مونا مظاهری کلهرودی

Oxidative degradation of oils, fats and high-fat food products during the processing and storage period, which leads to the reduction of organoleptic characteristics and nutritional value, is one of the most important challenges in the food industry. Adding antioxidants to foods is the most common method to reduce lipid oxidation rate. One of the most important features for a suitable antioxidant is the thermal stability during processing and storage period. In this research, the thermal stability of ethanolic and hexane extracts and essential oil of fennel seed compared to synthetic antioxidant BHA in soybean oil at temperature 90°C during a 28-day storage period by measuring peroxide, anisidine and oxidative stability indexes and totox value calculation were investigated. Extraction efficiency of extract with ethanol and n-hexane solvents and essential oil from fennel seed was obtained as 12.92%, 7.88% and 3.1%, respectively. The results of the research showed that the efficiency of all the studied antioxidants decrease during the storage period. Synthetic antioxidant BHA followed by fennel seed essential oil show the highest thermal stability. Ethanol and hexane extracts of fennel seeds did not show any significant difference with respect to the studied indexes and have the lowest thermal stability. As a natural antioxidant compound, fennel seed essential oil can be used as a substitute for synthetic antioxidants with proper thermal stability during the storage period.

Tenderization is one of the most important processes in the meat industry. This process is usually influenced by natural or artificial factors. Among the tenderizing methods, the application of natural compounds such as fruits and vegetables that have a high production rate, is of particular importance. Asparagus has a good proteolytic activity among various plant sources, which indicates there is a sufficient potential for its utilization in the meat industry. The purpose of this study was to evaluate the relationship between physicochemical and textural attributes of beefsteak marinated with asparagus (Asparagus officinalis L.) juice in improving meat tenderness based on mathematical equations as a fast, safe and cost-effective way to determine the quality of meat marinated with natural ingredients.

After extraction of asparagus juice by juicing method, the effect of different asparagus juice and balsamic vinegar treated samples including 25 ml asparagus juice, 25 ml asparagus juice+75 ml distilled water and 25 ml asparagus juice+10 ml balsamic vinegar+ 65 ml distilled water treatments on Warner-Bratzler shear force (WBSF), myofibrillar fragmentation index (MFI), collagen content, water holding capacity (WHC) and total protein solubility (TPS) were evaluated at 4 °C for 48 h. Then, the relationships between these variables (WBSF versus MFI and collagen content, TPS versus SPS and MPS, also MFI versus WHC) in improving beef M. semitendinosus steak tenderness were investigated and their equation was assigned. Also, correlation coefficient (R2) was used to determine the relationship between variables.

Results indicated decreased WBSF and increased MFI, collagen content, WHC as well as TPS in treated samples compared to control during storage (P<0.05). In the present study, the obtained relationships (between WBSF versus MFI and collagen content, TPS versus SPS and MPS, also MFI versus WHC) are simple linear regression equations. According to the results, the correlation between MFI and WBSF and the relationship between collagen content and WBSF was the reverse linear (P<0.05). While, the positive correlation was observed between total proteins solubility and solubility of sarcoplasmic and myofibrils proteins as well as the relationship between WHC and MFI (P<0.05). As the amount of low weight myofibrillar fragments produced from protein hydrolysis increases in sarcoplasm of muscle cell, the ability of these small peptides to bind water molecules increases, followed by improved solubility of sarcoplasmic, myofibrils and total proteins implies softer meat texture. On the other hand, increasing the solubility of collagen during cooking and converting it to soluble gelatin, especially in acidic condition provided by glycolysis / balsamic vinegar, can lead to reduced required force for cutting tissue, followed by more tender meat.

Based on the findings, asparagus juice influenced both myofibrillar proteins and connective tissues thereby, resulted in improving of physicochemical and textural characteristics of beefsteak, indicating the possibility of using asparagus juice to enhance the quality of meat and meat products. Therefore, the research aim to improve beefsteaks tenderness was achieved. The asparagus juice can be used as a new natural source in the formulation of seasoning, sauces and tenderizing agents, especially in the diet of the elderly people who have problems in swallowing and mastication to use more protein resources.