الفهرس 
Utilization of Some Herbs and Spices in The Production of Cream CheeseOnly 14 pages are availabe for public view
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Abstract
The main objective of the present study was to increase the shelf life of cream cheese which is susceptible to spoilage during storage by oxidation, undesirable changes in its organoleptic properties due to the growth of pathogenic microorganisms . This objective was achieved by adding some herbs and spices. These herbs and spices were ginger (zingiber officinale), caraway (Carum carvi L), turmeric (Curcuma domestica) and clove (Eugenia caryophyllata), rosemary (Rosemarinus officinalis) and thyme (Thymus vulgaris L).
The antioxidant and the antimicrobial activities of the methanolic extracts of these herbs and spices as well as their phenolic content and their identification by HPLC were studied.
The obtained results can be summarized in the following points:
1.The preliminary study showed that the best concentrations for the tested herbs and spices used to prepare cream cheese and well accepted by the panelists were 1.25, 1.25, 1.25, 0.3, 1.5 and 0.3 % for the powdered form of thyme, rosemary, caraway, clove, turmeric and ginger, respectively.
2.The methanolic extract of clove had the highest content of phenolics being 93.14 mg/g, whereas, the methanolic extract of caraway had only 8.5 mg/g. However, total phenolic content of the methanolic extract of thyme, rosemary, turmeric and ginger were27.40, 37.17, 27.40, and 15.87 mg/g , respectively.
3. Significant differences were noted between the extracted yields. The % yield varied between 5.32% in case of turmeric to 11.09 % in case of clove. The % yield were 5.81, 7.41, 7.58 and 8.47% for ginger, caraway, rosemary and thyme, respectively.
4.High performance liquid chromatography showed that clove had the highest concentrations of phenolic compounds compared with the other tested herbs and spices except for o-coumaric, salicylic and cinnamic acids in which rosemary was higher than clove in these compounds. The most phenolic compound that had the highest amount amongst the identified 16 phenolic compounds was benzoic acid. The main hydroxycynnamic acid in the tested herbs and spices was caffeic acid. However, p -coumaric acid occurred in small quantities except for clove, thyme and rosemary. They contained 67.67, 4.62 and 2.25 mg/100g, respectively.
5.The maximum reduction in radical scavenging activity amongst the studied herbs and spices as observed was rosemary (69.13%) which showed no significant difference with clove (66.29%) and thyme (65.80%). At the same time, they showed higher radical scavenging % compared with BHT and BHA. Turmeric, caraway and ginger showed lower reduction in radical scavenging activity being 21.01, 19.12 and 18.99 %, respectively.
6.The lowest IC50 values were detected for thyme, rosemary and clove (7.59, 7.23 and 7.54 mg/mL, respectively). On the other hand, ginger, turmeric and caraway had the highest values of IC50 (18.99, 21.01 and 19.12 mg/mL, respectively).The higher DPPH radical scavenging activity was associated with lower IC50 values.
7.In ferric reducing antioxidant power, no significant differences were observed in optical density among thyme (0.40), rosemary (0.28) and clove (0.40), but they were more effective as reducing agent than caraway (0.20) which did not have any significant difference with turmeric (0.21) and ginger (0.16).
8.There was a direct relationship between the phenolic content and DPPH radical scavenging tendency and FRAP of the methanolic extract of the tested spices and herbs with increasing their content of phenolic compounds.
9.The antimicrobial activity of the tested herbs and spices showed that:-
•The crude methanolic extract of clove (0.25mg) was more effective in inhibiting Staphylococcus aureus, Escherichia coli and Bacillus cereus than the other tested herbs and spices.
•The crude methanolic extract of thyme, rosemary and turmeric had MIC against Staphylococcus aureus at 1.25 mg. furthermore, the crude methanolic extract of ginger and caraway had MIC against Staphylococcus aureus at 2.5mg.
•The crude methanolic extract of rosemary and turmeric had MIC against Escherichia coli and Bacillus cereus at 1.25 mg. However, the MIC of crude methanolic extract of thyme, ginger and caraway against Escherichia coli and Bacillus cereus were 2.5mg.
10.The moisture content of cheese containing different ratios of the studied herbs and spices varied between 48.11% in case of cream cheese containing either rosemary or turmeric powder to 49.25%in case of cream cheese containing ginger powder. During storage, the moisture content in all samples of cream cheese containing different ratios of the studied herbs and spices was slightly increased during storage up to 2 weeks then slightly decreased again.
11.All samples of cream cheese containing different ratios of the studied herbs and spices had slightly lower values of titratable acidity comparing with the control sample even at the different periods of storage at 4ºC±1.As in case of the control sample, the titratable acidity of all cream cheese samples containing the different concentrations of the studied herbs and spices increased with increasing the storage period.
12.The pH value of the control sample was 4.74. This value decreased gradually with increasing the storage period. pH value of cream cheese at the end of storage period (21 days) was 4.36. Cream cheese samples containing different ratios of the studied herbs and spices showed the same trend. Slight variations in pH values were observed between cream cheese samples containing different ratios of the studied herbs and spices. In general, the pH values of cream cheese containing the studied herbs and spices were slightly higher than the control sample.
13.The control cheese sample contained 77.90% fat. Slight variations were noted after storage periods at 4±1 ºC. The fat content at the end of storage period (21 days) was 78.26%.
14.Soluble nitrogen (SN) as well as SN/TN ratio increased with increasing the storage periods at 4±1 ºC for the control sample. However, the addition of studied herbs and spices decreased slightly the development of SN and SN /TN.