Food Processing Commons^™

Wear Behaviors Of Process Cheese With Varying Formulations And The Development Of Predictive Models On Shreddability, Jason Young

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Process Cheese is manufactured by grinding, mixing, and heating with agitation one or more of the same varieties of natural cheese with an emulsifying agent to create a cheese with desirable properties. After process cheese is made, it is often sliced or shredded. Some of its properties affect how well it can be sliced or shredded and can lead to loss of material due to cheese sticking to equipment or being too crumbly. The loss of material, called wear behavior can incur significant losses to cheese manufacturing operations. The purpose of this study was to produce process cheese formulations with …

Effect Of Long Pasteurization Run Times On Bacterial Numbers In Milk, Brynli Tattersall

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This project was funded by the Western Dairy Center to understand how long a milk pasteurizer can be operated before increases in bacterial numbers are observed in the pasteurized milk. While pasteurization kills pathogenic bacteria there are some non-pathogenic bacteria that can survive and have the ability to become attached to the surfaces in the cooling sections of the pasteurizer. Some bacteria can also produce spores that survive pasteurization even if the bacterial cells are killed. Temperatures in the cooling section remain in a range suitable for growth of these heat-tolerant bacteria and can allow germination of bacterial spores. While …

Effects Of Processing And Packaging Modifications On The Quality And Shelf Life In Meats, Abdulla Khan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Shelf life of foods, mainly meat and meat products, is affected by its physical and chemical properties like color, pH, water holding capacity etc. In developed countries
food losses occur at production, retail and consumer levels with meat commodities accounting for 41% of the total loss in US during 2008. These losses are because of
spoilage due to inappropriate packaging, improper storage conditions, food wastage, and lack of consumer awareness. By focusing on shelf life and quality issues at the production level, we can overcome some of the major problems faced by the food manufacturers.

Active packaging is an innovative …

Texture Profile Analysis And Melting In Relation To Proteolysis As Influenced By Aging Temperature And Cultures In Cheddar Cheese, Taylor Rasmussen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Changes in cheese physical properties during aging are related to proteolysis by coagulant type, culture enzymes, and non-starter lactic acid bacteria (NSLAB). Storage temperature also affects aging rate. Cultures are important for flavor development , but less is understood about their role in melting and textural properties.

Our objective was to make Cheddar cheese using different cultures, to age it at 6 and 13°C, and measure physical and proteolytic properties over 12 mo to determine whether changes in texture and melting correlated with the extent of proteolysis that occurred during aging.

Cheese was manufactured using Lactococcus lactis starter culture either …

Prevention Of Pigment Deterioration And Lipid Oxidation In Ground Beef And Pork, Preetha Jayasingh

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Fresh beef was modified-atmosphere packaged in carbon monoxide or oxygen to prolong red surface color. After comparison of several packaging method using carbon monoxide, steaks pretreated with 5% carbon monoxide for 24 hours and then vacuum packaged had the best combination of color and microbial stability (5 weeks), with the least potential for carbon monoxide inhalation.

In the evaluation of ground beef in high-oxygen, modified-atmosphere-packaging, thiobarbituric-acid numbers increased over time, and the flavor was disliked slightly after 6 or 10 days of storage at 2° Celsius.

The antioxidant effect of milk-mineral was tested in raw and cooked ground pork stored …

The Influence Of Fat And Water On The Melted Cheese Characteristics Of Mozzarella Cheese, Robert Lloyd Fife

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effect of reducing the fat content of low-moisture part-skim Mozzarella cheese from 19% to less than 5% on melted cheese properties, i.e., apparent viscosity, cheese melt, and cook color, was investigated. Functional properties of melt and stretch and cook color were evaluated at d 1, 7, 14, and 28. A rapid microwave oven method underestimated the moisture content of the low fat cheeses by approximately 10%. Low fat cheese did not melt as well as did the low-moisture part-skim Mozzarella cheese although the moisture content of the low fat cheese (moisture content ranged from 62.5% to 63.6%) was greater …

Influence Of Storage Duration, Temperature, And Oxygen On Quality Of Stored Dehydrated Foods, Omima Ali Darag

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study was undertaken to determine the effect of oxygen absorber packets (OAP) (AGELESS Z.300 E) in improving the shelf-life of selected dried food products, including dried potato pearls, dried sliced apple, dried carrot, white rice, nonfat dry milk, all purpose flour, rolled oats, and wheat. Items were stored at four different temperatures (-20, 10, 21, and 29.5°C) over a period of 24 months with observations at 6-month intervals. Hunter colorimeter, thiobarbituric acid reactive substance (TBARS) germination rate, gluten weight, and volume were parameters used as quality indicators of various dried foods.

Statistical analysis indicated a significant time and temperature …

Aromatic Amino Acid Catabolism By Lactobacillus Spp.: Biochemistry And Contribution To Cheese Flavor Development, Sanjay Gummalla

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Amino acids derived from the degradation of casein in cheese serve as precursors for the generation of desirable and undesirable flavor compounds. Microbial degradation of aromatic amino acids is associated with the formation of aroma compounds that impart putrid-fecal, barny-utensil, and floral off-flavors in cheese, but pathways for their production had not been established. This study investigated Tyr and Phe catabolism by Lactobacillus casei and Lactobacillus helveticus cheese flavor adjuncts under simulated Cheddar cheese-ripening conditions (pH 5.2, 4% NaCl, 15°C, no sugar). Enzyme assays of cell-free extracts and micellar electrokinetic capillary chromatography of supernatants indicated that L. casei and L. …

The Effect Of Lactobacillus Helveticus And Propionibacterium Freudenreichii Ssp. Shermanii Combinations On Propensity For Split Defect In Swiss Cheese, Steven R. White

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

One of the least controlled defects in Swiss cheese is development of splits. Split defect is characterized by fissures or cracks in the body of the cheese that can be as short as 1 cm in length or long enough to span a 90-kg block. This defect appears during refrigerated storage after the cheese is removed from the warm room. Swiss cheese with splits is downgraded because it is unsuitable for use on high-speed slicing equipment (up to 1,000 slices per minute).

A 2x2x2 factorial experiment was used to determine the effect of different commercial Lactobacillus helveticus starters combined with …

Tryptophan Catabolism In Brevibacterium Linens Bl2, Madhavi Ummadi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Recent studies suggest aromatic amino acid catabolism by starter lactococci and flavor adjunct bacteria have a significant impact on off-flavor development during Cheddar cheese ripening. We hypothesized that a flavor adjunct bacterium, Brevibacterium linens BL2, produces off-flavor compounds from aromatic amino acid metabolism that will have a detrimental impact on cheese flavor.

The mechanism of tryptophan (Trp) catabolism in Brevibacterium linens BL2, was investigated in a chemically defined medium during incubation in laboratory conditions (no carbohydrate, pH 6.50, 220 rpm, 25°C) and cheese-like conditions (no carbohydrate, 4% NaCl, static incubation, l5°C). In laboratory conditions, metabolic studies and enzyme assays confirmed …

Biochemistry And Application Of Exopolysaccharide Production In Mozzarella Cheese Starter Cultures, Brent Petersen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study sought to investigate the role of the C₅₅ undecaprenol lipid carrier in the production of exopolysaccharide (EPS), the effect of exopolysaccharide producing (EPS⁺) starter cultures on the viscosity of Mozzarella cheese whey, and the possible protective characteristics of capsular EPS against freezing and freeze drying. Efforts to investigate the role of the lipid carrier in EPS production employed pAMbacA, a plasmid that encodes an enterococcallipid kinase that confers bacitracin resistance by increasing intracellular levels of undecaprenol phosphate lipid carrier. Unfortunately, this avenue of study was thwarted by the inability to demonstrate bacA …

Growth Of Clostridium Sporogenes Pa3679 In A Vacuum-Packaged Meat-Vegetable Product, Julie M. Racz

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Clostridium sporogenes PA 3679 spores were inoculated into a meat-vegetable mixture before extrusion, cooking, and vacuum packaging into "stewsticks" to simulate Clostridium botulinum growth. The experiment was a 3 x 5 x 2 x 3 factorial which determined the influence of pH, water activity, initial spore load, and storage period on spore survival. Spore levels decreased throughout storage for all treatments. Spore levels decreased linearly (P = 0.02) as water activity increased, in samples that were heated to kill vegetative cells and activate spores. Other significant interactions of heat-treated samples were observed with inoculum level (P < 0.01) and storage time (P < 0.01). Spore levels in stored products were also significantly affected by water activity * inoculum level (P = 0.03), pH * time, water activity * time (P = 0.01), inoculum level * time (P < 0.01), and water activity * inoculum levels * time (P < 0.01). The interaction between pH * water activity * time tended towards significance (P = 0.06). Most probable number estimates in nonheated samples accounted for naturally occurring viable cells and spores, and added spores and were significantly affected by the main effects of inoculum level (P < 0.01) and time (P < 0.01). The two-way interactions of water activity * inoculum level (P = 0.04), pH * inoculum level (P < 0.01), water activity * time (P < 0.01), and three-way interaction of pH * inoculum level * time (P = 0.03) were significant. Spore levels approached 10², or less …

Influence Of Commercial Starter Media On Biochemical Characteristics Of Lactococcus Lactus, Norman Bart Devries

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Five strains of Lactococcus lactis were inoculated individually into six commercial bulk set growth media, 11% non-fat dry milk (NDM), and Elliker's broth. After growth in each medium the strains were tested for rate of acid production, and activities of proteinase, aminopeptidase, and lipase/esterase. Growth in commercial starter media significantly influenced acid production rate (P = 0.040), aminopeptidase activity (P < 0.0001), and lipase/esterase activity (P < 0.0001) .

For selected strain/media combinations, the duration of induced aminopeptidase and lipase/esterase activity was followed. The chosen strains were grown in selected commercial bulk set media, reinoculated into 11% NDM, and enzyme activity was examined for five successive …

Tryptophan Catabolism By Lactobacillus Spp. : Biochemistry And Implications On Flavor Development In Reduced-Fat Cheddar Cheese, Sanjay Gummalla

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Amino acids derived from the degradation of casein in cheese serve as precursors for the generation of key flavor compounds. Microbial degradation of tryptophan (Trp) is thought to promote formation of aromatic compounds that impart putrid fecal or unclean flavors in cheese, but pathways for their production have not been established. This study investigated tryptophan catabolism by Lactobacillus casei LC301 and LC202 and Lactobacillus helveticus CNRZ32 and LH212 cheese flavor adjuncts in carbohydrate starvation (pH 6.5, 30 or 37°C, no sugar) and cheese-like conditions (pH 5.2, 4% NaCl, 15°C, no sugar). Enzyme assays of cell-free extracts revealed both species of …

Influence Of Stress Treatments On The Resistance Of Lactococcus Lactis To Freezing And Freeze-Drying, Chan Lin

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study investigated the effect of cold, heat, or osmotic shock treatment on the resistance of L. lactis subsp. cremoris MM160 and MM310 and Lactococcus lactis subsp. lactis MM210 and FG2 cheese starter bacteria to freezing and freeze-drying. The ability to withstand freezing at -60°C for 24 h was variable among lactococci, but resistance to this treatment was significantly improved (P < 0.05) in most strains by a 2-h cold shock at l0°C or a 25-min heat shock at 39°C (L. lactis subsp. cremoris) or 42°C (L. lactis subsp. lactis). Stress treatments that improved lactococcal freeze resistance were also found to significantly (P < 0.05) enhance the resistance of most strains to lyophilization. Increased resistance to freezing or lyophilization was not detected when stress treatments were performed in broth that contained erythromycin, which indicated stress-inducible proteins were involved in cell protection. Membrane fatty acid analysis of stress-treated cells suggested that enhanced resistance to freezing and lyophilization may be related to heat or cold shock-induced changes in cell membrane composition. Heat-shocked cells had a higher 19:0 cyclopropane fatty acid content than did control cells, and cold-shocked cells contained a lower ratio of saturated to unsaturated fatty acids. Other factors must also be involved in cell protection, however, because similar changes in membrane composition were also detected in strains whose resistance to freezing and lyophilization was not improved by heat or cold shock.

Establishing Threshold Levels Of Nitrite Causing Pinking Of Cooked Meat, Kevin M. Heaton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Sporadic problems with pink color defect, or pinking, has occurred in cooked meat products for decades. Pink color can be due to the presence of undenatured myoglobin, denatured globin hemochromes, or nitrosylhemochrome. This research documented the level of added nitrite that produced nitrosylhemochrome in processed meat rolls from fabricated beef round, pork shoulder, turkey breast, and chicken breast. For each meat type, preliminary studies were conducted to narrow the range at which added nitrite caused pinking. Subsequently, the nitrite levels were increased incrementally by 1-ppm, and pink color was measured by trained panelists and by a Hunter color meter. Nitrosylhemochrome …

Effect Of Ph, Fat Level, And Various Browning Agents On Composition, Color, Texture, And Sensory Characteristics Of Dark-Cutting Beef Patties, Igor V. Moiseev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Extra lean (3.3% fat) and lean (20.0% fat) hamburgers in three pH groups (≤ 6.0; 6.01-6.49; 6.50-6.92) were evaluated for cooking-temperature profile, total process lethality, and physical properties after cooking to 71°C by double-side frying on an electric grill. Neither cooking-temperature profile nor cooking time was affected by hamburger fat content or pH. Double-side frying to 71.1°C internal temperature was adequate for more than 6-log destruction of viable E. coli O157:H7 and Salmonella at the geometrical center of extra lean and lean hamburgers. The coldest spot was on the circumferential surface, as indicated by the presence of a red ring …

Evaluation Of Methods Used In Meat Iron Analyses And Iron Content Of Raw, Cooked, And Cured Meats, Eldred Merlyn Clark

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research project was divided into three parts. In the first part, heme, nonheme, and total iron methodologies for meats were evaluated. The accuracy, precision, and specificity of each method were determined by spike recoveries of heme and nonheme iron, and by analysis of National Institute of Science and Technology standard reference materials. The most reliable and practical methods were then used to determine the total, nonheme, and heme iron contents of various meats before and after cooking. The meats analyzed were beef, pork, lamb, chicken, and turkey. The wet-ashing technique was a novel procedure in which nitric acid was …

Microbiological And Sensory Effects Of Milk Processed For Extended Shelf Life And The Development Of Rapid Methods To Quantitate Spores And Lipase Activity, Michael R. Blake

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The initial aim of this work was to evaluate processing conditions for extended shelf life (ESL) milk to have a shelf life at refrigeration temperature of 60 d. Milk was processed on a pilot-scale ultra-high-temperature processing plant and evaluated for microbial and sensory quality over 60 d at 7°C storage. Results of this study showed that lower process temperatures were preferable to minimize cooked flavors and that the minimum safe processing temperature was 134°C for 4 s as determined by the destruction of bacterial spores in the processed milk.

Consumer preference panel results indicated that consumers preferred milk processed at …

Influence Of Ultra-High Temperature Process Parameters On Age Gelation Of Mille Concentrate, Mohamed A. Elhilaly

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this research was to investigate the effect of ultra-high temperature process parameters on age gelation of milk concentrate. Skim milk was concentrated to 2X (volume reduction) using reverse osmosis. The milk concentrate was preheated at 75 or 90°C for 20 or 50 s and UHT-processed at 138 or 145°C for 4 or 16 s. Sterilizing methods used were direct steam injection and indirect plate heat exchanger. The samples were aseptically collected in presterilized plastic containers and stored at 15 or 35°C. At 15°C storage temperature, the steam-injected samples gelled in 5 months when 4 s UHT time …

Microstructural Changes In Casein Micelles During Acidification Of Skim Milk, Hongwen Du

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pasteurized skim milk was acidified using glucono-δ-lactone (GDL) at 10, 20, 30, and 40°C or with 1.2% freeze-dried yogurt starter culture at 40°C. Milk coagulation was followed by measuring turbidity, curd firmness, particle size, and casein micelle microstructural changes using transmission electron microscopy .

The pH of milk was gradually lowered during acidification with GDL or starter culture. Acidification rate showed greater influence on turbidity change at 10°C than at 20, 30, or 40°C.

Average casein micelle size increased with decreasing temperature. The patterns of average micelle size versus pH were not affected by temperature. No great variation of average …

Fate Of Β-Lactoglobulin, Α-Lactalbumin, And Casein Proteins In Ultrafiltered Concentrated Milk After Ultra-High Temperature Processing, Mark Christopher Alleyne

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The problem of age gelation in ultra-high temperature (UHT) sterilized milk retentate (ultrafiltered 3x concentrated) is investigated in this work. Transmission electron microscopy (TEM), utilizing the microcube encapsulation technique and protocols for immunolocalization of milk proteins, provides insight into the phenomenon of age gelation of UHT-sterilized, ultrafiltered (UF) milk retentate. Primary antibodies (specific for the native as well as the complexed forms of milk proteins) and secondary antibodies (conjugated to gold probes) are used to elucidate the positions of the milk proteins in various samples of milk from the stage of milking through UHT sterilization and storage for 12 months, …

Effects Of Whey Protein Concentrate, Phosphate, And Sodium Hydroxide On Texture And Acceptability Of Turkey And Beef Rolls, Igor V. Moiseev

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Processed turkey rolls were prepared with 1 or 3% whey protein concentrates WPC-50 (pH=5.80), WPC-60 (pH=4.53) and WPC-75 (pH=6.85} containing 50, 60 and 75% protein along with controls (phosphate and no phosphate). Control rolls made with 0.5% phosphate had the highest bind strength, and sensory evaluation scores. Only WPC-75 (1%) was acceptable as a binding agent and flavor enhancer. WPC-60 reduced pink discoloration of rolls, but flavor, bind and cohesiveness scores were unacceptably low. WPC-50 was not an effective binding agent. In general, rolls made with 3% WPC had lower scores for intensity of turkey flavor.

Bind strength and sensory …

Manufacture Of A Dairy Dessert From Ultra-High Temperature Milk Concentrate, Mark H. Smith

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this project was to initiate development of a nonrefrigerated dairy dessert product. Milk was concentrated by pressure-driven filtration and then sterilized using ultra-high temperature (UHT) processing. Following sterilization, samples were aseptically inoculated with rennet to coagulate the milk, which was then stored at room temperature. These processing steps produced a dairy dessert that did not require refrigeration. I investigated the influence of total solids, milk fat, rennet dosage, storage temperature, and storage time on curd firmness and syneresis. I investigated the effect on curd firmness and syneresis of giving the concentrate a heat treatment prior to UHT …

A Study Of Factors Controlling Physical Properties Of Mozzarella Cheese And The Manufacture Of A Reduced Fat Mozzarella Cheese, Richard Kevin Merrill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Variables affecting the physical properties of Mozzarella cheese were investigated. The effects of various milk-clotting enzymes were examined. The type of milk coagulating enzyme used played a significant role in determining physical properties of direct acid Mozzarella cheese. Cook color was not affected by enzyme type, but melt and stretch were significantly affected.

Proteolytic nature of starter cultures was reviewed and recommendation s were give n. Cheese made with proteinase-deficient strains had more stretch after holding for 14 and 28 d than cheese made with non-deficient strains. Cheese made with pairs or single strains of L. helveticus had the same …

Anaerobic Treatment Of Whey Permeate Using Upflow Sludge Blanket Bioreactors, Seokhwan Hwang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Whey permeate was anaerobically digested in laboratory scale upflow anaerobic sludge blanket reactors. Nine hydraulic retention times between 5 and 0.2 days were examined with a fixed influent concentration of 10.6 ± 0.2 g COD/L.

Chemical oxygen demand removal efficiency ranged from 99.0 to 18.9% and maximum production rate of methane gas was 2.67 L/L/day at a hydraulic loading rate of 12.97 kg COD/m³/day. About 70% of the chemical oxygen demand removed was converted to methane.

Both the nonlinear least square method with 95% confidence interval and linear regression were used to evaluate kinetic coefficients. The maximum substrate …

Properties Of Low-Fat Yogurt Made From Ultrafiltered And Ultra-High Temperature Treated Milk, Richard Alan Dargan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Yogurts were made from intermediate-high temperature (100, 110, 120, and 130°C for 4 or 16 s), ultra-high temperature (140°C for 4 or 16 s), and vat heat (82°C for 20 min) treatments of skim milk fortified to 5% protein by either ultrafiltration or the addition of nonfat dry milk (NDM). Whey protein denaturation in heated milks increased with temperature and holding time from indirect plate heating and was highest in vat-heated milks. Whey protein denaturation and yogurt water-holding capacity increased with protein levels in the fortified milks compared to skim milk. Penetrometer gel strength and stirred viscosity in 21 day-old …

Influence Of Process Parameters In The Manufacture Of Cottage Cheese Curd From Ultrafiltered Skim Milk, Ronald Michael Raynes

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A processing procedure for the manufacture of directly acidified cottage cheese curd from 16% total solids ultrafiltered retentate was developed. The effects of preacidification of skim milk before ultrafiltration and heat treatment of retentate were investigated to improve the functional and sensory qualities of retentate curd.

Retentate directly acidified with phosphoric acid and glucono-delta-lactone to pH 4.7 formed a dense, rubbery curd that could not be handled well in a vat. A heat treatment of 71.1°C for 30 min applied to the retentate resulted in a curd with acceptable handling properties. However, this heat treatment caused the curd to shift …

Effects Of Potassium Lactate, Encapsulated Citric Acid And Storage Temperature On Microbial Growth And Shelf Life Of Pork Sticks, Yen-Kan Su

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A new product, pork sticks, was developed. Optimum shelf life and safety were major concerns associated with this product. Potassium lactate (3%) or citric acid (0.5%, 0.56%, 0.60% or 0.66%) was added to pork sticks to determine their effects on microbial growth, sensory evaluation, and shelf life when stored frozen (-20°C), refrigerated (2°C), or at room temperature (22°C). Two raw materials, pork blade meat (shoulder meat; 91% lean, 9% fat) and regular 80:20 pork trim (80% lean, 20% fat) were used. The consumer panel preferred lean pork sticks made from blade meat over high-fat pork sticks made from regular 80:20 …

Purification And Immunological Reactivity Of Commercial Microbial Milk Clotting Enzyme Preparations, Chima I. Osuala

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Commercial microbial milk clotting enzyme preparations were purified by immunoaffinity chromatography using purified antibody covalently coupled to porous glass beads as the column matrix. Commercial enzyme preparation diluted in 1 mM sodium acetate buffer at pH 5.0 was then biospecifically adsorbed to the column matrix by end-over-end mixing of the glass-antibody complex in the enzyme solution for 12 h at 5°C. The antibody bound enzyme adsorbed glass beads were soaked in .2 M glycine or ethanolarnine at pH 7.0 to block uncoupled reactive sites on the matrix. Following this, the column was washed with 1 mM sodium acetate …