Scientific journal

58 2019

Journal of Food and Nutrition Research
Summary No. 3 / 2019

Pohůnek, V. – Adamcová, M. – Kulišanová, I. – Šístková, I. – Rohlík, B.-A. – Ševčík, R.
Thermal inactivation of Aspergillus lacinosus ascospores as a function of temperature and soluble solids content in fruit jam
Journal of Food and Nutrition Research, 58, 2019, No. 3, s. 275-282

Václav Pohůnek, Department of Food Preservation, Faculty of Food and Biochemical Technology, University of Chemistry and Technology Prague, Technická 5, 16628 Prague 6 – Dejvice, Czech Republic. E-mail:

Received 27 March 2019; 1st revised 16 May 2019; 2nd revised 7 June 2019; accepted 11 June 2019; published online 10 September 2019

Summary: Moulds are the most frequently occurring spoilage microflora in jams, in particular the heat-resistant species of the Byssochlamys, Neosartorya and Aspergillus genera. An alarming number of uncommon heat-resistant isolates, such as Aspergillus lacinosus, with unknown thermal inactivation kinetic parameters, decimal reduction times (D values), were detected in recent studies. Aspergillus lacinosus, an ascospore-forming mould was isolated from commercially produced jams with reduced sugar content, during a thermal death study. The aim of our study was to determine D values for A. lacinosus in three types of matrices: physiological solution (PS, pH 6.6, refraction Rf = 1.2 °Brix), low-sugar jam (LSJ, pH 3.5, Rf = 57 °Brix) and extra-sugar jam (ESJ, pH 3.5, Rf = 65 °Brix) at 70–95 °C. ESJ was premium quality jam with minimal content of fruits 450 g per kilogram of product. Data obtained from thermal death curves showed various D values of A. lacinosus in these matrices, i.e. (23.25?±?7.21) min for PS, (8.18?±?3.56) min for LSJ and (4.89?±?1.89) min at 85 °C for ESJ. It was observed that ESJ had the lowest D value from all matrices for each temperature. Calculation of the temperature sensitivity of microorganisms (z values) showed the same phenomenon, the values ranging from 17.2 °C to 38.7 °C for strawberry jams and from 20.3 °C to 21.8 °C for forest fruit jams.

Keywords: heat-resistant mould; thermal treatment; inactivation; decimal reduction time; thermal sensitivity; thermal death curves

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