الفهرس | Only 14 pages are availabe for public view |
Abstract The aim of this study is to investigate the chemical components of cinnamon, rosemary and clove volatile oils by GC/Mass as well as the antioxidant and antimicrobial activity of these oils and their mixture (1:1:1, v:v:v) to select the best volatile oil or mixture and also the best concentration for preparing beef sausage. The effect of different exposure times to laser radiation (Helium-Neon laser wavelength at 632.8 nm) was also studied to select the best one for preparing and preserving of beef sausage. Results indicated that 23, 10, and 18 compounds were identified from cinnamon, rosemary, and clove which represented 97.26, 98.50 and 98.80 %, respectively. Cinnamaldehyde, 1, 8 Cineole, and Eugenol were the most abundant chemical compounds in cinnamon, rosemary, and clove volatile, respectively. Volatile oils mixture had higher antioxidant and antimicrobial activity than each volatile oil individually and could be arranged in descending order according to their antioxidant and antimicrobial potency as follows: volatile oil mixture ˃ cinnamon ˃ clove ˃ rosemary volatile oil. Based on antioxidant and antimicrobial results, it could be recommended to use a volatile oils mixture (cinnamon, clove and rosemary, 1:1:1, v: v: v) in the preparation of beef sausage. Also, results indicated that, 500 ppm of volatile oil mixture was the best concentration in preparation of beef sausage due to improve sensory properties when compared with other concentrations, and 18 minutes (9 min for each side) was the best exposure time to laser radiation for sausage because there weren’t any recorded negative changes in physiochemical properties of the product. Also in this study, the effect of best concentration of volatile oils mixture (500 ppm) and best exposure time of laser radiation (18 min) on quality attributes and shelf life of beef sausage during cold storage was investigated. Lipid oxidation (peroxide value, thiobarbituric acid, and acid value), pH value and total volatile nitrogen (TVN) of sausage treatments were not affected significantly by laser radiation or volatile oils mixture immediately after processing (at zero time) but affected (p<0.5) during cold storage. Sausage prepared with 500 ppm volatile oils mixture and exposed to laser irradiation (T3) had significantly lower lipid oxidation, pH and TVN than other sausage treatments at any time of cold storage. Moreover, microbial load (total bacteria count, psychrophilic bacteria, coliform group, lipolytic and proteolytic bacteria, Salmonella spp., Staphylococcus aureus and yeast and mold counts) of beef sausage decreased by exposure to laser radiation for 18 minutes (T1) and by adding the volatile oil mixture at 500 ppm (T2) as well as volatile oils mixture and laser radiation combination (T3) when compared with control sample. Therefore, the treatment of beef sausage with volatile oil mixture and laser radiation combination led to improve chemical, physical and sensory properties and more effective in reduction of microbial load and extending the shelf life of beef sausage to 20 days at 4±1ºC compared with sausage treated with volatile oils mixture only (15 days), sausage treated with laser rays only (10 days) and control sample (5 days). |