Mechanism of light-induced oxidation of nitrosylmyoglobin

Effect of heme proteins on the lipid molecule profile and aroma formation during hot air drying of non-smoked bacon

Heme proteins and their derivatives play important roles in inducing lipid oxidation to produce volatile compounds during bacon drying. This study investigated the effects of heme proteins and their derivatives (hemoglobin, myoglobin, nitrosylmyoglobin, hemin, Fe2+, and Fe3+) on lipid and volatiles profiles in the washed pig muscle (WPM) model. The results of the study indicated that the inducers primarily caused the oxidation of glycerophospholipids. Furthermore, hemoglobin and myoglobin had the most significant impact, and their potential substrates may include PE (O-18:2/20:4), PE (O-18:1/20:4), PC (16:0/18:1), and PE (O-18:2/18:2). Nitrosomyoglobin has limited ability to promote lipid oxidation and may protect ether phospholipids from oxidation. The analysis of the volatiles in the model revealed that heme proteins and their derivatives have the ability to induce the production of key aroma compounds. The descending order of effectiveness in inducing the production of aroma compounds is as follows: hemoglobin, myoglobin, hemin, and nitrosylmyoglobin. The effectiveness of Fe2+ and Fe3+ is similar to that of nitrosylmyoglobin.

Repackaging Nitrite-Embedded Dark-Cutting Steak in Aerobic Polyvinyl Chloride Film Decreases Surface Redness

The overall goal was to evaluate the effects of repackaging nitrite-embedded dark-cutting steaks in polyvinylchloride (PVC) film on surface color. Dark-cutting beef strip loins (n = 8; pH = 6.39) and USDA Low Choice beef strip loins (USDA Choice, n = 6; pH = 5.56) were selected at a commercial packing plant. Dark-cutting loins were bisected and randomly assigned to nonenhanced dark-cutting and enhanced dark-cutting with glucono delta-lactone and rosemary treatments. USDA Choice and nonenhanced dark-cutting steaks were vacuum packaged (VP) and served as controls, whereas enhanced dark-cutting steaks were packed in nitrite-embedded packaging (NP). Steaks from nonenhanced USDA Choice VP, nonenhanced dark-cutting VP, and enhanced dark-cutting NP loins were randomly assigned to 3, 6, or 9 d of dark storage.Following dark storage, steaks were repackaged in PVC and displayed for 6 d at 2°C. Instrumental color, visual color, and aerobic plate count were evaluated for all steaks. Enhanced dark-cutting steaks in NP increased (P < 0.05) a* values compared with USDA Choice and nonenhanced dark-cutting VP during 24 h of dark storage. Enhanced dark-cutting steaks packaged in NP had greater a* and L* values (P < 0.05) than nonenhanced dark-cutting VP steaks during dark storage. Upon repackaging the enhanced dark-cutting steaks from NP, nitric oxide myoglobin decreased (P < 0.05) during the first 12 h of display. Loss of nitric oxide myoglobin corresponds with a darker red appearance, increased surface discoloration, and decreased a* values.There were no differences (P > 0.05) in aerobic plate count between enhanced dark-cutting NP steaks and nonenhanced dark-cutting VP steaks after repackaging. In conclusion, NP improved surface redness; however, repackaging enhanced dark-cutting from NP steaks in PVC decreased color stability and redness of dark-cutting beef.

The Use of the Mixed Bacteria Limosilactobacillus fermentum and Staphylococcus carnosus in the Meat Curing Process with a Reduced Amount of Sodium Nitrite

The aim of the research was to estimate the possibility of using mixed bacteria cultures consisting of Lactobacillus fermentum S8 and Staphylococcus carnosus ATCC 51365 in the meat curing process with a reduced amount of sodium nitrite and to study the effect of bacteria on residual nitrites and nitrates, nitrosyl pigments content, colour, pH, redox potential, microbiologic, and the sensory quality of a cooked meat product. The study was performed on heat treated three-model meat treatments in cans: (C) a control treatment with NaNO2 at 100 mg/kg, (M) a treatment with NaNO2 at 50 mg/kg and (SL) a treatment with NaNO2 at 50 mg/kg and L. fermentum S8 at about 107 cfu/g and S. carnosus ATCC 51365 at about of 107 cfu/g. The research was performed after production and after cold storage. It was shown that using a mixed bacteria culture for meat curing had an influence (p < 0.05) on reducing nitrite and nitrate levels and increasing the amount of nitrosyl pigments in the SL treatment compared to the M treatment. Applying mixed bacteria in curing meat with NaNO2 at 50 mg/kg allowed for obtaining a higher redness in the cooked meat product after production, storage and exposure to light than in the product cured with NaNO2 at 100 mg/kg, with similar sensory and microbiological quality in both products.

Shelf-life Reduction as an Emerging Problem in Cooked Hams Underlines the Need for Improved Preservation Strategies

Cooked hams have gained an important position within the delicatessen market. Nowadays, consumers not only demand superior sensory properties but also request low levels of sodium and fat and the absence of conventional chemicals and preservatives used for the increase of the technological yield and shelf-life of the products. As a result, products that apply strict quality certificates or ''clean'' labels become increasingly important. However, such cooked hams suffer from a limited shelf-life. Besides some physicochemical effects, this is mainly due to microbial impact, despite the application of modified-atmosphere-packaging and chilling. Microbial spoilage is mostly due to the metabolic manifestation of lactic acid bacteria and Brochothrix thermosphacta, although Enterobacteriaceae and yeasts may occur too. Several preservation strategies have been developed to prolong the shelf-life of such vulnerable cooked meat products by targeting the microbial communities, with different rates of success. Whereas high-pressure treatments do not always pose a straightforward solution, a promising strategy relates to the use of bioprotective cultures containing lactic acid bacteria. The latter consist of strains that are deliberately added to the ham to outcompete undesirable microorganisms. Spoilage problems seem, however, to be specific for each product and processing line, underlining the importance of tailor-made solutions.