الفهرس 
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Abstract
The current study aimed to use whey protein concentrate (WPC) in the manufacture of some dairy products to achieve the maximum benefit from concentrated whey proteins, as they are considered a by- products unused, most of which are wasted in wastewater, causing a great environmental damage. Moreover, WPC is a product very rich in immune proteins, which makes it have many health benefits and some functional properties of interest to the food industry, such as solubility, emulsification, foaming, gelation, and viscosity development. In this regard the current study includes three main points: -
1- Manufacture of high-quality bio-Yogurt using WPC in different concentrations (2, 4 & 6%) and evaluate their effects on chemical composition, microbiological properties, rheological properties, sensory evaluation during cold storage at refrigerator temperature (5±2°C) for 15 days.
2- Preparing and characterization of edible whey protein concentrate edible films (WPCEF) containing different antimicrobial agents.
a) Manufacture WPC films containing chemical antimicrobial agents as sorbate, Nisin and sorbate & Nisin combined.
b) Manufacture WPC films containing natural antimicrobial agents with different concentrations such as essential oils of Rosemary and Marjoram.
3- Manufacture of white soft cheese coated with WPC films containing antimicrobial agents to extend the shelf life.
1) Effect of different concentrations from WPC (2, 4 and 6%) on chemical, microbiological, rheological and sensory properties of bio-Yogurt:
a) Chemical composition of bio-Yogurt:
• Total solid (TS%):
- TS% of control samples were higher than that of bio-Yogurt with WPC treatments.
- There were an increasing of TS% by increasing of WPC in all treatments.
- There was a gradual increasing of TS% by increasing of storage periods in all treatments.
• Fat content:
- Fat content of control samples was higher than that of bio-Yogurt with WPC treatments.
- There was a slightly decreases of fat content by increasing WPC in all treatments.
- After 15 days of storage, there were a slight decrease in fat content in all treatments.
• Total & soluble nitrogen percentages (TN & SN %):
- TN% of control samples were higher than that of bio-Yogurt with WPC treatments.
- There were decreasing of TN% by increasing of WPC in all treatments.
- TN% in fresh samples were; 0.480, 0.533, 0.563 and 0.587% for control, T1, T2 and T3; respectively.
- After 15 days of storage, there were a slight decrease in TN% in all treatments.
- SN% of control samples were lower than that of bio-Yogurt with WPC treatments.
- There were increasing of SN% by increasing of WPC in all treatments.
- After 15 days of storage, there were gradual increases in SN% in all treatments.
• Titratable acidity (TA):
- TA% of control samples were lower than that of bio-Yogurt with WPC treatments.
- There was a gradual increase of TA% with increasing of storage periods in all treatments.
- After 15 days of storage, there were gradual increases in TA% in all treatments.
b) Microbiological properties of bio-Yogurt:
• Total bacterial counts (TBC):
- In fresh samples, TBC for fresh control samples have the minimum count (8.64 log cfu/g), while the maximum was for that of T3 (9.22 log cfu/g).
- There were increasing of TBC by increasing of WPC in all treatments.
- During storage, TBC increased up to the fifth day of storage period, and then decreased up to the end of storage.
- The highest TBC was for T3, its recorded 7.30 log cfu/g, meanwhile the lowest was for the control samples (6.13 log cfu/g).
- The control samples had lower counts, while T3 had the highest counts in all treatments.
• Lactobacillus acidophilus counts:
- Lb. acidophilus was slightly different among treatments in fresh samples.
- In fresh samples, the control samples have the minimum counts (6.89 log cfu/g); in obvious T3 has the maximum counts (8.20 log cfu/g).
- The control samples had lower counts than that of other treatments.
- After 5 days of storage, there were an increase of Lactobacilli counts in all treatments.
- After 15 days of storage, there were a slight decrease in Lb. acidophilus counts for all treatments to be; 5.52, 6.46, 7.14 and 7.16 log cfu/g for control, T1, T2 and T3; respectively.
- The control samples had lower counts, while T3 had the highest counts in all treatments.
• Streptococcus thermophiles count:
- Str. thermophiles counts were slightly different in fresh samples of all treatments.
- In fresh samples, the minimum counts were 6.14 log cfu/g for control treatment; meanwhile, the maximum was 7.30 log cfu/g for T3 treatment.
- After 5 days of storage, there were an increases of Str. thermophiles counts in all treatments.
- After 15 days of storage there were decreases in Str. thermophiles counts being; 5.13, 5.87, 6.05 and 6.94 log cfu/g for control, T1, T2 and T3; respectively.
- The control samples had lower counts, while T3 had the highest counts in all treatments.
• Bifidobacterium bifidum count:
- In fresh samples, the minimum counts were 6.62 log cfu/g for control treatment; meanwhile, the maximum was 7.55 log cfu/g for T3.
- After 5 days of storage, there were an increase of Bifi. bifidum counts in all treatments.
- After 15 days of storage, there were decreases in Bifi. bifidum counts in all treatments.
- The lowest counts of Bifi. bifidum was for control samples; being 5.35 log cfu/g and the highest was for T3; 6.75 log cfu/g.
- The control samples had lower counts, while T3 had the highest counts in all treatments.
• Yeast and Mold count:
- All treatments were free from yeast & mold up to10 days of storage.
- After 15 days of storage, yeast & mold counts were; 2.42, 2.30, 2.22 and 2.10 log cfu/g for control, T1, T2 and T3; respectively.
• Coliform count:
- Coliform count was not detected in all treatments when fresh and along the storage periods.
c) Rheological properties:
• Syneresis:
- There were increases of syneresis in bio-Yogurt when fresh than that of other treatments.
- Addition of WPC decreased syneresis of T1, T2 and T3.
- Control samples have the highest syneresis when compared by WPC treatments.
- Syneresis of all treatments decreased by extending the storage up to 15 days.
• Density (g/cm3):
- Control samples have the lower density when compared by WPC treatments.
- Adding WPC increased density in all treatments, and T3 treatment has higher slightly density value comparing by other treatments.
- There were increasing of density by increasing of WPC and storage periods in all treatments.
• Firmness:
- There were increases of firmness by increasing of WPC and storage periods in all treatments.
- After 15 days of storage, there were gradual increases in firmness.
d) Organoleptic properties of bio-Yogurt:
• Flavor:
- Control samples have lower flavor compared by WPC treatments.
- After 15 days of storage, it was clear that the addition of WPC up to 6% was accepted. - The most acceptable bio-Yogurt was that made of 2 and 4% WPC.
• Body and texture:
- Fresh control samples had lower body and texture than that of treatments.
- Bio-Yogurt made with WPC stored for 7 days, no differences were observed for body and texture.
- Although WPC treatments of 2 and 4% had lowered scores by the end of storage, the WPC treatment of 6% has highest score comparing by the other treatments.
• Color and appearance:
- Fresh bio-Yogurt with 2, 4 and 6% WPC, as well as the control samples had higher color and appearance.
- After 15 days of storage, color and appearance of control samples and T1 & T2 had no differences.
- Color and appearance score decreased by increasing WPC to 6%.
• Total scores:
- Control samples have lower total score compared by WPC treatments.
- In fresh samples, treatments with 4 and 6% WPC were the most preferable, followed by the treatment of 2% WPC.
- The most accepted bio-Yogurt treatments were that of 2 and 4% WPC.
- Total scores decreased during storage up to 14 days in all treatments.
2) Characteristics of edible films:
a) physical properties of edible films:
• Film thickness (FT):
- Film thickness was; 0.29, 0.44, 0.28 and 0.24 mm for control, WPCS (2% Sorbate), WPCN (50 UI Nisin) and WPCSN (1% Sorbate & 25 UI Nisin); respectively.
- FT of WPCEF with the addition of different concentrations of Rosemary and Marjoram essential oils (0.2, 0.4 & 0.6%) were; 0.26, 0.30 & 0.25 and 0.29, 0.25 & 0.31 mm for WPCR and WPCM; respectively.
- The lowest of FT were 0.24 and 0.25 & 0.25 mm for WPCSN (1% Sorbate & 25 UI Nisin) and WPCM with 0.4% & WPCR with 0.6%; respectively.
• Water solubility of edible films (WSEF%):
- The lowest value of WSEF was 25.51% for WPCS treatment compared with control samples (32.91%), while rest of treatments were; 34.02 and 28.30% for WPCN, WPCSN; respectively.
- The mean of WSEF% with the addition of different concentrations of Rosemary and Marjoram essential oils (0.2, 0.4 and 0.6%) were; 28.61, 26.85 and 22.28 and 29.95, 26.38 and 23.39% for WPCR and WPCM; respectively.
- WSEF% decreased by increasing the concentrations of Rosemary and Marjoram essential oils in all treatments.
• Water vapor permeability (WVP):
- Control samples had higher WVP than that of other treatments.
- The highest value was for samples with 50 UI Nisin (0.054 g.mm/m2 mmHg), while the lowest value was for samples with the addition of 1% Sorbate & 25 UI Nisin (0.042 g.mm/m2 mmHg).
- The highest value was for samples with 0.4% Rosemary oil (0.060 g.mm/m2 mmHg), while the lowest value was for samples with the addition of 0.2% Marjoram oil (0.046 g.mm/m2 mmHg).
• Water vapor transmission (WVT):
- Control samples had higher WVT than that of other treatments.
- The highest value was for samples with 50 UI Nisin (18.69 g/s.m2), while the lowest value was for samples with the addition of 2% Sorbate (8.31 g/s.m2).
- The highest value of WVT was for samples with 0.6% Rosemary oil (19.85 g/s.m2), while the lowest value was for samples with the addition of 0.6% Marjoram oil (16.39 g/s.m2).
• Transparency of edible film (TEF):
- The highest value of TEF was for samples with 2% Sorbate at wave length 550 (43.13), while the lowest value was for samples with the addition of 50 UI Nisin at wave length 395 (8.13%).
- The highest value of TEF was for samples with 0.6% Marjoram oil at wave length 550 (39.50 nm), while the lowest value was for samples with the addition of 0.4% Rosemary oil at wave length 395 (7.80 nm).
b) Mechanical properties (tensile strength & elongation at break):
- Control samples had higher strength and percentage elongation than that of other treatments.
- The highest of tensile strength was in WPCSN films (4.376 N/m2), while the lower tensile strength was in WPCN (4.104 N/m2).
- Tensile strength and elongation percentages for WPCEF with the addition of different natural preservation (Rosemary & Marjoram oils) increased with increasing concentration of oils in all treatments.
- The highest of tensile strength and elongation percentages was in 0.6% WPCM films, while the lower was in 0.2% WPCR.
c) Anti-microbial activity of WPCEF with natural preservation (Rosemary & Marjoram oils):
- Small inhibition zone against tested microorganisms (Staph. aureus; E. coli; salmonella typhimurium; Aspergillus Niger and C. Albicans) was observed for WPCEF with the incorporation of essential oil at concentration 0.2%; while large inhibition was observed at concentration 0.4% and a very strong effect at the concentration 0.6%.
- The film composition was applied at a concentration of 0.4% Marjoram oil, taking into account the initial sensory evaluation of the consumer.
- For all studied microorganisms, increasing concentration of Marjoram or Rosemary oils in edible films resulted higher antimicrobial activity.
- Film disks containing 0.4% Marjoram or Rosemary had good inhibitory effect.
3) Application of edible coating on white soft cheese:
a) Chemical composition of coated white soft cheese with WPCEF by different treatments:
c) Moisture content:
- Fresh cheese had slight lower in moisture for control cheese compared to those coated by different preservation.
- The WPCS samples stored at 21 days had the lowest moisture content.
- There were decreases of moisture content with increasing storage periods up to 21 days in all treatments.
d) Titratable acidity (TA%):
- The TA% in fresh white soft cheese was lower in control samples compared with other treatments.
- The TA% increased with increasing of storage period up to 21 days in all treatments.
e) pH values:
- The pH values in fresh white soft cheese had higher value for control samples compared with other treatments.
- The pH values decreased with increasing of storage period up to 21 days in all treatments.
f) Total nitrogen percentages (TN%):
- Fresh cheese had slight lower in TN% for control cheese compared to those coated by different preservation.
- The WPCS samples stored at 21 days had the lowest TN.
- There were decreases of TN% with increasing storage periods up to 21 days in all treatments.
g) Soluble nitrogen percentages (SN%):
- The SN% in fresh cheese was slighter lower in the control cheese (0.011%) compared to those coated by different preservation.
- There were increases of SN% with increasing of storage periods in all treatments.
h) Ash percentages (Ash%):
- The ash% in fresh cheese was slighter lower in the control samples compared to those coated by different preservation.
- There were increases of ash% with increasing of storage periods in all treatments.
i) Fat content:
- The fat content was slighter lower in the control cheese compared to those coated by different preservation.
- The fat content increased during storage at 7 days from 17.28, 17.26, 17.23 and
- There were increases of fat content with increasing storage periods up to 21 days in all treatments.
b) Weight loss of coated white soft cheese with WPCEF by different treatments:
- The percent of weight loss started after 7 days of storage, and after 7 days the weight loss was significant gradually decreased.
- The highest weight loss was found for WPCS (4.94%), while the lowest was for WPCM treatment samples (4.82%).
- WPCSN film and WPCM film more effectively reduced the weight loss of cheese during storage than other treatments.
c) Microbiological properties of coated white soft cheese with WPCEF by different treatments:
1. Total bacterial count (TBC):
- The control samples had higher TBC than that of other treatments.
- There were increases of TBC with increasing of storage periods until 21 days in all treatment.
2. Spore forming bacterial count:
- The control samples had higher spore forming bacteria than that of other treatments.
- There were increases of spore forming bacteria with increasing of storage periods up to 21 days in all treatment.
3. Yeast and Mold count:
- The control samples had higher Yeast and Mold than that of other treatments.
- There were increases of Yeast and Mold with increasing of storage periods up to 21 days in all treatment.
4. Coliforms count:
- Coliform count was not detected in all treatments when fresh and along the storage periods.
d) Rheological properties of coated white soft cheese with WPCEF by different treatments:
1. Hardness (N):
- The control samples had higher hardness than that of other treatments.
- There were increases significantly of hardness with increasing of storage periods in all treatment.
- The hardness of all coated white soft cheese samples was high which was related to the weight loss results during storage.
2. Adhesiveness (mj):
- The control samples had higher adhesiveness than that of other treatments.
- There were increases of adhesiveness with increasing of storage periods in all treatment.
- The hardness of all coated white soft cheese samples was high which was related to the weight loss results during storage.
3. Cohesiveness ratio:
- The control samples had higher cohesiveness than that of other treatments.
- There were increases significantly of cohesiveness with increasing of storage periods in all treatment.
4. Springiness (mm):
- The control samples had higher springiness than that of other treatments.
- There were increases of springiness with increasing of storage periods in all treatment.
5. Gumminess (N):
- The control samples had higher gumminess than that of other treatments.
- There were increases of gumminess with increasing of storage periods in all treatment.
6. Chewiness (mj):
- The control samples had higher chewiness than that of other treatments.
- There were increases of chewiness with increasing of storage periods in all treatment.
e) Organoleptic properties of coated white soft cheese with WPCEF by different treatments:
1. Flavor:
- The control samples had lower flavor than that of other treatments.
- The fresh samples had higher flavor than that of other treatments, and decreased with increasing of storage periods in all treatments.
2. Body and texture:
- The control samples had lower body and texture than that of other treatments.
- The fresh samples had higher body and texture than that of other treatments, and decrease with increasing of storage periods in all treatments.
3. Color and appearance:
- The control samples had lower color and appearance than that of other treatments.
- There were decreases of body and texture with increasing of storage periods in all treatment.
- The fresh samples had higher color and appearance than that of other treatments, and decrease with increasing of storage periods in all treatments.
4. Total scores:
- The control samples had lower total scores than that of other treatments.
- The fresh samples had higher total scores than that of other treatments, and decrease with i