Levulose (D-fructose, fruit sugar), C6H12O6 is a white crystalline ketohexose. This sugar has distinctive properties which make it of commercial interest. It is more costly than ordinary table sugar (sucrose). Levulose is characterized by a high degree of sweetness (6), great solubility (20), and medical usefulness when administered intravenously. Joslin (21) and Root and Baker (32) found levulose to be of great value in the treatment of diabetes. According to Daniel (8), it is assimilated and oxidized more quickly than sucrose, supplying the necessary energy requirements for the human system. Additional uses of levulose have been reported by McGlumphy and Eichinger (27), which include its application to improve the quality and the flavor of jams, jellies, marmalades, canned fruits, carbonated beverages, and corn sugar. Plants of the family compositae contain large amounts of levulose polymers, but the dahlia, chicory, and Jerusalem artichoke are the most promising sources because of the high levulose content and the ease of production (13). The tubers of Jerusalem artichoke were used in this study because they offer an inexpensive and prolific source from which levulose can be extracted. Since most of the levulose units in the artichoke tubers are linked together to form inulin or carbohydrate intermediate compounds between inulin and levulose, it is necessary to hydrolyze the material in order to free the levulose. Several investigators have reported the use of acid compounds. Anderson and Greaves (1) used H2SO4 for hydrolysis, while Yamasaki (41) used HC1 for the same purpose. Kleiderer and Englis (23) obtained complete hydrolysis of inulin by use of CO2 and SO2 at a pressure of 1000 pounds per square inch at 150o C. for 60 minutes. As fare as can be determined from the literature, little work was done prior to 1953 using radioactive material to study peaceful uses of atomic energy. Since that time, a law was passed by the United States Congress authorizing the use of radioactive material for peaceful purposes, thereby making it possible to use atomic energy for this study. Since previous work has shown that gamma rays can convert starch to simple sugar (33), it was therefore, assumed that the inulin and other carbohydrate intermediates of Jerusalem artichoke upon hydrolysis by beta or gamma rays might yield fructose (35). The primary purpose of this study was to determine the effects of beta and gamma rays on inulin and other carbohydrate intermediate compounds present in the Jerusalem artichoke tubers and to compare the results with those obtained by hydrolysis with radiation plus hydrochloric acid.

This study was designed to answer a three-fold purpose. Primarily, it has endeavored to measure the inhibitory effect of three antibiotics (potassium pencillin, dihydrostreptomycin, and oxytetracycline) on lactic acid producing organisms. The lactic acid-producing organisms include Streptococcus lactis, Streptococcus thermophilis, and Lactobacillus bulgaricus. The determination of an effective dose of a given antibiotic which will inhibit 50 percent of the lactic acid-producing organism (E.D.50) will be established. A 50 percent cut in acid development will certainly lead to an inferior product. The secondary purpose has related to the detection of inhibitory substances (antibiotics) in milk. What is the possibility of detecting the concentration of antibiotic which correlates to the E.D.50 established in the first phase of the problem? The third purpose embraces a study of the sensitivity of tests for detecting inhibitory substances.

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.

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.