We are testing various cereal and legumes under high-pressure and observed that crude fat decreased significantly after pressurization (600 MPa). Is there any explanation?
I don't think HPP can increase the fat content per se, but it can help release or extract it. Is the difference found in actual content or percentage? Perhaps there could be a problem associated with quantification? What was the basis - wet, dry?
I don't think HPP can increase the fat content per se, but it can help release or extract it. Is the difference found in actual content or percentage? Perhaps there could be a problem associated with quantification? What was the basis - wet, dry?
Dr. Swamy- the fat decreased with pressure. The change is marginal upto 400 MPa but it is significant at 600 MPa and it is based on triplicate samples and few cereal and legume flours. It is all dry basis and we do have a brand new fat extractor not regular soxhlet. I found few literature they also have been reported drop in fat content. Could be fat hydrolysis.
fat hydrolysis with pressure is possible at an amount of 98-99% with specific conditions, but this opération is reversible, it can be aloso hydrolysed by lipases (enzymes in your matrix). hydrolysis products (free fat acids and, mono and di glycerides) will be extracted the same way like TG, but the glycerol witch is hydrosoluble will not be, if you use hexane or petrolium ether as extracting solvant.
glycerol represent near 7% in mass of the total lipids, if the decrease is near that you can suspect that there is an hydrolysis. you can aloso verify that with CCM fractionation of your lipidic extract.
errors can also be introduced by the méthod (is your new extractor validated)
hope that it was satisfactory, but more informations about your food matrix and your treatment conditions can help to clarify the situation
Jasim:
I misread your question as fat content increasing rather than decreasing. Sorry. Decrease can happen due to many reasons - hydrolysis could be the possible reason. Complexing with proteins and other macro molecules could be another. Bound lipids may not be easy to measure and when that happens due to HPP you could a register a lower fat content?. I am also curious as to how were they HPP treated? Did you measure any enzyme activity like lipase?
Thank you Dr. Swamy, Eduardo and Latifa for suggestions. We have not measured lipase acivity.
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