الفهرس 
CONTENTSOnly 14 pages are availabe for public view
 |  | from | 243 |  |  |
| | | from | 243 | | |
Abstract
Many studies illustrated several benefits of antioxidants, such as they destroy the free radicals that damage cells, protect it against premature abnormal aging and promote the growth of healthy cells.
Dietary fibers has been consumed for centuries and is recognized for having health benefits. It can provide a multitude of functional properties when they are incorporated in food systems. Several advantages of using fruit fibers in ice cream production are improvement in body.
Plant foods contain many different types of antioxidants and the antioxidant capacity is the cumulative capacity of food components to scavenge free radicals which were generated from environmental exposure to oxidizing pollutants, cigarette smoke and electromagnetic radiation. These plant foods became the most ingredients added to dairy products as natural antioxidants source to get more healthy products. As these ingredients could play a role in reducing the risk of some common diseases. So, it is very important to supplement the dairy products with natural antioxidants to obtain dairy products with high healthy benefits.
Therefore, this study was planned to study chemical analysis and identification of essential oils, namely; Marjoram (Origanum majorana), basil (Ocimum basilicum) and thyme (Thymus vulgaris), and study the antioxidant and antimicrobial activities of these oils, and finally study the using it in low fat ice cream making (LFIC). In addition, the study focuses on using the effect of dietary fiber from Dates and Orange in LFIC making.
Consequently this study included five parts:
A) The chemical analysis and identification of volatile oils:
In this part; the studied essential oils were analyzed and identified by using gas chromatography coupled with mass spectrometry (GC/MS).
The obtained results could be summarized as follows:-
• It could be noticed that, 17 compounds of marjoram essential oil were identified, that had values varied between 0.05 and 14.57%.
• Marjoram have an antioxidant effect; which mainly attributed to their phenolic contents.
• It could be noticed that, 19 compounds of basil essential oil were identified, that had values varied between 0.18 and 72.56%.
• It could be noticed that, 22 compounds of thyme essential oil were identified, that had values varied between 0.20 and 16.93%.
B) Antimicrobial activity of studied volatile oils:
In this part; the antimicrobial effect of studied essential oils at different concentration against some selected microorganisms, namely; Bacillus cereus, Escherichia coli O157:H7, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, Shigella dysenteriae, Aspergillus niger, Aspergillus flavus and Candida albicans were evaluated.
The obtained results could be summarized as follows:-
• All the studied strains of bacteria demonstrated some degree of sensitivity to the marjoram oil.
• Low concentrations of marjoram inhibited weakly the development of tested strains.
• Marjoram oil appeared preferentially more active with respect to high concentration especially in Staphylococcus aureus and Shigella dysenteriae.
• All the tested strains of fungal demonstrated some degree of sensitivity to the marjoram oil.
• It appeared preferentially more active with respect to high concentration especially in Candida albicans.
• There were growths of all studied bacteria and fungi in the low concentration of marjoram (2 µm).
• There was growth of Shigella dysenteriae up to 8 µm; whilst, the growth was appeared up to 4 µm in E. coli and Aspergillus flavus.
• All the tested strains of bacteria demonstrated some degree of sensitivity to the basil oil.
• Low concentrations of basil inhibited weakly the development of tested strains.
• It appeared preferentially more active with respect to high concentration especially in E. coli and Staphylococcus aureus.
• All the tested strains of fungal demonstrated some degree of sensitivity to the basil oil.
• There was growth of all studied bacteria as well as studied fungi in the low concentration of basil (2 µm).
• There were growth of Salmonella typhi up to 8 µm of basil oil; whilst, the growth was appeared up to 4 µm of basil oil in Shigella dysenteriae, Staphylococcus aureus and Pseudomonas aeruginosa.
• All the tested strains demonstrated some degree of sensitivity to the thyme volatile oil.
• Low concentrations of thyme essential oil inhibited weakly the development of tested strains.
• Thyme oil appeared preferentially more active with respect to high concentration especially in E. coli and Salmonella typhi as well as Aspergillus flavus.
• All the tested of fungal strains demonstrated some degree of sensitivity to the thyme oil.
• There was growth of all studied microbial in the low concentration of thyme oil (2 µm) except Aspergillus niger and Candida albicans. Moreover, there were not any growths of other concentrations.
C) Antioxidant activity of studied volatile oils:
In this part; the essential oils of; marjoram, basil and thyme were subjected to the antioxidant activity using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay at 10, 25, 50,100, 250, 500, 750 and 1000 µg and compared to synthetic antioxidant butylated hydroxyl toluene (BHT) under level 10 µg.
The obtained results could be summarized as follows:-
• It could be seen that, the high concentration of essential oils (1000 µg) recorded higher inhibition percentage of radical DPPH among all the concentrations of essential oils of; thyme (86.25%), basil (79.87%) and marjoram (66.13%).
• The inhibition percentage increased with increasing of essential oils concentration in all treatments.
• Thyme oil had higher activities than that of other studied essential oils (86.25%) under level 1000 µg, while, basil oil ranked the lowest value, actually 66.13% under the same level of concentration, and all essential oils had difference lower activities than that of BHT (89.63%) under all concentration levels (10 to 1000 µg).
• Antioxidant activity of different essential oils and BHT exhibited the effectiveness followed the sequence; BHT > thyme > basil > marjoram essential oil.
D) The using of natural antioxidant in LFIC making:
In this part; study the effect of studied essential oils with ratios; 20, 40 and 60 ppm on LFIC. The mixes of LFIC consisted of 3% fat, 14% SNF, 15% sugar, 0.3% carboxy methyl cellulose and 0.1% vanillin.
The obtained results could be summarized as follows:-
• There were slight increases of density with increasing marjoram oil concentration of LFIC.
• The control samples had lower density than that of LFIC with marjoram oil.
• The weight per gallon was slight increases with increasing marjoram oil concentration of LFIC.
• The control samples had lower values of weight per gallon than that of LFIC with marjoram oil.
• The overrun was decreased un significantly with increasing marjoram oil concentration, while the control samples had higher values than that of LFIC with marjoram oil.
• There were decreases of total bacterial and yeast & moulds counts in LFIC with increasing of marjoram oil level and with increasing storage period up to 30 days in all treatments.
• The control samples had higher counts of total bacteria and yeast & moulds than that of LFIC with marjoram oil in all treatments.
• There were not detected of psychotrophic bacteria and coliform group counts in all treatments of LFIC with marjoram oil.
• LFIC with marjoram essential oil had higher antioxidant activity than that of control samples.
• There were increases significantly of antioxidant activity in LFIC with increasing marjoram oil level in all treatments.
• LFIC with marjoram oil had lower total scores than that of control samples during storage periods up the 30 days in most treatments.
• LFIC fresh with 20 ppm of marjoram oil had superior scores, whilst, the samples with 60 ppm marjoram oil stored 30 days had a lower scores.
• There were slight increases un significantly of density with increasing basil oil concentration of LFIC.
• The weight per gallon was increased un significantly with increasing basil oil concentration of LFIC.
• The overrun was decreased un significantly with increasing basil oil concentration, while, the control samples had higher overrun than that of LFIC with basil oil.
• There were decreases of total bacterial and yeast & moulds counts in LFIC with increasing basil oil level and with increasing storage period up to 30 days in all treatments. While, control samples had higher counts of total bacteria and yeast & moulds than that of LFIC with basil oil in all treatments.
• There were not detected of psychotrophic bacteria and coliform group counts in all treatments of LFIC with basil oil.
• LFIC with basil oil had higher antioxidant activity than that of control samples.
• There were increases significantly of antioxidant activity in LFIC with increasing basil oil level in all treatments.
• LFIC with basil oil had lower total scores than that of control samples during storage periods up the 30 days in most treatments.
• LFIC fresh with 20 ppm of basil oil had superior scores, whilst the samples with 20 ppm of basil oil stored at 30 days at lower scores.
• There were slight decreases of density with increasing thyme oil concentration in most treatments, while the control samples had lower values than that of LFIC with thyme oil.
• The weight per gallon was decreases un significantly with increasing thyme oil concentration in most treatments, while the control samples had lower values than that of LFIC with thyme oil.
• The overrun was increased un significantly with increasing of thyme oil concentration, while the control samples had higher values than that of LFIC with thyme oils.
• There were decreases of total bacterial and yeast & moulds counts in LFIC with increasing thyme essential oil level and with increasing storage period up to 30 days in all treatments, while control samples had higher counts than that of LFIC with thyme oil in all treatments.
• There were not detected of psychotrophic bacteria and coliform group counts in all treatments of LFIC with thyme oil.
• LFIC with thyme oil had higher antioxidant activity than that of control samples.
• There were increases significantly of antioxidant activity in LFIC with increasing thyme oil level in all treatments.
• LFIC with thyme oil had lower total scores than that of control samples during storage periods up the 30 days in most treatments.
• LFIC fresh with 40 ppm of thyme oil had superior scores, whilst, the samples with 60 ppm of thyme essential oil stored 30 days had lower scores.
E) The using of dietary fiber from natural sources in LFIC making:
In this part of investigation, attempts have been made judge the dietary fiber from natural sources with suitability varying levels for making LFIC. It was prepared by replacing skimmed milk powder with Date fiber powder (DFP) or Orange fiber powder (OFP); with rate; 1.5, 2.5 and 3.5% to the mix to improve nutritional value and sensory properties of LFIC. The final products were stored at -18ºC for 30 days and evaluated for its microbiological analyses, rheological properties and sensory evaluation.
The obtained results could be summarized as follows:-
• The moisture content (on dry weight basis) of the Date was higher than that of DFP. This is principle due to the high level of sugars and Date. It was 12.68%.
• Ash and protein contents were higher in DFP than that of Date.
• DFP had higher of total dietary fiber and soluble dietary fiber as well as insoluble dietary fiber than that of Date.
• OFP had high total solids, ash, protein, carbohydrates, total dietary fiber (TDF), soluble dietary fiber (SDF) and Insoluble dietary fiber (IDF). Whilst, it low of fat content.
1) The using of DFP in LFIC making:
• There were increases significantly of density and weight per gallon in pounds with increasing DFP, while the control samples had lower values than that of LFIC with DFP.
• The overrun was decreased significantly with increasing DFP, while the control samples had higher values than that of LFIC with DFP.
• There were increases of total bacterial and yeast & moulds counts in LFIC with increasing DFP in most treatments, while there were decreases of their counts with increasing storage period up to 30 days in most treatments.
• The control samples had lower counts of total bacteria and yeast & moulds than that of LFIC with DFP.
• There were not detected of psychotrophic bacteria and coliform group counts in all treatments of LFIC with DFP.
• LFIC with DFP had higher body & texture and melting quality as well as appearance than that of control samples in most treatments.
• LFIC with DFP had higher total scores than that of control samples during storage periods up the 15 days in most treatments.
• LFIC fresh with DFP had higher scores than that of other treatments.
• The fresh samples with 2.5% DFP had superior scores, while the samples with 1.5%, stored at 30 days had a lower scores.
2) The using of OFP in LFIC making:
• There were increases significantly of density and weight per gallon in pounds with increasing OFP level; while, the control samples had lower values than that of LFIC with OFP.
• The overrun was decreased significantly with increasing OFP, while the control samples had higher values than that of LFIC with OFP.
• There were decreased of total bacterial and yeast & moulds counts in LFIC with increasing OFP in most treatments, while there were decreases of their counts with increasing storage period up to 30 days in most treatments.
• The control samples had higher counts of total bacteria and yeast & moulds than that of LFIC with OFP.
• There were not detected of psychotrophic bacteria and coliform group counts in all treatments of LFIC with OFP.
• The control samples had higher flavor, body & texture, melting quality, appearance as well as overall scores than that of LFIC with OFP in all treatments.
• Flavor, body & texture, melting quality, appearance as well as overall decreased with increasing OFP of LFIC in all treatments.
• LFIC with OFP had lower total scores than that of control samples in all treatments.
• The fresh samples with 1.5% OFP had superior scores among of LFIC with OFP; whilst, the samples contained 3.5%, stored at 30 days had the lower scores among of LFIC with OFP.
relatively low moisture content in Da