Effect of some food preservatives on the lipolytic activity of beef luncheon fungi

Abstract

Beef luncheon meat is one of the most popular meals in several countries in the world including Egypt. Thirty one fungal species and 3 species varieties were recovered from 30 samples of beef luncheon meat collected from different supermarkets in Qena. Alternaria, Aspergillus, Emericella, Mucor, Mycosphaerella, Penicillium and Rhizopus were the most common genera on the two types of media. From the above genera, the most prevalent species were Alternaria alternate, Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Emericella nidulans, Mucor racemosus, Mycosphaerella tassiana, Penicillium chrysogenum and Rhizopus stolonifer. Screening of fungi for their abilities to produce lipase enzyme showed that, ten isolates represented 32.26% of total isolates appeared high lipase production, while sixteen isolates (51.61%) were moderate and 5 isolates (16.13%) were low producers. Aspergillus niger, Fusarium oxysporum and Nectria haematococca produced the highest amount of lipase enzyme, so these fungi were used in further studies. The incorporation of five food preservatives (Disodium phosphate, sodium benzoate, citric acid, potassium sorbate and sodium citrate) individually in the culture medium of lipase production exhibited an inhibitive effect on the mycelial growth and enzyme production by Aspergillus niger, Fusarium oxysporum and Nectria haematococca.

Keywords: Beef luncheon fungi; Food preservatives; Lipase.

Fig. 1

Effect of food preservatives on lipase production by Aspergillus niger.

Fig. 2

Effect of food preservatives on mycelial growth of Aspergillus niger.

Fig. 3

Effect of food preservatives on lipase production by Fusarium oxysporum.

Fig. 4

Effect of food preservatives on mycelial growth of Fusarium oxysporum.

Fig. 5

Effect of food preservatives on lipase production by Nectria haematococca.

Fig. 6

Effect of food preservatives on mycelial growth of Nectria haematococca.