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Starch is a mixture of two polysaccharides, amylose (AM) and amylopectin, which occurs naturally in the form of microscopic granules that are abundantly found in tubers, roots, cereal grains and fruits. In order to bring out their functional properties as thickeners and texture enhancers, starch granules are often disrupted by heating in excess water. This process, which is referred to as gelatinisation, causes the granules to swell and exude a fraction of the starch polysaccharides, resulting in a dramatic increase in the viscosity of the starch suspension. Surfactants are known to affect the different aspects of the gelatinisation process and, in particular, the swelling properties of starch. Surfactants are also known to form helical inclusion complexes with AM, the formation of which plays an important role in many of the instances in which starch and surfactants interact. This work was carried out in order to gain insight into how the surfactant structure (head group and chain length) influences the swelling properties of starch and the molecular mechanisms behind these effects. The investigations involved the study of the temperature-induced gelatinisation of starch in the presence of surfactants as well as studies on the association of surfactants to AM in solution and the solubility of the resulting AM-surfactant complexes. Information on the extent of granule swelling upon heating was indirectly obtained by means of viscometry while insight on the molecular events taking place during gelatinisation was sought by means of differential scanning calorimetry (DSC) and confocal laser scanning microscopy (CLSM). Viscometric studies revealed that, with the exception of the cationic surfactants (alkyl trimethyl ammonium bromides), short-chain (C10, C12) surfactants induce an early swelling (swelling at lower temperatures than the control sample) in normal wheat starch granules, whereas their longer chain counterparts (C14, C16) have the opposite effect. Contrary to this finding, the effect of surfactants on the swelling of waxy wheat starch granules, an AM-free starch variety, is not influenced by the surfactant chain length but by the head group charge of the surfactant. The enhancing/restricting effect of surfactants on the swelling of normal wheat starch is not correlated to their effect on the early aspects of gelatinisation (onset of the gelatinisation transition) but is, in most cases, associated with the dissociation temperature of AM-surfactant complexes formed simultaneously as the granules gelatinise. CLSM studies revealed that, compared to a longer-chain surfactant (C16), a short-chain (C12) surfactant has the ability to penetrate further into the granule matrix during gelatinisation, which may favour its availability for interacting with different starch granule components during gelatinisation. Studies on the interactions between AM and surfactants with different chain length (C12 vs. C16) and head group (sodium sulphates vs. maltosides) revealed that the presence of a charged head group favours the water solubility of the resulting AM-surfactant complexes. However, this effect can be counteracted by the effect of the surfactant chain length: an increase in the chain length (C12 vs. C16) decreases the solubility of the complex. / QC 20100913

The effects of microbial growth, packaging film permeability, and freezing on the discoloration of beef was assessed by measuring myoglobin derivatives and specifically the rate of formation of metmyoglobin on the surface of Longissimus dorsi and Semimembranosus bovine muscles during 12 days of storage at 2°C. Frozen thawed sterile beef samples experienced higher metmyoglobin formation than fresh sterile beef samples. By day 2, up to 20% metmyoglobin was formed in the thawed samples whereas, the fresh samples reached this value after day 6. After 6 days, the growth of Pseudomonas florescence had a significant effect on myoglobin oxidation and this behavior continued for the remaining period of the storage. Gas barrier film and gas permeable film exhibited similar results at day 0 and day 3 of storage, however at day 6 of storage, samples packaged with the gas barrier film showed metmyoglobin percentage significantly higher that those packaged with gas permeable film. (Abstract shortened by UMI.)

Disease due to the consumption of food contaminated with enteric microorganisms has been well established. The first study described in this dissertation was designed to determine the effect of relative humidity on the pre-harvest survival of enteric pathogens on the surfaces of fresh produce. Additionally, Clostridium perfringens was evaluated as an indicator of fecal contamination on fresh produce. Pathogenic and surrogate microorganisms, including Escherichia coli O157:H7, Escherichia coli ATCC 25922, Salmonella enterica subsp. enterica, Shigella sonnei, C. perfringens, coliphage PRD1, feline calicivirus (FCV), and hepatitis A virus (HAV), were inoculated onto the surfaces of cantaloupe, iceberg lettuce, and bell peppers. Experiments were conducted in a controlled environment chamber. Survival of microorganisms on the produce surfaces was not uniformly affected by relative humidity. However, due to the survival of all microorganisms at least 14 days in at least one experiment, measures should be taken to lessen the exposure of produce to fecal contamination as harvest time approaches. C. perfringens survived longer than all other bacteria and feline calicivirus in all experiments, with the exception of E. coli O157:H7 and S. enterica subsp. enterica on lettuce. This trend suggests that C. perfringens may be an acceptable indicator of bacterial contamination and survival in various environments and on different types of crops. The second study was conducted to determine the intake of heterotrophic bacteria by the average person in the United States from food and water. A literature review was conducted to determine the concentration of heterotrophic plate count (HPC) bacteria in foods and water from the household tap. Food items from grocery stores and fast food restaurants in Tucson, AZ were also evaluated for HPC bacteria. It was determined that in the United States, 0.048 to 4.5% of the typical consumer's HPC bacteria intake is derived from water consumed from the household tap. Therefore, HPC bacteria in tap water do not represent a significant source of the total HPC bacteria consumed in the average diet of individuals in the United States.

A number of alternatives were considered to keep pecan processing economically competitive and sustainable. The industry needed a low risk evaluation technique for testing new high capital plant configurations. A simulation model was developed using the AweSimTM simulation system to form the model structure and framework. The Visual SLAMTM and Visual BASIC programming languages were used to build a network model that provided a mathematical-logical representation of the system. The model mathematically expresses all sub-processes including moisture conditioning, pasteurizing, cracking, shelling, sizing, manual and electronic sorting, resizing, resorting, and packaging. The pecan process simulation model consists of 24 RESOURCES, 353 ACTIVITIES, 48 AWAIT/QUEUE and FREE nodes, 83 BATCH and UNBATCH nodes, 79 ASSIGN nodes, 20 COLCT nodes, 39 GOON nodes, 10 other miscellaneous nodes and a graphic user interface (GUI). The model provides information on equipment utilization, delays, queues and bottlenecks for each process in the system. It also predicts total pecan cracked and total pecan packed, including details of production for each size class i.e. halves; large; medium; small; midget; fine; granule; and oil stock. The model was validated quantitatively by comparing output with actual production figures and qualitatively by plant management. Five options of process alternatives were simulated using the pecan simulation model. The first alternative (including 3 options) was a management proposed configuration for dual electronic sorting of pecan halves to reduce the shell pieces and ensure a lighter color product. Two options were found not viable as they required major capital investments and plant reconfiguration. The third option for dual sorting was found to be a viable process alternative with minor labor additions.

Mapping quantitative trait loci (QTL) using genetic markers is the first step in implementing marker assisted selection programs. Microsatellite loci and polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) were used as genetic markers for QTL affecting carcass traits: hot carcass weight (HCW), 12th rib fat thickness (FT), kidney, pelvic and heart fat (KPH) percentage, marbling score (MB), quality grade (QG), ribye area (REA) and yield grade (YG) and growth traits: weaning weight (WW) and yearling weight (YW). Phenotypic data were collected on seven Angus half-sib family groups with an average of 28 progeny per sire. DNA extracted from ear tissue samples was used evaluate nine microsatellites covering a 40 centimorgan (cM) region on chromosome 2, and thirteen microsatellite markers and one PCR-RFLP spanning 38 cM on chromosome 11. Each sire was heterozygous for an average of 4 markers for each chromosome. Data were analyzed by family with the interval-mapping program, ANIMAP. The results revealed that the region on chromosome 2 flanked by the microsatellite loci BM2808 and RM041 were strongly associated with KPH percentage (total LOD = 5.81) with an effect of about 1.5 phenotypic standard deviation in one family. Markers BMS2872 (46 cM), BMS2024 (55 cM), and BMS1126 (56.3 cM) on chromosome 2 tend to be associated with REA, HCW, and YW (total LOD of 2.8, 3.75 and 2.5). Regions nearby BMS989 (85.4 cM), BMS2208 (113.2 cM), and HEL 13 (114.5 cM) on chromosome 11 indicate linkage associated with KPH, FT and MB respectively (total LODs of 3.56, 3.1, and 2.54). All these marker-linked QTLs had an estimated effect more than .75 phenotypic standard deviation. These findings show that there are several chromosome regions associated with carcass traits in beef and demonstrate the power of genetic linkage analysis to detect these regions even in small families.

A study for non-destructive measurement and analysis of agricultural products was undertaken. Some enhancements were made to a spectrophotometer, DK-2A to meet the requirements of low uniform error band when using the factor analysis method. The instrument was modified by adding an integrating sphere, optical transducer, and electronic interface linked to a computer. The instrument was calibrated using targets traceable to NITS standards of BaSO₄ with mixtures of Carbon Black. This gave a range of known reflectance and provided consistent and reproducible data every 5 nm wavelengths between 350 nm and 800 nm. The spectral wavelength bands of the different biological materials were studied with target factor analysis. Target factors were applied in biological materials to characterize the important spectral properties. Pigment of foods, chlorophyll, carotenoid and myoglobin were separated from the spectral response of oranges, apples and meat. Their respective spectral signatures were determined.

Exergy analysis is applied in the thesis research to evaluate the energy usage of a pilot scale milk processing system. Using water as made-up fluid milk, the performance of separate components of the system was examined during steady state operation using both exergy and energy principles. The irreversibility distribution among these components was obtained to show the impact of energy degradation in each component on the overall system thermal performance. The difference between energy and exergy methods is discussed through comparisons of First and Second Law efficiencies to demonstrate the importance of exergy analysis. A mathematical programming model was constructed in terms of the exergy concept and solved numerically in an attempt to find a set of optimal operating state variables (temperatures and flow rates) under which irreversibility of the entire system is theoretically minimized. Finally, suggestions for operational management of the system and its components are presented which could increase the efficiency of energy usage in the system, thus reducing energy costs.

Three commercially available herbal tea preparations (Weightless, Female Toner, and PMS) and one single ingredient herbal preparation, Chaparral (Larrea tridentata), were sequentially extracted with solvents of decreasing polarity (water, methanol and chloroform) and the crude extracts obtained screened for toxic/mutagenic potentials using the brine shrimp (Artemia sp.), mouse acute toxicity, Salmonella/microsomal mutagenicity, and chicken embryo bioassays. The crude aqueous extract from Weightless Tea was very toxic to brine shrimp larvae and had a cathartic action in mice at the highest concentration tested. While Weightless tea crude water extract was not mutagenic to Salmonella typhimurium TA100 at the concentrations tested, three chromatographic isolates obtained from a silica Gel 60 column were mutagenic to the test organism. Two of these isolates were detoxified after inclusion of a microsomal activation system. The teratogenic potentials of these isolates are unknown as the results obtained from the chicken embryo bioassay were not conclusive.

<p> To promote its use in nutraceutical and functional food ingredients, jiaogulan (<i>Gynostemma pentaphyllium</i>) of different sources, genotypes and parts of the plant were investigated for their chemical profiles and biological properties. The first part of this research studied five commercial jiaogulan for their phytochemical profiles, and antioxidant, anti-proliferative and anti-inflammatory effects. It was found that individual jiaogulan samples significantly differed in their chemical and biological properties. The second part of this research further investigated phytochemical compositions and biological activities in different genotypes and parts of jiaogulan. The results indicated that different genotypes or plant parts of jiaogulan may have different biological activities. The results led to the third study to develop chromatographic fingerprinting techniques for differentiating genotypes and plant parts of jiaogulan using LC/MS. LC-MS fingerprints combined with PCA were able to differentiate diploid and tetraploid, and the leaf and whole botanical jiaogulan. The results from this research suggest the potential use of selected jiaogulan to improve human health while enhancing food agriculture economy, and indicate that HPLC fingerprinting may be a useful controlling the quality of jiaogulan.</p>