NULL

NULL

NULL

Forty samples of beef burger and sausage (20 for each) were collected from supermarkets in Assiut Governorate during the period from July to November 2011. Samples were mycologically analyzed using dichloran Rose Bengal Chloramphenicol (DRBC) and dichloran 18% glycerol (DG18) agar media. The total number of fungal species on DRBC was higher than that on DG18 (46 versus 31 species in case of beef burger and 41 versus 33 in sausage). In the individual samples the fungal load varied from 6 - 600 colonies/g whereas the number of fungal species fluctuated between 2 and 8 species. Aspergillus, Penicillium and yeasts were the most prevalent fungi contaminating 70-100 % of the samples. Aspergillus niger, A. terreus, A. flavus, Penicillium chrysogenum and P. citrinum were the most common mould species on both beef burger and sausage samples. Sequencing of rRNA gene revealed the identification of 12 species belonging to 6 genera of yeasts which comprised Candida parapsilosis, Galactomyces candidum, Pichia kudriavzevii and Trichosporon domesticum as common ones. Testing the natural occurrence of mycotoxins showed that diacetoxyscirpenol and zearalenone contaminated 25 and 5 % of beef burger samples respectively whereas aflatoxin B1 was found in only 10 % of sausage samples. Out of 24 fungal species isolated from both substrates 10 (40 %) were able to produce detectable quantities of mycotoxins. Aflatoxin B1 was detected in the extracts of A. flavus cultures while aflatoxin B1, B2, G1 and G2 were produced by three isolates of A. parasiticus. Sterigmatocystin was formed by one isolate of Emericella nidulans whereas fumonisin B1 was secreted by two isolates of F. verticillioides. Most fungal isolates were able to produce lipolytic and proteolytic enzymes with the most active belong to A. parasiticus and F. oxysporum, which were also toxinogenic.

This study was aimed to investigate the feasibility of bio- ethanol production by batch fermentation of kareish cheese whey. Two forms of whey; untreated (crude) whey containing 5% lactose and treated whey (deproteinized and concentrated to 14% lactose) were utilized. Fermentation processes were performed by two strains of Kluyveromyces marxianus and four strains of Saccharomyces cerevisiae which were previously recognized as ethanol- producing strains. Effects of different initial pH values, as well as, external supplementation of treated whey by four different nitrogen sources on the rate of ethanol production by two of the highest producing strains were also investigated. All the studied yeast strains were able to grow and produce ethanol from both crude and treated whey. Levels of ethanol production ranged between 3.4- 18.5g/l and 24.11-57.66 g/l from crude and treated whey, respectively. The most suitable initial pH maximizing ethanol yield was 5.5 and the best added nitrogen source was yeast extract. Maximum ethanol levels produced by K. marxianus ZMS3GU133329 and S.cerevisiae EC1118 from treated whey adjusted to pH 5.5 and supplemented by 0.3% yeast extract reached to 69.85 and 65.36 g/L, corresponding to 97.8 and 91.4% of the theoretical values, respectively. The kinetic parameters and productivity were calculated and discussed for all experiments.

This study was aimed to investigate the feasibility of bio- ethanol production by batch fermentation of kareish cheese whey. Two forms of whey; untreated (crude) whey containing 5% lactose and treated whey (deproteinized and concentrated to 14% lactose) were utilized. Fermentation processes were performed by two strains of Kluyveromyces marxianus and four strains of Saccharomyces cerevisiae which were previously recognized as ethanol- producing strains. Effects of different initial pH values, as well as, external supplementation of treated whey by four different nitrogen sources on the rate of ethanol production by two of the highest producing strains were also investigated. All the studied yeast strains were able to grow and produce ethanol from both crude and treated whey. Levels of ethanol production ranged between 3.4- 18.5g/l and 24.11-57.66 g/l from crude and treated whey, respectively. The most suitable initial pH maximizing ethanol yield was 5.5 and the best added nitrogen source was yeast extract. Maximum ethanol levels produced by K. marxianus ZMS3GU133329 and S.cerevisiae EC1118 from treated whey adjusted to pH 5.5 and supplemented by 0.3% yeast extract reached to 69.85 and 65.36 g/L, corresponding to 97.8 and 91.4% of the theoretical values, respectively. The kinetic parameters and productivity were calculated and discussed for all experiments.

Six high ethanol producer yeast strains (two strains of Kluyveromyces marixianus and four of Saccharomyces cerevisiae) were utilized to produce ethanol from treated and non-treated Egyptian sugar cane molasses with gravity (10, 15, 20, 30 & 33.3% sugar). The treated molasses was obtained by heating diluted molasses up to 90ºC and adjusting its pH to 4.5. All yeast strains used produced higher ethanol yield from non-treated molasses with 10% sugar than that obtained from the treated one with the same sugar concentration. On the other hand, treated molasses yielded better ethanol concentration than that gained from non-treated molasses with 15 – 25% sugar. Maximum ethanol production (125.89% g/l) was noticed with fermentation efficiency of 99.97% using S. cerevisiae EC1118 strain on 25% sugar treated molasses at 35ºC. The same strain gave low levels of ethanol when the sugar concentration of the treated molasses was either 30 or 33.3% at both fermentation temperatures used (35º and 40ºC). The kinetic parameters and productivity were calculated and discussed for all treatments.

Six high ethanol producer yeast strains (two strains of Kluyveromyces marixianus and four of Saccharomyces cerevisiae) were utilized to produce ethanol from treated and non-treated Egyptian sugar cane molasses with gravity (10, 15, 20, 30 & 33.3% sugar). The treated molasses was obtained by heating diluted molasses up to 90ºC and adjusting its pH to 4.5. All yeast strains used produced higher ethanol yield from non-treated molasses with 10% sugar than that obtained from the treated one with the same sugar concentration. On the other hand, treated molasses yielded better ethanol concentration than that gained from non-treated molasses with 15 – 25% sugar. Maximum ethanol production (125.89% g/l) was noticed with fermentation efficiency of 99.97% using S. cerevisiae EC1118 strain on 25% sugar treated molasses at 35ºC. The same strain gave low levels of ethanol when the sugar concentration of the treated molasses was either 30 or 33.3% at both fermentation temperatures used (35º and 40ºC). The kinetic parameters and productivity were calculated and discussed for all treatments.

NULL

NULL