One of the most popular types of fermented dairy products is cheese. The process of cheese aging ... more One of the most popular types of fermented dairy products is cheese. The process of cheese aging is essential for improving cheese quality, and health benefits. Ripened cheese at different times acquired wide diversity of characteristic aromas and textures due to establishing a cascade of intrinsic complex biochemical and metabolic outcomes, resulting in a dynamic shift in microbial flora. Various functional bioactive compounds could be released during the cheese ripening process. Many strategy approaches are employed to accelerate cheese ripening based on increasing lipolysis and proteolysis rate. During cheese aging, microbial spoilage as early and late blowing may occur so, designing smart ripening rooms are very essential equipped with computerized monitoring systems including sensors, software platforms, temperature, and humidity data loggers.
IOP Conference Series: Earth and Environmental Science, 2020
Physical properties of Dangke cheese can be improved by the ripening process through starter cult... more Physical properties of Dangke cheese can be improved by the ripening process through starter culture inoculation. The purpose of this study was to analyze the characteristics of Dangke cheese with different temperature and incubation time of ripening as well as their interaction by Lactococcus lactis inoculation. The research method used was experimental using a completely randomized design (CRD) with 2 (two) factors. The first factor (A) is the ripening temperature (5, 15, and 25°C) and the second factor (B) is the Ripening time (6, 9, and 12 days). Dangke is made by adding a papaya sap solution as coagulation. Microstructure was observed by a scanning electron microscope. The treatments were replicated three times each process. The data were processed statistically with variance analysis, followed by the least significant difference test. The results indicated that the ripening temperature affected the activity of L. lactis in carbohydrate degradation to produce lactic acid so tha...
Food-borne illnesses and microbial food contamination are crucial concerns and still issues of ma... more Food-borne illnesses and microbial food contamination are crucial concerns and still issues of major worldwide concern. Lysozyme (Lz) is an active protein against Gram-positive bacteria through its muramidase lytic activity, however, several authors could identify some antimicrobial peptides derived from native Lz that have an exaggerated and broad-spectrum antibacterial activity. Therefore, a lysozyme peptides preparation (LzP) is developed in order to broaden the Lz spectrum. In this work, we investigated the potential efficacy of LzP as a novel Nutra-preservative (food origin) agent against some pathogenic and spoilage bacteria. Our results showed that LzP demonstrated only 11% of the lysozyme lytic activity. However, LzP exhibited strong antibacterial activity against Escherichia coli, Salmonella enteritidis, and Pseudomonas species, while Salmonella typhi and Aeromonas hydrophila exhibited slight resistance. Despite the lowest LzP concentration (0.1%) employed, it performs stro...
Biochemical and Biophysical Research Communications, 1999
Cell-free extract prepared from a mixed culture consisting of strains belonging to the genera Kle... more Cell-free extract prepared from a mixed culture consisting of strains belonging to the genera Klebsiella and Rhodococcus grown in the presence of caffeine contains a novel enzyme, caffeine (1,3,7-trimethylxanthine) oxidase which catalyzes the oxidation of caffeine at the C-8 position to produce 1,3,7-trimethyluric acid. The enzyme was purified to homogeneity by a combination of ion-exchange and hydrophobic column chromatographies. Both native and SDS/PAGE of the purified enzyme showed a single protein band and the subunit molecular mass of the protein was determined to be 85 kDa. Dichlorophenol indophenol and cytochrome c served as good electron acceptors but NAD and NADP did not. Caffeine served as the best substrate with an apparent Km of 11.4 μM. various analogues of theobromine were also effective substrates for caffeine oxidase. The activity was inhibited by o-phenanthroline, H2O2, and methanol, but salicylate, thiol-group blocking reagents, and sodium arsenite, the known xanthine oxidase inhibitors, did not inhibit the reaction. The spectral characteristics of the purified enzyme suggest that it is a flavoprotein containing non-heme iron.
Serratia marcescens isolated from raw milk was found to produce extracellular lipase. The growth ... more Serratia marcescens isolated from raw milk was found to produce extracellular lipase. The growth of this organism could contribute to flavor defects in milk and dairy products. Serratia marcescens was streaked onto spirit blue agar medium, and lipolytic activity was detected after 6 h at 30°C and after 12 h at 6°C. The extracellular crude lipase was collected after inoculation of the organism into nutrient broth and then into skim milk. The crude lipase was purified to homogeneity by ion-exchange chromatography and gel filtration. The purified lipase had a final recovered activity of 45.42%. Its molecular mass was estimated by SDS-PAGE assay to be 52 kDa. The purified lipase was characterized; the optimum pH was likely between 8 and 9 and showed about 70 % of its activity at pH 6.6. The enzyme was very stable at pH 8 and lost about 30 % of its activity after holding for 24 h at 4°C in buffer of pH 6.6. The optimum temperature was observed at 37°C and exhibited high activity at 5°C. ...
The main objective of this study was to verify the effect of oral intake of a yolk-derived peptid... more The main objective of this study was to verify the effect of oral intake of a yolk-derived peptide preparation (HYP) obtained by enzymatic hydrolysis of yolk water-soluble protein on bone markers and bone density in 65 perimenopausal women with an average age of 47.6 AE 5.2 years. Subjects were divided into three groups, and then enrolled in a 6-month, randomized, double-blind clinical trial. Bone formation and resorption markers were measured at 0, 3, and 6 months, while bone mineral density (BMD) in the lumbar spines was measured at 0 and 6 months. Although the bone formation marker levels showed the similarity changes among the groups, bone resorption markers in the test HYP group were significantly decreased after 3 and 6 months in comparison to other groups (P < 0.05). After 6 months, BMD in the test HYP group maintained at healthy numerical values whereas BMD values were decreased in other groups. Hence HYP would be an antiosteoporotic agent originated from natural food to maintain bone health, especially for women.
Hundred and eighty random cheese samples, includes varities of cheese, soft (kareish and white); ... more Hundred and eighty random cheese samples, includes varities of cheese, soft (kareish and white); hard (Roomy); processed (Flamingo), beside machine and hand swabs were collected from different supermarkets (30 of each), at Qalubiya governorate, Egypt to investigate the incidence of Staphylococci with especial reference to MRSA strains. The results revealed that the mean value of Staphylococci and S. aureus counts (cfu/g) in kareish cheese samples were 3.16×105 and 6.57×104, respectively; for white cheese samples were 7.60×104 and 5.12×104, respectively; for Roomy cheese samples were 5.79×104 and 3.38×104, respectively; for Flamingo cheese samples were 2.96×104 and 1.05×104, respectively; for machine swab samples were 1.02×104 and 1.48×103, respectively and for hand swab samples were 1.43×104 and 3.71×103 (CFU/ml), respectively. A total of 118/180 (65.5%) isolates of staphylococci species, includes 55 S. aureus (30.6%). All 55 isolated S. aureus strains were coagulase positive while,...
Lactoferrin LF is a member of the transferrin family that is a cationic iron-binding protein. It ... more Lactoferrin LF is a member of the transferrin family that is a cationic iron-binding protein. It is an -kDa glycoprotein that is found in many secretions in the body and is highly present in milk and colostrums. It exerts antibacterial effects and has a wide range of biological activities. Moreover, it is considered as a precursor of different peptides that have multifunctional bioactivities. During the last decade, several applications of LF and its peptides have been discovered, which has led to its commercial production. Therefore, LF and its peptides can offer a variety of specialized ingredients that can be tailored to meet the needs of natural food preservatives and functional food ingredients.
A total of 234 randomly selected milk samples from different sources (110, 50, 34 and 40 samples)... more A total of 234 randomly selected milk samples from different sources (110, 50, 34 and 40 samples) from each of (market milk, collecting centers, bulk tank and UHT milk samples; respectively) were analyzed for the quinolones residues by rapid quinolones detection strip test. Results revealed that 17.3%, 14% and 20.6% of milk samples were positive for the presence of quinolones residues for market milk, collecting centers and bulk tank milk samples; respectively, while not detected in UHT milk samples. The positive milk samples were subjected to HPLC analysis for quantitative detection of ciprofloxacin residues, which were present in 11.8%, 8%, and 8.8% for market milk, collecting centers and bulk tank milk samples; respectively, with mean values of 17.37± 0.27, 18.02±0.7 and 17.79± 0.75 ppb; respectively. None of them had a concentration exceeded the maximum residual limit set by different international standards. Public health importance of ciprofloxacin residues was discussed.
One of the most popular types of fermented dairy products is cheese. The process of cheese aging ... more One of the most popular types of fermented dairy products is cheese. The process of cheese aging is essential for improving cheese quality, and health benefits. Ripened cheese at different times acquired wide diversity of characteristic aromas and textures due to establishing a cascade of intrinsic complex biochemical and metabolic outcomes, resulting in a dynamic shift in microbial flora. Various functional bioactive compounds could be released during the cheese ripening process. Many strategy approaches are employed to accelerate cheese ripening based on increasing lipolysis and proteolysis rate. During cheese aging, microbial spoilage as early and late blowing may occur so, designing smart ripening rooms are very essential equipped with computerized monitoring systems including sensors, software platforms, temperature, and humidity data loggers.
IOP Conference Series: Earth and Environmental Science, 2020
Physical properties of Dangke cheese can be improved by the ripening process through starter cult... more Physical properties of Dangke cheese can be improved by the ripening process through starter culture inoculation. The purpose of this study was to analyze the characteristics of Dangke cheese with different temperature and incubation time of ripening as well as their interaction by Lactococcus lactis inoculation. The research method used was experimental using a completely randomized design (CRD) with 2 (two) factors. The first factor (A) is the ripening temperature (5, 15, and 25°C) and the second factor (B) is the Ripening time (6, 9, and 12 days). Dangke is made by adding a papaya sap solution as coagulation. Microstructure was observed by a scanning electron microscope. The treatments were replicated three times each process. The data were processed statistically with variance analysis, followed by the least significant difference test. The results indicated that the ripening temperature affected the activity of L. lactis in carbohydrate degradation to produce lactic acid so tha...
Food-borne illnesses and microbial food contamination are crucial concerns and still issues of ma... more Food-borne illnesses and microbial food contamination are crucial concerns and still issues of major worldwide concern. Lysozyme (Lz) is an active protein against Gram-positive bacteria through its muramidase lytic activity, however, several authors could identify some antimicrobial peptides derived from native Lz that have an exaggerated and broad-spectrum antibacterial activity. Therefore, a lysozyme peptides preparation (LzP) is developed in order to broaden the Lz spectrum. In this work, we investigated the potential efficacy of LzP as a novel Nutra-preservative (food origin) agent against some pathogenic and spoilage bacteria. Our results showed that LzP demonstrated only 11% of the lysozyme lytic activity. However, LzP exhibited strong antibacterial activity against Escherichia coli, Salmonella enteritidis, and Pseudomonas species, while Salmonella typhi and Aeromonas hydrophila exhibited slight resistance. Despite the lowest LzP concentration (0.1%) employed, it performs stro...
Biochemical and Biophysical Research Communications, 1999
Cell-free extract prepared from a mixed culture consisting of strains belonging to the genera Kle... more Cell-free extract prepared from a mixed culture consisting of strains belonging to the genera Klebsiella and Rhodococcus grown in the presence of caffeine contains a novel enzyme, caffeine (1,3,7-trimethylxanthine) oxidase which catalyzes the oxidation of caffeine at the C-8 position to produce 1,3,7-trimethyluric acid. The enzyme was purified to homogeneity by a combination of ion-exchange and hydrophobic column chromatographies. Both native and SDS/PAGE of the purified enzyme showed a single protein band and the subunit molecular mass of the protein was determined to be 85 kDa. Dichlorophenol indophenol and cytochrome c served as good electron acceptors but NAD and NADP did not. Caffeine served as the best substrate with an apparent Km of 11.4 μM. various analogues of theobromine were also effective substrates for caffeine oxidase. The activity was inhibited by o-phenanthroline, H2O2, and methanol, but salicylate, thiol-group blocking reagents, and sodium arsenite, the known xanthine oxidase inhibitors, did not inhibit the reaction. The spectral characteristics of the purified enzyme suggest that it is a flavoprotein containing non-heme iron.
Serratia marcescens isolated from raw milk was found to produce extracellular lipase. The growth ... more Serratia marcescens isolated from raw milk was found to produce extracellular lipase. The growth of this organism could contribute to flavor defects in milk and dairy products. Serratia marcescens was streaked onto spirit blue agar medium, and lipolytic activity was detected after 6 h at 30°C and after 12 h at 6°C. The extracellular crude lipase was collected after inoculation of the organism into nutrient broth and then into skim milk. The crude lipase was purified to homogeneity by ion-exchange chromatography and gel filtration. The purified lipase had a final recovered activity of 45.42%. Its molecular mass was estimated by SDS-PAGE assay to be 52 kDa. The purified lipase was characterized; the optimum pH was likely between 8 and 9 and showed about 70 % of its activity at pH 6.6. The enzyme was very stable at pH 8 and lost about 30 % of its activity after holding for 24 h at 4°C in buffer of pH 6.6. The optimum temperature was observed at 37°C and exhibited high activity at 5°C. ...
The main objective of this study was to verify the effect of oral intake of a yolk-derived peptid... more The main objective of this study was to verify the effect of oral intake of a yolk-derived peptide preparation (HYP) obtained by enzymatic hydrolysis of yolk water-soluble protein on bone markers and bone density in 65 perimenopausal women with an average age of 47.6 AE 5.2 years. Subjects were divided into three groups, and then enrolled in a 6-month, randomized, double-blind clinical trial. Bone formation and resorption markers were measured at 0, 3, and 6 months, while bone mineral density (BMD) in the lumbar spines was measured at 0 and 6 months. Although the bone formation marker levels showed the similarity changes among the groups, bone resorption markers in the test HYP group were significantly decreased after 3 and 6 months in comparison to other groups (P < 0.05). After 6 months, BMD in the test HYP group maintained at healthy numerical values whereas BMD values were decreased in other groups. Hence HYP would be an antiosteoporotic agent originated from natural food to maintain bone health, especially for women.
Hundred and eighty random cheese samples, includes varities of cheese, soft (kareish and white); ... more Hundred and eighty random cheese samples, includes varities of cheese, soft (kareish and white); hard (Roomy); processed (Flamingo), beside machine and hand swabs were collected from different supermarkets (30 of each), at Qalubiya governorate, Egypt to investigate the incidence of Staphylococci with especial reference to MRSA strains. The results revealed that the mean value of Staphylococci and S. aureus counts (cfu/g) in kareish cheese samples were 3.16×105 and 6.57×104, respectively; for white cheese samples were 7.60×104 and 5.12×104, respectively; for Roomy cheese samples were 5.79×104 and 3.38×104, respectively; for Flamingo cheese samples were 2.96×104 and 1.05×104, respectively; for machine swab samples were 1.02×104 and 1.48×103, respectively and for hand swab samples were 1.43×104 and 3.71×103 (CFU/ml), respectively. A total of 118/180 (65.5%) isolates of staphylococci species, includes 55 S. aureus (30.6%). All 55 isolated S. aureus strains were coagulase positive while,...
Lactoferrin LF is a member of the transferrin family that is a cationic iron-binding protein. It ... more Lactoferrin LF is a member of the transferrin family that is a cationic iron-binding protein. It is an -kDa glycoprotein that is found in many secretions in the body and is highly present in milk and colostrums. It exerts antibacterial effects and has a wide range of biological activities. Moreover, it is considered as a precursor of different peptides that have multifunctional bioactivities. During the last decade, several applications of LF and its peptides have been discovered, which has led to its commercial production. Therefore, LF and its peptides can offer a variety of specialized ingredients that can be tailored to meet the needs of natural food preservatives and functional food ingredients.
A total of 234 randomly selected milk samples from different sources (110, 50, 34 and 40 samples)... more A total of 234 randomly selected milk samples from different sources (110, 50, 34 and 40 samples) from each of (market milk, collecting centers, bulk tank and UHT milk samples; respectively) were analyzed for the quinolones residues by rapid quinolones detection strip test. Results revealed that 17.3%, 14% and 20.6% of milk samples were positive for the presence of quinolones residues for market milk, collecting centers and bulk tank milk samples; respectively, while not detected in UHT milk samples. The positive milk samples were subjected to HPLC analysis for quantitative detection of ciprofloxacin residues, which were present in 11.8%, 8%, and 8.8% for market milk, collecting centers and bulk tank milk samples; respectively, with mean values of 17.37± 0.27, 18.02±0.7 and 17.79± 0.75 ppb; respectively. None of them had a concentration exceeded the maximum residual limit set by different international standards. Public health importance of ciprofloxacin residues was discussed.
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