Introduction: Meat quality is always very important for consumers. Tenderize meat one way to improve the quality of Meat and its products. In the study effect of three levels (0. 0025, 0. 005 and 0. 01 percent) of protease produced by Aspergillus niger on meat TENDERNESS during the 28 days of storage at 4 ° C were studied. Then treatments to control the physicochemical and sensory characteristics were evaluated. In this study tests the total soluble protein, moisture content, pH, colorimetric, texture analysis, water holding capacity and sensory evaluation of meat quality parameters were used. The results of the tests carried out showed that soluble proteins, pH and moisture content levels generated by increasing the enzyme from 0. 0025 to 0. 01 percent was significantly increased (P<0. 05), But on the rigidity by increasing the enzyme decreased firmness. Results also showed that water holding capacity has decreased, but all treatments during storage period 0/01 enzyme treatment showed the highest capacity at the end. Brightness index (L *) and yellowness index (b *) during maintenance treatments reduce the redness index (a *) increased. The sensory characteristics of diet supplemented with 0. 0025% of fungal enzymes and control the admission showed more acceptable. So this study using Aspergillus niger enzyme for use in to tenderize meat it considers appropriate. Materials and methods: For this purpose, 4 samples of 500 grams of Rhomboideus muscle from the 1. 5-year-old Holstein male calf from the Rock Company slaughterhouse were immediately prepared for killing. Samples were stored in a refrigerator at 4 ° C for 48 to 72 hours. Each muscle was maintained as a non-injectable control unit (control sample). Then injected into three other parts of the enzyme solution. Protein solution of Aspergillus Niger was obtained from the Iranian Institute of Science and Technology. Then injection of the extracts of the enzyme into the sequences by the injector with 0. 01% (AN 0/01), 0. 005% (AN 0/005) and 0. 0025% (AN 0/0025) (Mg / 100 grams of meat) of fungal protease separately into meat pieces. The pieces of meat were treated using an injector with 4 needles in each row with 10 needles with a spacing of 2. 8 cm and a pressure of 35 injections. After injection, the muscle samples were packed under vacuum and immediately stored at 4 ° C for 28 days. On the days 1, 7, 14, 21 and 28, the relevant tests were performed on the treatments. To measure the pH, 10 g of the milled meat was mixed in 90 g of deionised water. The prepared mixture was then plated with a rough filter paper (average watten-diameter of 150 mm). Finally, pH was measured using a digital pH meter. The homogeneous moisture content of the meat samples was measured using the oven method and according to AOAC standard No. 46/950. The basis of the test is based on the measurement of total nitrogen in foods, assuming that all N is a protein type and is based on the coefficients of N-to-protein conversion. To determine the protein values, use the method outlined in AOAC (1996). Used. To measure the protein, the Kjeldahl method was used by the Kjeldahl machine constructed in Japan. The color of the meat was measured by a color spectrometer (CR-300, Minolta, Co. Ltd., Japan) every seven days. White tile with b *: 1. 72; a *:-0. 02; L *: 97. 46 is considered as reference. This test was performed to examine the tissue texture strength of the specimens by using Feismann et al. (1999) by Brookfield Engineering Laboratories, USA at 4 ± 2 ° C. In this test, a cylindrical probe with a smooth cross-section with a diameter of 12. 7 mm and a speed of 1 ml / sec was used. In order to measure the water holding capacity, the amount of water extracted from the cutting surface of meat samples under 500 psi pressure and 1 minute time to the filter cassette was accurately weighed to 0. 001 g and was expressed as extractable moisture content. The evaluation of sensory features in terms of five factors including hardship, substrate, texture, color and general acceptance was performed using 10 evaluated trainees by Hedonic method by completing an evaluation questionnaire. To each of the mentioned factors, the privilege was allocated from 1 to 5. The way to score was based on the fact that the number 5 represents the highest score and the number 1 represents the lowest score all experiments were performed in a completely randomized design with three replications. Means were compared using SPSS 21 and based on Duncan's tests at 5% level. The resulting charts in the 2013 excel software were drafted and compared. Results & Discussion: There are several ways to improve the quality of meat and its better use in the production of meat products. One of these methods is to increase the solubility of the meat proteins and, consequently, to crumble and increase the properties of the emulsion and other functional properties such as increasing water holding capacity. Today the effects of the enzymes in plants, bacteria and fungi have been investigated. In this study, the Aspergillus Niger fungal enzyme was used to crust meat. One of the results of this study is that the fungal enzymes have been able to greatly increase the water content of the water, pH and soluble proteins in the flesh, due to increasing the duration of the enzyme's effect and the concentration of the enzyme on Insoluble proteins such as collagen and elastin are completely digestible and their nature has changed (Englund et al., 1968). Also, the results show that the enzyme breaks down some of the protein proteins and forms them in smaller molecular weight units. As you can see, increasing the amount of enzyme concentration on meat proteins has increased the amount of crust and solubility of meat proteins.