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Showcase Agricultural and Natural Resources Sciences

Effect of gas nanobubbles on the efficacy of peracetic acid and chlorine against Escherichia coli and Listeria monocytogenes

Effect of gas nanobubbles on the efficacy of peracetic acid and chlorine against Escherichia coli and Listeria monocytogenes

Primary Author: Arshdeep Singh

Faculty Sponsor: Minto Michael

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

Nanobubbles are defined as fine bubbles with diameter varying from 20 to 200 nm with distinctive surfactant properties because of their small size. Nanobubbles are proven effective in irrigation systems, fisheries, wastewater treatments and dentistry. This research was conducted to study the impact of gas nanobubbles on the efficacy of commonly used antimicrobials in food industry. This study was conducted as a completely randomized block design (three replications). Air, CO2 and N2 were used to generate nanobubbles in water. Peracetic acid and chlorine were used to make the nanobubble-antimicrobial solutions and were tested against Escherichia coli O157:H7 and Listeria monocytogenes. Antimicrobials mixed with water without any gas acted as controls. Nine-milliliter of antimicrobial solutions were taken into individual test tubes and inoculated with 1 ml of individual microbial inoculum. After the holding time of 1.5 and 3 min, 1 ml of the sample was taken, neutralized with Dey-Engley broth, and plated on brain heart infusion agar. pH and Eh of antimicrobial solutions were measured before and after the addition of master inoculum. After 3 min for E. coli, CO2 nanobubbles with chlorine was the most effective treatment with 6.4 log reductions as compared to 4.2 log reductions in control. For L. monocytogenes, CO2 nanobubbles with peracetic acid was most lethal treatment with 4.6 log reductions compared to 1.9 log reduction in control. This study demonstrated that efficacy of various antimicrobials can be increased by incorporating gas nanobubbles. Further, this method can be tested against other pathogens in different food matrices.

 

Determination of thermal inactivation parameters of Salmonella in nonfat dry milk and whole milk powder during four months storage

Determination of thermal inactivation parameters of Salmonella in nonfat dry milk and whole milk powder during four months storage

Primary Author: Amninder Singh Sekhon

Faculty Sponsor: Minto Michael

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

Principal Topic- Foodborne pathogens such as Salmonella can endure dry environments of milk powders for extended periods of time due to increased adaptability at low water activity (aw) levels and proliferate when powders are hydrated. This study focused to compare survivability and thermal resistance of Salmonella in NFDM and WMP stored for 120 days.

 

Methods- This study was designed as completely randomized with three replications. Milk powders were spray inoculated with 5-serovar Salmonella cocktail and dried back to original pre-inoculation aw. The D-values of Salmonella in inoculated NFDM and WMP were determined periodically (every 30 days, starting from day-one). The D and z-values were also performed for hydrated forms of NFDM and WMP. Rehydration (13% total solids w/v) was performed on days of performing D- and z-value study. Five separate thermal death time disks containing 5g or 5 mL of respective sample were transferred into five thermal-death-time, sealed and placed in hot-water baths set at 80, 85 and 90°C for inoculated powder, and 59, 62 and 65°C for hydrated inoculated powder. Samples were held for 0 to 56 minutes in hot-water baths and quickly transferred to cold-water baths at pre-determined time intervals. The samples were enumerated using injury-recovery media, and D- and z-values were calculated.

 

Results- During storage, heat resistance of Salmonella in WMP was statistically higher than NFDM. D-values of Salmonella on day 120 in WMP were 24.6, 11.4, and 7.0 minutes at 80, 85 and 90°C respectively as compared to 21.9, 9.2, and 5.2 min in NFDM.

 

Grain Protein Content Stability and Genomic Selection for Predicting the Grain Protein Content in Wheat

Grain Protein Content Stability and Genomic Selection for Predicting the Grain Protein Content in Wheat

Primary Author: Karansher Sandhu

Faculty Sponsor: Arron Carter

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

Grain protein content (GPC) is controlled by a complex genetic system, yet it is an important quality determinant for hard red spring wheat as it has a positive effect on bread and pasta quality. GPC is highly variable among genotypes and is also variable across different environments. Thus, understanding the genetic control of wheat GPC and identifying genotypes with less variation under different environments, is an important breeding goal. The objectives of this research were to identify wheat families having less variation for GPC across environments and identify quantitative trait loci (QTL) controlling the stability of GPC. We used 650 recombinant inbred lines from the spring wheat nested association mapping (NAM) population derived from 26 diverse founder parents each crossed to one common parent, ‘Berkut’. The population was phenotyped for three years (2014-16). Genomic prediction (GP) models were developed to predict GPC and GPC stability. The GPC was highly variable between these families across environments. We selected seven families that had less variation of GPC. The stability index of each genotype was obtained by Finlay-Wilkinson regression. Genome-wide association study (GWAS) identified eight significant QTLs using a Bonferroni correction of 0.05. This study also demonstrated that genome-wide trait prediction with ridge regression/best linear unbiased estimates reached up to r = 0.69. Overall, this study helped in the identification of QTLs controlling the stability of GPC. The genomic prediction accuracies suggest that genomic selection can be used to select breeding lines having higher protein content and improve genetic gain more rapidly.

 

Comparison of Microwave and Conventional Thermal Pasteurization of Frozen Green Beans

Comparison of Microwave and Conventional Thermal Pasteurization of Frozen Green Beans

Primary Author: ZHI QU

Faculty Sponsor: Juming Tang

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

PRINCIPAL TOPIC

Pasteurization is the process to eliminate pathogens and extend shelf life of food products. Consumer’s desire for high quality food and convenience has been a major driver for advancements of processing technologies. Microwave pasteurization can provide more rapid heating and better heating uniformity compared to conventional thermal pasteurization, thus holds potential to produce better quality vegetable products, such as fresh appearance and texture. The objective of this research was to study the influence of microwave and conventional thermal pasteurization on quality of green beans during storage at various cold chain temperatures.

METHOD

Thawed frozen green beans were vacuum sealed in 8 oz polymer trays, pasteurized in a pilot-scale 915 MHz Microwave Assisted Pasteurization System (MAPS) and conventional water bath (WB). The processed samples were stored at 10 and 2 °C. Color and chlorophyll content of green beans were quantified to elucidate the quality of the food.

RESULTS/IMPLICATIONS

For green beans, chlorophyll and green color suffered greater degradation when pasteurized using WB. During storage, under both temperatures, microwave pasteurized samples showed better color retention and higher chlorophyll content. And, microwave pasteurized green beans can be preserved for a longer time at 2°C (100 days) than WB heated one (80 days) with no package swelling observed. This implicates that microwave pasteurization might be a potential alternative to produce safe, high-quality vegetable products and preserve the quality during storage.

 

Cooling Rates of Spatter Deposits

Cooling Rates of Spatter Deposits

Primary Author: Claire Puleio

Faculty Sponsor: Catherine Cooper

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

Principal Topic

Magmatic spatter deposits form during volcanic eruptions wherein molten lava is projected from the volcano. The molten lava is erupted in fragments (clasts) and is deposited in the area immediately surrounding the eruptive vent of the volcano. These clasts can pile upon each other and form cone-like structures. Magmatic spatter occurs when erupted lava is hot enough to deform and adhere to other erupted clasts (agglutinate). The deformation and agglutination of spatter clasts have important implications regarding how spatter can transition from a stable deposit to a lava flow. When spatter re-melts and flows it can cause sudden collapse of the cone-like structures and quickly damage infrastructure or cause bodily harm to those in the path of the flow.

 

Method

A two-dimensional thermal diffusion model has been created in this study to predict how long it takes for spatter clasts to cool sufficiently enough that they no longer pose the risk of re-melting and forming a lava flow. This model predicts how spatter clasts cool over time when subjected to conduction, convection, and radiation and is applied to scenarios in which multiple spatter clasts of the same temperature are placed on top of one another.

 

Results/Implications

The model described in this research provides an indication for when the spatter deposit will cool sufficiently enough to stabilize. This research increases the understanding of magmatic spatter as well as the likelihood for associated volcanic hazards such as sudden collapse of spatter deposits and the rapid formation of lava flows.

 

A better screening tool to help combat a common pest of wheat

A better screening tool to help combat a common pest of wheat

Primary Author: Samuel Prather

Faculty Sponsor: Michael Pumphrey

 

Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Agricultural and Natural Resource Sciences

Campus: Pullman

 

Abstract:

 

Principle topic:

Hessian Fly [Mayetiola destructor (Say)] is a major pest of wheat in Washington as well as the entire USA. In its larval stage, Hessian fly feeds off the stems of wheat plants causing severe yield loss. While there are pesticides and management practices to combat Hessian fly, because of Hessian fly’s unique life cycle most are not effective. The best way to combat Hessian fly is through use of genetically resistant wheat varieties with one of the 35 known Hessian fly resistance genes. The impediment for breeders developing Hessian fly resistance varieties is a fast-cost-effective way to screen for the resistance, as the current method takes a long time and is very expensive.

Method:

Using a genetics technique known as linkage mapping my project’s goal was to find the genetic location of one of the 35 known genes that has been shown to work in Washington. And then create genetic markers which are an assay to test for that gene.

Results:

After leaning the location of our Hessian fly resistance gene of interest I created 3 genetic markers and validated them on a large panel of varieties. The results show these markers to be highly (>98%) accurate at detecting the presence of the gene. The old method of testing for this gene used by our lab cost ~$150 per test and took about 2 months. This new method using the genetic marker assay takes less than a week and cost ~$1 per test.