Food and Bioprocess Technology

, Volume 11, Issue 5, pp 1002–1011 | Cite as

Effect of Wheat Germ Heat Treatment by Fluidised Bed on the Kinetics of Lipase Inactivation

  • Renato D. Gili
  • María Cecilia Penci
  • Martín R. Torrez Irigoyen
  • Sergio A. Giner
  • Pablo D. Ribotta
Original Paper


Wheat germ is scrapped during milling due to their unfavourable baking properties and rapid deterioration. Although it is a low-cost by-product with remarkable nutritional features, its widespread utilisation is limited by the action of enzymes. On that basis, the effect of the germ stabilisation process by fluidisation with hot air was studied. Fluidisation, carried out with air between 90 and 150 °C, generated notable lipase inactivation, which reached a minimum residual activity of 15.5% from original. The total tocopherol contents of stabilised samples were not significantly affected. Colour attributes of treated samples showed slight changes compared with raw wheat germ. A mathematical model was fitted to colour data to predict the changes due to heat. A first-order kinetic model was applied to descript the thermal lipase inactivation. The inactivation rate constant, D value, Z value and the activation energy were calculated for this process. The results obtained in this study are expected to contribute to the optimisation of wheat germ stabilisation by fluidisation. This process may enable to obtain a food with good nutritional features for human consumption from a co-product of the wheat milling industry at a short time and high temperature.


Fluidisation Wheat germ Thermal kinetic inactivation Lipase activity Tocopherols 



Browning index


Browning index before thermal treatment


Maximum browning index reached in the thermal treatment


Decimal time, s


Activation energy (kJ mol−1)


Free fatty acids content, g of oleic acid kg−1 of oil


Free fatty acids content before incubation, g of oleic acid kg−1 of oil


Free fatty acids content after 48 h of incubation, g of oleic acid kg−1 of oil


Change in free fatty acids content, g of oleic acid kg−1 of oil


Browning rate constant, s−1


Enzyme inactivation rate constant, s−1


Peroxide value, meq O2 kg−1 oil


Universal gas constant, 8.314, kJ kmol−1 K−1


Time, s

\( {t}_{\frac{1}{2}} \)

Time which the half of the maximum BI is reached, s


Inlet air temperature, °C


Total tocopherol content, mg kg−1 oil


Whiteness index


value, °C



The authors would like to thank Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (PIP11220120100184), the Secretaría de Ciencia y Tecnología of Universidad Nacional de Córdoba (SeCyT-UNC) and the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT) (PICT2013 N°2327) for the financial support.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Instituto de Ciencia y Tecnología de Alimentos Córdoba (ICYTAC)CONICET-UNCCórdobaArgentina
  2. 2.Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y NaturalesFCEFyN-UNC. Instituto de Ciencia y Tecnología de los Alimentos (ICTA)CórdobaArgentina
  3. 3.Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA)CONICET-UNLPLa PlataArgentina

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