Chipping varieties and model systems were used to determine the role of potato
constituents on chip color. Composition was evaluated by HPLC and chip color
measured using a ColorQuest colorimeter. Reducing sugar (RS) content did not
completely explain color quality when present in low concentrations (<60 mg/lOOg).
Levels of ascorbic acid, glutamine and a chlorogenic acid isomer, along with RS,
showed high correlation with color. Sucrose was a poor estimator of chip color.
Model systems used leached potato slices infiltrated with solutions containing
sucrose, RS, ascorbic, chlorogenic and amino acids. Linear association of RS with L*
and hue angle and quadratic relationship with chroma of chips were found. Ascorbic acid
affected chroma and hue at low RS levels while chlorogenic acid was not involved in
color development.
Red potatoes {Solarium tuberosum and Solarium stenotomum) were evaluated as
potential source of natural red colorant. Cultivars (33) were screened for anthocyanin
content and qualitative composition. Monomeric anthocyanin content, determined by pH
differential, ranged between 4 and 40 mg/lOOg fresh weight (fw) tuber. Varieties 5847-1
and ND04069-4 showed high anthocyanin content (>35 mg/lOOg). Anthocyanin
composition was characterized by HPLC, spectral analysis and Mass Spectroscopy
(MS). The major anthocyanin was pelargonidin-3-rutinoside-5-glucoside acylated with
p-coumaric acid.
The presence of glycoalkaloids (α-solanine and α-chaconine) was detected by
MS and quantified by HPLC. Varieties NDO4069-4 and 5847-1 showed glycoalkaloid levels of 13 and 7 mg/lOOg fw, respectively. Glycoalkaloids were precipitated from
pigment concentrates by alkaline treatment. The best results were obtained at pH 8.0
with 30% monomeric anthocyanin degradation and 90% glycoalkaloid precipitation.
The color and pigment stability of chemically related anthocyanin extracts (red-fleshed
potatoes and radishes), the effect of pigment purity, and temperature were
evaluated in model juices (pH 3.5). Color (CIELch) and anthocyanin degradation was
monitored for 65 wks of storage. All model juices showed color similar to FD&C Red #
40. Excellent stability was obtained with all treatments in refrigeration. Anthocyanin
structure and extraction method affected pigment stability. At 25°C, higher stability was
obtained on juices colored with chemically purified radish anthocyanins (22 wk half-life)
and lowest with potato vegetable juice (10 wk half-life). / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27206 |
| Date | 04 June 1998 |
| Creators | Rodriguez-Saona, Luis Enrique |
| Contributors | Wrolstad, Donald E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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