Rapid detection of tertiary butylated hydroquinone in food samples using Mn-MOF@f-CNF composite-modified screen-printed electrode.

Hydroquinone-based organic molecules are often used as unavoidable preservatives in the food industry. Among these additives, tertiary butylated hydroquinone (TBHQ) is widely employed as a preservative in various processed foods. However, the potential health risks associated with the excessive presence of TBHQ in food products have raised significant concerns. To address this pressing issuea novel binder-free composite composed of a manganese metal-organic framework and functionalized carbon nanofibers (Mn-MOF/f-CNF) has been developed as an electrode modifier for the ultrasensitive detection of TBHQ in food samples. The Mn-MOF/f-CNF composite was achieved using the ultrasonication method, revealing a lamellar sheet-like structure of the Mn-MOF and the curly thread-like fibrous structure of f-CNF. The developed Mn-MOF/f-CNF/SPE sensor system resulted in well-defined redox signals for TBHQ detection in a neutral pH solution. Compared to the unmodified SPE system, the modified system showed approximately a 300 mV reduction in overpotential and a twofold increase in peak current signal for TBHQ detection. The Mn-MOF/f-CNF/SPE sensor system showed a linear concentration window of 0.01 to 800 µM with a sensitivity of 6.28 µA µM-1 cm-2 and the obtained detection limit was 1.36 nM. Additionally, the proposed sensor displayed excellent reproducibility and repeatable results with an RSD of less than 5%. The real-time applicability of the Mn-MOF/f-CNF/SPE sensor system was demonstrated using real samples such as potato chips and instant noodles, showing excellent results with a recovery range of 95.1-98.5%.

Research progress on natural preservatives of meat and meat products: classifications, mechanisms and applications.

Meat and meat products are highly susceptible to contamination by microorganisms and foodborne pathogens, which cause serious economic losses and health hazards. The large consumption and waste of meat and meat products means that there is a need for safe and effective preservation methods. Furthermore, toxicological aspects of chemical preservation techniques related to major health problems have sparked controversies and have prompted consumers and producers to turn to natural preservatives. Consequently, natural preservatives are being increasingly used to ensure the safety and quality of meat products as a result of customer preferences and biological efficacy. However, information on the current status of these preservatives is scattered and a comprehensive review is lacking. Here, we review current knowledge on the classification, mechanisms of natural preservatives and their applications in the preservation of meat and meat products, and also discuss the potential of natural preservatives to improve the safety of meat and meat products. The current status and the current research gaps in the extraction, application and controlled-release of natural antibacterial agents for meat preservation are also discussed in detail. This review may be useful to the development of efficient food preservation techniques in the meat industry. © 2024 Society of Chemical Industry.

Phenolic compounds in Nordic berry species and their application as potential natural food preservatives.

An increasing demand for natural food preservatives is raised by consumers. For Nordic berry species, abundance of phenolic compounds and potent activities of anti-oxidation and anti-bacteria enables a great potential as food preservatives. This review provides a systematic examination of current literature on phenolic profiles, anti-oxidative and anti-bacterial activities of various extracts of Nordic berry species, as well as the impact of various structure features of phenolics on the bioactivities. Special attention is placed on exploitation of leaves of berry species and pomaces after juice-pressing as side-streams of berry production and processing. The current progress and challenges in application of Nordic berry species as food preservatives are discussed. To fully explore the potential application of Nordic berry species in food industry and especially to valorize the side-streams of berry cultivation (leaves) and juice-pressing industry (pomaces), it is crucial to obtain extracts and fractions with targeted phenolic composition, which have high food preserving efficacy and minimal impact on sensory qualities of food products.

A Novel Strategy Based on Permanent Protein Modifications Induced by Formaldehyde for Food Safety Analysis.

The illegal additions of chemicals in food products are serious incidents threatening current public safety. To date, ideal methods to determine permanent traces of prohibited chemicals in foods are still lacking. For example, formaldehyde (FA) can be added illegally as a food preservative. However, most current methods that are dependent on the direct detection of FA are not able to determine if FA has ever been added once food products are rinsed completely. Herein, we present a novel approach relying upon protein modifications induced by FA (PMIF) to examine FA in foods. We reveal the entire catalog of PMIFs in food products by combining mass spectrometry analysis with unrestrictive identification of protein modifications. Consequently, four obvious PMIFs were identified and confirmed as markers to discriminate the addition of FA in foods. Our study demonstrates that the approach based on PMIFs enables detecting the imprinted trace of FA even if the food products have been washed thoroughly. Our work presents a novel strategy for analysis of chemical additives, offering broad potential applications in protein analysis and food safety.

Effect of calcium hydroxide mixed with preservatives on physicochemical characteristics and sensory shelf-life of corn tortilla.

BACKGROUND: The objective of the study was to evaluate the physicochemical characteristics and shelf-life of corn tortilla stored at room temperature (25 °C) using aw modifiers (propylene glycol and glycerol) and pH modifiers (fumaric acid and sodium benzoate) as preservatives combined with calcium hydroxide. Detection thresholds were used to determine the maximum preservative concentration and calcium hydroxide. Physicochemical characterization and sensory evaluation were used to determine the stability and sensory shelf-life of tortillas. RESULTS: Control, calcium hydroxide, calcium hydroxide + fumaric acid, calcium hydroxide + glycerol, calcium hydroxide + propylene glycol, and calcium hydroxide + sodium benzoate treatments had rounded half-lives of 1, 2, 1, 2, 2, and 2 days respectively. Glycerol combined with calcium hydroxide resulted in tortillas with lower pH variations over time. Mold presence was the critical attribute causing tortilla rejection. CONCLUSION: The use of aw modifiers had a better effect in preserving corn tortilla, as the concentration of pH modifiers at detection threshold levels was not able to reach an optimum performance when combined with calcium hydroxide. © 2021 Society of Chemical Industry.

Antioxidant activity of purslane extract and its inhibitory effect on the lipid and protein oxidation of rabbit meat patties during chilled storage.

BACKGROUND: Currently, synthetic antioxidants have been widely used to retard lipid and protein oxidation in the meat industry. However, consumers have concerns about these synthetic antioxidants because of their potential toxicological effects. Accordingly, natural antioxidants can be used as a result of their health safety compared to synthetic antioxidants. The present research aimed to assess the protective effects of purslane (Portulaca oleracea L.) extract (PE) against lipid and protein oxidation under chilled storage for 12 days. Rabbit meat patties were divided into five experimental groups: control (without extract), butylated hydroxytoluene BHT (with 0.02% BHT, w/w) and the different concentrations of PE (0.1%, 0.3% and 0.5%, w/w) added to rabbit meat patty labeled as 0.1% PE, 0.3% PE and 0.5% PE groups, respectively. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, lipid oxidation and protein oxidation were determined, and kinetic models were employed. RESULTS: PE showed the strongest DPPH and ABTS radical scavenging activity, and the half maximal inhibitory concentrations (i.e. IC50 ) of DPPH and ABTS radicals were 5.112 ± 0.384 and 12.607 ± 2.130 µg mL-1 , respectively. Samples that were treated with PE showed low lipid and protein oxidation. Furthermore, the results of kinetic models indicated that PE could reduce the rates of lipid and protein oxidation. CONCLUSION: PE showed a preservative effect with respect exerting a protective effect against lipid and protein oxidation under chilled storage conditions. Our findings demonstrate the strong potential of PE as a natural antioxidant in meat and meat products. © 2020 Society of Chemical Industry.

Influence of epicatechin on oxidation-induced physicochemical and digestibility changes in porcine myofibrillar proteins during refrigerated storage.

BACKGROUND: The influence of epicatechin (EC) on the physicochemical properties and digestibility changes of porcine myofibrillar protein (MP) under oxidative stress during refrigerated storage was investigated. RESULTS: The incubation of MP suspensions (20 mg mL-1 in piperazine-N,N'-bis(2-ethanesulfonic acid) buffer, with 0.6 mol L-1 sodium chloride, pH 6.25) at 4 °C for 24 h under an iron-catalyzed hydroxyl radical generating system (Fenton reaction) promoted the formation of thiobarbituric acid reactive substances and protein carbonyls, which was attenuated by EC (5, 50, and 100 µmol g-1 protein). Reduced protein sulfhydryl content, tryptophan fluorescence, protein solubility, as well as increased surface hydrophobicity were found by the co-incubation of EC. Analysis by scanning electron microscopy revealed increased protein aggregation and fragments in oxidized MP, which were further enhanced by the addition of EC. However, the protein digestibility of MP was not affected. CONCLUSION: EC was demonstrated to be effective in alleviating lipid oxidation and protein carbonylation in MP under oxidative stress. Additionally, the physicochemical and digestibility changes accompanying the incorporation of EC was complicated due to the possible phenol-protein interactions. An in-depth understanding of protein physicochemical and digestibility changes will be helpful in the application of polyphenolic compounds as antioxidants in low-temperature-processed muscle foods. © 2020 Society of Chemical Industry.

Orthogonal Hyphenation of Planar and Liquid Chromatography for Mass Spectrometry of Biomarkers out of the Bioassay Matrix (NP-HPTLC-UV/vis/FLD-Bioassay-RP/IEX-HPLC-UV/vis-ESI-MS).

Bioprofiling on the planar chromatogram with in situ biological/enzymatic assays is a powerful bioanalytical screening tool for the nontargeted detection of known and especially unknown/unidentified bioactive compounds directly in multicomponent mixtures (e.g., foods, spices, and botanicals). However, together with the bioactive zone, the adsorbed bioassay medium is eluted into the mass spectrometer (MS) and interfering with evaluation. Another sample track without bioassay has thus been handled in parallel. Hence, for a direct zone elution from the bioautogram, different setups were investigated to reduce the impact of the bioassay medium load. A biocompatible filter, orthogonal reversed-phase/cation-exchange columns (RP/IEX-HPLC), UV/vis detector, and a Rheodyne valve were installed between the zone eluting interface (after normal-phase high-performance thin-layer chromatography-multi-imaging-bioassay, NP-HPTLC-UV/vis/FLD-bioassay) and the MS. For the negative electrospray ionization mode (ESI-), an RP-18e-HPLC column and valve switch were exploited. After gradient optimization, the RP-column retarded the eluted polar compounds and split-off the salts of the bioassay medium in the first minutes. This reduced the bioassay load and separated analyte signals thereof. However, most bioassay medium mass signals were predominantly detectable in ESI+-MS. Here, the reduction of bioassay matrix signals was achieved by integrating a mixed-mode RP/IEX column. Finally, two different superhyphenations were successfully proven: NP-HPLC-UV/vis/FLD-bioassay-RP-HPLC-UV/vis-ESI--MS with a valve switch and NP-HPLC-UV/vis/FLD-bioassay-RP/IEX-HPLC-UV/vis-ESI±-MS with or without it. Although the original bioprofiling (NP-HPTLC-UV/vis/FLD-bioassay) was prolonged from 3 to 13 min per sample, such superhyphenations covering chemistry/biology/mass spectrometry are considered as an efficient nontarget bioanalytical tool for fast evaluation of complex samples.

Pomegranate Peel as Suitable Source of High-Added Value Bioactives: Tailored Functionalized Meat Products.

In the last few years, the consumer's concern with the relationship between health and diet has led to the search of foods with functional properties beyond the nutritional. In this framework, the consumption of pomegranate has increased due to their sensorial attributes and remarkable amounts of bioactive compounds, which generate, at the same time, huge amounts of by-products. A search in the Scopus database for the last 10 years has revealed the rising interest in pomegranate peel (PP), the main residue from this fruit. The meat industry is a food sector that has had to search for new alternatives to substitute the use of synthetic preservatives by new natural additives, to extend the self-life and keep the quality attributes of their processed products. This review sets out the main bioactivities of PP extracts, and their incorporation in meat products is elaborated. PP is a good source of bioactive compounds, including phenolic acids, flavonoids and hydrolyzable tannins, which have beneficial health effects. It can be concluded that the reformulation of meat products with PP extracts is a suitable strategy for enhancing their technological characteristics, in addition to conferring functional properties that make them healthier and potentially more acceptable for the consumer.

Development of a capillary zone electrophoresis method to determine natamycin in food and a comparison with a liquid chromatography method.

BACKGROUND: Natamycin is often added to pastries, cheeses, and beverages. The residual amount of natamycin should be less than 10 mg kg-1 . The current method for its determination in various foodstuffs is high-performance liquid chromatography (HPLC). Capillary electrophoresis (CE) is a simple, fast, and environmentally friendly method with low reagent consumption and comparable separation performance. However, no reports were found on the determination of natamycin in foods by CE. A CE method to determine natamycin is therefore sought. RESULTS: Natamycin in foods was determined by the capillary zone electrophoresis (CZE) method with ultraviolet-visible (UV) detection. Separation conditions were optimized as 20 mM Na2 HPO4 , pH 9.2, with 25 kV applied voltage, and UV detection at 306 nm. Under optimal conditions, electrophoretic analysis was completed in less than 4 min, with a limit of detection (LOD) of 0.065 µg mL-1 and limit of quantitation (LOQ) of 0.22 µg mL-1 . A good linear relationship (r2 = 0.999) was obtained at the range of 0.1-25 µg mL-1 . A comparison with the HPLC-UV method was also carried out according to the National Standards of the People's Republic of China. CONCLUSION: The results obtained by the CZE and HPLC methods are comparable but the proposed CZE method can help us obtain a shorter detection time at low cost. © 2019 Society of Chemical Industry.

Effects of active edible coating based on thyme and garlic essential oils on lamb meat shelf life after long-term frozen storage.

BACKGROUND: The frozen preservation of lamb meat could be crucial for successful international trade. The shelf life of thawed meat is shorter than that of fresh meat, so techniques or procedures are required to improve post-thawing meat quality attributes. This study investigated the effect of alginate-based edible coatings after the incorporation of essential oils of thyme (Thymus vulgaris L.) and garlic (Allium sativum L.) on thawed lamb meat (longissimus thoracis et lumborum muscle) quality after long-term frozen storage. Meat samples came from ten light lambs and the evolution of attributes related to shelf life, such as water-holding capacity, color stability, and lipid oxidation, was monitored during display (1, 4 and 7 days). Four meat treatments were evaluated: control (CON, uncoated meat), edible coat of alginate meat (ECA), and ECA with thyme or garlic essential oils (0.05%) (THY and GAR). RESULTS: The alginate-based edible coatings decreased exudative losses (P < 0.001) and modified color characteristics, especially increasing yellowness (P < 0.001) and chrome (P < 0.001). GAR decreased redness (P < 0.001) and the oxy/met ratio [R (630/580) wavelength light reflectance] or discoloration [R (630-580)]. THY was the treatment that best retained color during display and also showed a significantly lower lipid oxidation (P < 0.05) than CON and ECA, whereas GAR presented intermediate values. CONCLUSION: The addition of bioactive essential oils to alginate-based edible coatings improved preservation and shelf life of lamb meat after thawing. © 2019 Society of Chemical Industry.

A new advanced packaging system for extending the shelf life of refrigerated farmed fish fillets.

BACKGROUND: An innovative pilot-plant packaging was developed and evaluated for applying oregano essential oil (OEO) vapours in conditions of high vacuum for exploring the antimicrobial effect of essential oil vapours applied immediately before packaging of fish fillets. Farmed sea bream (Sparus aurata) fresh fillets have been used as a model for validating this new technology. These fillets, as a refrigerated product under modified atmosphere packaging (MAP), have a relatively short shelf life (12-14 days) mainly due to the fast microbial growth. The effects of conventional OEO dippings [pretreatment dipping (0.1% of OEO) of whole fish (T1) and filleted sea bream (T2)] were compared with the OEO application in vapour phase (67 µL L-1 ) under vacuum (5-10 hPa) immediately before MAP fillet packaging (T3). RESULTS: T3/T2 samples showed the lowest microbial growth after 28 days at 4 °C, with loads up to 1/2.6 log units for Enterobacteria/lactic acid bacteria compared to untreated samples. The initial trimethylamine nitrogen (TMA-N) content (2.6 mg kg-1 ) increased in T1 and T2/T3 samples by 9.6 and 6/7 units, respectively, after 28 days. Quality Index Method (QIM) better reflected the fish fillets shelf life than texture and colour measurements. The shelf life of T3/T2 samples was established in at least 28 days (4 °C), while the QIM threshold (6) was exceeded after 7/21 days in untreated/T1 fillets. CONCLUSION: The fish shelf life was extended with vapour OEO treatment using this new technology, similarly to OEO dipping treatment, according to QIM, corroborated by the microbial quality and TMA-N contents. © 2020 Society of Chemical Industry.

The Association between the Preservative Agents in Foods and the Risk of Breast Cancer.

In the etiology of breast malignancy, dietary habits and lifestyle-related risk factors in the coherence of cancer prevention guidelines, e.g., WCRF/AICR is well documented. In addition, the consumption of staple food products rich in carbohydrate as major calorie resources such as potato, bread, and ready-to-eat cereals are partly object to having roles in breast tumorigenesis. In this review, the possible associations of preservatives and nutritive risk factors of staple foods in dietary patterns with breast cancer development based on the experimental and observational cohort-based studies were discussed. In this regard, the influence kinetics of insulin, insulin-like growth factor-1, and insulin-activated AMPK/Akt pathway on sorts of starch and protein is a concerning biologic concept in promoting the risk of tumorigenesis. Hence, Akt-dependent controlled proliferation, induced apoptosis, and controlled oxidative stress in specific condition could be concentrated as the preventive strategies. Although preservatives such as sorbate, benzoate, and nitrate are considered Generally Recognized as Safe, there are some issues concerning the safety of their applications, including the possibility of allergies and immunosuppressive effects from benzoate, the formation of carcinogenic nitrosamines from nitrites, and interaction sorbate with nitrite in the stomach which consequently can be resulted in the production of a series of genotoxic compounds.

Effects of sodium alginate-based coating pretreatment on drying characteristics and quality of heat pump dried scallop adductors.

BACKGROUND: Drying efficiency and quality maintenance are the major concerns of both manufactures and consumers. Heat pump drying (HPD) is suitable for heat sensitive foodstuffs due to its ability to independently control the drying operation parameters. However, lower drying rate and energy efficiency in the later period of HPD are the bottlenecks that restrain its application. A novel approach using hydrocolloids as pretreatment coatings prior to drying was designed to solve these problems. The effects of sodium alginate (SA) coating, drying temperatures and air velocities on the drying characteristics and quality attributes of scallop adductors were evaluated. RESULTS: Drying took place in the falling rate period. Drying time decreased with increasing temperature, air velocity and SA coating. The Two Term model and the Wang and Singh model gained the best fit for thin-layer drying of scallop adductors and SA film, respectively. Effective moisture diffusivity increased with temperature, velocity and SA coating and were in the range 7.352-14.620 × 10-11 , 9.890-17.100 × 10-11 and 2.348-4.604 × 10-10  m2  s-1 for uncoated scallop adductors, SA coated scallop adductors and SA films, respectively. The activation energies for SA films, coated and uncoated scallop adductors were 17.07, 20.78 and 26.17 kJ mol-1 , respectively. Dried scallop adductors with SA coating pretreatment exhibited a significant lower value of shrinkage rate and hardness, and higher value of toughness than uncoated ones at 30 °C and 2.0 m s-1 (P < 0.05). CONCLUSION: Hydrocolloid coating is a promising pretreatment in improving HPD efficiency and enhancing quality attributes of dried scallop adductors. © 2019 Society of Chemical Industry.

Effects of edible coating containing nano-emulsion of Aloe vera and eugenol on the physicochemical properties of shrimp during cold storage.

BACKGROUND: Shrimp is nowadays recognized as a rich source of proteins and omega-3 fatty acids. Edible nano-emulsion coatings containing eugenol, as an antioxidant agent, and Aloe vera, as a functional compound, were prepared for the storage of pink shrimp over 7 days at 277 K. Samples of the nano-emulsion were prepared under ultrasonication using 0, 10 and 20 g L-1 of Aloe vera as well as 0, 15 and 30 mL L-1 of eugenol along with Tween 80. RESULTS: Results indicated that the low pH of Aloe vera reduced that of the nano-emulsions while the particle size and turbidity increased with increasing Aloe vera concentration. Moreover, both colour and antioxidant activity of the nano-emulsions were significantly affected by eugenol and Aloe vera concentrations (p < 0.05). Increasing eugenol concentration led to increased nano-emulsion pickup but to reduced lightness. Higher concentrations of Aloe vera significantly (p < 0.05) decreased drip loss, cooking loss, pH rise and oxidation rates but enhanced hardness in the shrimp samples. CONCLUSIONS: The best results were recorded for the nano-emulsion coating containing 30 mL L-1 of eugenol and 20 g L-1 of Aloe vera. The nano-emulsion was successfully able to upgrade shrimp quality over 7 days of cold storage. © 2019 Society of Chemical Industry.

Novel natural food preservatives and applications in seafood preservation: a review.

Food preservative additives are natural or synthetic substances which delay degradation in foods caused by microbial growth, enzyme activity, and oxidation. Until recently, the use of synthetic additives in food was more common. However, synthetic additives have not been widely accepted by consumers in recent years due to their assumed adverse effects on their health. Therefore, the tendency of consumers to natural additives is increasing day-by-day. Seafood is an easily perishable food due to its chemical composition. Immediately after harvest, changes in odor, taste, and texture in fishery products can be noticed. For this reason, measures to protect the product must be taken immediately after harvest or catching. Various preservation methods have been developed. In addition to various technological methods, preservative additives are used in fresh or processed seafood as well as in other foods. This review focuses on novel natural preservatives from different sources such as plants, bacteria, fungi, animals and algae, and their use in seafood to protect quality and prolong shelf life. © 2018 Society of Chemical Industry.

Effects of rosemary (Rosmarinus officinalis L.) extracts and dry ice on the physicochemical stability of omega-3 fatty-acid-fortified surimi-like meat products.

BACKGROUND: Lipid peroxidation entails major quality degradation in omega-3 (ω-3) fatty-acid-fortified surimi-like meat products upon storage. Currently, the use of label-friendly alternatives to synthetic antioxidants is encouraged in the industry. Hence, we aimed to examine the applicability of the hurdle-technology concept, using an 80% (v/v) ethanol solution to obtain rosemary extracts (REs) containing substantial amounts of polyphenol, and dry ice (DI) which can create a cryogenic environment, on the physicochemical stabilities of ω-3 fatty-acid (FA)-fortified meat products after manufacturing and storage periods. The polyphenolic profiles of the REs were also investigated. RESULTS: Carnosol and rosmarinic acid are major phenolic components in REs. Furthermore, DI addition during the chopping procedure increased (P < 0.05) whiteness values and hardness of products, while total ω-3 and ω-6 FAs were relatively well preserved (P < 0.05) in products with flaxseed oil premixed with RE. During 14-day storage at 4 °C, combined treatment with RE and DI decreased (P < 0.05) thiobarbituric acid reactive substance (TBARS) levels and the centrifugation loss of products. Single or combined treatment with RE and/or DI decreased (P < 0.05) TBARS levels in products after 60 days of storage at -20 °C. CONCLUSION: Due to the antioxidant-polyphenol profile of REs and a possible oxygen exclusion of DI treatment under atmospheric pressure during food manufacturing, application of the hurdle-technology concept, using treatment with both RE and DI, can reduce lipid peroxidation and maintain a greater water-holding capacity of ω-3 FA-fortified meat products upon storage. © 2019 Society of Chemical Industry.

Effectiveness of five flavored Tunisian olive oils on Anisakis larvae type 1: application of cinnamon and rosemary oil in industrial anchovy marinating process.

BACKGROUND: Anisakidosis is caused by the ingestion of raw or undercooked fish or cephalopods containing viable Anisakis larvae. Several natural extracts, oils, essential oils, and their compounds have been tested against Anisakis. In this study the effectiveness of Tunisian olive oil with different spices or plants (cardamom, cinnamon, ginger, laurel, and rosemary) was tested against Anisakis larvae type 1. RESULTS: For the in vitro test, larvae were submerged separately in the oils mentioned above and observed to check viability. Cinnamon oil was the most effective against parasites with lethal time (LT) scores being LT50 = 1.5 days and LT100 = 3 days, followed by rosemary. Laurel, cardamom, and ginger oils were less effective. For the ex vivo experiment, cinnamon, and rosemary oils were tested in anchovy fillets, previously artificially parasitized. Cinnamon was the most effective against parasites (dead after 4 days) as compared to rosemary (7 days). CONCLUSION: The use of cinnamon and rosemary-flavored olive oil in the industrial marinating process can be considered as an efficient alternative to the freezing process required by European Regulation EC No 853/2004 to devitalize Anisakis. © 2019 Society of Chemical Industry.

The inhibition mechanism of ϵ-polylysine against Bacillus cereus emerging in surimi gel during refrigerated storage.

BACKGROUND: Refrigeration is commonly used in the processing and storage of surimi products. However, refrigerated surimi products are susceptible to microbial contamination, which leads to deterioration of the products and shortens their shelf life. The aims of the present study were therefore to evaluate the effects of ϵ-polylysine (ϵ-PL) on spoilage bacteria in surimi products, and to investigate the antibacterial mechanism of Bacillus cereus, which is the dominant spoilage bacterium. RESULTS: ϵ-Polylysine with a high degree of polymerization (20-30K) proved able to decrease the total number of colonies in surimi products and showed an obvious antibacterial effect against B. cereus. After ϵ-PL treatments, the distinct broken areas on the bacterial surfaces and the aggregations of cells were observed by scanning electron microscope (SEM). The intracellular materials, such as small molecules, soluble proteins, and deoxyribonucleic acids in the cells were analyzed, which revealed the destructive effects of ϵ-PL on bacterial cells. Experiments with propidium iodide (PI) infiltration experiments verified that the permeability of cell membranes was enhanced by ϵ-PL treatment. CONCLUSION: These results indicated that ϵ-PL could destroy the cell membranes and change the permeability of B. cereus, and subsequently the cell contents leaked out to achieve antibacterial effects. © 2018 Society of Chemical Industry.

Sulfite-free lamb burger meat: antimicrobial and antioxidant properties of green tea and carvacrol.

BACKGROUND: Sulfite is commonly used to preserve lamb burger meat in the EU. Nevertheless, its consumption has been related to certain health problems, which has increased consumer demand for sulfite-free products. Natural compounds with antioxidant and antimicrobial properties may be a feasible alternative to preserve lamb burger meat. This study evaluated the antimicrobial and antioxidant properties of carvacrol, green tea and their combination in preserving lamb burger meat. Their effect was also compared with that of 400 ppm sulfite. RESULTS: Lamb burger meat was mixed with different concentrations of the extracts, packaged aerobically and displayed for 8 days at 4 °C. Total polyphenols, thiobarbituric acid reactive substances, colour, and microbial and sensory analyses were performed. Both green tea and carvacrol avoided lipid oxidation even at 300 ppm, while only carvacrol, which showed a concentration-dependent action, delayed discolouration and microbial growth. Carvacrol and green tea also limited the development of oxidation odour and flavour, but the former brought about herbal odours and flavours to the meat. On the other hand, sulfite provided a higher colour stability and lower microbial counts than both natural compounds but presented a higher lipid oxidation. CONCLUSION: Carvacrol seems to be a promising alternative to replace sulfite in lamb burger meat, whereas green tea should be combined with an antimicrobial agent. © 2018 Society of Chemical Industry.