Effects of reduced levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate on levels of volatile and biogenic amines

Sulphur dioxide (SO₂) is an important preservative for wine, but its presence in foods can cause allergies and this has given impetus to the research for alternatives. The aim of this study was to reduce levels of sulfite in wine production using mixtures with lysozyme and dimethyl dicarbonate and examine the influence on levels of volatile and biogenic amines. To do so, vinifications were carried out using lysozyme, dimethyl dicarbonate (DMDC) and mixtures of these with SO₂ in different concentrations (25 and 50 mg l^?1). Results were compared with a control vinification with only SO₂ (50 mg l^?1). Mixing low concentrations of SO₂ with lysozyme and DMDC reduced the concentration of biogenic amines (histamine, tyramine, putrescine, cadaverine, phenylethylamine + spermidine and spermine). In general, the total concentration of volatile amines (dimethylamine, isopropylamine, isobutylamine, pyrrolidine, ethylamine, diethylamine, amylamine and hexylamine) was higher in the sample fermented only with SO₂. The concentrations of amines with secondary amino groups (dimethylamine, diethylamine, pyrrolidine) were higher in the sample only fermented with SO₂ than those fermented with DMDC and lysozyme or with a mixture of preservatives. When SO₂ was the only preservative in wine, total amine concentration (biogenic and volatile amines) was higher than for the rest of the treatments. Lysozyme by itself, and lysozyme mixed with SO₂, both reduced the formation of biogenic amines but given the antioxidant activity of SO₂ the use of the preservative mixture seems more advisable.     

二甲基二碳酸盐用于鲜切胡萝卜杀菌的条件优化研究

应用响应面法优化了二甲基二碳酸盐(DMDC)用于鲜切胡萝卜杀菌的条件。运用统计软件Design-Expert8.0.5b中的Box-Behnken响应面设计,以DMDC浓度、料液比、杀菌时间为自变量,以杀灭的细菌总数的死亡数量级(Y1)和杀灭的霉菌和酵母菌总数的死亡数量级(Y2)为响应值,建立了DMDC杀菌的回归模型,并对其进行了实验验证;同时,利用模型的响应面对影响DMDC杀菌的关键环节及其相互作用进行了深入的探讨。实验得到优化后的杀菌条件参数为:DMDC浓度200mg/L、料液比1:3、杀菌时间2min,得到杀灭细菌和杀灭霉菌和酵母的优化实验结果为:Y1=3.515,Y2=2.632。     

Inactivation of different strains of Escherichia coli O157:H7 in various apple ciders treated with dimethyl dicarbonate (DMDC) and sulfur dioxide (SO2) as an alternative method

Escherichia coli has been identified as the causative agent in numerous foodborne illness outbreaks associated with the consumption of fresh apple cider. Apple cider has a pH which is normally below 4.0 and would not be considered a medium capable of supporting the growth of foodborne pathogens. The association of unpasteurized apple cider with foodborne illness due to E. coli O157:H7 has however, led to increased interest in potential alternative methods to produce pathogen free cider. Apple cider was prepared from eight different apple cultivars, inoculated with approximately 10⁶–10⁷ CFU of three strains of E. coli O157:H7 per ml (933, ATCC 43889, and ATCC 43895) and tested to determine the effectiveness of sulfur dioxide (SO₂) and dimethyl dicarbonate (DMDC). Bacterial populations for treated and untreated samples were then enumerated by using non-selective media. Eight different ciders were treated with DMDC (125 and 250 ppm) and SO₂ (25, 50, 75, 100 ppm). Greater than a 5-log reduction was achieved at room temperature with 250 ppm of DMDC and 50 ppm of SO₂ after the incubation time of 6 h and 24 h, respectively. Addition of DMDC and/or SO₂ may offer an inexpensive alternative to thermal pasteurization for the production of safe apple cider for small apple cider producers.     

Improvement of SO2 adsorption capacity of fiber web surface produced from continous graphene oxide fiber

Sulphur dioxide (SO₂) is an important atmospheric pollutant, and capture of SO₂ is of great importance for the environment, human health and market. Carbon based materials, especially activated carbon, are mostly used for adsorption purposes. However, there is a notable lack on adsorption of SO₂ on graphene oxide (GO) fibers and fiber web surface. In this study, the effect of addition of activated carbon, pH of GO dispersions, hydrazine reduction and oxygen/argon plasma treatment on SO₂ adsorption of GO fiber web surface were evaluated. It was seen that GO fiber web surface with activated carbon provides high SO₂ adsorption (896 mg SO₂/g) which is very higher than many of carbon based materials presented in the literatures. Single coagulation bath increases surface roughness of fiber and provides higher functional group than three coagulation baths leading to higher SO₂ adsorption capacity.     

Effect of alternative preservatives on the microbial quality, lipid stability and sensory evaluation of boerewors

Boerewors is a South African fresh sausage preserved with 450mg/kg sulphur dioxide (SO(2)). The preservative effects of rosemary (Ros; 260mg/kg) and chitosan (Chi; 10g/kg) were compared to SO(2). Eight boerewors models were formulated. Microbial, colour, lipid and sensory characteristics were evaluated. Chi and Chi in combination with other preservatives had a significant effect on reducing total bacterial, coliform and Enterobacteriaceae counts, comparable to SO(2). Chi, however, had a better effect on decreasing yeasts and mould counts than SO(2). Chi showed good colour properties comparable to SO(2). Ros showed comparable lipid stability to SO(2) but better when compared to Chi. Ros had a better effect on the sensory taste when compared to Chi, but SO(2) was still preferred. Reduced levels of 100mg/kg SO(2) showed good antimicrobial and colour effects in combination with Chi and in combination with Ros as antioxidant and improving the sensory properties. Alternative preservatives can be used to reduce the SO(2) content of boerewors.     

Change of polyphenol oxidase activity, color, and browning degree during storage of cloudy apple juice treated by supercritical carbon dioxide

The effects of supercritical carbon dioxide (SCCO₂) treatment of 8, 15, 22, and 30 MPa for 60 min at 55 °C on polyphenol oxidase (PPO) activity, color, and browning degree in cloudy apple juice during storage at 4 °C for 4-weeks were investigated. The SCCO₂ treatment had significant effects on inactivation of PPO and the least residual activity of PPO was 38.50% at 30 MPa. The restoration of PPO residual activity after SCCO₂ treatment was also observed, which was dependent on the pressure level. A greater reduction of lightness L and a minor increase of redness a of cloudy apple juices after SCCO₂ treatment occurred. Moreover, the total color difference (ΔE), which was significantly less than that of untreated sample, was decreased by enhancing the pressure level. The changes of lightness L and browning degree A during storage were well fitted to a first-order kinetic model. The rate constants of k _L and k _A of samples subjected to SCCO₂ treatment reduced from 4.75×10⁻² to 0.42×10⁻² and 37.19×10⁻² to 8.02×10⁻², respectively, when pressure increased from 0 MPa (untreated sample) to 30 MPa.     

Pre-fermentative replacement of sulphur dioxide by lysozyme and oenological tannins: Effect on the formation and evolution of volatile compounds during the bottle storage of white wines

In this work, the effects on the volatile profile of the pre-fermentative substitution of SO₂ with lysozyme and oenological tannins were studied in white wines. At the same time, in order to understand the changes of volatile compounds in SO₂-free wines, the evolution of volatiles was evaluated over 1 year of storage in bottles. For this purpose, a number of laboratory scale fermentations of SauvignonBlanc musts were carried out and the effects of three variables (SO₂, lysozyme and oenological tannins) were investigated by means of GC–MS analysis. Results showed that the replacement of SO₂ with lysozyme and oenological tannins influenced the volatile composition of wines at the end of the alcoholic fermentation. Wines fermented with SO₂ showed higher total alcohol amounts, while the presence of oenological tannins augmented the level of esters. The presence of SO₂ influenced also the alcohols and esters profiles of wines during bottle storage. Moreover, the presence of oenological tannins displayed a positive role in maintaining the amounts of esters over certain levels in wine stored for 1 year, likely due to their oxygen scavenging ability. By contrast, acids were less affected by the investigated adjuvants both at the end of the alcoholic fermentation and during the storage time.     

粮仓储粮霉变CO2法监测值主要影响因素

利用检测粮堆二氧化碳(CO_2)浓度变化的方法对储粮霉变进行监测,但该方法为间接测定,需对影响粮堆CO_2检测值的粮堆相关因素及传感器相关参数进行全面分析。试验结果表明,不同温度下储粮中霉菌生长早期阶段的霉菌增长量均与CO_2浓度变化同步,两者相关性系数0.99;较低的温度可使霉菌生长产气量显著降低,在霉菌生长量相当的状态下,30℃比20℃条件下测得的粮堆CO_2浓度值高4.7倍。粮食颗粒间空隙度等多种因素均可显著影响CO_2气体扩散,稻谷粮堆比小麦粮堆的孔隙度高约30%,稻谷粮堆在相距CO_2发生源50cm的监测点比小麦粮堆测得的峰值浓度高50%,峰值时间提前4d。对粮堆不同深度发生的霉变(距粮面1,2m),监测点设在粮面下3m可减少外界气体交换的影响,监测效果优于深度为1m的监测点。CO_2气体检测过程中,高的取样气流速度可显著降低检测值;对于各种规格的输气管道,适宜的检测气体取样量为管道内部理论体积的1.5倍。通过合理设定参数,CO_2法可灵敏地监测储粮霉菌活动。     

Inactivation and reactivation of horseradish peroxidase treated with supercritical carbon dioxide

Effects of supercritical carbon dioxide (SCCO₂) on the activity of horseradish peroxidase (HRP) in pH 5.6 acetate buffer solution were investigated. SCCO₂ treatment could effectively inactivate HRP. Higher pressure, higher temperature, and longer treatment time caused more inactivation. The maximum reduction of HRP activity reached nearly 90% at 30 MPa and 55 °C for 60 min. Analysis of first-order reaction kinetic data (characterized by a rate constant k and by a decimal reduction time D) showed that D value was closely related to the pressure and temperature of SCCO₂ treatment. Higher pressures or higher temperatures resulted in lower D values (higher k), the D value of HRP was minimized to 64.52 min treated by the combination of 30 MPa and 55 °C. The Z _p, representing the range of applied pressure between which the D values change by a factor of 10, was 114.81 MPa. The activity of HRP treated by SCCO₂ was reactivated significantly after initial 7-day storage at 4 °C apart from the samples at 30 MPa for 60 min, indicating the HRP inactivation may be reversible and the reactivation of HRP is dependent on the pressure level and treatment time.     

Fermentation of sulphite-free white musts with added lysozyme and oenological tannins: Nitrogen consumption and biogenic amines composition of final wines

The influence on amino acid consumption and biogenic amines composition of white wines obtained by replacing SO₂ during fermentation with lysozyme and tannins was studied. At the same time, the fermentative performance of two low SO₂ producing selected yeasts strains was evaluated. For this purpose, a series of laboratory-scale fermentations of fresh white must and a HPLC-DAD method for the analysis of amino acids, biogenic amines and ammonium ion were undertaken. The presence of SO₂ or lysozyme affected the consumption of nitrogen as a function of the yeast strain, while oenological tannin had no substantial influence. Strain 1042 increased the consumption of total YAN in the presence of SO₂, as a consequence of the enhanced utilization of ammonium ion and a number of amino acids. By contrast, strain 333 tended not to change the total YAN uptake, whatever the juice treatment, and reduced the consumption of aspartic and glutamic acids, GABA and other compounds in the case of samples added with SO₂. When compared with lysozyme addition, for both strains, SO₂ increased the consumption of alanine and glutamine, the latter being a major contributor to the assimilable nitrogen of the must. No influence of must treatments was found on the content of biogenic amines in the final wines.     

Changes in microorganism, enzyme, aroma of hami melon (Cucumis melo L.) juice treated with dense phase carbon dioxide and stored at 4 °C

The effects of dense phase carbon dioxide (DP-CO₂) treatment of 8, 15, 22, 30 and 35 MPa for 5 min, 15 min, 30 min, 45 min, 60 min at 35 °C, 45 °C, 55 °C, 65 °C on microorganism, enzyme, and aroma compounds in hami melon juice during storage at 4 °C for 4-weeks were investigated. Meanwhile, the color, browning degree, and Vitamin C were also studied. The DP-CO₂ treatment had significant effects on inactivation of microorganism and enzyme. It was indicated that higher pressure caused more inactivation of microbial total count and enzyme activity. When it reached 35 Mpa, 55 °C, 60 min, the microorganism was totally inactivated. The least residual activity of polyphenol oxidase (PPO), peroxidase (POD), and lipoxygenase (LOX) was 25.26%, 38.46 and 0.02% at 35MP, respectively. The restoration of PPO, POD and LOX residual activity after DP-CO₂ treatment was also observed, which was dependent on the pressure level. The aroma compounds were less affected after being treated with DP-CO₂, and the flavor of the melon juice was close to the fresh juice after storage at 4 °C for 4 weeks and did not produced cook off-odor. The changes of lightness L and browning degree A during storage were well fitted to a first-order kinetic model. The Vitamin C concentration decreased by DP-CO₂ processing, but this loss was lower than of the untreated sample.

Industrial relevance

Hami melon is highly appreciated for its nutritional quality and special flavor. The flesh of melon is heat sensitive, the sensitive nutrients, color and aromatic profile will be spoiled greatly or off-odour when it was produced with high temperature treatment. Dense phase carbon dioxide processing (DP-CO₂) is important to find an innovative food process to inactivate the enzyme and microorganism and protect the nutrient and unique flavor. In this study, the data proved that DP-CO₂ processing is a promising non-thermal alternative pasteurization to preserved fresh-squeezed melon juice.     

Effect of stunning systems on meat quality of Manchego suckling lamb packed under modified atmospheres

The effects of the type of stunning (TS) [electrically vs. gas] and packing in modified atmospheres (MA) [MA-A: 30% CO₂/70% O₂; MA-B: 30% CO₂/69.3% N₂/0.7% CO; MA-C: 40% CO₂/60% N₂] on meat quality (pH), drip losses (DL), water holding capacity (WHC), shear force (SF) and instrumental colour (L^∗, and C^∗chroma) of suckling lamb of the Spanish Manchego breed at 7, 14 and 21 d post-packing was studied. Acceptance of meat samples (on the basis of colour and odour) was determined. In general neither the TS nor the MA affected the pH values. Meat from the gas stunned lambs had the lowest DL (P < 0.001 at 14 d post-packing), but lower WHC (more water expelled; P < 0.01 at 14 and 21 d post-packing), was more tender (P < 0.01) and had higher L^∗ (P < 0.001 at 14 d post-packing) and C^∗ values (P < 0.001) than the electrically stunned group. Similar values of WHC and SF were observed for all MA types but the use of CO in the packs (MA-B) caused less DL, gave the highest C^∗ values, acceptability and colour stability with time of storage.     

吹扫捕集气相色谱法测定粮食中熏蒸剂氰与氰化氢残留量

采用吹扫捕集气相色谱法建立了熏蒸剂氰和氰化氢在粮食(玉米、高粱、稻谷、小麦和大麦)中的分析方法,对粮食中氰和氰化氢预处理的吹扫温度、吹扫载气(N2)流量和吹扫时间等参数进行了优化,分析了吹扫捕集气相色谱测定的回收率、精密度、检出限和定量限等质量控制参数,并测定了实际熏蒸粮食中氰及其降解产物氰化氢残留量.结果表明,用50％磷酸溶液作溶剂,吹扫温度80℃、吹扫载气(N2)流量40 mL/min和吹扫时间90 rain为最佳的吹扫方法参数.采用该方法测定粮食中氰和氰化氢的加标回收率分别为90.88％～96.25％和91.17％～95.83％,相对标准偏差(RSD)分别为0.36％～5.55％和0.90％～6.24％(n=6),检出限(LOD)分别为0.003 6 mg/kg和0.005 3 mg/kg(S/N=3),定量限(LOQ)分别为0.012 0 mg/kg和0.017 7mg/kg (S/N=10).用吹扫捕集法检测熏蒸粮食中氰其降解产物氰化氢的残留量与溶剂顶空法测定结果相一致.     

Enrichment of tocopherols in modified soy deodorizer distillate using supercritical carbon dioxide extraction

Supercritical carbon dioxide (SC-CO₂) extraction of chemically modified Soy Deodorizer Distillate (DOD) at three levels of pressure (180–300 bar) and temperature (40–60 °C) to optimize the conditions for enrichment of tocopherols in the raffinate was carried out. After modification, soy DOD contained about 90% of fatty acid methyl esters (FAME), showed improved solubility in SC-CO₂, and better extraction rate. Since fatty acid methyl esters are more volatile, they are extracted preferentially over tocopherols and other high molecular weight compounds. Higher levels of pressure and temperature resulted in increased solubility of compounds with high molecular weight and tocopherols due to increased density of SC CO₂. So the extraction at higher pressures and temperatures resulted in a better yield of FAME along with tocopherols in the extract and this in turn decreased the degree of enrichment of tocopherols in the raffinate. However, specific level of pressure and temperature of extraction caused the increase in the solubility of FAME due to their volatility and results in enhanced enrichment of tocopherols in the raffinate. It was observed that the enrichment of tocopherols to ten times the original concentration of feed occurred at extraction pressure of 180 bar and temperature of 60 °C of SC-CO₂.     

A study on parameters of potential cocoa butter analogue synthesis from camel hump by lipase-catalysed interesterification in supercritical CO2 using response surface methodology

A potential cocoa butter analogue was prepared from camel hump fat and tristearin by enzymatic interesterification in supercritical carbon dioxide (SC–CO₂) using immobilised Thermomyces lanuginosus lipase (Lipozyme TL IM) as a biocatalyst. Response surface methodology (RSM) was used to investigate the effects of pressure, temperature, tristearin/camel hump fat ratio, water content, and incubation time on TAG distribution of cocoa butter analogue. The process conditions were optimised by conducting experiments at five different levels. A second order polynomial response surface equation was developed to indicate the effect of variables on TAG distribution of cocoa butter analogue. Overlaid contour plots generated using the response surface equations showed that all TAG components of cocoa butter analogue are significantly affected by the experimental independent variables. The pressure of 10 MPa; temperature of 42 °C; SSS/CHF ratio of 1.15:1; water content of 10% (w/w); and incubation time of 3 h were found to be the optimum conditions to achieve the most similar cocoa butter analogue to the corresponding cocoa butter.     

Effect of different carbon dioxide concentrations and exposure times in stunning of slaughter pigs: Impact on animal welfare and meat quality

The objective of this study was to determine the impact of different slaughter procedures on animal welfare and meat quality. Before slaughter in a dip-lift, one-gondola system, 460 pigs were exposed to an atmosphere containing either 80% or 90% CO(2) for 70 or 100s, and at the longer exposure time with stun-to-stick intervals of either 25-35 or 40-50s. Clinical parameters (reflexes, catecholamines and lactate) showed deficiencies in animal welfare after stunning with 80% CO(2) for 70 and 100s, with an interval of 40-50s, and with 90% CO(2) for 70s. Stunning with 80% CO(2) for 70 or 100s always induced stress, as indicated by higher lactate levels, and reduced meat quality as indicated by low pH(24) values (5.4 in Musculus longissimus and 5.5 in Musculus semimembranosus) and low impedance (Py(24)) values, especially in combination with the longer stun-to-stick interval (40-50s). Stunning with 80% or 90% CO(2) in a dip-lift system was found to be acceptable for animal welfare (percentage of clinical reflexes) only in combination with the longer exposure time of 100s and the shorter stun-to-stick times of 25-35s. When 90% CO(2) was used, the longer stun-to-stick interval of 40-50s also gave results acceptable with regard to animal welfare. Generally, in comparison to 80% CO(2) stunning meat quality was superior (higher pH(24) and Py(24) values) after stunning with 90% CO(2).     

Mechanisms of oxidative browning of wine

Oxidative browning is a long-standing problem in winemaking and sulphur dioxide is the generally used antioxidant to control wine browning. However, concerns over its ability to induce severe allergic reactions have created a great need for its reduction or replacement in recent years. Furthermore, ascorbic acid seems unsuccessful as an alternative antioxidant in winemaking. So a comprehensive understanding of the chemistry of wine browning is essential to study new antioxidant(s) for the protection of wine from browning. The review systematically outlines the mechanisms of wine browning including enzymic and non-enzymic browning happening in winemaking and discusses the central roles performed by iron and copper in the chemistry of wine oxidation. Iron and copper might play a central role in initiating wine non-enzymic browning, and this has important implications in studying antioxidant substitute for sulphur dioxide in wine.     

Oxidative stress-dependent inhibition of yeast cell growth by farnesylamine and its possible relation to amine oxidase in the mitochondrial fraction

Among various analogs of the isoprenoid farnesol (FOH), farnesylamine (FNH2) inhibited the growth of the budding yeast Saccharomyces cerevisiae by accelerating cellular reactive oxygen species (ROS) generation. Unlike the case with FOH, however, FNH2 did not cause mitochondrial transmembrane potential (mtDeltaPsi) hyperpolarization so that FNH2-treated cells were not protected against ROS production by inhibiting the proton pumping function of mitochondrial F(O)F1-ATPase. FNH2 promoted ROS generation even in cells of a respiration-deficient mutant, indicating a yeast metabolic pathway other than mitochondrial electron transport as the origin of ROS. FNH2 oxidase activity was detected in the yeast mitochondrial fraction, which produces hydrogen peroxide (H2O2) in the reaction with either FNH2 or geranylgeranylamine (GGNH2), in addition to polyamine oxidase activity specific for spermine. GGNH2 also exhibited the growth inhibitory effect with the accompanying induction of ROS generation, while such an activity was not detected with any of the polyamines tested or geranylamine. FNH2 oxidase, which was sensitive to a typical copper-chelating agent, diethyldithiocarbamic acid (DDC), could be solubilized with Triton X-100, and detected as a single band upon activity staining with FNH2 but not with spermine in polyacrylamide gel electrophoresis. FNH2-treated cells were partly protected against ROS production by the additional supplementation of DDC in the medium. Our results suggest the involvement of H2O2 production due to direct oxidation of FNH2 by copper amine oxidase in oxidative stress-dependent inhibition of yeast cell growth.     

Extraction of tocopherol-enriched oils from Kalahari melon and roselle seeds by supercritical fluid extraction (SFE-CO2)

Tocopherol-enriched oil was extracted by supercritical fluid extraction of carbon dioxide (SFE-CO₂) from Kalahari melon and roselle seeds. The SFE-CO₂ process was optimised using response surface methodology (RSM) with central composite design (CCD). Three SFE-CO₂ parameters namely extracting pressure, extracting temperature, and flow rate of carbon dioxide were examined. The optimal SFE-CO₂ conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The optimal SFE-CO₂ conditions for the extraction tocopherol-enriched oil from Kalahari melon seeds were: extracting pressure 290 bar, extracting temperature 58 °C, and flow rate of carbon dioxide 20 ml/min. The optimum conditions for roselle seeds were extracting pressure 200 bar, extracting temperature 80 °C, and flow rate of carbon dioxide 20 ml/min. These optimum conditions yielded tocopherol concentration of 274.74 and 89.75 mg/100 g oil from Kalahari seed and roselle seed, respectively. No significant (P > 0.05) differences were obtained between the experimental and predicted values.     

Synthesis,characterisation and analytical application of Fe3O4@SiO2@polyaminoquinoline magnetic nanocomposite for the extraction and pre-concentration of Cd(II) and Pb(II) in food samples

This work describes a novel Fe₃O₄@SiO₂@polyaminoquinoline magnetic nanocomposite and its application in the pre-concentration of Cd(II) and Pb(II) ions. The parameters affecting the pre-concentration procedure were optimised by a Box–Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount and pH) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent, and elution time) were selected as main factors in the optimisation study of the elution step. Following the sorption and elution of analytes, the ions were quantified by flame atomic absorption spectrometry (FASS). The limits of detection were 0.1 and 0.7 ng ml^?1 for Cd(II) and Pb(II) ions, respectively. All the relative standard deviations were less than 7.6%. The sorption capacities of this new sorbent were 57 mg g^?1 for Cd(II) and 73 mg g^?1 for Pb(II). Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of these heavy metal ions from seafood and agricultural samples and satisfactory results were obtained.