Anastasia Jeanetta Natania

Project 1: Texture Analysis of Plant-Based Meat Analogues Prepared From The Extrusion of Yellow Pea Isolates

Consumer interest towards high protein plant-based products has increased due to environmental and animal welfare factors, driving the need for the development of plant meat analogues. Understanding the formation mechanism of fibrous plant protein materials can be used to develop a plant-based meat product or meat analogue. Texture plays a large role in consumer acceptability and consumers continue to search for a product that resembles the mouthfeel and texture of real meat. The aim of this experiment are to determine the plant-based protein extrudates’ cutting and compression behavior through texture analysis and see how these behaviors compare to the sample’s composition. Samples were first prepared by extruding pea protein at different moisture contents. The extrudate’s weight and dimensions were measured prior to and after being hydrated in deionized water for 96 hours to determine water holding capacity. Cutting behavior was determined using a TA-42 knife probe with a 45 degree blade angle while compression behavior was determined using a 10 mm compression probe and the resulting data was analyzed using the Stable Micro Systems TA.XT Texture Analyser. There is no significant difference in water holding capacity, and differences in the force and distance required for 95% compression were observed between samples. Future work can be done to understand the texture behaviors of different plant proteins and consumer acceptance towards the desired texture of meat analogues through sensory testing.

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Project 2: Resistance and Nutrient Use in Streptomyces Populations Between High- and Low-Input Soils

Inhibitory species interactions can generate increases in pathogen-suppressive Streptomyces populations that can lead to disease suppressive soil microbiomes. Soil nutrient status may influence the ability of isolates to inhibit other bacteria, because antibiotic production is a costly metabolic investment. However, ‘fitness tradeoffs’ are believed to limit the accumulation of inhibitory and resistant capacities among soil populations. Here we characterized nutrient use and resistance phenotypes among Streptomyces isolates from high- and low-nutrient input soils. Niche width and growth efficiency were determined using Biolog SF-P2 plates. Streptomyces from high-input soils were found to utilize different nutrients compared to low-input soils. In contrast to our expectation, isolates from high-nutrient soils that were more resistant to inhibition had greater niche widths and growth efficiencies. In contrast, highly-susceptible isolates from high-nutrient soils had the lowest growth efficiencies, suggesting that susceptibility (not resistance) was associated with lower fitness. However, no fitness tradeoffs were observed between resistant and susceptible isolates in low-nutrient soils. The lack of evidence for fitness tradeoffs in low-nutrient soils could suggest that Streptomyces populations minimize costs associated with critical competitive traits such as antibiotic resistance, possibly by reducing investments in other key fitness traits such as survival. Soil nutrient status affects species interactions and the tradeoff costs for antibiotic resistance, possibly as high-nutrient soils may invest in antibiotic inhibition while low-nutrient soils may prioritize growth efficiency; further work can be done to understand the relationship between susceptibility and inhibitory abilities through understanding specific resistant mechanisms in highly resistant and highly susceptible individual populations.

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