Monday, April 23, 2012

Questions for Next Experimental Design



In thinking of additional tests for our long-term sauce study, I think we need to consider what we've learned from Micro and apply that.  I'm thinking in terms of chemistry - functional groups, decomposition reactions/catabolism, and organic compounds - carbs, lipids, and proteins.  And also cell structure, enzymes & metabolism, and microbial growth.  If we have an understanding of how and why some of the sauces have a change in color, odor, and viscosity, then I think that would lead us to our next experimental design.  On Saturday, as I was driving to Little Rock, I had a lot of time (3 1/2 hours) to think about our research and I came up with a series of questions. 

  • What is the chemistry behind the change in color & odor that we’ve observed?  Are we seeing a significant change in viscosity or texture?  How come we are not seeing a significant change in pH?
  • What are the organic compounds in the sauces?  What type of chemical breakdown is happening?  How do we measure this?
  • Regarding proteins – what is the source of protein in the sauces?  Could it be cell components from ingredients like wheat or soy?  What enzymes are at work breaking proteins down?  Proteases or peptidases?  Are the proteins being denatured or deaminated?  As for enzymes, they are influenced by temp, pH, and substrate concentration so how does this tie into the data we’ve collected so far?
  • Catabolism requires energy so where is that energy coming from?  Our current sauces show that yeast is present and Dr. Bates said it is probably Saccharomyces.  Yeast ferments producing 2 ATP in glycolysis and then ethanol and CO2 as end products.   Could this be what I smelled in some of our previous sauces? 
  • What are the requirements for microbial growth?  Is aerobic or anaerobic respiration occurring?  What is being metabolized – carb, lipid or protein? 
  • Consider the ETC where O2 is the final electron acceptor and H2O is formed.  Does this water then become available for microbial growth or other chemical reactions?  Is this the water activity?

Thursday, April 5, 2012

First Assay in Short-term Study for Food Microbiology

We completed our first assay for the short-term study we are doing for a company who makes sauces.  Their customers asked them how long they can store the large totes of various sauces at room temperature in their warehouses before it spoils.  Our task, as undergrad research students, was to set up an experiment for accelerated shelf-life to determine which sauces may be stored at ambient temps.

This is the first time any of us conducted scientific research.  Although we tested samples of sauce over a two week period, it took us longer to complete the study as we had to learn new lab techniques.  We collected data for pH, viscosity, odor & color change, and CFU's for 18 different sauces at three different temperatures:  4, 30, 37.

We are now in the process of writing our first scientific paper, which we will be presenting at a conference in the Fall.  Today we started a second assay on 5 new sauces.  This time we will be collecting data over a four week period.  Eventually, we will be setting up a long-term shelf-life study.

I'll be posting our paper when it is finished.  But we've got a ways to go in turning our basic rough draft into an actual scientific paper.  It's a learning curve.