Document Type : Original Article
Authors
1
Dairy Department, Faculty of Agriculture, Assiut University, Assiut.
2
2Dairy Science Department, Faculty of Agriculture, Assiut University
3
Dairy Science Department, Fac. of Agric., Assiut Univ.
Abstract
Laban rayeb manufactured under a good sanitation and hygiene conditions from lactic acid bacteria isolated, from Laban Rayeb Produced by small dairy plant in Assuit city, Cow’s milk heat treated at 73 ° C and cooled to 37 ° C were inoculated by either isolated Lactobacillus sp or Streptococci sp culture or mixture of them at 1: 1 by weight, to produce a Laban Rayeb in sterile laboratory conditions. The produced Laban Rayeb analyzed as fresh and during period stored for 15 days at 5 ± 2 ° C. The mean acidity, total solids, total nitrogen and soluble nitrogen content in control Laban Rayeb were of 0.7, 11.36 ,0.44, and 0.112 % on the first day of storage which increased to 0.76, 11.52 ,0.49 and 0.169 % after 15 days of storage respectively .While the mean acidity, total solids, total nitrogen, and soluble nitrogen in the samples of Laban Rayeb made by Streptococci sp were of 0.74, 11.33, 0.44 and 0.114 % on the first day of storage which increased with storage to 0.95, 12.22, 0.61 and 0.160 % after 15 days. While these Acidity, Total solid, total nitrogen and soluble nitrogen values of Laban Rayeb inoculated by Lactobacillus sp were 0.76, 11.16, 0.45 and 0.103 %, at first day of storage, which increased to 0.96, 11.75, 0.59, and 146% after 15 days of storage respectively. The Laban Rayeb produced using Lactobacillus sp and Streptococci sp gave the following values 0.84, 11.36, 0.42 and 0.123% respectively and by increasing the storage period these values acidity, total solids, total nitrogen and soluble nitrogen values were increased to reach 1.2, 11.9, 0.55 and 0.192% after 15 days of storage respectively. The total bacterial count values in control Laban Rayeb, Laban Rayeb made by single Streptococci sp, by single Lactobacilli sp and by mixed Lactobacillus sp and Streptococci sp respectively were of 5.12, 6.21, 6.27, 6.29 log (cfu/ml) on the first day of storage and increased to 8.87, 9.13, 9.20 , 8.64 log (cfu/ml) after 15 days of storage. While The mean Logarithm of lactic acid bacteria of Lactobacilli sp. count values in control Laban Rayeb, Laban Rayeb produced by Streptococci sp, Lactobacilli sp and Lactobacillus sp and Streptococci sp were of 5.22, 5.46, 7.14, 7.15 log (cfu/ml) on the first day of storage and increased to 7.73, 8.13, 9.22, 9.46 log (cfu/ml) after 15 days of storage , The mean Logarithm of Streptococci sp. values in control Laban Rayeb, Laban Rayeb produced by Streptococci sp, Lactobacilli sp and Lactobacillus sp mixed with Streptococci sp were of 4.86, 6.93, 4.12, 7.15 log (cfu/ml) on the first day of storage and increased to 7.42, 9.98, 8.17, 8.76 log (cfu/ml) after 15 days of storage ,The mean Logarithm count of lactic acid bacteria of proteolytic bacteria values in control Laban Rayeb, Laban Rayeb made by Streptococci sp, Lactobacilli sp and mixed of Lactobacillus sp and Streptococci sp were 1.61, 3.54, 3.18, 3.32 log (cfu/ml) on the first day of storage which increased to 5.34, 6.45, 6.56, 6.75 log (cfu/ml) after 15 days of storage . Molds and yeasts and coliform bacteria were not detected.
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