Identification and characterization of volatile compounds in bovine plasma

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Parcher, Karen
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Food Technology

Bovine plasma proteins (BPP) are an economical source of high quality proteins that enhance gel strength and improve the emulsion capacity of food systems. However, off-flavors in the spray-dried plasma often result in finished food products with an unacceptable flavor, limiting the use of BPP. The objectives of this research were to identify the source of the volatile compounds in plasma and to test the effects of antioxidant addition, processing conditions and storage time on the formation of volatile compounds. Heat and oxygen exposure during the spray drying process initiate lipid oxidation in BPP as there are few oxidation compounds in liquid plasma and a significant amount in the spray-dried plasma, with hexanal being the principal volatile compound identified. Antioxidants (TBHQ, PG, BHT, rosemary) were added to BPP concentrate prior to drying in either a gas-fired or electric spray drier. The plasma dried with a gas-fired drier showed a significant (p<0.05) decrease in hexanal content compared with a control sample in the TBHQ, PG and BHT treatments while the rosemary treatment was not significant. Also, control samples from the electric drier had a significantly lower (p<0.05) total volatile count than control samples from the gas drier. The effect of residence time (zero and 20 minutes) and storage time (zero and eight weeks) was studied on plasma samples dried in a gas-fired drier and treated with either TBHQ or a rosemary concentrate. Data showed that longer residence and storage times both significantly (p<0.05) increased the amounts of hexanal produced in the spray-dried plasma. The spray drying process initiates lipid oxidation in BPP but the amount of volatiles formed can be reduced through the addition of antioxidants, use of an electric spray drier or by minimizing residence and storage times. All of these factors will help to reduce the formation of volatile flavor compounds and improve the quality of spray-dried BPP.

Tue Jan 01 00:00:00 UTC 2002