الفهرس 
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Abstract
This investigation was carried out to study the production of low-fat beef burger using suitable fat replacer carrageenan at 0.3, 0.5 and 1%, carboxymethyl cellulose at 1.5, 3 and 4.5%, soy flour at 5, 10 and 15% and goat meat at 25, 50 and 100% and some natural additives to improve flavor and as preservative, in addition to control sample without additives. All samples were stored at -20˚C for 3 months. At zero time and during storage period, burger samples were analyzed before and after grilling of raw beef burger. Chemical, physical as well as sensory evaluations were performed. Likewise, total lipid fractions of raw and grilled studied beef burger samples were assessed by using thin layer chromatography by the end of frozen storage. Meanwhile, fatty acids composition were determined by the end of frozen storage for samples having the best sensory scores.
The data could be summarized as follows:
1. Gross chemical composition of beef, goat meat (chevon) and fat replacers.
- Results showed that gross chemical composition of fresh beef for moisture, protein, fat, ash and carbohydrate contents were 65.67%, 53.89%, 40.49%, 2.71% and 2.91% (on dwb), respectively. TBA, TVBN and pH values were 0.105 mg malonaldehyde/kg sample, 11.30 mg N/100g sample and 5.47; respectively.
- Low-fat beef used in this study was characterized by high moisture, protein and ash content 72.23%, 7562% and 3.24%; respectively, while it had low fat and carbohydrate content 20.71% and 0.43% (on dwb); respectively. TBA, TVBN and pH values were 0.045 mg malonaldehyde/kg sample, 8.40 mg N/100g sample and 5.18; respectively.
- Goat meat (chevon) had moisture, protein, fat, ash, carbohydrate content and pH value 72.60%, 77.99%, 12.96%, 5.58%, 3.47% (on dwb) and 5.60; respectively.
- Carrageenan had moisture, protein, fat, ash, carbohydrate content and pH value 2.72%, 2.57%, 0.38%, 7.40 %, 86.93% (on dwb) and 4.70; respectively.
- Carboxymethyl cellulose had moisture, protein, fat, ash, carbohydrate content and pH value 2.76%, 2.49%, 0.14%, 8%, 86.61% (on dwb) and 4.40; respectively.
- Low-fat soy flour had moisture, protein, fat, ash, carbohydrate content and pH value 4.30%, 49.04%, 7.24%, 6.69%, 37.03% (on dwb) and 7.85; respectively.
2. Chemical composition of frozen beef burger before and after grilling.
- All low-fat beef burgers had higher moisture content with high significant difference than that of control sample in both zero time and during frozen storage, while low-fat beef burger which contained goat meat at different ratios (25, 50 and 100%) had the highest moisture content 70.02%, 70.03% and 70.34%; respectively but the control sample had 56.82%. Moreover, the moisture content of low-fat beef burger studied samples were decreased with significant difference as the ratio of fat replacer increased. The frozen storage and grilling of beef burger caused continuous decrease with significant difference in moisture content for all treatments.
- Beef burger with goat meat had higher protein content with a significant difference compared to control whether at zero time or during frozen storage 75.35%, 75.51% and 76.87% for samples containing 25, 50 and 100% goat meat, followed by treatment containing soy flour at levels (5, 10 and 15%) 74.09%, 69.10% and 68.19% (on dwb); respectively. Furthermore, the percentage of protein content were approximately similar and high in both carrageenan and carboxymethyl cellulose treatments at different ratios than that of control sample, but lower than the treatments containing goat meat and low-fat soy flour. Meanwhile, it was 28.90% for control sample. The percentage of protein content decrease with a significant difference as the level of fat replacer increased. The frozen storage and grilling of beef burger led to gradually decrease with significant difference in protein content for all treatments.
- All treatments containing additives ingredients as fat replacers had high ash content with high significant difference when compared to control sample (5.08%) at zero time of frozen storage. Moreover, increasing ratio of fat replacer caused increasing in ash content with a significant difference in comparison within each treatment. Generally, ash content increased with a statistical significant difference during frozen storage and after grilling beef burger.
- Results illustrated that the fat content of control sample had high amount of fat (58.29%) with high significant difference than other treatments having less amount of fat by manually reducing of visible fat in all beef burger prepared by adding fat replacers. By advancement of frozen storage the fat content of all treatments was increased on the expense of losses in moisture and protein percentage. While, grilling beef burger caused a clear reduction with a significant difference in fat content for all studied beef burger samples.
- Incorporation of fat replacers (carrageenan, CMC, soy flour and goat meat) resulted in increasing of total carbohydrates content with a significant difference of low-fat beef burger treatments. While, the treatment containing goat meat at different ratios had the least content of carbohydrate content than all treatments. As the ratio of fat replacers increased the carbohydrate content increased with statistical significant difference in comparison within each treatment. Moreover, the frozen storage and grilling resulted in an increase of total carbohydrate with a significant difference for all treatments.
- Caloric values of treatments containing fat replacers were lower with a significant difference than the control sample 671.02 k.cal/100g. On the contrary, grilling of beef burger showed highly reduction in caloric values, while during frozen storage the caloric values were gradually increased with statistical significant difference for all treatments.
- The treatment containing soy flour at different ratios had the lowest TBA values with a significant difference as compared to control sample having TBA value 0.452 mg malonaldehyde/ kg sample. On the other hand, grilled beef burger had higher TBA values with highly significant difference than that obtained for raw beef burger. Moreover, TBA values increased with no significant difference as long as time of frozen storage increased for all studied beef burger samples.
- The total volatile basic nitrogen was highest for control sample and samples containing goat meat with a significant difference at different levels at any given time of frozen storage. Carrageenan, CMC and soy flour as fat substitutes reduced the level of TVBN values which was found to increase continuously during frozen storage at -20˚C for all treatments.
- The highest total soluble nitrogen was found in case of beef burger containing soy flour with statistical significant difference at different ratios. While, the protein solubility decreased as time of frozen storage increased for all treatments.
- Extending storage time of studied beef burger samples as influenced by different fat replacers at -20˚C up to 3 months was accompanied by remarkable decrease with a significant difference in soluble protein nitrogen. While was accompanied by a gradual increase with a significant difference in non protein nitrogen content.
3. Physical properties
- Data indicated that treatment having soy flour at different ratios recorded the highest pH values with highly significant difference as compared with other treatments. On the contrary, the pH values of treatments containing carrageenan and carboxymethyl cellulose approximately were similar and lower than that of control sample. Moreover, slight increase in pH values with no significant difference were noticed in all treatments throughout the frozen storage period.
- The water holding capacity was improved by adding fat replacers with a significant difference as compared to control sample (5.65cm2). The highest WHC values were (3.84, 3.51 and 3.20 cm2) for treatment containing soy flour at levels (5, 10 and 15%); respectively. The water holding capacity decreased with statistical significant difference during frozen storage for all treatments.
- The percentage of shrinkage decreased with a significant difference by adding fat replacers than that of control sample (30.53%). In all beef burger studied samples the percentage of shrinkage increased with statistical significant difference by the progressive frozen storage period.
- Higher percentage of cooking loss was recorded for control formula 32.67% with a significant difference when compared with other beef burger treatments containing fat replacers. Cooking loss progressively increased as the period of frozen storage increased up to 3 months.
- Higher percentage of cooking yield with highly significant difference was recorded for treatment containing soy flour at levels (5, 10 and 15%) 77.88%, 85.87% and 89.18%; respectively. Meanwhile, the lowest cooking yield was 67.33% for control sample. The percentage of cooking yield were decreased with a significant difference during frozen storage period for all treatments.
4. Sensory evaluations
- The sensory evaluation of samples by panelists was indicated that the best samples which gained high scores for color with a significant difference were 9.4 for control sample, 9.1 for sample containing carrageenan at level 0.3%, 9.2 for sample containing CMC at level 1.5%, 9.7 for sample containing soy flour at level 5% and 9.4 for sample containing 25% goat meat. While, the more fat replacers ratio addition the less color score was found. Color scores decreased with no significant difference in some cases as frozen storage time increased for all treatments.
- Statistical analysis indicated that there were no significant difference between control and other treatment for chewiness. Furthermore, chewiness increased with a significant difference as addition of fat replacers ratio increased but decreased with no significant difference in most cases as long of frozen storage time increased for all treatments.
- Results showed that taste and flavor scores of control sample , samples containing carrageenan at level 0.3%, CMC at level 1.5%, soy flour at level 5% and sample containing 25% goat meat were significantly higher than other samples. While, the lowest score with a significant difference was for sample having 100% goat meat. Taste and flavor scores decreased with a statistical significant difference in most cases throughout the frozen storage period.
- Addition of fat replacers at different ratios resulted in an increasing in appearance and texture scores with a significant difference except in sample containing soy flour at level 15%. Appearance and texture scores decreased with a significant difference in most cases as the period of frozen storage increased up to 3 months.
- The control sample, samples containing carrageenan at level 0.3%, CMC at level 1.5%, soy flour at level 5% and goat meat at level 25% had the highest overall acceptability with statistical significant difference than other samples until the end of frozen storage. Meanwhile, sample containing 100% goat meat recorded the lowest score for overall acceptability. Overall acceptability scores decreased with a significant difference in most cases as long as time of frozen storage increased for all treatments.
5. Total lipid fractions by using thin layer chromatography
- The data revealed that the total lipids of beef burger were fractionated to seven fractions namely: phospholipids, monoglycerides, cholesterol, diglycerides, free fatty acids, triglycerides and hydrocarbons by TLC technique.
- Grilling of beef burger reduced the content of triglycerides and increased the contents of monoglycerides, diglycerides, free fatty acids and hydrocarbons in all samples.
6. Fatty acids composition
- Fatty acids composition were determined for samples having the best sensory scores by the end time of frozen storage. The data revealed that saturated fatty acids were C12:0, C14:0, C16:0, C17:0andC18:0. Predominated, major monounsaturated fatty acids were C16:1, C17:1, C18:1 and C20:1; and the major polyunsaturated fatty acids were descendingly: C18:2, C18:3. Among these fatty acids, the fatty acid C18:1 represented the highest relative percentage of all identified fatty acids.
- Results showed that the control sample had higher contents of saturated fatty acids and lesser contents of unsaturated fatty acids than other samples.
- Data indicated that the sample containing 25% goat meat had higher contents of unsaturated fatty acids than other samples as well as it had a higher percentage of oleic C18:1 about 42.30%.