John R. Mount

ANTIMICROBIAL ACTIVITY OF ESSENTIAL OILS FROM PLANTS AGAINST SELECTED PATHOGENIC AND SAPROPHYTIC MICROORGANISMS

The beneficial health effects of extracts from many types of plants that are used as seasoning agents in foods and beverages have been claimed for centuries. The purpose of this study was to examine the effectiveness of selected herb and spice essential oils for control of growth and survival of microorganisms. Inhibition of growth was tested by the paper disc agar diffusion method. Antibiotic susceptibility discs were used as control. Minimum lethal concentration (MLC) was determined by the tube dilution method. Essential oils from anise, angelica, basil, carrot, celery, cardamom, coriander, dill weed, fennel, oregano, parsley, and rosemary were evaluated. Inhibition ranged from complete with oregano to no inhibition with carrot oil for each of the test strains that included: Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O:157:H7, Yersinia enterocolitica, Pseudomonas aeruginosa, Lactobacillus plantarum, Aspergillus niger, Geotrichum, and Rhodotorula. Oregano essential oil showed the greatest inhibition (zone, > or = 70 to 80 mm) (MLC, approximately 8 ppm). Coriander and basil were also highly inhibitory (MLC, approximately 25 to 50 ppm) to E. coli O:157:H7 and to the other bacteria and fungi tested. Anise oil was not particularly inhibitory to bacteria (inhibition zone, approximately 25 mm); however, anise oil was highly inhibitory to molds. Because some of the herbal and spice essential oils are highly inhibitory to selected pathogenic and spoilage microorganisms, they may provide alternatives and supplements to conventional antimicrobial additives in foods.

Effects of ultrasound on milk homogenization and fermentation with yogurt starter

Abstract The effects of ultrasound on milk homogenization and yogurt fermentation were studied. Microscopic photographs were used to check the size distribution of fat globules to evaluate the homogenization effect. The pH change during yogurt fermentation, water holding capacity, viscosity and syneresis for finished yogurt were evaluated. It was found that high amplitude ultrasound has a very good homogenization effect compared with conventional homogenization. Longer exposure times improved the ultrasound homogenization effect. Sonication after inoculation reduced the total fermentation time by 0.5 h. Increasing the ultrasound amplitude level before inoculation significantly improved the water holding capacity and viscosity and reduced syneresis. Sonication after inoculation did not decrease the syneresis effect but did increase water holding capacity and viscosity.

Prevalence of Salmonella in Diverse Environmental Farm Samples

The development of suitable intervention strategies to control Salmonella populations at the farm level requires reliable data on the occurrence and prevalence of the pathogen. Previous studies on Salmonella prevalence have focused on acquiring data from specific farm types and/or selected regions. The purpose of this study was to evaluate the distribution of this pathogen across a variety of farm types and regions in order to generate comparative data from a diverse group of environmental samples. Farm samples (n = 2,496) were collected quarterly from 18 different farms across five states (Tennessee, North Carolina, Alabama, California, and Washington) over a 24-month period. The participating farms included beef and dairy cattle operations, swine production and farrowing facilities, and poultry farms (both broiler chicken and turkey). The samples were analyzed for the presence of Salmonella by means of the U.S. Food and Drug Administrations Bacteriological Analytical Manual methods optimized for farm samples. Salmonella isolates were characterized by automated riboprinting. Salmonella serovars were recovered from 4.7% of all samples. The majority of positive findings were isolated from swine farms (57.3%). The occurrence of Salmonella was lower on dairy farms (17.9%), poultry farms (16.2%), and beef cattle farms (8.5%). The most commonly isolated serovar was Salmonella Anatum (48.4%), which was isolated notably more frequently than the next most common Salmonella serovars, Arizonae (12.1%) and Javiana (8.8%). The results of this study suggest that significant reservoirs of Salmonella populations still exist on swine production facilities and to a lesser extent in other animal production facilities. Data showed that the surrounding farm environment could be an important source of contamination.

Occurrence of Escherichia coli O157:H7 in diverse farm environments

In the United States, foodborne outbreaks of Escherichia coli O157:H7 illness have often been linked to the consumption of contaminated, undercooked ground beef. However, the occurrence of E. coli O157:H7 has also been reported in other farm animals. The objective of this study was to evaluate the occurrence of E. coli O157:H7 on diverse farm types and from a variety of farm samples. Rectal swabs (n=1686) and environmental samples (n=576) were collected from 16 farms in five states over 24 months and analyzed for the presence of E. coli O157:H7. Overall, E. coli O157:H7 was found in 3.6% of beef cattle, 3.4% of dairy cattle, 0.9% of chicken, 7.5% of turkey, and 8.9% of swine samples. The pathogen was isolated sporadically from each of the environmental sample types. Of particular concern was the isolation of E. coli O157:H7 from fresh feed samples, indicating a potential vector for transmission. The data from this study indicate a high occurrence of E. coli O157:H7 on swine and turkey farms. This unexpected result suggests that more research on the occurrence of E. coli O157:H7 on these types of farms is required in order to better understand potential reservoirs of pathogenic E. coli.

Survival of Campylobacter jejuni in modified atmosphere packaged Turkey roll

Survival of Campylobacter jejuni , inoculated into turkey roll slices and stored under seven different atmospheric mixtures, was determined. Turkey roll samples were stored at 4°C for 18 d and at 21°C for 48 h. The effects of various atmospheric mixtures on aerobic, psychrotrophic, and lactic acid bacterial populations were also determined throughout storage. Campylobacter jejuni was inactivated under all atmospheric gas mixtures tested throughout storage. Increasing CO2 concentration inside the package from 0% to 100% CO2 resulted in a lower rate of inactivation of C. jejuni at both storage temperatures. Increases in CO2 concentrations provided greater inhibition of aerobic and psychrotrophic populations as compared to low CO2 levels. The effect of CO2 on survival of C. jejuni and growth rate of aerobic, psychrotrophic, and lactic acid bacteria was more pronounced at 4°C. Campylobacter s were isolated from inoculated turkey roll held under all atmospheres by enrichment procedures on the 18th day and 48th hour of storage at 4 and 21°C, respectively, with an initial population of log 6.0 Campylobacter s/g. However, no Campylobacter s were isolated by 18 d of storage at 4°C by direct plating.

Osmotic dehydration of apple slices with CaCl2 and sucrose limits decay caused by Penicillium expansum, Colletotrichum acutatum, and Botrytis cinerea and does not promote Listeria monocytogenes or total aerobic population growth

The interaction of Penicillium expansum Link, Colletotrichum acutatum, and Botrytis cinerea Pers.:Fr. with Listeria monocytogenes on osmotically dehydrated apple slices was evaluated. In mineral analyses of the slices, the calcium content of the peel and flesh tissues increased by 4- and 11-fold, respectively, when processed in 2% CaCl2. These slices also exhibited less decay by P. expansum, C. acutatum, and B. cinerea. Inoculation of slices with P. expansum resulted in a decrease in the pH of the flesh tissue at the infection site, while the pHs of slices infected with C. acutatum and B. cinerea increased and remained stable, respectively. Total mold population increased in wounds inoculated with P. expansum or C. acutatum. The presence of L. monocytogenes in the wounds did not significantly affect mold growth. The association of P. expansum and L. monocytogenes on apple slices resulted in a decrease in the bacterial population, whereas L. monocytogenes survived when slices were inoculated with C. acutatum. When associated with B. cinerea, there was a fourfold decrease in the L. monocytogenes population when slices were treated with 2% CaCl2. The total aerobic population was not significantly affected by the type of microorganism added to the wounds or by the osmotic treatment. These data show that osmotic dehydration with 2% CaCl2 combined with 20% sucrose limits decay of apple slices and does not promote bacterial or total aerobic population growth.

Sodium Reduction in Canned Beans After Draining, Rinsing

Health and culinary professionals and consumers increasingly seek practical ways to reduce sodium intake, as advised in science-based dietary guidance. In response, this study determined whether draining and rinsing significantly reduces sodium in canned beans. References in dietary guidance and popular literature support this practice; only limited, dated scientific data substantiate this advice, conducted only on past product formulations. Sodium per label-size serving was measured for multiple brands of five canned bean varieties: in packing liquid; drained of packing liquid; and drained of packing liquid and then rinsed. Both draining and draining followed by rinsing significantly reduce sodium in canned beans.

Osmotic dehydration of apple slices using a Sucrose/CaCl2 combination to control spoilage caused by Botrytis cinerea, Colletotrichum acutatum, and Penicillium expansum

The efficacy of sucrose combined with CaCl2 during osmotic dehydration (OD) was tested for the control of Botrytis cinerea, Colletotrichum acutatum, and Penicillium expansum growth on lightly processed apple slices. The objective of this work was to determine whether the addition of CaCl2 in the osmotic solutions would limit the proliferation of fungal decay organisms. Slices were submitted to OD for 1 h at 25 degrees C in solutions containing 5 to 65% sucrose. Calcium chloride was added to a similar set of sucrose solutions at 0 to 8%. Control slices were made of untreated slices, and slices were processed in water. The mass ratio of the slices did not vary when fruit pieces were processed in solutions containing 5 to 65% sucrose. These slices showed a high susceptibility to spoilage compared to the control slices not submitted to OD: a significant twofold and 60% increase in decay area caused by B. cinerea and P. expansum, respectively, was observed when slices were processed in 50% sucrose/0% CaCl2; C. acutatum showed a significant 50% increase in decay area when slices were processed in 20% sucrose/0% CaCl2. Calcium uptake was significantly increased when slices were processed in CaCl2 solutions, and the highest Ca content was observed when processed in 8% CaCl2, reaching 40 times that of the control slices processed in water. Calcium-treated slices were less susceptible to spoilage by all three pathogens, and the most effective combination in reducing apple slice spoilage was 20 to 30% sucrose combined with 2% CaCl2.