The story of the development of food preservation is as old as the story of man. Cavemen and nomadic tribesmen have little heed to food preservation. They threw away the food left when their hunger was satisfied and searched for more when famished . However, from the time men began to settle down and have permanent homes, the need for some means of retarding food spoilage has been evident.

Four lots of Cottage cheese were made from the same pasteurized skimmilk; three lots by a direct acid procedure, and a fourth control lot by a conventional culture method. Direct acid curd was formed by cooling the skimmilk to 4C, acidifying to pH 4.6 with concentrated HCl, and warming by electrical resistance to 32C without agitation. Prior to acidification, the three direct-acid lots were treated as follows: 1- No culture, 2- 5% lactic culture added and the pH allowed to reach 6.0, 3- Same as 2 except the pH was allowed to reach S.S. The control lot was set at 32C with 5% lactic culture, and cut at the A-C end point. All lots were cut with 6.35 mm knives, cooked to 62C in 120 min, washed, drained and creamed. Growth of lactic streptococci in skimmilk prior to making direct-acid Cottage cheese increased the non-protein nitrogen in the milk, increased the firmness and moisture content of the uncreamed curd, and significantly improved the meatiness and body and texture scores of the creamed Cottage cheese. Addition of calcium chloride, disodium phosphate, and sodium citrate to Cottage cheese milk did not improve the body and texture of direct acid Cottage cheese.

Each year in the State of Utah, thousands of pounds of a number of varieties of bulk end packaged cheese are returned to the manufacturing plants from the stores and other distribution points. The main reasons are: broken wrapper or rind, crushed or otherwise mutilated package, and mold development.

Ice cream mix was fermented with yogurt cultures of Streptococcus thermophilus and Lactobacillus bulgaricus to four different pH's then frozen in a batch ice cream freezer. A consumer panel of 120 people tasted samples of strawberry flavored product with pH's of 4.4, 4.7, 5.1, and 5.4 and commercial frozen yogurt as a standard. Results from the panel were used to predict a preferred pH of 4.9. Another panel of 181 people compared product at pH 4.9 with 10, 15 and 20% strawberry flavoring. There was not a statistically significant difference among levels of flavoring. Starter culture populations and lactase activity were monitored for one month both in yogurt and in the frozen fermented ice cream mix. Lactase activity and colony counts progressively decreased in refrigerated yogurt at 4°C during the 30-day period. In frozen fermented ice cream mix, lactase activity and colony counts decreased slightly. The fermented ice cream mix can be held frozen for more than one month with active lactase activity, and viable colony counts, but refrigerated yogurt does not have a shelf life of more than one month.

The Technicon OSCC II was evaluated for application in dairy herd improvement central laboratories. Dilution using a Fisher Autodiluter made sample preparation for assay less time consuming and more convenient and resulted in the same accuracy as with the manual syringe technique. Sample storage and the presence of a potassium dichromate preservative tablet had little effect on somatic cell count when tested within two days at room temperatures (20-23 C) or within four days at refrigeration temperatures (4-7 C). The preservative tablet caused an average increase of 14,000 cells/ml. The average cell count dropped 26 percent following two days at 20-23 C. Potassium dichromate interfered with the protein determination of milk using the Udy dye-binding method. There were poor correlations between somatic cells and various milk components from 1292 random milk samples from three herds during a six month survey. The best correlation found between somatic cells and casein/protein (%) was -0.32 in the G. W. Salisbury herd and -0.58 in the Utah State University herd in January, 1974. Cost of running a somatic cell count was estimated to be 6.6 cents if 10,000 samples were assayed monthly.

The Bureau of Indian Affairs has recently completed or is now in the process of building 19 new grade schools on the Navajo reservation. Some of these schools are boarding schools, and some are day schools, but each new school needs school lunch personnel. To meet this need intermountain School added to their curriculum a course in Quantity Foods to be given to Junior and Senior High School girls as a two year vocation. This necessitated the development of a 2 year course outline for the 2 year Quantity Food class, which gave the girls 4 hours daily practical training in quantity foods in a well equipped institutional kitchen. This also gave the girls experience in using institutional equipment and in planning, preparing and serving meals for 50 daily. In addition to the need on the Reservation for school lunch personnel, the Bureau of Indian Affairs pays good wages for a High School graduate with vocational (quantity food) training. The beginning salary may range from $4,440 per year to $5,540 per year, depending on their G. S. grade. They receive the fringe benefits paid all government employees, one day a month accumulative sick leave, 13 annual leave, 8 paid national holidays, and a good retirement program. If the students do not desire to return to the reservation schools after training, they can secure employment in hospitals, nursing homes, private or tribal restaurants. Emphasis is placed in this course on quantity cooking and not waitress training, because cooks receive higher salaries. Each week an elementary class of Indian students was served lunch and had an opportunity to eat family style, on tablecloths, dishes, etc, and to practice good manners, table etiquette, and other accepted social graces. Before the class started, the Instructional Dining room and kitchen had to be equipped with stoves, ovens, dishwasher, storage cupboards, dishes, tableclothes, pans, etc. Information on a detailed course outline for this age level and for Navajo girls was practically non-existant. An outline was developed for the course of study to be used each of the two years. The first time each one was taught adaptations or deletions were made to meet the needs of these quantity foods girls, and the program. The resulting course of study are presented in this paper.

The metachromatic agar-diffusion test of Lachica, Hoeprich, and Genigeorgis (1971) was modified by adding 17 ml of the agar medium to a 100 by 15 mm plastic petri dish, using 5 µl samples and 3 mm wells. The test detected 0.5 ng/ml of thermonuclease in 3 hr at 37 C. This was equivalent to 106 to 10 7 cells/ml of Staphylococcus aureus strains 196 E, 14458, and 19095 grown in Brain Heart Infusion (BHI) broth. The test sensitivity was decreased ten fold in raw and pasteurized milk. One-half gram of cheese was dissolved in 4.5 ml of 0.1 M sodium citrate for quantitative studies. When staphylococcal (>8 x 10 /ml) contaminated raw milk was pasteurized and made into cheese, more thermonuclease activity/ml was noted in the curd than whey. During prolonged storage at 4 C, thermonuclease activity decreased in raw and pasteurized milk and laboratory made cheese. Bacillus subtilus, Streptococcus faecalis var liquefaciens, Streptococcus thermophilus, and Streptococcus cremoris strain ML8 reduced thermonuclease activity during growth incubation in BHI broth. Thermonuclease was detected directly in staphylococcal contaminated 7 laboratory aged cheese (>10 /gm) without prior purification, concentration, or extraction procedures.

Lycopene has recently received interest as an antioxidant in human tissues. These same antioxidant properties present challenges in preventing oxidative degradation within food products. In this research, degradation of lycopene in model emulsion systems was examined to better understand the chemical stability of this potential functional food ingredient. Lycopene in corn oil or hexadecane was used to make oil-in-water emulsions using small molecule surfactants. Emulsion color loss was used to estimate lycopene loss and was monitored using an integrating sphere. Lipid hydroperoxide and hexanal formation was used to monitor the development of lipid oxidation. Oxidation and color loss were found to be influenced by surfactant type, with the fastest rates occurring in emulsions stabilized by anionic sodium dodecyl sulfate (SDS) and slower rates occurring in emulsions stabilized by cationic dodecyltrimethylammonium bromide (DTAB) and nonionic Brij 35. Lycopene oxidized in the presence and absence of unsaturated fatty acids, suggesting that degradation can occur by mechanisms that do not involve lipid oxidation products. Further understanding of the mechanisms of lycopene degradation was gained by exposing emulsions to light, varied pH, a metal chelator, and a free radical scavenger. Results suggest that transition metal induced oxidation of lycopene may be the predominant mechanism of degradation at low pHs where transition metal solubility is high. At higher pHs, where metal solubility is lower, attack by free radicals was also found to be contributing to lycopene oxidation. The role of ferric and ferrous species of iron in lycopene degradation was also investigated. In SDS-stabilized emulsions, and in bulk hexadecane, lycopene was found to degrade fastest in the presence of ferric iron. Ferrozine chelation testing show that this degradation is likely due to the reaction of lycopene with ferric ions to produce the ferrous species and a lycopene radical cation. In nonionic, Brij 35 and Tween 20 emulsions, ferrous iron resulted in the most rapid lycopene degradation. While further work is needed to clarify these findings, results from ferrozine analyses suggests that ferrous ions may be oxidized to the ferric species by naturally present hydroperoxides present in the surfactants, and then go on to attack lycopene.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1983. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 187-195. / by Masakatsu Akedo. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Nutrition and Food Science, 1984. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 150-157. / by J. Antonio Torres. / Ph.D.