Search Results

You are looking at 21 - 30 of 116 items for :

  • Refine by Access: All x
Clear All
Free access

M.S. Padda and D. H. Picha

Phenolic acids are one of several classes of naturally occurring antioxidant compounds found in sweetpotato. Simplified but reliable methodologies were developed to quantitate total and individual phenolic acids in sweetpotato roots. Total phenolic acid content was measured using both Folin-Denis and Folin-Ciocalteu reagents. The Folin-Ciocalteu reagent gave an overestimation of total phenolic acids due to the absorbance of interfering compounds (i.e., reducing sugars and ascorbic acid). The average total phenolic acid content in `Beauregard' sweetpotatoes was 60.9 mg/100 g fresh weight. Individual phenolic acids were separated with two reversed-phase C18 columns of different dimensions and particle size. The columns tested were a 7 × 53 mm, 3 μm, Alltima Rocket (Alltech Assoc.) and a 3.9 × 150mm, 4 μm, Nova-Pak (Waters Corp.). Different mobile phases were also evaluated. The Alltima C18 column using a mobile phase of 1% (v/v) formic acid aqueous solution: acetonitrile: 2-propanol, pH 2.5 (70:22:8) provided the best separation of individual phenolic acids. Total analysis time was less than 5 minutes. Chlorogenic acid was the major phenolic acid found in sweetpotato root tissue (15.8 mg/100 g fresh weight). In a comparison of different tissue preparation states (fresh, frozen, freeze-dried), fresh tissue gave the highest concentration of total and individual phenolic acids. Among the 3 extraction solvents tested (80% methanol, 80% ethanol, and 80% acetone), 80% methanol and 80% ethanol gave higher, but similar, phenolic acid extraction efficiency.

Full access

Jan Narciso and Anne Plotto

A comparison of sanitizers for fresh-cut mango (Mangifera indica cv. Keitt) was made. Mangos were obtained from a farm in Homestead, Fla., and stored at 15 °C until processed. Before cutting, fruit were dipped in solutions of either sodium hypochlorite (NaOCl) (200 ppm) or peroxyacetic acid (100 ppm). The cut pieces were dipped in acidified sodium chlorite (NaClO2) (200 ppm, pH 2.6) or dilute peroxyacetic acid (50 ppm) for 30 seconds. Resulting cut slices were placed in polystyrene clamshell food containers and stored at 5 °C for 21 days. Samples in the clamshells were tested for changes in microbial stability and for quality parameters every 7 days. Results showed that even though the fruit slices were sanitized after cutting, cut fruit microbial populations were related to the method of whole fruit sanitation. After 15-21 days in storage at 5 °C, cut slices from whole fruit sanitized with peroxyacetic acid that were subsequently treated with dilute peroxyacetic acid or acidified NaClO2 had less contamination [<1 colony-forming unit (cfu) per gram] than samples cut from whole fruit sanitized with NaOCl (<1000 to 3700 cfu/g). These data demonstrate that the method of whole fruit sanitation plays a role in determining the cleanliness of the cut fruit. These sanitizer systems (peroxyacetic acid on whole fruit followed by peroxyacetic acid or acidified NaClO2 on cut slices) effectively reduced microbial growth and kept microbial counts low on cut fruit surfaces for 21 days when compared to cut fruit slices from NaOCl-treated whole fruit.

Open access

Ellen T. Paparozzi and H.B. Tukey Jr.

Abstract

Leaves of Betula alleghaniensis Britt. (yellow birch) and Phaseolus vulgaris L cv. Red Kidney (bean) were examined microscopically during development and after exposure to simulated rain of pH 5.5, 4.3, 3.2, and 2.8. Yellow birch leaves attained maximal leaf area, midvein length, and cuticle thickness at 21 days. Trichomes were either long, unicellular, or multicellular with caplike head and stalk. Epicuticular wax was a bumpy and amorphous layer. The 2nd trifoliolate leaf of red kidney bean attained maximal leaf area, midvein length, and cuticle thickness when the 3rd trifoliolate leaf was expanding. Trichomes present were long, with a unicellular head and a multicellular base; long, unicellular, and terminally hooked; and small and multicellular. Epicuticular wax was present as small irregular flakes. After 2 days of pH 2.8 and 4 days of pH 3.2 simulated acid rain, round yellow and small tan lesions appeared on birch and bean leaves, respectively. Most injury occurred on or between small veins. Most trichome types were uninjured. Lesions formed as a result of collapsed epidermal and highly plasmolyzed palisade cells. The cuticle was still present over injured epidermal cells and epicuticular waxes were unchanged. There was no statistical difference in mean cuticle thickness due to pH of simulated rain.

Open access

Dilip R. Panthee

oxysporum f.sp. lycopersici (Sacc.) Snyd. and Hans.) (races 1 and 2) ( I/I and I-2/I-2 genes), late blight (LB) ( Ph-2/ph-2 and Ph-3/ph-3 genes), Tomato mosaic virus (ToMV) ( Tm2/tm2 gene), and Tomato spotted wilt virus (TSWV) ( Sw-5/sw-5 gene

Free access

Paula Craig and Janet C. Cole

Wet Earth (WE) is a recycled paper product that may substitute for peat moss as a growth substrate. WE is available at various pH levels and may be formulated using: 1) paper production byproducts (WES), or 2) recycled corrugated cardboard (WEC). Use of WE by commercial growers would reduce demand for both landfill space and for slowly renewable resources such as peat and pine bark. Experiment objectives included: analyzing plant performance of azaleas (Rhododendron obtusum `Hino Crimson') in WE-based growth substrates at pH 3.4 and pH 6.6 and in peat-based growth substrates (Trial pH), 2) analyzing plant performance of WES, WEC, and peat moss-based growth substrates (Trial SC), and 3) determining changes, if any, in substrate physical properties from planting to harvest. Shadehouse experiments were conducted in summer of 1996. Ratios of pine bark to WE tested were 100% pine bark, 1:3, 1:1, 3: l, and 100% WE by volume. Plant heights, widths, and visual quality ratings were obtained monthly throughout the 16-week experiment. Leaf, shoot, and root dry weights and leaf nitrogen concentration were determined at harvest. Changes in volume, bulk density, porosity, and air space were also measured. Plants performed poorly in WES, pH 3.4, with mortality exceeding 90%. Peat and WEC yielded similar (and best) results. Optimum plant performance for all substrates occurred in 1: 3 and 1: 1 (WE: pine bark) mixes. At concentrations over 50%, increases in bulk density and reductions in volume and percent air space in WE substrates were severe enough to negatively impact root growth and plant quality.

Free access

Randy G. Gardner and Dilip R. Panthee

combination of the Ph-2 and Ph-3 genes ( Gardner and Panthee, 2010a ). NC 2 Grape is an indeterminate, compact growth habit (brachytic, br gene) grape tomato line, which has a high sugar level and carries the ripening inhibitor ( rin ) gene ( Gardner and

Free access

Dilip R. Panthee and Randy G. Gardner

resistance to late blight ( Ph-2 and Ph-3 genes combined) and early blight (C. 1943 and PI 126445 sources) along with verticillium wilt resistance ( Ve gene) and fusarium wilt races 1 and 2 resistance ( I and I-2 genes) ( Gardner and Panthee, 2010

Free access

Yan Cheng, Qian Wang, Qingyu Ban, Jianfeng Geng, Xiao Wei Zhang, Ying Yi, and Xilin Hou

and third), whereas the other six unconditional QTLs ( ph2-5 , ph3-7 , ph8-2 , ph8-3 , ph8-4 , and ph8-5 ) were detected more than once at different measuring stages. In 2007, two of seven unconditional QTLs ( ph8-2 and ph14-2 ) were only

Free access

Bryan J. Peterson and William R. Graves

. palustris in soilless media across a range of pH; 2) assess whether pH of soils where the genotypes were native corresponds to early responses of seedlings to pH in a horticultural substrate; and 3) characterize phenotypic differences of horticultural

Free access

Dilip R. Panthee and Randy G. Gardner

of parent line NC 161L began when a cross was made in the fall of 2005 between NC 2CELBR and TB (x)-9, an F 2 selection of the Japanese pink-fruited, greenhouse hybrid tomato ‘Momotaro’ (‘Tough Boy’). NC 2CELBR was the source of the Ph-2 and Ph-3