Ripening pear flavor volatiles : identification, biosynthesis and sensory perception Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/76537384f

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Volatile compounds of eight pear varieties were isolated and identified by GC/MS. A total of 112 components were identified from headspace of intact fruits, including 47 compounds reported for the first time in pear. The volatile profiles of these pear varieties were characterized by esters, alcohols, hydrocarbons, aldehydes and ketones. Qualitative and quantitative differences of compounds in the profiles are discussed in terms of flavor differences between pear varieties. Analysis of volatiles isolated from eating-ripe pears by direct sniffing GC indicated that a group of nine esters including 2-methylpropyl-, butyl-, pentyl- and hexyl acetates, butyl butanoate, ethyl hexanoate, methyl trans-2, cis-4-, ethyl trans-2, cis-4- and ethyl cis-2, cis-4- decadienoates from 'Bartlett', 'Cornice' and 'Anjou' pear possessed strong, specific pear-like aroma. A second group of esters was also found to possess very positive aroma and can significantly affect overall sensation by serving as 'contributory to flavor compounds'. A newly developed, solid-phase microextraction technique was used to follow changes of volatile production of 'Bartlett', 'Packham's Triumph' and 'Anjou' pears during ripening. The major esters were found to increase at different rates and times during fruit ripening. Highly significant correlations between specific groups of odor-active compounds and pear flavor intensity during ripening indicated the significant contribution of volatiles to overall pear flavor. The effects of harvest maturity on volatiles differed between fruit varieties. 'Bartlett' harvested at all maturities, upon ripening produced similar amounts of flavor constituents. Higher volatile production was observed in early harvested 'Packham's Triumph'. Delayed harvest significantly reduced volatile production in 'Anjou'. Prolonged storage of fruits resulted in severe reduction of volatile esters in 'Packham's Triumph' and 'Anjou'. Alcohol acyltransferase, the ester synthesizing enzyme was isolated from 'Bartlett', partially purified, and its properties characterized. The enzyme was estimated to have a molecular weight of 40 kD and was most active at pH 7.5 and 3O°C. The enzyme has Km= 0.6 mM and Vmax = 0.3 nmol/min for hexanol and Km= 53 μM and Vmax = 0.2 nmol/min for acetyl-CoA. Maximum activity of the enzyme was obtained when hexanol and acetyl-CoA were used as substrates.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using Scamax Scan+ V.1.0.32.10766 on a Scanmax 412CD by InoTec in PDF format. LuraDocument PDF Compressor V.5.8.71.50 used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2011-11-22T18:13:35Z (GMT). No. of bitstreams: 1 SUWANAGULANAWAT1996.pdf: 3365208 bytes, checksum: a6770e0c738c571a3629c57a741e07b7 (MD5) Previous issue date: 1996-03-07
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2011-11-22T18:13:35Z (GMT) No. of bitstreams: 1 SUWANAGULANAWAT1996.pdf: 3365208 bytes, checksum: a6770e0c738c571a3629c57a741e07b7 (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2011-11-10T23:09:36Z (GMT) No. of bitstreams: 1 SUWANAGULANAWAT1996.pdf: 3365208 bytes, checksum: a6770e0c738c571a3629c57a741e07b7 (MD5)
  • description.provenance : Submitted by Erin Clark (ecscannerosu@gmail.com) on 2011-11-10T17:13:56Z No. of bitstreams: 1 SUWANAGULANAWAT1996.pdf: 3365208 bytes, checksum: a6770e0c738c571a3629c57a741e07b7 (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items