eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
199
212
10.21608/jfds.2014.52762
52762
Original Article
ACID-INDUCED GELATION OF SODIUM ALGINATE: EFFECT OF THERMAL ANNEALING AND CONCENTRATION
A. Agoub
1
S. Hasan
2
S. Mohamed
3
S. Abousalloum
4
Department of Food Sciences and Technology, University Omar Almukhtar, Elbeida, Libya.
Department of Food Sciences and Technology, University Omar Almukhtar, Elbeida, Libya.
Department of Food Sciences and Technology, University Omar Almukhtar, Elbeida, Libya.
Department of Food Sciences and Technology, University Omar Almukhtar, Elbeida, Libya.
Gelation on slow acidification by hydrolysis of D-glucono--lactone (GDL) has been studied for guluronate-rich sodium alginate from Laminaria hyperborea. Network formation by alginate–GDL mixtures during holding at 25°C was monitored by low-amplitude oscillatory measurements of storage modulus (G') and loss modulus (G") at 1 rad s-1 and 0.5 % strain.
For samples in which the final pH was held constant (at 3.0) and alginate concentration (c) was varied, the slope of log G' versus log c decreased progressively with increasing concentration towards a limiting value of 2 (c2-dependence), as seen for other gelling biopolymers.
A numerical analysis is reported which demonstrates that the concentration of GDL required to achieve a constant value of final pH increases in direct proportion to the concentration of alginate used.
Thermal annealing (heating to 85°C and cooling back to 25°C ) of samples acidified to pH 3.0 caused a large (~10-fold) increase in G' at low concentration (0.5 wt % alginate), attributed to a co-operative disorder–order transition during cooling by chain segments freed by disaggregation during heating. Increase in modulus on cooling became progressively smaller as the concentration of alginate was increased to 1.0 wt %, and at 1.5 wt % was replaced by a sharp decrease, attributed to excessive aggregation (incipient precipitation) of the acidified polymer.
https://jfds.journals.ekb.eg/article_52762_817df4c1155bc182f2bd80774bf087e3.pdf
Alginate
Alginic acid
GDL
Gelation
rheology
eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
213
220
10.21608/jfds.2014.52764
52764
Original Article
EFFECT OF XANTHAN AND GUAR GUM ADDITION ON RHEOLOGICAL CHARACTERISTICS OF LIBYAN WHEAT DOUGH تأثير إضافة صمغ الجوار و الزنثان على الصفات الريولوجيه لدقيق القمح الليبي (اشريشره)
نصر عبدالمولى
nasser2008ly@yahoo.com
1
عبدالرسول سلطان
2
هدى صالح
3
جامعة عمر المختار – کلية الزراعة – قسم علوم وتقنية الأغذية
جامعة عمر المختار – کلية الزراعة – قسم علوم وتقنية الأغذية
جامعة عمر المختار – کلية الزراعة – قسم علوم وتقنية الأغذية
ترکيزات مختلفة من صمغ الجوار (0.0٪، 0.5،٪.750٪ و 1%)، خلطت مع ترکيزات مختلفة من صمغ الزنثان (0.0٪، 0.5٪، 0.75٪ و 1.0٪)، أضيف الخليط إلى دقيق القمح المحلى الليبي (شريشره).وقد اظهرت النتائج ان دقيق القمح الليبي بدون أي إضافة کان لديه قيم منخفضة في الامتصاصية ، والوقت اللازم لتطوير العجينة و ثباتية العجينة، ودرجة الضعف. إضافة خليط من صمغ الجوار وصمغ الزنثان إلى الدقيق أدى إلى زيادة واضحة في زمن تطور العجينة و الثباتية و کذلک انخفضت درجة الضعف. زمن تطور العجينة و الثباتية و الامتصاصية کانت لها علاقة طردية مع زيادة ترکيز الزنثان. کذلک تحسنت قيم المرونة والطاقة (القوة) عند إضافة الزنثان والجوار معاً.
https://jfds.journals.ekb.eg/article_52764_f3fad855ba18fd0818c5e9339b73014b.pdf
eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
221
233
10.21608/jfds.2014.52765
52765
Original Article
SENSORY EVAeLUATION AND STALING OF BREAD PRODUCED BY MIXED STARTER OF Saccharomyces Cerevisiae and L.plantarum
M. Swelim
1
Fardous Bassouny
2
S. El-Sayed
3
Nahla Hassan
4
Manal Ibrahim
5
Botany Department, Faculty of science, Banha University.
Botany Department, Faculty of science, Banha University.
Agricultural Microbiology Department, Agricultural Research Center, Giza, Egypt.
Food Technology Research Institute, Agricultural Research Center, Giza, Egypt.
Food Technology Research Institute, Agricultural Research Center, Giza, Egypt.
Impact of processed conditions and type of starter cultivars on characteristics of wheat dough bread by using mixed starter cultivars of Sacch. cerevisiae and L. plantarum was estimated. L. plantarum seemed to be more effective in combination with Sacch. cerevisiae on the dough volume. Dough produced by starter containing L. plantarum characterized with lower PH and higher total titratable acidity (TTA) and moisture content, in comparison with control treatment. Highly significant differences in aroma and crumb texture were recorded with bread produced by starter culture containing L. plantarum. The obtained results also revealed significant differences in bread firmness which reflected the staling and its rate among the tested treatments after 1, 3, 5 and 6 days during storage time at room temperature. Data also confirmed a processing technique using L. planturium mixed with Sacch.cerevisia to enhance organoleptic properties of produced bread.
https://jfds.journals.ekb.eg/article_52765_85ca9a39f29afc0b6c14a930436c68b9.pdf
eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
235
245
10.21608/jfds.2014.52766
52766
Original Article
QUALITY OF RICOTTA CHEESE AS AFFECTED WITH THE WAY ACIDIFICATION .
M. Gomaa
1
S. ELSokkary
2
M. Abdel - Aziz
3
M. Refaey
4
Dairy Department, Faculty of agriculture Mansoura university ,EGYPT.
Dairy Department, Faculty of agriculture Mansoura university ,EGYPT.
Dairy Department, Faculty of agriculture Mansoura university ,EGYPT.
Dairy Department, Faculty of agriculture Mansoura university ,EGYPT.
Ricotta cheese was made from skim milk by direct acidification with, lactic, phosphoric,GDL,ABT starter and yogurt starter(streptococcus thermophillus ,lactobacillus delbrukii subsp bulgaricus) at pH 5.9- 5.8 at 87 -88˚c . Cheese was made by using yogurt starter had a higher yield(17.5% ), compared with other acid coagulant . (16- 15.75-15%) Respectively , Cheese treated with phosphoric acid and yogurt starter had the highest total solids(31.59-31.33%), compared with other treatments (31.05, 30.02, 29.93%)while the cheese made with yoghurt starter and phosphoric acid had the highest total protein content(24.24, 24.20%) than that from in the other treatments(24.15, 23.15, 23.10% ), either fresh or during storage period .In addition ,cheese made by using phosphoric acid had the highest fat content(2.25%), either fresh or during storage period, compared with other treatments (2.20-1.65-1.2-1.80 % ). While cheese made using by yoghurt starter had the highest rheological properties, where hardness ,cohesiveness, springiness ,gumminess, chewiness, modules ( 5119(N)-0.74(ratio)- 11.42(mm)- 3793(N)- 4336.96(J)- 146.8(J) respectively, compared with other treatments, while cheese coagulated with phosphoric acid had the highest adhesiveness of 1067.26(J). cheese treat with ABT starter had the highest modulus (162.23) while the cheese made with phosphoric acid had the lowest highest rheological properties as hardness , springiness ,gumminess, chewiness and modules were 2145 -9.49-1381 -13107.21 -73.43 respectively. Cheese made with lactic acid had the lowest adhesiveness of 764.05(J) ,than the cheese treated with lactic acid which obtained the lowest cohesiveness of ratio ( 0.63) . Cheese made by using phosphoric acid had lower total bacteria (T.C), proteolytic bacteria count ,lipolytic bacteria counts and moulds and yeasts (M&Y). On the other hand, cheese treated with yogurt starter and phosphoric acid had higher scoring points of 86- 84.8 % either fresh or during storage, compared with the cheese treated GDL which had the lowest scoring points of 72.2 % .
https://jfds.journals.ekb.eg/article_52766_03e3af2014fbfc8a255333e04a8fa831.pdf
Ricotta cheese
Milk
lactic acid
phosphoric acid
yogurt starter
GDL and ABT starter
eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
247
263
10.21608/jfds.2014.52768
52768
Original Article
ANTIOXIDANT PROPERTIES OF SOME EXTRACTS FROM GAMMA IRRADIATED TOMATO (Lycopersicon esculentum L.) POMACE
H. Khalaf
1
A. Sharoba
2
R. El Sadani
3
Fawzia El Nashaby
4
S. Elshiemy
dr.sabry_elshiemy@yahoo.com
5
Food Science Department, Faculty of Agriculture, Benha University, Egypt.
Food Science Department, Faculty of Agriculture, Benha University, Egypt.
Food Science Department, Faculty of Agriculture, Benha University, Egypt.
Nuclear Research Center, Atomic Energy Authority, Cairo, Egypt
plant Research Department, Nuclear Research Center, Atomic Energy Authority, Cairo, Egypt
In this study, the gamma radiation processing of tomato pomace samples was carried out at dose levels of 0, 1, 3 and 5 kGy. The total phenolic content, total flavonoids content and antioxidant activity properties of both non-irradiated and irradiated samples extracted in acetone 70%, methanol and chloroform: ethyl acetate (1:1) were assessed. The obtained data showed that, the total phenolic content increased with an increase in radiation dose for all extractions. Extracted Phenolic content from tomato pomace by using acetone (70%) was higher than those extracted by other solvents, whereas the phenolic content in acetone extract was increased from 182.579 mg GAE/100 g-1 for the control sample to 191.445 mg GAE/100 g-1 for the 3 kGy radiation-processed samples. Three methods were carried out to determine the antioxidant activity of tomato pomace, the first method was the radical scavenging activity against 2, 2′-diphenyl-1-picrylhydrazyl (DPPH), acetone extract exhibited greater scavenging activity than those extracted by other solvents. The same trend was also observed by using the second method of β- carotene bleaching assay and third method of ferric reducing antioxidant power (FRAP). The Highest ratio of β- carotene reducing power was achieved with acetone extract at 3 kGy whereas reached to 61.14%. Twelve phenolic acids component were identified in both non-irradiated and irradiated at 3kGy tomato pomace extracts by HPLC. Acetone extract of gamma irradiated and non-irradiated tomato pomace was tested for this antioxidant activity against oxidative stability of sunflower oil. The overall results indicated that, the highest oxidative stability (10.6 hr.) was obtained by using gamma irradiated tomato pomace at 3 kGy extract compared with those of the other doses. Finally, the obtained data showed that, tomato pomace is a very promising source of bioactive compounds and it is a very potential natural source of antioxidant compounds.
https://jfds.journals.ekb.eg/article_52768_325c4d0bb3e55bf826cb4f2abe3f56f7.pdf
Tomato pomace- gamma irradiation
phenolic compounds – Flavonoid compounds-Antioxidant activity
High performance liquid chromatography (HPLC)
eng
Mansoura University, Faculty of Agriculture
Journal of Food and Dairy Sciences
2090-3650
2090-3731
2014-04-01
5
4
265
278
10.21608/jfds.2014.52770
52770
Original Article
THE IMPACT OF ORGANIC AGRICULTURE ON THE QUALITY CHARACTERISTICS OF SOME FRUITS, VEGETABLES AND MEDICINAL PLANTS
S. Mohsen
1
M. Haseeb
2
S. Abulroos
3
Department of Food Science,Faculty of Agriculture Cairo University, Gyza, Egypt
Department of Soil Sciences, Faculty of Agriculture Cairo University, Giza, Egypt
Department of Soil Sciences, Faculty of Agriculture Cairo University, Giza, Egypt
In the present study physical and chemical characteristics of orange fruits, tomato, green beans, fennel and lemongrass as affected by organic agriculture were studied. The phytochemicals characteristics of orange and tomato juice were also determined in the organic samples compared to conventional products. The results showed thatorganic management decreased the percentage of peels and reducing sugars and increased juice percentages and ascorbic acid in organic orange fruits. In addition organic orange juice had better taste, odor and texture. Organic management also decreased the weight of peel and pulp and the percentage of TSS and increased juice percentage and the content of ascorbic acid, total phenol and lycopen in tomato as compared to conventional management.Organic managementof green beans increased percentage of protin, starch, reducing sugar and total sugarcompared toconventionalmanagement .Organic management of lemon grass increased the oil percentage, the percentage of a-Myrcene, and Citral and decreased Anethole(Estragole) content as compared to the conventional product.Organic management of fennel increased the percentage of Anethole and decreased the percentage of D-Limonene in the oil as compared to conventional one.
https://jfds.journals.ekb.eg/article_52770_ffa0e085384998988ce2c0769bb06a96.pdf