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Paul Wilson

Jalapeños are versatile peppers with both green and mature-red peppers used fresh and in processed products. Peppers can be dried, pickled whole in brine or as salted mash for sauces. Mature fruit can also be smoked and dried to produce chipotle which can be used in several ways including preparation of sauces. Although there are many individual cultivars of jalapeño peppers available, little is known of their processing characteristics. Most food processors still rely on fresh-market supplies rather than contracting specific cultivars which might provide better processing characteristics. A study was begun in Summer 2005 at LSU to provide information concerning the processing characteristics of commonly available jalapeño cultivars. Over a 3-year period, each cultivar will be evaluated in fresh form, as pickled whole fruit, as salted mash and as smoked chipotle. Besides good cultural production qualities, pepper cultivars that will be manufactured into processed products should have 1) acceptable and consistent heat content, 2) good stable color and, 3) consistent/suitable size (for whole pack). Seventeen jalapeño cultivars were evaluated in fresh green, brine-cured green and mature-red state for fruit surface color, average fruit weight, dry weight, and percent seed.

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Edward Bush, Paul Wilson, and Gloria McClure

A study to determine the influence of light duration on seed germination was performed in a temperature-controlled growth chamber. Light treatments consisted of 0 (control), 6, 8, 10, 12 and 14 h of light exposure. Cool fluorescent light bulbs provided 19 μMol·m-2·s-1 light. Fifty seeds of each treatment were placed into separately labeled 6.0-cm-diameter petri dishes lined with Whatman #42 filter papers moistened with 2 mL of distilled water. Seed of both species germinated poorly in the control treatment. Mean time of germination (MTG) and germination percentage increased for both species when seeds were exposed to light. Pre-soaking seed in gibberellic acid (GA) significantly improved germination percentages of both species compared to the untreated control. Centipedegrass germination percentage and MTG also increased with light exposure. Carpetgrass seed germination was not enhanced by GA treatments with light exposure. The results of this experiment suggests that, if seed are covered too deeply, excluding light, MTG and percentage germination will be reduced. However, pre-soaking seed in a GA solution can improve dark germination by as much as 50% for both grass species.

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Nolan Farace, Charles E. Johnson, Paul W. Wilson, and Witoon Prinvawiwatkul

Fruits from five mayhaw selections were harvested and frozen at –2 °C. Juice was extracted with a steamer and kept in storage at 5 °C until processing. Percent soluble solids, percent malic acid, initial pH, and color were then determined for postharvest characteristics. 550 mL juice was placed in a 2000-mL beaker and heated until boiling. Dry pectin mixed with a portion of the total sugar equivalent to 5–10 times the weight of the pectin was sprinkled into the boiling juice. Once pectin was in solution, the amount of sugar to obtain a ratio of ≈45 parts fruit: 55 parts sugar was added to the mixture. The mixture was cooked until the soluble solid reading reached 65% and then poured into jars to cool to room temperature. The five mayhaw jellies alone with one commercial apple and one commercial mayhaw were evaluated using a panel preference test. Evaluation was based on a scale from dislike extremely to like extremely. Preference scores indicated that mayhaw jellies were preferred to a commercially available apple jelly. There was a definite preference to deep red colored jellies. The specific varietal jellies were preferred to a commercially available mayhaw jelly.

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Paul W. Wilson, David H. Picha, and John M. Aselage

Changes in fructose, sucrose, and glucose were investigated in cured roots of `Beauregard', `Jewel' and `Travis' sweet potatoes stored at 15°C and 1.5°C for 8 wk. Samples of 6 roots each in triplicate were analyzed at 2 wk intervals. At each interval, samples were also heated for 5, 10, 20 or 40 min. at 100°C to determine changes in rate of maltose conversion. Roots stored at 15°C displayed gradual or no increase in sugars over the 8 wk. Roots stored at 1.5°C increased more rapidly in sugars, especially fructose, over the same time. `Jewel' had the greatest increase in the sugars when stored at 1.5°C. There was no consistent pattern of maltose conversion in roots stored at 15°C over the 8 wk storage time. Roots stored at 1.5°C displayed a reduction in ability to convert starch to maltose upon heating. Less maltose was produced with increasing time of storag at 1.5°C. `Beauregard' and `Jewel' changed the most, while `Travis' changed only slightly.

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Edward Bush, Paul Wilson, Dennis Shepard, and James McCrimmon

An experiment to determine the nonstructural carbohydrate composition and nodal survival (LT50) of common carpetgrass was conducted between 1993 and 1994 at Baton Rouge, La. Nonstructural carbohydrates in stolons were primarily sucrose [70-130 mg·g-1 dry weight (DW)] and starch (8-33 mg·g-1 DW). Total nonstructural carbohydrate (TNC) composition of stolons ranged between 30 to 165 mg·g-1 DW. Node survival following exposure to 2 °C ranged from 0% in August-sampled grass to 48% in December. The LT50 following acclimation under field conditions was -2 to -4 °C. Environmental factors influenced nonstructural carbohydrate composition, partitioning, and node survival. No relationship between TNC concentration and low-temperature tolerance was found. This research confirms previous reports that low-temperature tolerance of carpetgrass is very poor, and its culture may be limited to geographical areas having moderate winter temperatures.

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Virginia Thaxton, Ed Bush, Ann Gray, and Paul Wilson

Proper irrigation practices are important in the production of container-grown woody ornamentals. When choosing irrigation methods, nurserymen must attempt to maximize production and comply with public policies mandating decreased water usage and runoff. One of these methods schedules irrigation based on plant demand, using tensiometers to measure matric potential of the substrate. While tensiometers have been used successfully with agronomic crops in the field, their effectiveness in irrigation management of large container-grown woody ornamentals has not been extensively tested. The objective of this study was to determine the effect of four irrigation treatments (7 cb tensiometer setting, 14 cb tensiometer setting, 1 time a day application, 4 times a day application) on the production of the ornamental tree Bald Cypress over a 9-month period. Growth differed significantly among treatments. The highest growth index was observed in the 4 times a day and the 7 cb tensiometer treatments, followed by the 1 time a day and 14 cb treatments, respectively. Effluent and leachate (pH, EC, N, P, K) were also measured. Percent effluent volume was highly variable, with maximum volume occurring in June for the 7 cb setting (82%) and in October for the 1 time a day treatment (47%). Higher pH values (7.0 to 8.0) initially occurred in the timed irrigation treatments and higher EC values (2.0–6.0 mmhos) were found in tensiometer treatments; over time, differences among treatments decreased for both variables. Substrate concentrations of N, P and K varied significantly among treatments, while no significant differences were found in the leaf tissue analysis.

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Edward Bush, Ann Gray, Virginia Thaxton, and Paul Wilson

Proper irrigation management is essential for producing quality container-grown woody ornamentals and reducing off-site runoff. Research has shown that tensiometers can be used as an effective tool to schedule irrigation for woody ornamentals. The objective of this experiment was to compare the effect of cyclic and tensiometric irrigation methods on growth of lantana. Lantana camara `New Gold' liners were established in a 3 pine bark: 1 peat:1 mason sand (by volume) medium. Low-tension switch tensiometers were compared to scheduled overhead [one time a day (1×) at 0600 and cyclic irrigation three times a day (3×) at 0600, 1200, and 1800] for the production of 1-gallon lantana plants. Three low-tension tensiometers (1/block) were set at 7 cb and allowed to irrigate over a 12-hour period. Three separate planting dates occurred and then terminated after ≈7 weeks. Tensiometric irrigation increased root and shoot growth compared to scheduled irrigation for the 24 May 1999 harvest date. Cyclic irrigation produced plants with shoot and total root weights >1× and tensiometer treatments for the September harvest date. Tensiometers sharply reduced irrigation requirements compared to scheduled irrigation volume by at least 50% of the 1× and 3× treatments weekly. Analysis of nutrients in leachate for June indicated increased B and Fe concentrations in the 3× irrigation treatment. Lower concentrations of Ca, Mg, and Na were measured in August. Lantana growth was acceptable for all irrigation treatments and harvest dates.

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Foong M. Koh, Gloria B. McClure, and Paul W. Wilson

In Summer 2003, sorbic acid was detected in a processed Louisiana product that had been shipped internationally. This discovery caused the food product to be rejected by the foreign market since sorbic acid was not declared on the label. The source was eventually traced by an analytical lab to a garlic powder component used in the product. Subsequent evaluations by the lab of fresh and dried garlic products obtained from stores indicated sorbic acid. The presence of sorbic acid suggested that it might either be a contaminant or a previously unreported naturally occurring component of garlic. To determine which was more likely, 12 garlic varieties were planted in Baton Rouge, La., during September 2003 and harvested the following spring. In addition to this harvested garlic, fresh garlic, garlic juice and garlic powder were purchased in May 2004 from three local stores. All these samples plus the original product were analyzed for sorbic acid using spectrophotometry and HPLC methods at the LSU Horticulture Dept. None of the samples contained measurable quantities of sorbic acid except for the original product. Since there appears to be no naturally occurring sorbic acid in garlic, it is likely that at least a portion of the fresh and processed garlic distributed in the U.S. during 2003 may have been adulterated with sorbic acid.

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Paul W. Wilson, Gloria B. McClure, and Julian C. Miller Hall

The demand for hot sauce products continues to expand in the U.S. In the case of jalapeno pepper sauce, there are many cultivars available for sauce production but those best suited for processing have not been adequately determined. Six cultivars (four replications) of jalapeno peppers (`Coyame', `Grande', `Jalapeno-M', `Mitla', `Tula' and `Veracruz') were evaluated for mash fermentation. The attributes studied during mash aging were color spectra, capsaicin content and fermentable sugars. Fructose and glucose were the predominant sugars in jalapeno peppers and these sugars were utilized gradually with time indicating slow fermentation by microorganisms in the 15% salt mash. Capsaicin and dihydrocapsaicin were the predominant capsaicinoids in the jalapeno peppers with `Tula' containing the greatest concentration and `Veracruz' the least. All mashes displayed an apparent and unexpected rise in measurable capsaicinoids up to 6 months with a decline at 12 months. Color changes in the pepper mash were rapid initially but slowed after the first month of fermentation. Percent reflectance in fresh ground peppers was strongest in the range of 550–560 nm but, after salting, reflectance shifted to 580–590 nm and remained throughout the fermentation. Based on the characteristics tested, any of these cultivars would make a suitable mash for sauce. The heat content of the final product could be controlled by cultivar selection or through blending.

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Edward W. Bush, Paul Wilson, Dennis P. Shepard, and Gloria McClure

Priming or presoaking seed of common carpetgrass (Axonopus affinis Chase) and centipedegrass [Eremochloa ophiuroides Munro. (Kunz)] increased germination percentage and decreased mean time of germination (MTG) at 20, 25, and 30 °C. The effect of presoaking and priming was dependent on grass species and temperature. The optimum seed germination temperature for both of these warm-season species was 30 °C. Maximum effect on common carpetgrass or centipedegrass seeds was achieved by priming in 2% KNO3; higher concentrations did not improve germination percentage or MTG, and 4% was in some cases detrimental. Germination was higher and MTG lower at 20 and 30 °C than at 15 °C. Presoaking common carpetgrass and centipedegrass seeds was the most efficient seed enhancement treatment for germination at 30 °C.