Reaction of nitrite with ascorbic acid and its significant role in nitrite-cured food

The decrease in concentration of free nitrite in an aqueous reaction solution made by mixing nitrite and ascorbic acid was studied. This decrease resulted information of a reaction product which transferred NO to ferricytochrome c to form ferrocytochrome c nitroso compound. From the solution containing the reaction product, nitrite could be regenerated spontaneously and suddenly by physical agitation. Oxygen was apparently not necessary for regeneration nitrite from the reaction solution. It does not seem that the regeneration of nitrite was responsible for a bimolecular dismutation of nitrosoascorbic acid in a reverse direction proposed by Fox and Thomson (Biochemistry2, 465; 1963). Heating of the reaction solution at less than 100°C resulted in a loss of nitrite from the solution, which was greater with increasing concentration of ascorbic acid. The reaction product formed between nitrite and ascorbic acid is probably responsible not only for nitrosation reactions, but also for the loss of nitrite observed during curing of meat.     

Inhibition of Papain in Meat by Potato Protein or Ascorbic Acid

Three methods (Warner-Bratzler shear, myofibril fragmentation index, and sensory panel evaluation) were used to determine effectiveness of ascorbic acid or potato inhibitor on papain activity in meat. Potato inhibitor at 0.6, 0.8, and 1.0 mg/mL did not sustain inhibition of papain activity in meat. While 2.5 × 10^--³M ascorbic acid inhibited papain in meat, this quantity of ascorbic acid induced off-flavor which was unacceptable to sensory panelists. A lower level of 2.5 × 10^--⁴ M would retard but not completely eliminate papain activity while producing more acceptable sensory results.     

抗坏血酸结合自发气调包装对灵武长枣贮藏品质和抗氧化性的影响

目的：探明外源抗坏血酸（ascorbic acid,AsA）处理与自发气调包装（modified atmosphere package,MAP）对灵武长枣贮藏品质的协同保鲜效果。方法：将灵武长枣经0.3 g/100 mL AsA溶液浸泡后分别用聚乙烯和0.03 mm厚的低密度聚乙烯（low-density polyethylene,LDPE）两种MAP进行包装,分析冷藏过程中的果实理化品质与抗氧化能力的变化情况。结果：AsA与MAP的复合保鲜效果均在不同程度上优于单独使用MAP或AsA;其中LDPE活性气调包装结合AsA处理能显著减缓灵武长枣果实硬度和可滴定酸含量的降低（P＜0.05）,抑制果实呼吸速率和相对电导率的上升,维持果实AsA、总酚和类黄酮含量,提高抗氧化能力。结论：AsA结合MAP可以有效提高灵武长枣贮藏品质,延长贮藏期,其中采用AsA结合LDPE活性气调包装的保鲜效果最好。     

Inhibition of Mushroom Polyphenoloxidase by Ascorbic Acid Derivatives

Ascorbic acid (AA), dehydroascorbic acid (dehydroAA), isoascorbic acid (isoAA), ascorbic acid-2-phosphate (AA-2- PO₄), and ascorbic acid-2-sulfate (AA-2-SO₄) were tested as inhibitors of mushroom polyphenoloxidase (PPO). Kinetic analysis indicated that AA and isoAA were more effective than dehydroAA. The half times (t_1/2) that decreased 50% of PPO activity for AA, isoAA and dehydroAA were 2.5, 3.1, and 1.9 hr, respectively, and the concentrations that inhibited half of PPO activity were as follows: ascorbic acid, 0.04 mM, isoAA, 0.25 mM; and dehydroAA, 7.5 mM. Electron spin resonance studies demonstrated that the Cu²⁺ of PPO was reduced to Cu⁺ by AA. AA-2-PO₄ and AA-2-SO₄ were not inhibitors for PPO. However, the digestion of AA-2-PO₄ with acid phosphatase yielded AA to inhibit PPO activity. AA-2-SO₄ was found to be a poor substrate for sulfatase.     

糙米发芽过程中抗坏血酸的生成特性

研究了糙米发芽过程中抗坏血酸的生成特性,并就生成特性与稻米品质的相关性进行了初步探讨,研究结果表明:(1)稻谷的干种子中几乎不存在抗坏血酸,在发芽过程中逐渐生成,AsA的生成在发芽实验中有增减变化,DasA则呈现单调增加趋势。(2)糙米的陈化程度对抗坏血酸的生成有影响,陈化抑制了抗坏血酸的生成。(3)抗坏血酸的生成特性能更好的表达稻米陈化过程中食味的变化。     

原花青素、抗坏血酸、蒜泥对低温香肠NaNO2残留量的影响

肉制品中残留的亚硝酸盐有害于人体健康.本试验中将抗坏血酸、原花青素和蒜泥添加至香肠中,研究它们对亚硝酸钠残留量的影响.采用分光光度法测定香肠中亚硝酸钠的残留量,结合感观评定确定抗坏血酸、原花青素、蒜泥的最佳添加范围.通过正交试验,确定这3种物质混合的最佳混合比例.试验结果表明:随着功能成分添加量的增加,香肠中亚硝酸钠残...     

差分脉冲伏安法对果蔬中亚硝酸盐和抗坏血酸的同时测定

采用对苯二酚（Hydroquinone，HQ）催化甲烷氧化菌素（Methanobactin，Mb）还原氯金酸合成纳米金（Gold Nanoparticles，AuNPs），利用电沉积法将Mb@AuNPs修饰到裸金电极表面，制备Mb@AuNPs/Au电极。采用差分脉冲伏安法对亚硝酸盐和抗坏血酸进行同时测定并对条件进行优化，结果表明:电极组装条件为电沉积扫速100 mV/s、扫描圈数为40圈；检测体系为浓度0.20 mol/L pH6.5的磷酸盐缓冲溶液，在2~5600 μmol/L和1~6000 μmol/L的线性范围内，Mb@AuNPs/Au对亚硝酸盐和抗坏血酸同时检测的氧化峰电流与浓度呈良好的线性关系（R2>0.9928），检出限分别为0.31和0.57 μmol/L。实际样品中亚硝酸盐和抗坏血酸的加标回收率范围分别为92.59%~109.26%、90.01%~103.51%，表明该方法具有良好的重现性和稳定性，可用于果蔬中亚硝酸盐和抗坏血酸的同时测定。     

L-Ascorbic Acid and Its 2-Phosphorylated Derivatives in Selected Foods: Vitamin C Fortification and Antioxidant Properties

Two carbonated beverages fortified with 30 mg L-ascorbic acid (AsA) equivalents/250 mL in the form of L-ascorbate 2-monophosphate (AsMP) and stored at 25–35°C retained more vitamin C than those with added AsA or L-ascorbate 2-polyphosphate (AsPP). Breads enriched with ferrous iron and fortified with 560 AsA eq./100g flour in the form of AsPP and AsA retained 40% and 5% vitamin C, respectively, after 6 davs at 25°C. Bran (40%) flakes fortified with 0.19% AsA ea. as AsMP and AsPP gave much improved retention of vitamin C during storage for 7 mo at 25–40°C and 7–11% moisture levels. The sodium salts of AsA, AsMP, and AsPP, when injected into whole eye of round beef at 0.18% AsA eq., inhibited hexanal formation after the meat was roasted and stored for 5 days at 5°C. Those sodium salts did not prevent accumulation of peroxides in peanut paste.     

EXTENDING THE CHILLED SHELF LIFE OF VACUUM-PACKAGED GROUND BEEF USING ASCORBIC ACID, NITRITE OR SALT

The objective of this study was to extend the shelf life of ground beef in chilled conditions. Samples were treated with 2% salt, 2% salt  +  500-ppm ascorbic acid, or 2% salt  +  100-ppm sodium nitrite. The control sample did not contain any additives. Protein, nitrite, moisture contents, pH, thiobarbituric acid (TBA) value, color attributes and microbial counts of samples were determined. Samples were vacuum packaged and stored in refrigeration, and chemical and microbial analyses were performed throughout storage. The pH of samples decreased during storage, and the sample having 2% salt and 500-ppm ascorbic acid had the greatest pH decline. TBA values generally increased ( P <  0.05) with storage time. Samples having 2% salt  +  500-ppm ascorbic acid had the lowest TBA value. On a given storage day, samples having 2% salt  +  100-ppm sodium nitrite had lower microbial microbial count than other samples, indicating the antibacterial effect of nitrite. A significant storage time  ×  treatment interaction ( P <  0.05) existed for almost all quality parameters studied.

PRACTICAL APPLICATIONS

Ground beef has commercial importance for the meat industry in Turkey. Meat processors have difficulties in marketing ground beef because of its relatively low shelf life. By adding ascorbic acid or salt, it is possible to extend shelf life and preserve its color, and to limit lipid oxidation, which will collectively help to increase market share of ground beef.     

Effects of Ascorbic Acid and Antioxidants on the Color of Irradiated Ground Beef

Irradiation significantly decreased the redness of ground beef (P < 0.05), and the visible color of beef changed from a bright red to a green/brown, depending on the age of meat. Addition of ascorbic acid (0.1%, wt/ wt) in ground beef prior to irradiation prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. Ground beef with added ascorbic acid had significantly lower oxidation‐reduction potential than the control (P < 0.05), and the low oxidation‐reduction potential of meat helped maintain the heme pigments in reduced form. Sesamol +α‐tocopherol had no effect in stabilizing color of irradiated beef.     

Headspace concentration of selected dry-cured aroma compounds in model systems as affected by curing agents

The effect of curing agents (sodium chloride, nitrate, nitrite, glucose, and ascorbic acid) on the headspace concentration of six volatile compounds (2-methyl-butanal, 3-methyl-butanal, 2-pentanone, hexanal, methional, and octanal) has been studied. These volatile compounds were selected based on their presence and contribution to the flavour of typical Spanish dry-cured meat products. The release of volatile compounds to the headspace has been studied by using solid-phase microextraction (SPME) and gas chromatography analysis. The main effect was produced by sodium chloride, because it produced a salting-out effect on all the volatile compounds studied. Furthermore, the presence of nitrite, nitrate, and ascorbic acid in the solution also produced an increase in the headspace concentration of the volatile compounds while glucose decreased the headspace concentration of octanal and hexanal. The changes in the relative proportions of volatile compounds due to the effect of curing agents should be taken into account as they may change the flavour perception of dry-cured meat products.     

SURFACE MORPHOLOGY OF TUMBLED CURED BEEF

Samples from bovine semimembranosus were injected to contain (1) 2.5% salt, 0.5% sodium tripolyphosphate (STPP), 156ppm sodium nitrite and 550 ppm ascorbic acid or (2) 156 ppm sodium nitrite and 550 ppm ascorbic acid. The product was then subjected to tumbling and heat processing. Treatment (1) produced a layer of coagulated protein on the surface of the meat and a layer of flattened fibers under the protein layer. Treatment (2) had a layer of protein, but exhibited less fiber flattening. Samples of treatment (1), but which were not tumbled, had neither a layer of protein nor flattened fibers. Measurement of water vapor loss from the meat surface revealed that there was no difference between tumbled and nontumbled treatments.     

Control of Enzymatic Browning in Apple with Ascorbic Acid Derivatives, Polyphenol Oxidase Inhibitors, and Complexing Agents

Novel browning inhibitors were evaluated in raw apple juice and on the cut surface of apple plugs, using quantitative measurements of color changes during storage to assess treatment effectiveness. Ascorbic acid-2-phosphate (AAP) and -triphosphate (AATP) showed promise for cut surfaces but were ineffective in juice. Ascorbic acid-6-fatty acid esters showed anti-browning activity in juice. Cinnamate and benzoate inhibited browning in juice but induced browning when applied to cut surfaces. Combinations of β-cyclodextrin with ascorbic acid (AA), AAP or ascorbyl palmitate were effective in juice but not on cut surfaces. Combinations of AA with an acidic polyphosphate were highly effective with both juice and cut surfaces.     

冷鲜调理肉三种乳酸菌发酵剂的筛选

为筛选出符合冷鲜调理肉制品发酵的优质乳酸菌发酵剂,对3株乳酸菌的发酵特性进行研究,通过耐盐、耐亚硝酸盐、产粘、产酸能力、蛋白质和脂肪分解能力、菌种间的拮抗作用等试验对其进行优势菌种筛选。结果表明,菌株LLSL、LP、LGG对食盐和亚硝酸盐具有较好的耐受性,能在6%的食盐溶液和150 mg/L亚硝酸盐溶液中存活,能有效产酸,无降解蛋白质和脂肪能力,不产气、不产氨、不产H2S;其中,菌株LLSL、LP不产粘,两者间无拮抗作用,可作为于冷鲜调理肉制品的发酵剂;菌株LGG产粘,影响冷鲜调理肉制品的感官品质和内部组织状态,不适合作为冷鲜调理肉制品的发酵剂。     

Ascorbate oxidase from starfruit (Averrhoa carambola): preparation and its application in the determination of ascorbic acid from fruit juices

A study was conducted to utilize ascorbate oxidase (AAO) from very immature starfruit for the enzymatic determination of ascorbic acid (AsA) in colored samples. The enzyme preparation was carried out by a combination of (NH₄)₂SO₄ fractionation, DEAE-Toyopearl 650 M and ultrafiltration. A calibration curve for AsA was constructed by plotting the amount of AsA oxidized by the enzyme at a specified reaction time against the absorbance. The curve showed a linear relationship in the range of 0–100 μg ml⁻¹ AsA used. Using the plot, the values of AsA in juice samples were determined and compared with the conventional 2,6-dichloroindophenol method.     

茶叶浸提液对肉制品中亚硝酸盐的清除效应

研究茶叶浸提液对降低肉制品中亚硝酸盐残留的作用,以提高肉制品食用安全性。根据茶叶浸提温度、浸提时间、茶叶浸提液用量和反应时间、反应液pH对降低肉制品中亚硝酸盐残留的效果,采用正交试验选择茶叶浸提液清除亚硝酸盐的最佳工艺条件。茶叶浸提液[物料比(g/mL)1∶10,90℃水浴浸提60 min]清除亚硝酸盐的最佳条件为12 mL提取液在pH 5.0的反应液中反应20 min,体外清除率最大为56.83%;对肉制品(20 g)中亚硝酸钠的清除效果达到44%以上。此研究为茶叶浸提液降低肉制品中亚硝酸盐残留应用于实际生产提供理论参考。     

Antioxidant effect of turmeric powder,nitrite and ascorbic acid on stored chicken mince

This investigation was carried out to evaluate the antioxidant effect of turmeric (turmeric 1000 ppm, turmeric 5000 ppm), nitrite (nitrite 200 ppm) and ascorbic acid (ascorbic acid 500 ppm) on raw minced chicken stored at 4 ± 1 °C. Physicochemical properties [pH, water activity, cooking loss, thiobarbituric acid (TBA) value, peroxide value (PV), free fatty acid (FFA)] were evaluated on 0, 2, 4 and 6th day of storage. Highly significant differences (P < 0.01) in pH, TBA value, PV and FFA value were noticed between treatments and between storage periods. TBA values were observed to be lowest for nitrite 200 ppm and then turmeric 5000 ppm, and there was no significant difference between nitrite 200 ppm and turmeric 5000 ppm, and both were superior to ascorbic acid 500 ppm and turmeric 1000 ppm. Among different treatments, PV was found to be lowest in turmeric 5000 ppm and highest in nitrite 200 ppm. FFA value was found to be lowest in turmeric 5000 ppm and highest in ascorbic acid 500 ppm among all treated samples. It can be concluded that turmeric has potential to replace synthetic antioxidants presently used in meat processing with many added advantages.     

Effect of Iron Form, Temperature, and Inoculation with Clostridium botulinum Spores on Residual Nitrite in Meat and Model Systems

The effect of iron form (ferrous, ferric, heme), temperature and botulinal spores on nitrite level was determined in meat. In model systems, ferritin iron was also included, and ascorbate was used as a reducing agent. Reduced hemoglobin caused the most rapid nitrite depletion in both systems. Ferrous iron caused faster nitrite depletion in model systems than in meat. Ferrous iron reduced nitrite readily in model systems at 27°C, but not at 5°C. Ferritin iron did not affect nitrite level. In meat at 27°C, nitrite depletion was much faster in inoculated samples. Protein-bound nitrite levels were higher in meat with added ionic iron. In cured meat with added ionic iron, iron-NO-protein complexes may form, lowering the amount of nitric oxide (NO) available to inhibit botulinal spore outgrowth.     

Sulfhydryl and Ascorbic Acid Relationships in Selected Vegetables and Fruits

Selected vegetables and fruits were analyzed for ascorbic acid, total sulfur, and sulfhydryl-containing (-SH) fractions, shortly after harvest and after 3 wk storage at 2°C and 95–100% relative humidity. More than 95% of the original ascorbic acid content was retained in broccoli and brussels sprouts. Ascorbic acid stability in fruits appeared to be due to low pH but that did not explain high retention in broccoli and brussels sprouts. Initial ascorbic acid correlated with total sulfur (r = 0.909). Weaker correlations were found between total −SH and protein −SH fractions and ascorbic acid content (r = 0.626 and 0.672). The quantity of sulfhydryl containing compounds did not explain ascorbic acid retention mechanisms of the vegetables.     

Effect of ascorbic acid and alpha-tocopherol on storage stability of beef steaks

Fresh beef loin steaks were dipped in solutions of (1) 70% ethyl alcohol (EtOH). (2) 70% EtOH containing 3% -ascorbic acid (AsA), (3) 70% EtOH containing 0·08% --tocopherol (Toc) and (4) 70% EtOH containing 3% AsA plus 0·08% Toc for 20 s, then drained for 10 s. Control samples received no dip treatment. After 3, 6, 9 and 13 days of storage at 4°C, the samples were evaluated for MetMb formation, TBA number and viable bacterial count. The beef steaks given AsA treatment maintained an acceptable meat colour for 13 days of storage. The TBA numbers of samples dipped in EtOH containing AsA stored for 13 days were significantly lower than those of controls, and in samples dipped in solutions without AsA. At 9 and 13 days of storage, the AsA plus Toc-treated samples gave lower TBA numbers than the samples given AsA treatment only. Viable bacterial counts were not affected by AsA, Toc or AsA plus Toc treatment. Beef loin steaks dipped in EtOH solution maintained a viable bacterial count of 10⁶ after 13 days of storage.