Apples growing in New Zealand, Argentina, Mexico, Michigan and
Washington were used to provide the compositional data and to
develop the analytical procedures for the use in verification of
authenticity of apple juices.
High Performance Liquid Chromatography (HPLC) techniques were
applied for glucose, fructose, sucrose, sorbitol, malic, citric,
quinic, shikimic, fumaric, chlorogenic acid, and
hydroxymethylfurfural (HMF). L-malic acid was determined by an
enzymic method. Sep-Pak C18 cartridge, anion exchange resin and
millipore filter were used for sample preparation of HPLC.
Influence of postharvest storage on sucrose and sorbitol
content was observed but it had no effect on the glucose/fructose
ratios. Quinic was the next most abundant acid in all the apple
varieties examined. Paired t-test showed good agreement (p<0.01)
between HPLC and enzymic determination for malic acid.
Significantly high variability in chlorogenic acid content limits
its utility. The influence of processing procedures on the phenolic
compound was observed by comparison with commercial, self-pressed and gelatin treated apple juices.
All apple juices showed two characteristic UV absorption maxima
at around 280nm and 320nm, the ratio of the two maxima being
relatively constant. First, second derivative spectra and
fluorescence excitation and emission maxima were measured. As the
order of derivative increased, the spectra became more complex and
the resolution was enhanced.
For the stable carbon isotope ratio analysis, juice, pulp,
seeds and sugars, acids, and phenolics were fractionated using ion
exchange resins and polyclar AT. Mass spectrometric measurements of
¹³C/ ¹²C ratio from whole juices showed low variability as
compared to other fractions. Organic acids showed more negative
values than the sugars. Phenolic fraction was most enriched in
¹²C when compared to the juice by as much as 4.6 ppt.
The evidence suggests that postharvest storage and processing
conditions played an important role in the variability of apple
juice components. There are no marked differences in del ¹³C
values with regard to apple variety or geographic origins. / Graduation date: 1985
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27433 |
| Date | 24 September 1984 |
| Creators | Lee, Hyoung S. |
| Contributors | Wrolstad, Ronald E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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