الفهرس 
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Abstract
A total of 120 samples of Laban Rayeb pasteurized and homemade were collected randomly from supermarkets at Alexandria Governorate. The collected samples were dispatched directly to the laboratory of food hygiene department with a minimum of delay in an ice box where they were prepared for sanitary and microbiological evaluation.
7.1. Sensory evaluation of examined Rayeb samples:
7.1.1. Flavour:
. 70% of examined brand A samples had normal flavor while the incidence of slight acetaldehyde were in 30% of samples. 100% of examined brand B samples had normal flavor. 88% of examined brand C samples had normal flavor while the incidence of slight acetaldehyde were in 12% of samples.100% of examined brand D samples had normal flavor. 100% of examined brand E samples had normal flavor while 63% of examined homemade Laban Rayeb samples had normal flavor while the incidence of definite acetaldehyde were in 29% of samples
7.1.2. Body and Texture:
100% of examined brand A samples had normal Body and Texture.76% of examined brand B samples had normal Body and Texture while the incidence of slight too thin Body and Texture were in 24% of samples.100% of examined brand C samples had normal Body and Texture. 100% of examined brand D samples had normal Body and Texture. 70% of examined brand E samples had normal Body and Texture while the incidence of slight too thin Body and Texture were in 30% of samples while 69% of examined homemade Laban Rayeb samples had normal Body and Texture while the incidence of slight too firm Body and Texture were in 31% of samples.
7.1.3. Appearance:
88% of examined brand A samples had normal appearance while the incidence of Yellow white appearance in 12% of samples. 100% of examined brand B samples had normal appearance. 76% of examined brand C samples had normal appearance. While the incidence of Yellow white appearance in 24% of samples. 88% of examined brand D samples had a normal appearance while the incidence of Yellow white appearance in 12% of samples. 88% of examined brand E samples had normal appearance while the incidence of Yellow white appearance in 12% of samples while 63% of examined homemade Laban Rayeb samples had normal appearance while the incidence of Lumpiness appearance in 26% of samples and yellow white in 11% of the samples.
Homemade Laban Rayeb samples are the lowest quality in flavor, body and texture and appearance (63%, 69% and 63% were normal) while sterilized Rayeb samples were the highest quality.
In comparison of the samples with normal physical properities, results revealed that the flavor for brands B, D, and E were on the top (100%) for each while brand c came later (88%) and brand A (70%). Body and texture for brands A, C and D was 100% normal then E by 70%. Appearance Excellency went for brand B 100% then A, D and E 88% for each.
7.2. Laboratory evaluation of examined Rayeb:
7.2.1. Chemical composition of examined Rayeb:
7.2.1.1. Fat composition
The mean values of Fat% in homemade Rayeb samples with minimum 0.5% and the maximum Fat% were 3% while the mean value was 1.75 ± 0.21%. Pasteurized Rayeb brand A samples was minimum 1.5% and the maximum Fat% were 2.50% while the mean value was 2.00 ± 0.05%. pasteurized Rayeb brand B samples was minimum 1.55% and the maximum Fat% were 2.25% while the mean value was 1.9 ± 0.22%. pasteurized Rayeb brand C samples was minimum 1.62% and the maximum Fat% were 2.45% while the mean value was 2.00 ± 0.15%. pasteurized Rayeb brand D samples was minimum 1.5% and the maximum Fat% were 2.50% while the mean value was 2.00 ± 0.11%. pasteurized Rayeb brand E samples was minimum 1.52% and the maximum Fat% were 1.74% while the mean value was 1.63 ± 0.07%.
7.2.1.2. Solids not fat (SNF)
The mean values of SNF% in homemade Rayeb samples was minimum 4.56 % and the maximum% was 15.68 % while the mean value was 10.12 ± 0.35%. pasteurized Rayeb samples brand A was minimum 6.55% and the maximum Minerals % were 8.70 % while the mean value was 7.62 ± 0.1%. pasteurized Rayeb samples brand B was minimum 6.55% and the maximum Minerals % were 7.63 % while the mean value was 6.81 ± 0.10%. pasteurized Rayeb samples brand C was minimum 6.7% and the maximum Minerals % were 8.22 % while the mean value was 7.46 ± 0.04%. pasteurized Rayeb samples brand D was minimum 6.75% and the maximum Minerals % were 8.55 % while the mean value was 7.65 ± 0.20%. pasteurized Rayeb samples brand E was minimum 6.12% and the maximum Minerals % were 8.65 % while the mean value was 7.38 ± 0.05%.
The results revealed that the chemical composition of homemade Rayeb samples has wide variation while pasteurized Rayeb samples hasn’t such variation because Rayeb in industries underwent processing and fat standardization.
7.2.2. Sanitary evaluation
7.2.2.1. Acidity percent:
The minimum titratable acidity were 0.9, 0.7, 1.0, 0.7, 0.8 and 1.3, the maximum titratable acidity were 1.6, 1.2, 1.7, 1.5, 1.6 and 1.8 while the mean values of the titratable acidity were 1.15 ± 0.05, 0.86 ± 0.04, 1.25 ± 0.06, 1.04 ± 0.05, 1.19 ± 0.08 and 1.55 ± 0.00 for examined Laban Rayeb brands A, B, C, D, E and homemade Laban Rayeb respectively.
7.2.2.2. pH:
The minimum pH values were 4.0, 4.0, 3.8, 3.9, 3.9 and 3.7, the maximum pH value were 4.7, 4.5, 4.8, 4.6, 4.7 and 4.3 while the mean values were 4.25 ± 0.05, 4.18 ± 0.04, 4.4 ± 0.07, 4.21 ± 0.05, 4.33 ± 0.07 and 4.07 ± 0.03 for examined Laban Rayeb brands A, B, C, D, E and homemade respectively.
7.2.3. Microbiological evaluation of examined Rayeb samples:
7.2.3.1. Total coliform count:
The incidence of coliforms in examined Laban Rayeb samples was 12%, 89% and the count ranged between minimum 5.0 x 102 and 9.6 x 102, the maximum 9.0 x 102 and 1.3 x 105 while the mean values were 7.0 x 102 ± 2.0 x 102 and 0.5 x 105 ± 0.06 x 105 for examined Laban Rayeb brands C and F respectively. Brands A, B, D and E have negative results
It was found that 100% of the examined Rayeb samples brands A, B, D and E were complied with the Egyptian standards (2005) and 0% were out of specification. it was found that 88% and 11% of the examined Rayeb samples brands C and homemade Laban Rayeb respectively were complied with the Egyptian standards (2005).
7.2.3.2. Total Enterococci count:
The count ranged between minimum 1.0 x 102, 2.0 x 102, 1.0 x 102, 1.0 x 102, 1.0 x 102 and 1.0x 103, the maximum 1.3 x 103, 1.5 x 103, 4.0 x 103, 7.0 x 102, 3.5x 103 and 4.8x 104 while the mean values were 5.0 x 102 ± 1.4 x 102, 0.65 x 103 ± 0.2 x 103, 0.9 x 103 ± 0.4 x 103, 3.6x 102 ± 1.2 x 102, 1.07 x 103 ± 0. 4 x 103 and 1.6 x 104 ± 0.4 x 104 for examined Laban Rayeb brands A, B, C, D, E and F respectively. It’s obvious that homemade Laban Rayeb has the highest count of Enterococci than other brands.
It was found that 41.15%, 64.71%, 47.06%, 64.71%, 58.83% and 62.86% of the examined Rayeb samples brands A, B,C, D, E and F were complied with the Egyptian standards (2005) while 58.85%, 35.29%, 52.94%, 35.29%, 41.17% and 37.14% were out of specification
7.2.3.3. Total S. aureus count:
The count ranged between minimum 1x102, 2.0 x 102, 1.0 x 102, 6x102, 1.0 x 102 and 1.0x 103, the maximum 1x102, 6.0 x 102, 4.0 x 102, 6x102, 5.0 x 102 and 2.1 x 104 while the mean values were 1x102, 4.0 x 102 ± 1.1 x 102, 3.0 x 102 ± 0.5 x 102, 6x102, 2.25 x 102 ± 0.94 x 102 and 0.42 x 104 ± 0.09 x 104 for examined Laban Rayeb brands A, B, C, D, E and homemade respectively. It’s obvious that homemade Laban Rayeb has the highest count of S. aureus than other brands.
It was found that 94.12%, 82.36%, 70.59%, 94.12%, 76.48% and 31.43% of the examined Rayeb samples brands A, B,C, D, E and homemade were complied with the Egyptian standards (2005) while 5.88%, 17.64%, 29.41%, 5.88%, 23.52% and 68.57% were out of specification.
7.2.3.4. Total Yeast count:
The minimum yeast count were 1.0 x 103 for brands A, B, C, D and E while 5.0x 104 for homemade Laban Rayeb , the maximum pH value were 1.3 x 104, 8.0 x 103, 3.7 x 104, 2.0 x 103, 3.0x 103 and 3.4x 106 while the mean value were 3.6 x 103 ± 1.4 x 103, 3.1 x 103 ± 1.02 x 103, 0.72 x 104 ± 0.31 x 104, 1.2 x 103 ± 0.2 x 103, 1.7 x 103 ± 0.2 x 103 and 0.8 x 106 ± 0.15 x 106 for examined Laban Rayeb brands A, B, C, D, E and homemade respectively.
The frequency distribution of isolated yeast from brands A, B, C, D and E were Candida albinos 7 (24.1 %), 13 (68.4 %), 22 (55 %), 6 (50 %), 8 (57.1 %) and 34 (34.7 %), Candida guillormondi 1 (3.4 %), 1 (5.3 %), 0, 0, 0, 5 (5.1 %) and Candida parapsillosis, 0, 0, 0, 0, 0 and 5 (5.1 %), Candida pseudotropicalis 2 (7 %), 0, 0, 0, 0 and 9 (9.2 %), Candida tropical is 0, 0, 0, 5 (41.7 %), 0 and 6 (6.1 %), Rhodotorulla glutinis 3 (10.3 %), 2 (10 %), 0, 0, 0 and 3 (3.1 %), Rhodotorulla Pichia 0, 0, 0, 0, 0 and 8 (8.2 %), Rhodotorulla rubra 16 (55.2 %), 0, 20 (45.5 %), 0, 5 (35.7 %) and 15 (15.3 %), Torulopsis spp. 0, 3 (15.8 %), 0, 1 (8.3 %), 0 and 7 (7.1 %), Zygosaccharomyces spp. 0, 0, 2 (4.5 %), 0, 1 (7.2 %) and 6 (6.1 %) for examined Laban Rayeb brands A, B, C, D, E and homemade Laban Rayeb respectively.
It was found that 58.95%, 52.95%, 35.3%, 70.59%, 58.83% and 0% of the examined Rayeb samples brands A, B,C, D, E and homemade were complied with the Egyptian standards (2005) while 41.05%, 47.05%, 64.70%, 29.41%, 41.17% and 100% were out of specification..
7.2.3.5. Total Mould count:
The minimum mould count were 1.0 x 103 for brands A, B, C, D and E while 1.0 x 104 for homemade Rayeb samples, the maximum mold count were 2.0 x 103, 6.0 x 103, 6.0 x 103, 3.0 x 103, 4.0 x 103 and 3.3 x 105 while the mean values were 1.4 x 103 ± 0.2 x 103, 2.7 x 103 ± 0.6 x 103, 2.6 x 103 ± 0.4 x 103, 1.7x 103 ± 0.2 x 103, 1.7 x 103 ± 0.4 x 103 and 0.94 x 105 ± 0.14 x 105 for examined Laban Rayeb brands A, B, C, D, E and homemade respectively.
frequency distribution of isolated moulds from brands A, B, C, D and E were Aspergillus flavus 1 (9.09 %), 5 (18.51 %), 6 (16.21 %), 3 (30 %), 3 (20 %) and 6 (8.69 %), Aspergillus niger 0, 0, 1 (2.70 %), 0, 0 and 4 (5.79 %), Cladosporium species 3 (27.27 %), 1 (3.70 %), 7 (18.91 %), 2 (20 %), 1 (6.66 %) and 13 (18.84 %), Curvularia 0, 0, 0, 0, 0 and 3 (4.34 %), Geotrichium candidium 6 (54.4 %), 16 (29.25 %), 17 (45.94 %), 4 (40 %), 8 (53.33 %) and 25 (36.23 %), Fusarium spp. 0, 0, 0, 0, 0 and 7 (10.14 %), Penicillium chysogenum 1 (9.09 %), 3 (11.11 %), 5 (13.51 %), 0, 0, 2 (13.33 %) and 11 (15.94 %), Trichophyton rubrum 0, 2 (7.40 %), 1 (2.70 %), 1 (10 %), 1 (6.66 %) and 0 respectively.
It was found that 47.06%, 41.18%, 17.65%, 70.59%, 47.06% and 0% of the examined Rayeb samples brands A, B,C, D, E and homemade were complied with the Egyptian standards (2005) while 52.94%, 58.82%, 82.35%, 29.41%, 52.94% and 100% were out of specification.