Life Sciences Commons^™

Enzymatic Synthesis Of Maltodextrin Fatty Acid Esters And Their Emulsion Stabilizing And Microbial Inhibitory Properties, Namhyeon Park

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Food additives have been one of the traditional methods for preserving foods and are still in everyday use for multiple reasons. As the market size of processed foods grows, the use of food additives is increasing. Simultaneously, consumers try to avoid specific food additives or demand less processed foods because of several potential health concerns, suggesting the need for safe food additives.

In this environment, one group of food additives consisting of carbohydrates and fatty acids have received attention because of its nontoxicity and biodegradability with diverse functions. Notably, carbohydrate fatty acid compounds made of sucrose have been approved and …

Exploring The Connection Between Acid Exposure And Virulence In Listeria Monocytogenes, Minghao Li

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Listeria monocytogenes is a gram-positive food-borne pathogen that is widely dispersed in the environment and can cause listeriosis with high fatality rates when consumed in contaminated food products. They are capable of growing over a wide range condition. Listeria is also able to tolerate adverse conditions which allows the bacterium to survive in unfavorable environments. The ubiquitous nature of L. monocytogenes makes it difficult to eliminate from food systems. One major problem in the food industry is the survival of L. monocytogenes under sublethal low pH-environment since organic acids are widely used as food decontaminants. Prior research has suggested that …

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 …

Microbiological, Thermal Inactivation, And Sensory Characteristics Of Beef Eye-Of-Round Subprimals And Steaks Processed With High-Pressure Needleless Injection, Laura Kahealani Jefferies

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

High-pressure needleless injection (HPNI) is a process where small-diameter, high-velocity burst of liquid, penetrate foods at pressures ≤ 10,000 psi. The potential of HPNI as an enhancing technique for meat was studied. In study 1, HPNI translocated surface E. coli O157 into the interior of beef eye-of-round subprimals with an incidence of 40 (±7), 25 (±8), and 25 (±8)% for meat that had been surface-inoculated with a four-strain cocktail at 0.5, 1, and 2 log₁₀ CFU/cm², respectively. Run-off water contained 2, 2, and 3 log₁₀ CFU/ml and was used for HPNI of additional subprimals, which resulted …

The Effect Of Exopolysaccharide-Producing Streptococcus Thermophilus Mr1c On Functionality In High Moisture Cheddar-Type Cheese, Tyler J. Singleton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Differences in texture at any particular stage of ripening depend upon differences in the basic structure and the extent to which the basic structure is modified by physical parameters. Thus, very young cheeses of the same variety differ in texture because of variations in pH and in salt, moisture, and fat content. How well a cheese melts and shreds depend on its texture and physical parameters. Streptococcus thermophilus MR1C produces an exopolysaccharide (EPS) that is tightly associated with the bacterial cell wall. Addition of S. thermophilus MR1C to the cheese make will increase the moisture of the cheese 2-3% …

Use Of Fourier Transform Infrared Spectroscopy For The Classification And Identification Of Bacteria Of Importance To The Food Industry, Sarah Pegram

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The aim of this work was to use Fourier Transform Infrared Spectroscopy to characterize and identify bacteria of particular significance to the food industry. FT-IR spectroscopy is a rapid technique that can be applied to all groups of bacteria. The two objectives were to determine a suitable sampling procedure to record a spectrum and to determine a suitable statistical technique to identify characteristic regions of the spectrum associated with the genus and, potentially, the species. Pure cultures of bacteria were grown in broth, suspended in saline and dried to produce a film on a halide salt crystal. These films were …

Comparative Effects Of Sodium Levulinate And Sodium Lactate On Microbial Growth, Color, And Thiobarbituric Acid (Tba) Values Of Fresh Pork And Turkey Sausages During Storage, Mihir N. Vasavada

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This study compared the effects of 1.4 or 2.7% sodium levulinate or sodium lactate on aerobic plate count (APC), color, pH, and TBA value of fresh pork and turkey sausage. Both sodium lactate and levulinate inhibited growth of aerobic microorganisms during storage, compared to controls. Bacteriostatic effects of sodium lactate were dose dependent, wherein 2.7% lactate was significantly more antimicrobial than 1.4% lactate. This was not the case for sodium levulinate, where 1.4% sodium levulinate was as inhibitory to microbial growth as 2.7% sodium levulinate. Additionally, 1.4% sodium levulinate was as inhibitory to microbial growth as the higher level (2.7%) …

Rapid Detection Of Listeria Monocytogenes, Wim Lippens

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Listeria monocytogenes is a foodbome pathogen that can cause severe illness and even death. It is found in dairy and meat products. The focus is on rapid detection since conventional methods are time consuming (4-5 days). Pre-enrichment steps, as part of those methods, are time consuming. Our objective was to develop a detection system without a pre-enrichment step, giving a final result within 2 to 4 h.

In the concept of "the need for speed," a detection system with an antibody-based capture technique, followed by polymerase chain reaction (PCR), was developed. Glass beads coated with a Listeria polyclonal antibody were …

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 …

Characterization Of The Proteolytic System In Lactococcus Lactis Starter Cultures, Christina Beer

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The proteolytic system of Lactococcus lactis starter cultures influences both flavor and the characteristic body and texture of cheese. The ability to further understand and control how different components of this proteolytic system work together to hydrolyze milk proteins would be of immense importance to the dairy industry.

The goal of this research was to characterize Lactococcus lactis subsp. lactis starter bacteria with varying prt operon compositions by proteinase specificity, aminopeptidase and lipase activities, growth, and influence on cheese flavor. By using a cheese slurry system, a statistical model to predict milk protein hydrolysis patterns was developed.

Lactococcus lactis subsp. …

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.

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 …

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 …

Effects Of Iron Fortification On Microbiological, Physical, Chemical, And Organoleptic Properties Of Yogurt, Sharareh Hekmat

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

It has been shown that iron binds strongly to the proteins in milk, and our aim was to determine whether or not this binding was affected by lowering pH in the manufacture of yogurt. Iron-protein complexing was studied using two different techniques. 1) Skim milk was fortified with 10 mg iron/100 ml and the pH of the milk was adjusted to 6.7, 6.2, 5.8, 5.3, 4.5, and 4.0. The milk was fractionated by ultracentrifugation at 52,000 x g for 60 minutes. The pellets and serum were then analyzed for iron, calcium, and phosphorus content by inductively coupled plasma spectroscopy. SDS-PAGE …

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 …

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 …

Survival Of Lactobacillus Acidophilus And Bifidobacteria Bifidum In Ice Cream For Use As A Probiotic Food, Sharareh Hekmat

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ice cream mix (12% fat, 11% milk solids nonfat, 12.5% sugar, and 4.5% corn syrup solids) was fermented with Lactobacillus acidophilus and Bifidobacterium bifidum. Half of the mix was heat treated at 82°C for 30 minutes and cooled to 40-41°C. The other half was warmed to 40-41°C and inoculated with the starter cultures. Both were made into ice cream and stored at -29°C. Survival of L. acidophilus and B. bifidum and of ẞ-galactosidase activity were monitored during 17 weeks of frozen storage. Reinforced clostridial medium was used to enumerate culture bacteria. Colony counts, after fermentation, for both L. acidophilus …

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 …

Effect Of Proteolytic Activity Of The Lactic Cultures On Mozzarella Cheese Quality, Wen-Hsu Amos Wang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Mozzarella cheese market is growing rapidly. Major concerns with cheese meltability and color have arisen in the fast food industry. Pre starter culture was used in this study to improve the physical properties of Mozzarella cheese. Three tests (stretch test, melt test, and browning test) were modified to evaluate the quality of cheese.

A stretch test using the Brookfield helipath viscometer to stretch the cheese sample at 60°C was successful in distinguishing cheeses from different make procedures and from different proteolytic strains. A melt test using a glass tube to hold the cheese flow at 110°C for 60 min …

Factors Affecting Growth Of Proteinase Positive And Proteinase Negative Streptococcus Cremoris Uc310 In Ultrafiltered Milk Retentate, Brent Karl Pope

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Whole milks were adjusted to pH 5.8, 6.2, or 6. 7 with HCl and batch pasteurized at 63°C for 30 min. Each was concentrated 5:1 (40% total solids) through a single tube polysulfone membrane Abcor ultrafiltration unit. Lactose (L), casein hydrolysate (CH), and one of two brands of yeast extract (YE1, YE2) were added into cooled retentates at 0.1, 0.3, 0.5, 0. 7 or 0.9% and equilibrated overnight at 4°C. Five percent proteinase positive (Prt+) Streptococcus cremoris UC 310+ (v/w) milk based culture was added. Unfortified retentate was also inoculated with 0.1, 0.3, 0.5, 0. 7 or 0.9% starter and …

Effect Of Proteolytic Enzymes On Transfection And Transformation Of Streptococcus Lactis Protoplasts And Transformation Of Streptococcus Cremoris, Steven A. Woskow

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effect of proteolytic enzymes on the transformation and transfection of Streptococcus lactis LM2301 protoplasts was examined in an attempt to eliminate the variability observed. By using both chymotrypsin and mutanolysin to form protoplasts followed by spread plating, consistent frequencies of 104 to 105 transformants per μg of pGB301 DNA, and 105 transfectants per μg of c2 bacteriophage DNA where achieved. Optimum transformation and transfection frequencies were obtained when 16 h cultures were treated simultaneously with 25 U/ml mutanolysin and 1.25 U/ml chymotrypsin for 15 min. Trypsin and pronase in conjunction with mutanolysin also increased transformation frequencies higher than when …

Effects Of Micrococci On Improving Sensory Acceptability Of Mutton Summer Sausage, Hoon Jung

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effects of micrococci on sensory characteristics of different batches of summer sausages were determined. Sixty four salt-tolerant indigenous isolates were selected from beef or mutton treated with 1.5 or 3.0% sodium chloride and 120 ppm sodium nitrite, and held at 5 or 10 C for 5 days. These isolates (61/64) were identified as staphylococci and micrococci. Summer sausages were made from several lamb, ewe, and ram carcasses which were hand deboned and blended after grinding to contain 22% fat. Six summer sausage treatments were prepared using two different sources of commercial starter cultures including Micrococcus species or Micrococcus varians …

Milk Protein Analysis By Automated Ultraviolet Spectroscopy, R. Ford Wilkinson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An automated continuous flow analysis for milk protein utilizing ultraviolet spectroscopy resulted in a correlation coefficient of 0.972 and a standard estimate of error of 0.082 percent protein when 30 samples were compared with the acid orange 12 dye binding method. Milk was solubilized in 95-105 volumes of acetic acid using the Technicon Auto Analyzer II and measured for absorbance at 274 nanometers. No deviation from the standard method due to mastitis and varying milk fat concentration was observed. A theoretical model indicated a possible standard estimate of error 0.059 percent protein due to inter- and intra-breed variation in milk …

The Effects Of Gamma Irradiation, Color Mutation And Various Subatmospheric Pressures On The Growth And Patulin Production By Penicillium Expansum And Penicillium Patulum, Karl B. Adams

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To assess the effects of gamma radiation at low doses, spores of Penicillium expansum NRRL 971 and Penicillium patulum NRRL 989 were exposed to doses of 0, 50, 100, 150, and 200 krads. The amount of patulin for each culture was quantitatively determined and growth at each dose was evaluated. The results showed a 31% increase in the amount of patulin synthesis after a dose of 150 krads for Penicillium expansum. At 200 krads, both fungi showed low levels of patulin production and inhibited growth.

Eight color mutants of P. expansum and eight color mutants of P. patulum were produced …