberry fruit (Yamashita et al., 1975(Yamashita et al., , 1976a. The ester formation was located in the separated mesocarp cells and in the protoplasts of strawberry (Ueda et al., 1976).In this paper, biosynthesis of volatile alcohol and esters from aldehyde in strawberries at different stages of maturity and relationship between ester formation and volatile fatty acid in strawberries are discussed. MATERIALS AND METHODS Strawberries.Strawberries (Fragaria ananassa Duchesne var. Hoko) used were grown at Chibaken Agricultural Experiment Station in 1976. Samples were collected at 5, 10, 20, 30, 40, and 45 days after blooming.Reaction of Pentanal with Strawberries. A whole strawberry fruit was placed in a wide-mouthed, 100-mL Erlenmyer flask and 5 pL of pentanal was added onto the inside wall of the flask. Then the flask was sealed with a glass stopper equipped with a small silicone rubber septum and kept at 30 "C in a water bath in the dark for 1 h.Control Test. A whole strawberry was incubated in a flask without addition of pentanal under the same conditions as mentioned above.Analysis of Headspace Volatiles. Three milliliters of vapor sample in the flask was taken out through the silicone rubber septum by means of a gas-tight syringe and injected into a gas chromatograph equipped with a flame ionization detector. The two gas chromatographic systems (25% PEG 1000 and 30% Silicone DC 550 on Chromosorb W AW) were employed for the identification and determination of pentanal, 1-pentanol, and 1-pentyl esters as described elsewhere (Yamashita et al., 1976a)...

the nonpackaged broccoli. These results suggest that, under anaerobic condition, the volatile sulfur compounds are formed by the deterioration of cellular membrane lipids and loss of intracellular compartmentation, allowing the enzyme-substrate reaction to proceed.

No abstract