Studies on the Ripening of Cheddar Cheese: Identification of Nonstarter Lactic Acid Bacteria Isolated from Cheese and their Role in Flavor Development, and the Formation of Calcium Lactate Crystals.
In 1999, U.S. natural cheese production had the largest growth since 1992 – up 6% or 451.9 million pounds over 1998 levels. American-style cheese varieties represented 45% of the total U.S. cheese production, and Cheddar cheese accounted for 79% of the American-style cheese produced. This suggests the importance of Cheddar cheese to the U.S. cheese industry, and California is the second leading producer of natural cheese in the U.S.
Several quality attributes of Cheddar cheese are taken into consideration in its suitability for marketing. For retail cuts and slices, which are packaged in clear plastic wrapping, the appearance of the cheese affects the visual appeal to customers. Some of the body, textural and uniformity of color characteristics of retail cuts of Cheddar cheese come into play in the visual appeal to the customers. Open texture either caused by mechanical or gas-induced openings, seamy curd defect, localized bleaching of color, and the prevalence of white crystalline encrustations are some of the defects that diminish the visual appeal of the cheese. Some consumers often mistake the crystals to be surface mold growth. Visual defects are often magnified in aged cheese, which fetch premium price. The occurrence of white crystalline encrustation is a common defect. Cheeses with such defects are generally returned and become an economic loss to the manufacturer. Although the identity of the white crystalline material and its probable causative agents has more or less been established, a clear understanding of the phenomenon of formation of the crystals is unknown. Therefore, knowledge of how crystals form and why they form in cheese would help derive control measures necessary to prevent crystal formation and would lead to insuring quality cheese and increased profitability to the cheese industry.
Modeling Height to Crown Base and Ladder Fuels in Giant Sequoia Groves.
This proposed research will develop models of the height to live crown base of conifer trees within the new Giant Sequoia Monument in the Sierra Nevada. One set of models will be developed using commonly measured tree and stand density measures (called distance independent models). Another set of models will be developed using information about the neighboring trees and vegetation (distance dependent models). We will investigate whether the inclusion of distance to neighbors is a significant improvement over the distance independent models. Both types of models can be incorporated into models of fire spread. Models of fire spread are very important in the Giant Sequoia groves because they currently have very high fuel loads due to decades of wildfire exclusion. Most of the giant sequoia groves in the Giant Sequoia National Monument are currently at high to extreme risk of catastrophic loss to wildfire under 90th percentile burning conditions (recent analysis done by Sequoia NF). Wildfire behavior in forested canopies is not well understood. These new models will enable fire management personnel to plan more effective fuel treatment strategies to protect the groves. Also, distance dependent models of ladder fuels (vertical structures that allow fires to spread to the tops of trees) will be developed using the distance dependent data.
In addition to the development of models, inventories of the giant sequoia groves will take place. Groves will be sampled for live trees, dead trees, down logs, understory vegetation (hardwoods, shrubs, forbs and grasses), surface fuels and duff. Sampling will be intense enough to reasonably assure a standard error of 15 percent for basal area per acre for live trees. Inventories use the U.S. Forest Service Forest Inventory and Analysis (FIA) process and have proven to result in a detailed and accurate documentation of existing forest structure and species composition. These inventories will be used for comparisons across the groves as well as for management purposes and future research projects.
Evaluation of Annual Bluegrass Performance Under Different Soil Depths in a Sand-Based Soil System.
Annual bluegrass is a turfgrass species with broad genetic diversity ranging from light green annual to dark green perennial biovars. This grass species is one of four commonly used for golf course greens due to its adaptation to the close mowing and high wear associated with the game of golf. Annual bluegrass is the preferred grass species for golf course greens throughout much of California, where cool moist climates are found on irrigated turfgrass surfaces. Unfortunately, this grass species has poor tolerance to temperatures exceeding 30 C. Heat stress experienced during the summer months in California results in reduced root depth and increased susceptibility to several disease pathogens. During periods of heat stress, it is not uncommon for these factors to cause necrosis on large areas of turfgrass surfaces. Personal observations and industry interviews have identified poor root depth and infection from fungal pathogens as two of the primary casual agents for annual bluegrass failure on golf course greens during heat stress. Previous research into proper management for annual bluegrass has been limited to fertility regimes and pest control. Funding of this research will be used to evaluate optimal management techniques to improve root depth for annual bluegrass during heat stress. One aspect of the study will examine moisture retention and annual bluegrass performance under 4 root-zone media depths in sand-based golf course greens constructed according to specifications produced by the United States Golf Association. Specifically objectives of this study will evaluate 3, 8, 10, and 12 inch root-zone profiles in providing adequate moisture retention and soil media depth for optimal root growth for this grass species. Secondly, this research will evaluate integrated management programs for control of fungal pathogens inhibiting root growth. Numerous chemical fungicides will be screened alone and in an integrated program to define optimal control of the fungal pathogens Colletotrichum graminicola and Sclerotinia homoeocarpa. These screens will be conducted during periods of conducive environmental conditions favoring each pathogens. Results from this research will improve knowledge in management of annual bluegrass during critical periods of heat stress.
Ecological Studies and Natural Enemy Evaluations for Citrus Peelminer.
The citrus peelminer, Marmara gulosa, is a lepidopteran rind and stem miner of citrus and other plant species. The peelminer was introduced into the southern San Joaquin Valley of California from Coachella Valley approximately three to four years ago. Subsequent to its introduction it has spread as far north as Fresno County and populations have exploded on susceptible varieties with as high as 70% fruit infestations in the Exeter area in 2001. Initial studies (conducted by UC and CDFA personnel) have shown that natural enemies endemic to the Central Valley that attack mining-type insects are largely ineffective at population control. Initial field studies on growth and development of peelminer on grapefruit indicated three factors contributing to the economic threat posed by this species: 1. Individual miners create extensive mines on fruit (average = 20 inches) and that there are several individuals (~10) per fruit. 2. Out of 100 individuals, 30% survived through the winter as late instar larvae on the rinds of infested fruit. Another 20% exited the fruit for pupation. 3. There was extensive mining on the stems of certain citrus varieties and extensive use of alternate host plant species. Research objectives include continuation of ecological studies of peelminer and releases of natural enemies for its control.
Development of Successful Sex Determination Method of Bovine Embryos Utilizing Embryo Biopsy and PCR.
Producers of domestic livestock strive to improve genetic influences in their herds. This requires identification, and propagation of animals that demonstrate desirable characteristics. The more animals available from which to select, the greater the opportunity to discover high-performance animals. Predetermination of the sex of offspring would provide a greater number of males or females from which to select the top individuals that will contribute the genetics to the next generation. Many attempts at sexing semen and identification of sex in preimplantation embryos have been mildly successful. However, recent advances in gene amplification enable investigators to use sex-specific probes to determine sex in only 1 cell removed from embryos. The biopsy method has had variable success in fresh embryos. However, manipulation of cryopreserved embryos reduces viability of the embryos (Bredbacka, 1998). Therefore, novel approaches to improve pregnancy rates may result in effective reproductive rates. One such approach is to vary the number of manipulated, cryopreserved embryos transferred into each recipient to increase the chances of successful pregnancy. The proposed research will identify the most successful techniques to biopsy and sex embryos using the mouse as a model animal. DNA from collected cells will be amplified using polymerase chain reaction (PCR) or sex specific probes to determine sex. Secondly, the most effective techniques will be applied to cattle embryos and survival rates in micromanipulated, cryopreserved embryos will be determined. Finally, recipients will be implanted with one or two embryos that sex has been previously determined. Pregnancy rates, including the incidence of twinning, will be recorded. The hypothesis is: A single method for sexing bovine cryopreserved embryos can yield high accuracy and high pregnancy rates for the desired sex.
Estimation of Distribution Uniformity from Field Evaluations of Irrigation Systems.
Distribution Uniformity (DU) measures how evenly an irrigation system distributes water to all portions of the irrigated area. Field evaluations are conducted to assess the DUs of actual operating irrigation systems, and to provide diagnostic guides for system or management improvements. In the field evaluation procedure, measurements are taken to characterize individual factors (components) which each contribute to the overall system DU. Presently, an approximate procedure is used to estimate the system DU from the component DUs, until more correct mathematical procedures have been developed. It is the goal of this project to establish those mathematical procedures.
Specifically, the objectives of the Estimation of Distribution Uniformity from Field Evaluations of Irrigation Systems project are to:
(1) Collect field evaluation data on typical irrigation systems within the San Joaquin Valley.
(2) Develop the mathematical procedures to determine the overall distribution of irrigation amounts from the measurements on each component.
(3) Describe the overall distribution of irrigation amounts in a mathematical form that will support further use of the data for uniformity and other studies.
(4) Validate or improve the currently used procedure for estimating system DUs from field evaluation data on uniformity components.
Prior work in each of these areas has been limited to theoretical computer simulations, and in many instances has not considered the full range of components affecting overall uniformity. The opportunity exists to place theory on a solid footing by basing the uniformity studies on real irrigation systems and actual field evaluation measurements.
The project will result in improved tools for analyzing irrigation uniformity. The currently used DU estimation techniques will either be validated, or improved upon if they are found to be lacking.
Farm cooperators, irrigation districts and government agencies have expressed interest and financial support for the field evaluations of irrigation systems in order to improve irrigation systems, verify the performance of new systems, and the characterize the irrigation systems within a region. Improved tools for analyzing field evaluation data will strengthen the evaluation program.
Elucidating the Genetic Mechanism of Glyphosate (Roundup) Resistance in a Biotype of Weedy Ryegrass (Iolium spp).
In a project conducted during several labs in Advanced Weed Science (PPSC 405), we demonstrated that the genetic mechanism of glyphosate (Roundup) resistance in a weedy ryegrass was not the result of genetic transfer from Roundup Ready crop species. We propose to take the next step by isolating and sequencing the target site in susceptible and genetically modified plant species so that we can better understand how the resistant ryegrass may be so tolerant of glyphosate. We will acquire the sequence for the “Roundup Ready ® gene” (i.e.CP4-EPSPS) from the U.S. Patent Office under which Monsanto has patents for its Roundup Ready technology. Next, we will compare these target site sequences with that of the glyphosate resistant ryegrass biotype. Single amino acid substitutions in the EPSPS enzyme have conferred glyphosate resistance to two other weed species, and we want to see if one of these substitutions might be explaining the ryegrass resistance. Understanding the mechanism for glyphosate resistance is significant because Roundup Ready crops on which Roundup is applied for weed control comprise a significant portion of farmed acreage in the US and California. Over 50% of the cotton in California was Roundup Ready in 2001 and that number is projected to increase for 2002. Glyphosate is currently a very effective broad-spectrum herbicide that controls almost any plant species that isn’t Roundup Ready. It has no soil activity, breaks down readily in the environment, and is relatively non-toxic to humans or animals. Preserving its mode of action by slowing down the development of resistance in the weed populations will increase the useful life of this relatively nontoxic herbicide. We can better understand how to preserve the glyphosate mode of action by understanding how weeds are developing resistance to it. This project is designed to answer questions regarding the genetic mechanisms of glyphosate resistance and will accentuate an already successful, meaningful lab exercise for undergraduate and graduate students. This project is also designed for students to acquire data for their senior projects and masters theses.
Process Improvement for Fresh Mozzarella Cheese.
Fresh mozzarella cheese is a high-moisture, perishable commodity, and is one of the many dairy products produced in California, the largest dairy manufacturing state in the nation. This fresh cheese may be improved through treatment of its cooling and packing water with ozone. Ozone gas, a potent germicide, is a tri-atomic form of oxygen. Upon release of ozone’s germicidal energy, it reverts back to oxygen thus making ozone a safe and environmental chemical for use in food processing. Ozone is the strongest oxidizing germicide readily available and its ability to kill microorganisms is well established. The impact of ozone exposure on product quality sensory attributes is largely unknown. As a result of the germicidal efficacy of ozone in cooling water and packaging water, it is unknown as to what extent ozone will extend or diminish shelf-life of the treated product.
Additionally, facility sanitation and general production process improvement will be investigated. Preliminary data indicates variability in cheese stability over time and this may be due to inadequacies in the sanitation regime prior to or during production. Any changes to the production process may result in changes to the product's sensory attributes, thus process improvement will be correlated with product improvement. This seed-grant study is designed to elicit answers to these questions and industry concerns, thus providing data for development of a grant proposal intended for subsequent submission to an outside funding agency. The ability to extend shelf-life and product safety through utilization of existing technologies can have a positive economic impact for the manufacturers and positive health ramifications for the populace of the state and the nation.
Data Collection from a Microturbine Operating on a Covered Lagoon Methane Recovery System.
This proposal is to fund the data collection from the lagoon-type methane recovery system at the Cal Poly dairy, which has approximately 300 cows, calves and heifers. The project at present consists of a 14,000 cubic meter (4 million gallons) earthen lagoon, with pump and piping to transfer the dilute dairy manure wastewater from the solids separator to the new lagoon. Also included is a 45-mil thickness, reinforced polypropylene lagoon cover of approximately 4600 square meters including Styrofoam floats, weights, tie-down and gas manifold system. This covers approximately 90% of the total lagoon surface area. The existing biogas handing system includes piping to condensate trap, gas meter, gas blower and continuous-ignition flare. A 30 KW Capstone microturbine with associated compressor and heat exchanger has also been obtained for converting the biogas into electricity. Previous CSU-ARI and WRBEP grants have paid for purchase and installation of the equipment, and this proposal is to fund the operation of this equipment. Matching funding will be received from FlexEnergy to test a “Flex-Microturbine” which is an improved model of the Capstone unit. The research plan is to operate the lagoon-microturbine system for one year in order to obtain a complete set of data including all the operating parameters – wastewater flows, biogas production, electrical production, and air emissions. This project will provide the following environmental and economic benefits: odor control by capturing the manure gases including ammonia; preventing methane, a significant greenhouse gas, from escaping into the atmosphere; reducing water pollution; and providing the economic benefit of electricity worth over $15,000 annually.
Sudden Oak Death Distribution, Detection, Ecological Impact, Control, and Spread Modeling.
In recent years, an alarming disease was found killing oaks in Marin County and has now spread to 10 surrounding counties. The cause of this disease was identified only last year to be a fungal pathogen Phytophthera ramorum. The disease this pathogen causes is called Sudden Oak Death (SOD).
Since 1995, SOD has been confirmed from southern Mendocino County to Big Sur, and is particularly severe in Marin, Santa Cruz, and Monterey Counties. Dying trees have been observed in urban and rural forests and woodlands. The main species of affected overstory plants are coast live oak, California black, and tanoak. The disease has also spread to Shreve's oak, California laurel, California buckeye, bigleaf maple, toyon, huckleberry, honeysuckle, rhododendrons, and arrowroot. Concern now exists that the pathogen may spread throughout California oak forests, be transported to the forests of other western states and even to the eastern United States. In fact SOD was discovered in Southern Oregon through aerial survey work in 2001. With the discovery of the pathogen on rhododendrons, there exists a much greater risk of human transport of the disease via ornamental plants. The actual current geographic range of SOD Phytophthera is unknown.
Project Objectives include:
1) Statewide Survey of Extent of SOD-this will result in a comprehensive analysis and reporting of the extent of SOD in the State.
2) Predicting SOD Spread using GIS and Remote Sensing: A GIS model will be developed that will be verified by continued monitoring of the spread of SOD. At the end of the project a predictive spread model will be available. Landscape effects will also be modeled to show the impact of SOD on landscapes.
3) Ecological Consequences of SOD progression in oak woodlands: This data will become incorporated into the GIS model and will show the impact of SOD on oak ecosystems.
4) Testing of Existing Phytophthora Control Compounds: Efficacy testing will determine if a compound has the potential to be utilized to control SOD.