ABSTRACT
BACKGROUND: Carnosic acid (CA) and rosmarinic acid (RA) are potent antioxidants. The effectiveness of an antioxidant in a food system is dependent on a range of factors such as concentration, phenolic content, physical state of the substrate, processing and storage. However, the antioxidant activity of powder vs liquid and higher vs lower phenols is not clear in different matrices. In this study, OxiKan-WS4 (4.0% RA), OxiKan-S10 (10% CA) and OxiKan-R8 (8% CA) were investigated against lipid oxidation in raw and cooked ground chicken patties during refrigerated storage. RESULTS: OxiKan-WS4 had the highest (P < 0.05) total phenolic content, whereas OxiKan-S10 and OxiKan-R8 exhibited higher DPPH radical-scavenging activity and reducing power relative to OxiKan-WS4. Lipid oxidation was minimized in meat with added extracts, as indicated by lower (P < 0.05) thiobarbituric acid-reactive substances, peroxide value and free fatty acid. Addition of natural antioxidant extracts at 10 mg equivalent total phenols per 100 g meat did not affect the sensory scores relative to non-treated controls. CONCLUSION: This study demonstrates that the physical state (powder vs liquid) of CA or RA plays an important role in determining their antioxidant efficacy.
Subject(s)
Abietanes/pharmacology , Antioxidants/pharmacology , Cinnamates/pharmacology , Cooking , Depsides/pharmacology , Meat/analysis , Phenols/pharmacology , Plant Extracts/pharmacology , Animals , Chickens , Fatty Acids/analysis , Food Preservation/methods , Lipid Peroxidation/drug effects , Oxidation-Reduction , Rosmarinus/chemistry , Salvia/chemistry , Thiobarbituric Acid Reactive Substances/metabolism , Rosmarinic AcidABSTRACT
Bacterial proteases have extensive applications in various fields of industrial microbiology. In this study, protease-producing organisms were screened on skimmed milk agar media using serial dilution. Through microbial biomass production, biochemical tests, protease-specific activity, and 16 s RNA gene sequencing, the isolates were identified as Bacillus subtilis and submitted to NCBI. The strain accession numbers were designated as A1 (MT903972), A2 (MT903996), A4 (MT904091), and A5 (MT904796). The strain A4 Bacillus subtilis showed highest protease-specific activity as 76,153.84 U/mg. A4 Bacillus subtilis was unaffected by Ca2+, Cu2+, Fe2+, Hg2+, Mg2+, Na, Fe2+, and Zn2+ but was inhibited by 80% by Mn2+ (5 mM). The protease activity was inhibited by up to 30% by iodoacetamide (5 mM). These findings confirm the enzyme to be a cysteine protease which was further confirmed by MALDI-TOF. The identified protease showed 71% sequence similarity with Bacillus subtilis cysteine protease. The crude cysteine protease significantly aided in fabric stain removal when added to a generic detergent. It also aided in the recovery of silver from used X-ray films and de-hairing of goat skin hides and showed decent application in meat tenderization. Thus, the isolated cysteine protease has high potential for industrial applications.