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David E. Kopsell, William M. Randle, and Mark A. Eiteman

Onion (Allium cepa L.) pungency changes during storage. To better understand these flavor changes, seven onion cultivars representing different storage duration, photoperiodic requirement, and flavor intensity were greenhouse grown and the bulbs stored for 3 or 6 months at 5±3 °C, 0.8 to 1.1 kPa vapor pressure deficit. Bulbs were evaluated using high-pressure liquid chromatography quantification for changes in S-alk(en)yl cysteine sulfoxide (ACSO) flavor precursors and γ-glutamyl peptide (γ-GP) biosynthetic intermediates before storage and monthly thereafter. Before and during storage, cultivars differed in total ACSO, (+) S-methyl-L-cysteine sulfoxide (MCSO), trans-(+)-S-(1-propenyl)-L-cysteine sulfoxide (PRENCSO), (+) propyl-L-cysteine sulfoxide (PCSO), S-2 carboxypropyl glutathione (2-CARB), and γ-L-glutamyl-S-(1-propenyl)-L-cysteine sulfoxide (γGPECSO) concentration. During storage MCSO generally decreased while PRENCSO increased in concentration for most cultivars. The linear increase in PRENCSO concentration during storage was accompanied by a linear decrease in γGPECSO concentration. While not measured in this study, these trends indicate γ-glutamyl transpeptidase activity throughout bulb storage. γ-Glutamyl transpeptidase was previously reported to be active only in the later stages of bulb storage or during bulb sprouting. Changes in ACSO and γ-GP compounds during storage did not follow previously reported changes during storage for enzymatically formed pyruvic acid (EPY) for these cultivars. To better understand what causes flavor changes in onions during storage, future investigations should include analysis of the enzymes involved in flavor development and ACSO hydrolysis products.

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Chen-Yi Hung, John R. Murray, Sarah M. Ohmann, and Cindy B.S. Tong

HPLC analyses, and Alan G. Smith for advice and the use of his lab space. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely

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Ninghang Wang, Chao Zhang, Sainan Bian, Pengjie Chang, Lingjuan Xuan, Lijie Fan, Qin Yu, Zhigao Liu, Cuihua Gu, Shouzhou Zhang, Yaling Wang, and Yamei Shen

typical species and four corresponding cultivars, were investigated to analyze their flavonoids by high-performance liquid chromatography coupled with diode array detection (HPLC-DAD) as well as HPLC with electrospray ionization and mass spectrometry (HPLC

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Ni Jia, Qing-Yan Shu, Dan-Hua Wang, Liang-Sheng Wang, Zheng-An Liu, Hong-Xu Ren, Yan-Jun Xu, Dai-Ke Tian, and Kenneth Michael Tilt

objective of our study was to identify and characterize the anthocyanins in herbaceous peony species from different regions of the world using reverse-phase high-performance liquid chromatography (HPLC) with diode array detection in tandem with electrospray

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Yi Gong, Ronald B. Pegg, Adrian L. Kerrihard, Brad E. Lewis, and Richard J. Heerema

Technology (Athens), vacuum packed, and stored at −80 °C until analyzed. Extraction of phenolic compounds (as lyophilized hydrophilic extracts). Before all analyses [TPC, hydrophilic-oxygen radical absorbing capacity (H-ORAC FL ), and HPLC], a lyophilized

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Kelechi Ogbuji, Gloria S. McCutcheon, Alvin M. Simmons, Maurice E. Snook, Howard F. Harrison, and Amnon Levi

, NY) equipped with a 6-mm diameter sawtooth grinder type of tissue cutter. The solutions were filtered through 0.45-μm nylon-66 filters in preparation for HPLC analysis. High-performance liquid chromatography analysis. Extracts were analyzed once by

Open access

James C. Fulton, Francisco O. Holguin, Robert L. Steiner, and Mark E. Uchanski

) was followed for HPLC. During the first year, 6 mg of tissue per sample was extracted; the following year, 25 mg per sample was used. Samples were saponified with 1 mL of 2 N methanolic potassium hydroxide, vortexed for 30 s, and heated at 50 °C for 1

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Panthip Boonsong, Natta Laohakunjit, Orapin Kerdchoechuen, and Frank B. Matta

plants using ultraviolet-visible spectrophotometry and HPLC. This research will provide information on the presence, color, and number of pigments and polyphenols (colorants) in plant extracts for possible use as hair coloring dyes. Materials and Methods

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Yifei Wang, Stephanie K. Fong, Ajay P. Singh, Nicholi Vorsa, and Jennifer Johnson-Cicalese

V. tenellum . By using HPLC and LC-ESI-MS-MS, the objectives of the study were to investigate 1) flavonoid (anthocyanins, flavonols, and proanthocyanidins) and organic acid profiles of different blueberry species, 2) variation of flavonoid and

Open access

Calen McKenzie, Ivette Guzman, Ciro Velasco-Cruz, and Paul W. Bosland

., 2012 ). About 1.0 g of fresh leaf tissue from each sample was ground in a mortar and pestle with 15 mL of reagent high-performance liquid chromatography (HPLC)-grade ethanol (Sigma-Aldrich, St. Louis, MO) as the extraction solvent. The ethanolic leaf