Arab Journal of Food & Nutrition Published by Arab Center for Nutrition Volume 11, No. 25, 2011 Abstracts from Master and Doctorate Theses from Jordan Univesities Related to Food and Nutrition Compiled by Dr.Hamed Takruri Dr.Salma Tukan Volume 11, No. 25, 2011 1 Arab Journal of Food & Nutrition Published temporarily two times a year (with an annual supplement) by Arab Center for Nutrition Focuses on Food, Nutrition, and Food Security in the Arab Countries. Volume 11, No.25,2011 Chief Editor Dr.Abdulrahman O.Musaiger Arab Center for Nutrition, Kingdom of Bahrain Editorial Board Dr.Hamed Takruri Jordan University-Jordan Dr Abdulmunem Sadiq Qatar University-Qatar Dr Hamaza Abu-tarboush King Saud University- Saudi Arabia Dr Najat Mokhtar Bin Tofil University - Morocco Secretary Fatima Ali Esmail (Secretary) Dr.Hamed Takruri (Language assistance) Correspondence Chief Editor, Arab Journal of Food and Nutrition Arab Center for Nutrition P.O.Box:26924, Manama- Kingdom of Bahrain Tel: 00973 17343460 Fax: 00973 17346339 Email:[email protected] SSRM 255 ISSN 1608-8352 Arab Journal of Food & Nutrition Abstracts from Master and Doctorate Theses from Jordan Univesities Related to Food and Nutrition Compiled by Dr.Hamed Takruri Dr.Salma Tukan Volume 11, No. 25, 2011 2 Arab Journal of Food & Nutrition List A: English Abstracts of Master Student Theses in Jordan in Food Science and Technology until December,2010. 1. Effect of Yeasts on the Quality and Shelf Life of Labaneh (1990) Maha M. Abu – Jaber\ University of Jordan Supervisor: Dr. Mohammed Isam Yamani Labaneh samples from 19 producers were examined for the presence of yeasts, and for their effect on its shelf life and sensoric properties. Directly after packaging, the mean yeast counts were 2.6 x 106 /g, 4.4 x 106 /g and 2.6 x 105/g for psychrotrophic , mesophilic and facultative thermophilic yeasts, respectively. The percentages of samples showing yeast counts above 106/g were 45, 50 and 5 for psychrotrophic, mesophilic and facultative thermophilic yeasts, respectively. Signs of spoilage were observed in 25 % of the labaneh samples at the same day of packaging. This indicates high initial contamination with yeasts that could be attributed to poor hygienic practices through any of the steps of labaneh production. At expiry date (14 d at 7 °C) the mean yeast counts increased to 1.1 x 107/g, 1.4 x 107/g and 2.3 x 106/g for psychrotrophic mesophilic and facultative thermophilic, respectively. The percentages of samples that showed yeast counts above 106/g increased to 70, 75 and 35 for psychrotrophic, mesophilic, and facultative thermophilic, respectively. All labaneh samples produced by the traditional method were spoiled at expiry, while the labaneh samples produced by the mechanized method showed yeast count < 10/g directly after packaging and at expiry. This was proved to be due to the addition of mycostatic agents. Isolated yeasts were identified to species level Saccharomyces cerevisiae biovars were the most frequently isolated yeasts found in all the samples containing yeasts. Trichosporon brassicae, Cryptococcus curvatus and Kluyveromyces marxianus (var. lactis and bulgaricus) followed Sacch. cerevisiae with an occurrence of 33.34%, 27.78% and 16.67 %, respectively. Trichosporon cutaneum, Debaromyces hansenii Pichia farinosa var. lodderi, Geotrichum candidum and Candida blankii were the least frequent yeasts with an occurrence of 5.56 % for each species. The predominance and growth of these species in labaneh could be attributed to their ability to utilize the available carbon sources (glucose, galactose, lactose, lactic acid ) in labaneh, grow at different temperatures of labaneh processing (25°C, 43°C) and storage (7°C) and to produce lipolytic and proteolytic enzymes. The effect of yeast growth on the sensoric quality of labaneh was carried out using six yeast species K. marxianus var. lactis, Tr, cutaneum, G. candidum and Sacch. cerevisiae biovar 1 and 4 by inoculating these yeasts into pasteurized labaneh. Pasteurized labaneh without yeasts was used as a control sample. Paired preference test was used to investigate which samples in each pair (control 1 3 Volume 11, No. 25, 2011 Arab Journal of Food & Nutrition vs. labaneh containing yeast) were preferred most often. 79, 78 untrained assessors (students, workers at the faculty of agriculture) examined three different pairs of samples in two sessions, respectively. Sensory evaluation results showed that control sample was preferred significantly (P < 0.05, P< 0.001) over labaneh containing Sacch. cerevisiae biovar 1 and G. candidum, respectively. There were no significant differences (P<0.05) between control and labaneh containing K. marxianus var. lactis, Sacch. cerevisiae biovar 4, Cr. curvatus and Tr. cutaneum. This means that addition of yeasts might not increase the preference of inoculated labaneh over yeast-free labaneh. This study confirmed that yeasts were the main cause of labaneh spoilage even when kept under refrigeration. Furthermore, it showed that the use of yeasts in labaneh would not increase its preference by the majority of the consumers. Therefore, the negative aspects of yeast growth in labaneh should be overcome by strict hygienic practices throughout the steps of processing. Accordingly, it was recommended that directly after packaging labaneh should not contain more than 10 yeasts per gram and the expiry should be reduced to one week instead of two in order to avoid labaneh spoilage during refrigerated storage. Volume 11, No. 25, 2011 4 2 Arab Journal of Food & Nutrition 2. A Chemical and Microbial Study of Jameed Cheese Produced in Jordan (1991) Yosef H. Tawalbeh\ University of Jordan Supervisor: Dr. Malik S. Haddadin This study was carried out to give an indication about the proximate chemical composition and the microbial status of sheep and goat jameed produced in different areas in Jordan. The chemical and microbial changes which occur at the end of each jameed processing stages were also studied. The proximate composition of sheep jameed showed (51.42 ) % protein and (19.7) % fat. It contained naturally significant amounts of calcium (0.21) % phosphorus (0.75) % and salt (11) %. On the other hand, goat jameed contained (39.37) % protein and (31.7) % fat.Its content of calcium was (0.09) % of phosphorus (0.75) % and of salt (10.8) %. It was found that the standard plate and the yeast and muld in sheep jameed were (5.4 × 104 – 7 × 105), (2.2 × 102 – 8.8 × 102 cell / 1 g) respectively, while in goat jameed were (8.8 × 105 – 9.9 × 106), (1.6 × 103 – 1 × 104 cell / 1 g) respectively. Fat content, non – protein nitrogen percent and titrable acidity in goat jameed were higher than that in sheep jameed, where as goat jameed had a lower level of lactose compared to sheep jameed. The standard plate, yeast and mould counts in goat jameed were higher than their levels in sheep jameed. The main results of microbial and chemical studies at the end of each traditional jameed processing stagein many farms in different Jordanian areas were the following: - The changes occurred in lactose, non – protein nitrogen, PH and titrable acidity indicate that the microbial activity during goat jameed processing stages was higer than that in sheep jameed processing stages. Total solid and ash percentages in concentrated sheep buttermilk and sheep jameed were higher than those processed from goat milk. Fat percent in concentrated goat buttermilk and goat jameed were higher than that noticed in sheep milk products. 5 Volume3 11, No. 25, 2011 Arab Journal of Food & Nutrition 3. A Study of the Microbial Quality of a Sample of Hoummos B’tehineh (Chickpea Dip) Produced in Jordan (1992) Basim A. Al-Dababseh\ University of Jordan Supervisor:D. Mohammed Isam Yamani Hoummos is a very popular dish in many Middle Eastern countries. It is gaining rather wide acceptance internationally. Nowadays hoummos is prepared by mechanical blending of boiled chickpeas, lemon juice or citric acid, garlic, salt and tehineh (oily viscous fluid obtained by milling of dehulled and roasted white sesame seeds) into a smooth mix. Olive oil and occasionally parsley are used as a dressing. Hoummos is not subjected to and further heat treatment before consumption. Sixty hoummos samples from 15 producers were examined in winter and summer for aerobic plate count (APC), lactic acid bacteria (LAB), yeasts and moulds, coliforms, Escherichia coli, Staphylococcus aureus and Salmonella. Tehineh, as a major ingredient used in hoummos preparation, was also included in the study. In winter samples APC ranged between 1.1x104/g and 2.2x108/g, with an average of 2.7x107/g and between 3.5x106/g and 8.2x108/g, with an average of 1.9x108/g in summer samples. LAB count ranged from 4.0x103/g to 2.0x108/g, with an average of 1.6x107/g in winter samples, while in summer samples it ranged from 2.5x106/g to 8.2x108/g, with an average of 1.6x108/g. In all samples APC and LAB count were very close, The LAB isolated were Streptococcus lactis, group D Streptococcus, Leuconostoc oenos, Leuconostoc lactis and Leuconostoc dextranicum. Yeast count ranged between 8.8x10/g and 8.5x104/g, with an average of 1.5x104/g in winter samples and from 3.6x102/g to 3.6x105/g, with an average of 4.2x104/g in summer samples. Coliform count ranged from <10 to 1.3x104, with an average of 2.2x103/g in winter samples, while in summer samples it ranged from 1.9x102 to 3.3x106, with an average of 2.9x105/g. Escherichia coli and Staphylococcus aureus counts were < big for all hoummos samples which were examined. Salmonella was not isolated from any of the samples. Variations in the microbial counts of the microorganisms enumerated were noticed in hoummos samples of different producers as well as within individual producers.