Abstract
In this study, the effect of rosemary extract in two free and encapsulated forms to increase the shelf life of beef meat during a 28‐day refrigerated storage period was investigated. For this purpose, rosemary was extracted using different extraction methods including ultrasound, solvent, and supercritical fluid extraction. The amount of phenolic compounds, antioxidant properties (free radical scavenging capacity of DPPH radical, ferric reducing antioxidant power), and antimicrobial activity of rosemary extract against pathogenic bacteria were evaluated. According to the results, the highest amount of phenolic compounds, antioxidant, and antimicrobial activity was observed in rosemary extracted by ultrasound method that used for next study (p < .05). In order to encapsulation of the rosemary extract, basil seed gum and soybean protein isolate separately and in combination form (1:1 w:w ratio) were used as carriers. Based on the particle size, zeta potential, and encapsulation efficiency tests, the best carriers were soybean protein isolate that used as a carrier for encapsulation. Then, to investigate the effect of rosemary extract to increase the shelf life of beef meat, 5 treatments including control, rosemary extract with concentrations of 800 ppm and 1,600 ppm, and nano‐capsulation form of it with 800 ppm and 1,600 ppm concentrations were selected and they were periodically evaluated for chemical and microbial analysis (peroxide value, Thiobarbituric acid, color index, pH, and total viable count). The results showed that rosemary extract has an antimicrobial and antioxidant properties which could increasingly delay microbial spoilage and lipid oxidation of beef meat fillets, nano‐capsulation form of rosemary could increase these qualities. The best results were observed in nano‐capsulation of rosemary extract with 1,600 ppm (p < .05) as well as increased the shelf life of fillets till 21st day. Therefore, it seems that encapsulated rosemary extract could be used as a natural preservative in beef meat and meat products.
Highlights
Meat and meat products have a high corruption capability due to high moisture and lipid content and rich in protein and minerals
The phenolic compounds of rosemary extract obtained by ultrasound method were significantly higher than the other extraction methods (699.13 μg/g dry weight) (p < .05), the phenolic compounds in the supercritical fluid extraction treatment were 5,665.37 μg/g dry weight and the lowest amount of it was observed in water–ethanol treatment (410.4 μg/g dry weight) (p < .05)
The results of the current study showed that in all concentrations, the highest and the lowest in the ferric reducing antioxidant power (FRAP) were in ultrasound extraction and solvent methods, respectively (Figure 1b) and rosemary extracted by ultrasound method had a higher antioxidant activity than TBHQ at 1,600 ppm (p < .05)
Summary
Meat and meat products have a high corruption capability due to high moisture and lipid content and rich in protein and minerals. The most common chemical changes in meat products are lipid oxidation. Lipid oxidation is a complex process and depends on the chemical composition of meat, access to light, oxygen, and storage temperature, and it causes undesirable changes in the sensory properties (color, texture, and flavor) and the nutritional quality of meat (Devatkal, Thorat, & Manjunatha, 2014; Shah, Bosco, & Mir, 2014). Using antioxidant and antimicrobial preservatives in meat and meat products is very common to prevent the lipid oxidation and spoilage and increased the shelf life and quality of products. Consumers considering the harmful effects of chemical and synthetic food preserves were eager to use the natural preservatives derived from plant, animal, and microbial resources that in addition to increase the shelf life of food products and protect from the harmful effects of chemical preservatives (Burt, 2004). In addition to the antioxidant properties, these compounds have antimicrobial, anticancer, and antimutagenic properties (Dawidowiez, Wianowska, & Baraniak, 2006)
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