Investigations were carried out to isolate, identify, and to characterize, major volatile components of tomato fruit. Simultaneously, the confirmation was extended to the reported tomato volatiles. The volatile extracts from field- and artificially - ripe fruits were compared qualitatively as well as quantitatively. The changes which occurred in the volatile components of the fruit at the onset of senescence also were delineated. A typical chromatogram from field-ripe tomatoes contained 60 peaks. The functional group properties of individual peaks were derived by chemical analysis. The short-chain (C3-C6) alcohols represented 10 per cent, aldehydes and ketones 32 per cent, and hydrocarbons, long-chain alcohols, and esters were in 58 per cent of the total amount of the volatiles from the field-ripe fruits. Among alcohols and carbonyls, 3-pantanol, 1-nonanal, 1-decanal, and 1-dodecanal and among esters, propyl acetate, geranyl acetate, and cetronellyl butyrate were tentatively identified as volatile compounds of tomato fruit. Linalyl acetate, citronellyl butyrate, and geranyl butyrate were identified for the first time as the components of tomato volatiles. Comparisons of volatile concentrations of field- and artificially - ripe tomatoes were made. IN the latter category of fruits the concentrations of 1-butanol, 3-pentanol, 2-methyl-3-hexanol, 3-methyl-butanal, 2,3-butanedione, propyl acetate, isopentyl butyrate, and other unidentified carbonyls were higher than those observed in the field-ripe fruits. These short-chain compounds, especially the C4-C6 moities, probably are formed in their maximum concentrations during the early stages of maturation. Under the conditions of restricted nutrient availability, sun light, and limited enzymatic activity during artificial ripening, the long-chain compounds are not sunthesized appreciably. The concentrations of some of these short-chain compounds may be to a level of masking the effects of more desirable compounds contributory to ripe tomato aroma. Notably, a pulp from the artificially ripe fruits lacked the characteristic ripe tomato aroma. The concentrations of the long-chain carbonyls and the terpene esters were low in the artificially ripe tomatoes as compared to the field-ripe ones. This may indicate major contribution of these compounds to ripe tomato aroma. An attempt has been made to theorize the mechanisms of the biogenesis of these components of tomato volatiles. The concentrations of the volatiles from field-ripe and overripe tomatoes were compared. During overripening the amounts of alcohols, aldehydes, ketones, acetates, and propionates generally decreased. However, the concentrations of diacetyl and butyric acid esters increased. It was assumed that at the onset of senescence the metabolic pathways for the formation of diacetyl and butyric acid were highly operative in tomato fruit. The mechanisms of these pathways were postulated.

Mastitis is found to some degree all over the world where cows are used for milk production. It could be classed as one of the most perplexing problems of milk production in the airy industry. The loss to the producer and the manufacturer is of considerable importance. Today sub-clinical mastitis is probably the most common form. This type of infection is commonly so mild that it passes without recognition. It will be investigated in this study. The influence of mastitis on milk composition has not been studied extensively. Very little research has been done on the influence of mastitic milk when manufactured into various dairy products. In this study, cheddar cheese and cottage cheese will be made from abnormal milk to determine the influence of sub-clinical mastitis.

Rennin is the main milk-clotting enzyme in the fourth stomach of young calves. This enzyme has been crystallized and studied by several workers such as Hankinson, Berridee, and Ernstrom, and found to be heterogeneous. It is a proteolytic enzyme, which exhibits its maximum activity on hemoglobin, bovine serum albumin, and casein in the region of pH 3.4 - 4.0. It has a specificity similar to, but narrower than, that of pepsin.

Protein was the first substance recognized as a vital part of living tissue. About 18 percent of the human body is in the form of protein, and certain protein constituents can be obtained only from dietary sources. Since meat is the chief source of protein in the normal diet, this study was aimed primarily at factors influencing quality of meat. The problem included two particular meats, lamb and turkey. The per capita consumption of lamb in the United States is lower than that for any other meat. In 1944 in the United States 6.7 pounds of lamb were eaten per capita. This amount decreased to a low of 3.4 pounds in 1951 but was followed by an increase . In 1958, a new low of 4.1 pounds per capita consumption was reported . Several factors such as regional differences, customs, supply, and habits can be listed as factors influencing these changes. The Western United States represents almost half of the total sheep production in this country, and Utah ranks among the leading Western states. Sheep and lambs produced on Utah farms in 1961 totaled 1,188,000 and represented a dollar value of $19,483,000. Palatability and tenderness of lamb can be attributed directly to the quality of the animal at the time of slaughter . Quality is determined by several factors including fat covering, which in turn is determined by the feeding regime. Thus, the producer is vitally concerned with the best feeding plan to produce the highest quality animal, while the housewife is likewise looking for the best buy for her money. The objective of the first phase of this study was to show the effect of varying rates of weight gain on palatability and tenderness of lamb . The year 1960 was a revolution to the turkey industry with a one third increase of turkey production over the previous year. In the years since the World War II, turkey consumption in the United States has nearly doubled. This can be attributed to the fact that convenience was greatly increased with the availability of eviscerated ready-to-cook turkeys, the availability of frozen turkeys throughout the entire year, some decline in prices of turkey meat compared with most other meats, and the fact that smaller turkeys or parts of the whole carcass were available as well as other factors. Many recent advances in processing turkeys have been made to decrease the time and labor spent. Technical machinery and newer methods are now used to produce the oven-ready birds. Factors, such as scalding time and temperatures, methods of feather removal, chilling time and chilling methods, freezing rates, and cooking methods have been shown to have an influence on the tenderness of turkey. As new methods and machinery are developed for shortening processing time, the effect on the tenderness of the final product should be a prime consideration. It was the primary objective of the second phase of this study to show the effect of length of chilling time as influenced by method of chilling on the tenderness of roasted turkeys . Other variables that were considered were sex differences, method of feather removal, and method of cooking.

Burke says, "Product inferiority constitutes the greatest menace to the success and progress of any industry." The ice cream industry is no exception. Improvement in the quality of dairy products is a challenge that always faces the industry. Today's products are good, but they can be improved, Sherbet is one product that should be improved most. Many ice cream manufacturers are losing a great potential market because sherbets generally are of poor quality.

The shallow, wave-swept sea floor off the central Oregon coast is used by 0-age flatfishes as a nursery ground. This dissertation is based on a series of projects designed to: 1) identify the dominant meiobenthic nematodes present in a coastal nursery area; 2) describe the important temporal and spatial scales of nematode variability at this site; 3) discuss the role of sediment disturbance in structuring nematode assemblages; and 4) relate seasonal and spatial differences in the distributions of meiobenthos to observed changes in the diet of flatfishes. The 19 numerically dominant nematode species found at the study site showed significant fluctuations in density over a 15 month period, yet their rank order based on abundance did not change. Four mechanisms capable of producing seasonal changes in nematode abundance without altering species proportions are discussed: winnowing from sediments, non-selective predation, seasonally variable food resources, and compensatory links between birth and death rates among species. Significant differences in the abundance of nematodes were found over horizontal distances of kilometers and centimeters. Sediment disturbance contributes to the generation of these spatial patterns. Over broad scales there were two distinct faunal groups associated with different water depths. The division between these assemblages was closely correlated with the threshold depth at which sediments are influenced by passing waves. On small scales (<0.25 m²), the distributions of the numerically dominant species varied seasonally. In the winter, frequent storm activity mixes the bottom sediments and randomly distributes the fauna over the sea floor. In the late spring and summer, physical disruption of sediments is minimal and biological factors, e.g., attraction between males and females, lead to aggregation. Food habits of juvenile English sole were a function of location of capture within the study area, season, and fish length. Diets of fish less than 35 mm SL varied greatly both between seasons in the same year and between years. Diets of English sole captured in trawls obtained at the same depth and different depths were similar in January 1979 but were highly variable in May 1979. These temporal and spatial differences in feeding are thought to be related to seasonal changes in the abundance and spatial distributions of benthic prey. / Graduation date: 1982

Histamine (or scombroid) fish poisoning the most frequently reported illness associated with consumption of fish despite efforts of its control. The lack of adequate control measures and unreliable detection method for histamine-producing bacteria (HPB) can in part be responsible for the high incidence of the disease. The aim of the studies was to address these concerns. Available detection methods were compared and related to histamine-production. Next, a DNA probe based on the histidine decarboxylase (hdc) gene was developed and applied to colony lift hybridization for enumeration of HPB from fish. Finally, the used of phosphate as a control of HPB was examined. The results demonstrated that the potentiometric, and PCR detection methods accurately detected high-HPB but did not detect the low histamine producing isolates. Although, the culture-based Nivens method, detected low histamine-producing bacteria, it resulted in 38% false positive responses. A hdc-probe mix from four HPB detected all 73 high-histamine producing bacteria in DNA dot-blot hybridization. However, six low and seventy-three non-HPB were not detected. Application of the hdc-probe mix in colony-lift hybridization resulted in more accurate quantification of HPB compared to the commonly used Nivenâs method. Phosphate treatment of mahi-mahi samples significantly reduced histamine-production by increasing the surface pH of the fish muscle. The ability not only to detect but enumerate histamine-producing bacteria in fish is important for evaluating the potential risks and to develop adequate control strategies prior to formation of toxic levels of histamine.

Acidification is used as a hurdle in many minimally processed foods. Decreased pH (pH 5.5) may enhance survival and virulence factor expression of E. coli O157:H7 (EC). The objective of this research was to determine the effect of different organic acids and pH on the expression of three virulence factor genes (stx2, hlyA, eaeA) in EC. Gene fusions containing the lacZ gene inserted into the stx2, eaeA or hlyA genes were created in E. coli O157:H7 with and without a functional rpoS gene. Overnight cultures were inoculated into tryptic soy broth acidified with citric, malic, lactic, or hydrochloric acid at pH 6.0, 5.5, 5.0, or 4.5 or apple juice (pH 3.5). Cell growth characteristics were characterized, and β-galactosidase activity of stressed or control cells (neutral pH, no acid) was subsequently determined to follow virulence factor production. Production of all three virulence factors was increased at pH 5.5 or 5.0 compared to production at neutral pH (p<0.05). Acid type impacted production of EaeA and StxII, but had no effect on HlyA. Production of StxII and HlyA was not detected in apple juice. At pH 5.5, cell growth was slowest in lactic acid, followed by malic and citric acids then HCl. At pH 5.0, the slowest growth was observed in citric acid, followed by malic acid, lactic acid and HCl. At pH 4.5, no growth occurred in citric, malic and lactic acids, and cell numbers decreased over a period of 5 days. In HCl at pH 4.5, cells grew slowly and increased by 2 logs over a 5-day period. Sublethal acid stress impacts virulence factor expression of E. coli O157:H7 and these effects are impacted by pH and acid type.

Lactacin B is a class II bacteriocin produced by Lactobacillus acidophilus NCFM (Barefoot and Klaenhammer 1983). Mutational, nucleotide sequence, and transcriptional analyses revealed that the genetic determinants responsible for lactacin B regulation and production are located on a 9.5 kb polycistronic region (LBA1803-LBA1791) of the L. acidophilus NCFM chromosome. The lab operon comprised 12 putative open reading frames (ORFs) organized into three clusters: a production and regulation cluster encoding putative proteins that resemble two component signal transduction systems of the AgrC-AgrA type; an export cluster encoding putative proteins that resemble ATP-binding cassette (ABC) transporters and accessory proteins, and the final cluster composed of three putative proteins of unknown functionality. Each cluster was separated by an intrinsic terminator, the strongest terminators flanked the entire lactacin B region (ΔG = -13.4kcal/mol and ΔG = -17.0kcal/mol respectively). A total of 7 genes with unknown functionality were situated in this region, each containing a double-glycine leader motif characteristic of bacteriocin structural genes and their precursors. Insertional inactivation of the gene believed to encode an ABC transporter (labT) completely abolished bacteriocin activity, implicating this region in lactacin B production. Cloning of the first four genes within this region (LBA1803-LBA1800) onto a high copy number plasmid resulted in markedly higher levels of lactacin B activity compared to the control. These ORFs encoded proteins typical to bacteriocin peptides; small, cationic peptides, each with an N-terminal double glycine leader motif. Experiments with chemically synthesized peptides revealed that LBA1800 was not inhibitory, but induced lactacin B production in broth cultures. The genetic organization of the region indicates that lactacin B production is regulated through the three component regulatory system common to many class II bacteriocin systems.

Commercial turkey flocks in North Carolina are frequently colonized with Campylobacter coli strains that are resistant to several antimicrobials and have been designated multidrug resistant (MDR). Multiple locus sequence typing (MLST) showed that the major sequence types (STs) were turkey-specific. Further subtyping using fla typing, pulsed field gel electrophoresis (PFGE) with SmaI and KpnI as well as plasmid profiles revealed that each of the major MDR STs contained strains of related, but distinct subtypes, providing evidence for genomic diversification within these STs. Numerous strains, with indistinguishable PFGE profiles, but different fla types suggested selection for specific flagellin sequences. The observed correlation between STs and the MDR profiles of the microbes indicates that MLST-based typing holds potential for source-tracking applications specific to the animal source (turkeys) and the antimicrobial resistance profile (MDR) of C. coli. The molecular basis for resistance of MDR strains to selected antimicrobials was investigated, and tetracycline resistant isolates were shown to harbor tet(O). Natural transformation studies were used to study the mechanism of transfer of antibiotic resistance genes in C. coli. Resistance to erythromycin and nalidixic acid/ciprofloxacin mediated by chromosomal sequences, were easily transferred from MDR strains to other C. coli, whereas resistance to tetracycline and kanamycin was not possible by transformation, suggesting that genes mediating these resistance attributes were plasmid-borne in MDR strains. Interestingly, tetracycline resistance could be readily transferred by transformation using DNA from another clonal group of C. coli strains prevalent in turkeys, suggesting chromosomal presence of the tetracycline resistance gene. MDR strains were found to be stable and maintained their MDR phenotype over 60 serial passages in vitro. The strains maintained their PFGE and plasmid profiles; and only minor differences in MICs before and after the 60 passages were observed. The findings from this study suggest that the certain strain types and clonal groups are prevalent among MDR C. coli from turkeys, and that resistance determinants to certain antibiotics can be transferred from these MDR strains to other C. coli strains.