467066 The Lemgo D- and z-Value Database for Food – an Instrument for the Dimensioning of Pasteurization Process

Monday, November 14, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Knut Schwarzer, Patrick Wilhelm, Jan Schneider and Ulrich Müller, Institute for Food Technology ILT.NRW, Ostwestfalen-Lippe University of Applied Sciences, Lemgo, Germany

The meaning of ‘minimal processing’ in the food industry is to reduce the usage of material and resources without a loss in quality or security. This principle still hasn’t yet arrived in pasteurization processes for food and packaging. In practice most of the time rough estimations of death rates are the basis for the parametrization. Often it depends for the most part on the experience of the chief engineer. Major safety margins are necessary to provide secure products.

For example, in beer pasteurization state of the art is to applicate twenty pasteurization units (PU) for a safe product. This base upon a series of publications from the 50th of the last century [1–3]. Latterly some big breweries tried to reduce the heat impact to their beer to only 8 PU without losing any product security.

On the other side to underdose pasteurization can lead to a loss of food safety and if the worst comes to the worst expensive product recalls and an immense image loss [4].

New products with modern ingredients like vitamin preparations or probiotic not only are more damageable to heat, they also susceptible for microbial spoilage. Thus a precise regulation of the pasteurization process is more important than ever.

In science this problem is known and a lot of research is done to scan the thermal death rates of microorganisms. Several hundreds of publications are available each describing the thermal death of one or a few species in a specific medium. For industrial food engineer or food scientists it is difficult to keep track of all the data. For this a database has been developed at the Institute of Food Technology.NRW (ILT.NRW). The “Lemgo D- and z-value Database for Food” (LDzBase) is an open access database [5]

Because the majority of existing data are given as D- and z-values this was our first choice of data model. A D-value describes the decimal reduction time; this means the time necessary to reduce the microorganism by the factor of 10 at a given temperature. The z-value describes the temperature dependency of the D-value. It is the change in temperature necessary to change the D-value by the factor of 10. By now the database consists of about 6,000 D-values for 140 species at about 2,700 different environmental conditions [6]. The data can facilitate the dimensioning of pasteurization processes. Comparing the different potential spoiling organisms will show those species that needing the most intensive heat exposure for the necessary reduction.

A comparison within species can be used for meta-analysis of the collected data. With 700 D-values concerning Listeria monocytogenes you can get a good overview about the influence of the medium, the microorganism live in. Factors like pH-value, aw -value or salt concentration can influence the mortality by the factor of 1,000 and more.

In our contribution we will introduce the database and show how to work with the data.

[1] Baselt, F. C.; Dayharsh, C. A.; Del Vecchio, H. W.: Thermal deathtime studies on beer spoilage organisms - III. A.S.B.C. Proceedings, S. 141–146, 1954.

[2] Dayharsh, C. A.; Del Vechio, H. W.: Thermal deathtime studies on beer spoilage organisms - II. A.S.B.C. Proceedings, S. 48–52, 1952.

[3] Del Vecchio, H. W.; Dayharsh, C. A.; Baselt, F. C.: Thermal deathtime studies on beer spoilage organisms – I. A.S.B.C. Proceedings, Bd. 1951, S. 45–50.

[4] Oliver Daumen, B.: Aseptische Abfüllanlagen. Teil 1: KZE-Anlagen in der Praxis. Brauwelt, 28/29, S. 905–912, 2003.

[5] Schwarzer, K.: Lemgo D- and z-value Database for Food, http://www.hs-owl.de/fb4/ldzbase/, [Datum des Zugriffs] 09.05.2016.

[6] Schwarzer, K.; Schneider, J.; Müller, U.; Becker, B.; Wilhelm, P.: Lemgo Database for D- and z-values. Brauwelt International, Nr. 5, S. 252–256, 2010.


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