الفهرس 
Food additivesOnly 14 pages are availabe for public view
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Abstract
Food additives have been defined by the FAO/WHO: as substances which are added intentionally to food, generally in small quantities, to improve the appearance, flavor, texture or other storage properties. Additives may be intentional or incidental. Intentional additives are added on purpose to perform specific functions. Incidental additives have no function in the finished food, but become part of it through some phase of production, processing, storage or packaging. Normally, they are present only in trace amounts.
The aim of the this study was to assess the effects of addition of Chitosan and/or Nigella sativa as preservatives on organoleptic properties and microbiological quality of Kariech cheese and assess of the synergistic effect of Chitosan and Nigella sativa oil on the prevention and protection of colon cancer in laboratory animals.
To fulfill these aims the following was carried out:
Kariech cheese was purchased from the local market and was divided into the following:
1- The first part was considered as control part.
2- The second part was mixed with Chitosan at three levels:
- Low concentration: 1%
- Medium concentration: 2%
- High concentration: 4%
3- The third part was mixed with N. sativa oil at three levels.
- Low concentration: 0.5%.
- Medium concentration: 1.25%.
- High concentration: 3%.
4- The fourth part was mixed with both Chitosan and Nigella sativa oil
- Low concentration - 1% chitosan and 0.5% N. sativa oil
- Medium concentration - 2% chitosan and 1.25% N. sativa oil
- High concentration - 4% chitosan and 3% N. sativa oil
After thorough mixing, a portion of each addition level of chitosan and/ or Nigella sativa oil was subjected to the organoleptic examination and to the microbiological examination (zero time). The rest was stored at refrigerated temperature, and subjected to microbiological examination after 3, 7, 10, 14, 17, 21, 24, 28 days of storage.
A total of 165 male mice at the age of 3 months were selected with approximately the same weight. Mice were randomly divided into three groups.
GI: Mice fed Kariech cheese supplemented with/ without chitosan and/ or Nigella sativa oil without injection of dimethyl hydrazine dihydrochroide (DMH)
GII: Mice fed Kariech cheese supplemented with/ without chitosan and/ or Nigella sativa oil and injected DMH at the same time.
GIII: Mice fed Kariech cheese supplemented with/ without chitosan and/ or Nigella sativa oil for six weeks and injected DMH after 15 days of feeding.
Results of the present study revealed the following:
1- Supplementing of Kariech cheese with 1% Chitosan, 0.5% N. Sativa oil or a combination of 1% Chitosan and 0.5% N. Sativa oil resulted in a non significant decrease of the scores of odour, taste, color and texture of Kariech cheese. Higher supplementing levels of Chitosan, N. sativa oil and a combination of both resulted in a significant decrease of their scores.
2- Supplementing Chitosan to kariech cheese showed no significant effect on the total aerobic mesophilic bacterial count of the cheese. Moreover, after 28 days of storage kariech cheese supplemented with 2% or 4% Chitosan showed higher counts than plain cheese. However, after 3 and 10 days of storage plain kariech cheese showed higher Total aerobic mesophilic bacterial count than cheese supplemented with 1%, 2% and 4% chitosan, indicating chitosan can be used to preserve kariech cheese for only 10 days.
3- Supplementing 1.25% and 3% N. sativa oil to kariech cheese showed a significant effect on the total aerobic mesophilic bacterial count of the cheese. However, cheese supplemented with 0.5% N. sativa oil showed lowest Total aerobic mesophilic bacterial count up to 7 days of storage as well as after 17 days of storage. However, after 24 days all supplementing levels showed lower counts than plain kariech cheese. After 28 days of storage, kariech cheese supplemented with 0.5%, 1.25% and 3% N. sativa oil showed higher counts than plain cheese.
4- Supplementing both Chitosan and N. sativa oil showed no significant effect on the total aerobic mesophilic bacterial count, however, supplementing both 4% Chitosan and 3% N. sativa oil to kariech cheese showed lower Total aerobic mesophilic bacterial count than plain cheese or cheese supplemented with both Chitosan and N. sativa oil at lower levels.
5- Supplementing 1% and 2% chitosan to kariech cheese showed significant decrease of coliforms counts. However, supplementing 4% chitosan resulted in non significant increase of coliform counts.
6- Supplementing N. sativa oil to kariech cheese resulted in a non significant effect on coliforms count.
7- Supplementing both Chitosan and N. sativa oil showed significant reduction of the coliforms counts up to 24 days.
8- Fecal coliform was not detected in any kariech cheese supplemented with Chitosan or N. sativa oil in all concentrations, although it was detected in the control at counts up to 2.1 10 MPN/g.
9- Supplementing Chitosan and N. sativa oil together decreased the fecal coliform count of cheese. After 24 days of storage fecal coliform was not detected in all Kariech cheese supplemented with different concentrations of both Chitosan and N. sativa oil, moreover after 7 days it was not detected in Kariech cheese supplemented with 2% Chitosan and 1.25% N. sativa oil and it was not detected after 21 days in kariech cheese supplemented with 1% chitosan and 0.5 N. sativa oil.
10- Supplementing 1%, 2% and 4% Chitosan to kariech cheese showed significant decrease of the mold and yeast counts of kariech cheese. In the mean time supplementing 1% Chitosan resulted in the lowest counts.
11- Supplementing 0.5%, 1.25% and 3% N. sativa oil to kariech cheese resulted in a significant decrease of the mold and yeast counts. Moreover, after 24 and 28 days of storage plain kariech cheese showed higher counts than the three levels of N. sativa oil supplemented cheese.
12- Supplementing both Chitosan and N. sativa oil to kariech cheese at the three different levels resulted in significant effects on mold and yeast counts. A concentration of 2% Chitosan and 1.25% N. sativa oil showed the best effect on these counts. where the lowest counts were found in cheese at this level of supplements after 14,17,21 and 28 days of storage. However, higher supplementing levels (4% chitosan + 3% N. sativa oil) showed the lowest counts up to 14 days of storage.
13- Regarding colon hyperplasia control group (GI) showed no or mild hyperplasia in all cases at 4, 6 weeks; while GII (initiation phase) showed moderate hyperplasia in nearly 40-50%, at 2, 4 weeks, reduced to 18% at 6 weeks. In preinitiation group (GIII) hyperplasia appeared in nearly 90% of cases at 4 weeks reduced to 10% after 6 weeks.
14- Regarding colon atypia/dysplasia. Control group (GI) showed no atypia along the period of the study. Atypia appeared at nearly 54%-45% in group II at 2nd 4th weeks respectively; reduced to 9% at 6 weeks, similar changes were seen in GIII where 73% of cases showed atypia at 4 weeks reduced to 17% at 6 weeks No malignancy could be detected, this may be due to the proven anti-neoplastic properties of these food additives (Chitosan, N. sativa oil) specially when given at pre-imitiation stages explained by several studies confirmed this antineoplastic or protective effect of N. sativa oil.
15- Regarding colitis, feeding mice on cheese only diets causing thick slimmy faeces, that cause alteration of stenetic (hyperplastic) segments and dilated atrophic segments; Application of Chitosan (due to its thick fibers) may cause temporary chronic irritation and inflammation of the colon, these changes receeded after 6 weeks. Kariech cheese supplemented with Chitosan and or N. sativa oil improved stools and normalize the colon.
It recommended to:
• Based on vitro studies, Chitosan and N. sativa oil are recommended to be sued as preservatives for kariech cheese as they improve its keeping quality through decreasing coliform, fecal coliform and mold and yeast counts.
• Based on vivo studies, researches are needed to confirm the anticarcinogenic and anti-inflammatory effects of Chitosan and N. sativa oil on GIT cancers; particularly colon cancer.