Impact of spoilage microorganisms on some dairy products

Research Abstract

ABSTRACT Food spoilage is a complex process and excessive amounts of foods are lost due to microbial spoilage even with modern day preservation techniques. The aim of this study was to assess the microbiological quality of some dairy products in Beni-suef city, Egypt. A total of 210 samples of some dairy products (Kareish, Tallaga, Ras cheeses, small scale and large scale yoghurt, small scale and large scale cream samples) (30 of each) were collected from local retail stores, dairy shops and farmers' markets in Beni-Suef city. All samples were analysed for total bacterial count (TBC), total coliforms count, total yeast and mold count, total psychrotrophic count, lipolytic count and proteolytic count. The mean value of Kareish cheese and small scale cream for TBC were 1.07×107 ± 5.64 ×106 and 3.35×106 ± 1.23×106cfu/g, respectively. The mean values of Kareish, Tallaga, Ras cheeses, small scale yoghurt and small scale cream for total coliforms count were 2.55×105 ±1.59×105, 9.58×102 ± 4.32×102, 88.10 ± 21.11, 1.94×102 ± 79.47 and 1.58×104 ± 5.85×103cfu/g, respectively. The mean values for total yeast and mold count were 1.83×105 ± 9.25×104, 6.10×102 ± 3.35×102, 54.67 ± 22.04, 2.66×105 ± 8.07×104 and 2.57×104 ± 2.10×104cfu/g, respectively. The mean values for total psychrotrophic count were 2.89×107 ± 1.36×107, 1.16×106 ± 7.00×105, 2.46×106 ± 4.50×105, 7.81×105 ± 3.37×105 and 2.51×106 ± 6.95×105cfu/g, respectively. The mean values for lipolytic count were 1.23×106 ± 5.18×105, 9.32×105 ± 5.63×105, 2.91×106 ± 4.13×105, 2.32×105 ± 8.68×104 and 3.00×106 ± 7.34×105cfu/g, respectively. The mean value for proteolytic count were 1.16×106 ± 4.88×105, 9.94×105 ± 6.03×105, 5.85×106 ± 7.58×105, 3.32×105 ± 2.12×105 and 5.21×106 ± 1.27×106cfu/g, respectively. In conclusion, the presence of these organisms indicated that the examined dairy products were of inferior quality which reflects unhygienic measures, inadequate heat treatment during the manufacture, using bad quality ingredients or additives and improper sanitation during handling, storage and distribution.

Research Keywords

Lipolytic bacteria, Spoilage, Coliforms, Ras cheese, Yoghurt