Food Engineering/Manufacturing/Cold Filling Salad Dressing

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Question
I am in the process of developing organic salad dressings that I would like to sell commercially.  As part of my brand, I need these salad dressings to be as natural and organic as possible, which would preclude the use of any artificial preservatives such as sodium bisulfite, potassium sorbate, etc.  (only preservatives such as vinegar and fresh lemon juice permitted).  I also need the dressings to be shelf stable without refrigeration (would say “refrigerate after opening” on the labels).  Two of my dressings, ingredients listed below, lose a lot of the flavor when I heat them to around 180 degrees F. for thermally processing.  

Is there a certain acidity (or other requirement) that allows me cold fill these dressings for food safety/spoilage without adding artificial preservatives or doing a long study?

I have read in the fda code that food with a PH below 4.2 is considered non-tcs.   See table B of link (http://www.fda.gov/Food/FoodScienceResearch/SafePracticesforFoodProcesses/ucm094).  Would that mean if I kept the acidity below 4.2 it would be safe for a cold fill?  Just because it is food safe does it mean that I still need to consider spoilage?  I would like to be able to store the dressings at room temperature for at least 6 months.
 
Finally, based on your knowledge, assuming am able to cold fill these dressings for food safety / spoilage, is there a risk of the dressings losing significant flavor while in storage since the dressings won’t have artificial preservatives.   

Dressing 1
Fresh garlic, water, white wine vinegar, vegetable oil, lemon juice, salt/pepper, guar gum, dried spices
Dressings 2

Fresh parsley, Vegetable oil, capers, white wine vinegar, fresh garlic, salt, fresh lemon juice, dried spices

Any guidance and/or references are greatly appreciated.   

Thanks,
Michael

Answer
The pH is critical. Products with pH below about 3.8 are cold filled safely. They may still have viable spoilage organisms, such as yeasts and molds. Water activity also contributes to stability. Few microbes grow below water activity of 0.85. You can heat to lower temperatures, say 160 F and hold just for a few seconds - 72 to be exact. This might be mild enough for your products. As I read the FDA guidance, pH below 4.2 does not require time/temperature control for safety. I am a little surprised, as my experience has been with lower pH products.  

Food Engineering/Manufacturing

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J. Peter Clark

Expertise

How various processed foods are made; ways to improve manufacturing; how to make a new food product.

Experience

Employment history: Research Engineer, U.S.Agricultural Research Service, Associate Professor Chemical Engineering, Virginia Tech, Director of Research, Continental Baking Company, President, Epstein Process Engineering, Inc., Vice Presdent Technology, Fluor Daniel, Inc., Consultant to the Process Industries

Organizations: American Institute of Chemical Engineers (Fellow) Institute of Food Technologists, American Association of Cereal Chemists, American Association of Candy Technologists, American Society of Agricultural Engineers,

Publications: Several Encyclopedias (Kirk and Othmer, Chemical Technology; Food Science, Food Technology and Nutrition; Wiley Encyclopedia of Food Science and Technology; Encyclopedia of Life Support Systems); five books, two book chapters; numerous journals.

Education: BSChE Notre Dame PhD University of California, Berkeley

Awards: AIChE Food, Pharmaceutical and Bioengineering Division Award 1998

Clients: Major food processing and pharamaceutical companies.

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