Expert: J. Peter Clark - 8/27/2008

Question
Hello,

I am in a Chinese Cooking class at Culinary School and I have to write a paper on how plum sauce/duck sauce is manufactured.  I have to write about the process of manufacturing the sauce, bottling, spoilage, etc..

Can you provide me some information on this?  I would greatly appreciate it.

Any information would be helpful  

Answer
I do not know all the ingredients of plum sauce - presumably you do, though. The process to make it commercially would involve mixing the ingredients in a heated kettle equipped with an agitator or mixer. The mixture would be heated and stirred until solids are dissolved, starch is dispersed (if used - many chinese sauces are thickened with corn starch), and the sauce is heated to about 180 - 190 F. Meanwhile, bottles are cleaned either by washing or by blowing with air to remove dust. I think the sauce would be filled hot into the bottles, the caps put on, the bottles inverted to sterilize the caps, and then the bottles cooled by spraying with cold water. This is called hot filling and is common for sauces. It is also possible that the sauce could be filled warm or even cool - at room temperature - if it is determined that it poses no hazard to health. This depends on its pH (acidity) and water activity. Experimentally, sauce samples would be filled at room temperature and then held at room temperature or warmer to see what happens. One form of spoilage is growth of yeast or mold. Another might be the growth or survival of pathogens - disease causing microorganisms, which are detected by microbiologists. If such growth occurs in untreated sauce, then the experiment is repeated after heating the sauce to establish that the sauce has been made commercially sterile, meaning it will not spoil nor cause illness after storage. If heating does not work, then the sauce must be kept refrigerated.