الفهرس 
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Abstract
Mozzarella cheese is a fresh soft cheese of “Pasta Filata” family, originated from Italy, with a characteristic “chicken breast” fibrous structure with unique melting and stretching properties (Sandrou & Arvanitoyannis, 2000). Rheological, sensory, and nutritional qualities of the cheese are depends on milk fat. However, the increased awareness of people on fitness and healthy. Life style has resulted in an increased demand for low-calorie foods, i.e.low and reduced fat cheeses without compromising flavour and texture. Low-fat cheese has bland taste, firm and rubbery texture, and dull colour attributed to loss of plasticizing property of the fat and increased cross-linking of proteins. Various techniques developed to improve the texture of low and reduced fat cheeses included process modifications, use of special starter cultures and fat replacers. Fat replacers are water-dispersible substances, which improve the sensory and functional properties of low-fat cheese through the associated moisture-retaining effect as well as providing the sensation of a creamy, soft, moist texture. There are two main types of fat replacers recommended in dairy products: micro-proteins or carbohydrates. Polysaccharide extracts from some plants are fat replacers of carbohydrate origin that act as a thickening agent, stabilizer and suspending agent, and are used in a variety of dairy products for their technological and nutritional advantages. Thereby, the present study was undertaken to: Improving the functional properties of low-fat and fat-free mozzarella cheese and extending its shelf life, through the use of polysaccharide extracts of some plants (okra - Molokhia- artichoke) that were incorporated during the manufacture of cheese and preserved by freezing at a temperature of -20℃ after cooling in the refrigerator for two days. The freezing scheme was designed to study its effect on the functional properties and shelf life of the produced cheese. The results indicated as follows:
1: The physico-chemical properties
The pH values changed significantly (P < 0.05) for cheese with a decrease in fat percentage, as the value decreased from (5.32) for full-fat cheese (C 1) to 5.21 in cheese with 100% reduced fat (C 5). The inclusion of plant extract in cheese appeared to significantly decrease (P < 0.05) in the pH values of treatment T1 and T3 (okra and artichoke, respectively), while it was a non-significant decrease for treatment T2 (molokhia). On the contrary, the acidity gradually increased in mozzarella cheese with a decrease in fat content. While the addition of vegetable extracts (okra -Molokhia - artichoke) increased the acidity percentage compared to cheese made without additives. Okra and artichoke had the highest (P < 0.05) values of acidity at all levels of fat. The pH and acidity values changed slightly during the storage period for all treatments with or without plant extracts and remained in the range from 5.15 to 5.30 and 0.81 to 0.91% for pH and acidity % respectively. However, the statistical analysis showed that the changes were not significant (P < 0.05) between fresh and stored cheese, while they were significant (P < 0.05) among the treatments. 75 The moisture content was affected by the decrease in the fat content as the values increased gradually from 50.1% for the full-fat control cheese (C1) to (52.67, 53.66, 55.43 and 57.21) for C2, C3, C4 and C5, respectively. The addition of vegetable extracts also led to an increase (P < 0.05) in the moisture content of the low-fat cheese for all treatments compared to the low-fat cheese (C2 to C5) without addition, the treatments of okra (T1) and artichoke (T3) recorded the highest moisture content. cheese moisture non-significant decreased (P> 0.05) in all treatments during storage.