Flavor and Antibotulinal Evaluation of Sorbic Acid-Containing Bacon

Bacon was prepared in a single pumping operation with a nitrite-free brine containing suspended, finely pulverized sorbic acid with the regular curing agents. The bacon, after being processed, was evaluated for susceptibility to Clostridium botulinum spore outgrowth and for taste panel acceptability using a 9-point hedonic scale. Sorbic acid levels of 0.13% or higher in the processed bacon gave nearly complete protection against spore outgrowth (as determined by gas production in aluminum cans) for the duration of the 6 months abuse period. The increase in antibotulinal efficacy with sorbic acid was generally associated with a lower pH. Flavor scores of control, nitrite-cured, and sorbic acid-cured bacon showed no significant differences among the three samples. After storage for 6 wk at 0–2°C, there was a decrease in the flavor scores, but the only statistically significant decrease was in the nitrite-cured bacon.     

Growth and Toxin Production by Clostridium botulinum in Model Acldified Systems

TPGY medium was acidified to pH 4.20, 4.60, 5.00 and 5.40 with acetic or citric acid. The media were inoculated with spores from three strains of C. botulinum type A, B or E. Growth, pH, and toxin production under anaerobic conditions were monitored for 8 wk. Spores of C. botulinum types A and B were incapable of outgrowth and toxin production at pH 4.60 or below when incubated at 35°C. Spores of C. botulinum type E were capable of growth and toxin production at 26°C in citric acid acidified systems at pH 4.20. Growth and toxin production were not detected below pH 5.00 when acetic acid was used.     

Nitrite,nitrite alternatives,and the control of clostridium botulinum in cured meats

Historically, nitrite has been a component of meat‐curing additives for several centuries. In recent years the safety of nitrite as an additive in cured meats has been questioned mainly because of the possible formation of carcinogenic nitrosamines. Nitrite has many important functions in meat curing including its role in color development, flavor, antioxidant properties, and antimicrobial activity. The inhibition of Clostridium botulinum growth and toxin production is an especially important antimicrobial property of nitrite. This review discusses the effects of processing, curing ingredients (especially nitrite), and storage of cured meats in relation to the control of C. botulinum. If nitrite is eliminated from cured meats or the level of usage decreased, then alternatives for the antibotulinal function of nitrite need to be considered. Several potential alternatives including sorbates, parabens, and biological acidulants are discussed.     

Simultaneous determination of nine preservatives in food by liquid chromatography with the aid of coagulant in the clean-up process

ABSTRACT

A simple HPLC method was developed for the simultaneous analysis of nine preservatives in food including benzoic acid, sorbic acid, dehydroacetic acid, methyl paraben, ethyl paraben, isopropyl paraben, propyl paraben, isobutyl paraben and butyl paraben. Samples were extracted with 60 v/v% methanol containing poly-aluminium chloride (PAC) and sodium hydroxide prior to analysis. PAC, which is normally used as a coagulant, was successfully applied to remove interfering substances from the samples. The method showed good linearity with coefficients of determination higher than 0.999 over the range of 0.2–5 µg ml^–1 for all target preservatives. LOQs of the method were in the range of 0.002–0.008 g kg^–1. Method performance was evaluated in a variety of foods demonstrated to have quantitative recoveries of 81.7–102.5% with satisfactory intra-day precision of < 3.7% and inter-day precision of < 6.5%. The method also demonstrated applicability to real foods containing preservatives.     

Blood Fraction Effects on the Antibotulinal Efficacy of Nitrite in Model Beef Sausages

Toxin production by Clostridium botulinum was studied in a model cured beef sausage containing 0–5% added dried bovine blood fractions. Controls which contained nitrite but without blood fractions, were toxic by bioassay in 3 wk at 27°C. Controls without nitrite or blood fractions were toxic at 1 wk, while model sausages supplemented with hemoglobin, red cells, or whole blood were toxic in 1–3 wk. Plasma yielded no detectable toxin for 4 to > 10 wk depending upon addition level. Sausages showing delayed toxigenesis had pH values lower than those which developed toxin earlier. These results demonstrated that use of blood fractions that increased iron levels in beef above 30 μ.g/g interfered with the antibotulinal efficacy of sodium nitrite.     

Analysis and quantification of parabens in cosmetic products by utilizing hollow fibre-supported liquid membrane and high performance liquid chromatography with ultraviolet detection

A simple and direct method based on hollow fibre-supported liquid membrane (HFSLM) extraction and liquid chromatography equipped with a UV detector was developed for analysis and quantification of parabens in cosmetic products. The parabens analysed included methyl, ethyl, propyl, isobutyl and butyl paraben. The HFSLM extraction was carried out by employing di- n -hexyl ether as organic liquid that was immobilized in the hollow fibre membrane. The HFSLM extraction is simple, cheap, minimizes the use of solvents and uses disposable material. In an investigation of 11 paraben-containing cosmetic products, the levels of parabens (sum of all parabens in a product) ranged from 0.43% to 0.79% (w/w) for skin care products, 0.07–0.44% for hair fixing gels and 0.30–0.52% for soap solutions. The levels of individual parabens in individual cosmetic products ranged between 0.03% and 0.42% w/w for skin care products, 0.07% and 0.26% w/w for hair fixing gels and between 0.11% and 0.34% w/w for soap solutions. Parabens were found in the highest concentrations in skin care products followed by soap solutions and the least amounts were found in hair fixing gels. Of the paraben-containing products tested, all of them contained methyl paraben and about 90% contained propyl paraben in addition to methyl paraben. One product contained all the parabens analysed.     

Antibotulinal Activity of Methyl and Ethyl Fumarates in Comminuted Nitrite-Free Bacon

Mono- and dimethyl and ethyl esters of fumaric acid were evaluated for their antibotulinal efficacy in cans of comminuted nitrite-free bacon. At 0.125%, all were equal or superior to 120 ppm nitrite in preventing toxin formation in cans incubated at 30°C for 8 wk. No cans swelled or became toxic when mono- or dimethyl fumarate was added. With monoethyl fumarate, two cans out of twenty swelled but were nontoxic. The least effective ester was diethyl fumarate but its activity was equal to that of 120 ppm nitrite.     

Dose-response of the cultured bovine lens to butyl, methyl and propyl parabens

Pre-screening of cosmetic ingredients is vital for consumer safety. Previous in vivo techniques, such as the Draize test, have proved to be unreliable in predicting ocular irritancy and therefore there is a need for alternate testing methodologies. One such test is the scanning laser in vitro assay system which quantifies irritancy based on the focusing ability of the cultured bovine lens. In combination with confocal microscopy, a more thorough documentation of ocular irritancy can be achieved. This study investigates the response of cultured bovine lenses over time to butyl, methyl and propyl parabens, which are common antimicrobial agents found in cosmetic and ophthalmic products. The focusing ability of the lens was measured with an automated laser scanner over a period of 96 h. At 120 h post-treatment, the lenses were analysed by using a confocal laser scanning microscope to determine the characteristics of nuclei, and the morphology and distribution of mitochondria within the lenses. Irritancy to the three parabens was investigated at both an optical and cellular level. Each of the parabens was tested at 0.002% and 0.2%, where the 0.2% butyl paraben was found to be the most irritating.     

Inhibition of Clostridium botulinum by Antioxidants and Related Phenolic Compounds in Comminuted Pork

Antioxidants, esters of p-hydroxybenzoic acid and gallic acid, and related phenolic compounds were evaluated for their activity against growth and toxin production of C. botulinum types A and B in comminuted pork. With an inoculum level of 8,000 spores/g of meat most of the chemicals at a concentration of 1,000 ppm delayed first swell formation for less than 3 days beyond the control. For most compounds, the time to first swell formation beyond that of the control increased as the spore level per g of meat decreased. 8-Hydroxyquinoline at a concentration of 200 ppm or in combination with sodium nitrite (40 ppm) inhibited the growth and toxin production of C. botulinum in comminuted pork for 60 days at 27°C. 8-Hydroxyquinoline was more active in inhibition of growth and toxin production of C. botulinum in comminuted pork than in prereduced Thiotone-yeast extract-glucose broth.     

高效液相色谱法同时检测酱油中7种防腐剂

建立利用高效液相色谱法同时测定调味品中苯甲酸、山梨酸、脱氢乙酸及对羟基苯甲酸甲、乙、丙、丁酯7种防腐剂的方法。该方法中酱油样品经Oasis HLB柱进行固相萃取净化后用Warters-C18柱(4.6mm×250mm,5μm),乙酸铵-乙腈溶液为流动相进行梯度洗脱,并在230、260nm波长处检测,结果在0.4～100mg/L的线性范围内测得7种物质的线性相关系数均大于0.9994,方法检出限介于0.28～0.55mg/L之间,各个组分的回收率范围在84.4%～102.3%之间。该方法可以应用于测定这7种物质在酱油中的含量。     

Effect of Sodium Acid Pyrophosphate in Combination with Sodium Nitrite or Sodium Nitrite/Potassium Sorbate on Clostridium botulinum Growth and Toxin Production in Beef/Pork Frankfurter Emulsions

Combinations of sodium acid pyrophosphate (SAPP) with added sodium nitrite and/or potassium sorbate were tested at various pH levels to determine effectiveness in delaying Clostridium botulinum growth and toxin production in frankfurter emulsions. Formulations containing sodium nitrite (40 ppm), potassium sorbate (0.26%) and SAPP (0.4%) resulted in a greater delay of toxin production (12–18 days) than other combinations (6–12 days) having similar pH values. Treatments containing 0.4% SAPP appeared to be more inhibitory than their counterparts without SAPP, displaying less numbers of toxic samples during the 53-day storage period at 27°C. Aerobic mesophilic colony counts and residual nitrite data showed little difference among treatments.     

Effects of Sodium Chloride Reduction and Polyphosphate Addition on Clostridium Botulinum Toxin Production in Turkey Frankfurters

Mechanically deboned turkey meat emulsions were made with 1.0, 1.5, 2.0, 2.5, or 3.0% salt (NaCl), or with combinations of 1.5% or 2.0% salt with 0.4% sodium tripolyphosphate (TPP), sodium hexametaphosphate (HMP), or sodium acid pyrophosphate (SAPP). Sodium nitrite levels were constant at 150 ppm. Emulsions were inoculated with a mixture of 10 strains of C. botulinum (10³/g) and incubated at 27°C. Increasing NaCl content from 1.0% to 3.0% delayed toxin production by 3 days on the average. Toxin production was detected earlier when TPP was added, HMP had no effect, and SAPP delayed toxin production.     

Nachweis von Clostridium botulinum Typ A, B, E und F mittels real-time-PCR

Clostridium botulinum is a Gram-positive, anaerobic, spore-performing bacterium with the ability to produce under certain conditions a protein with a characteristical neurotoxicity. Intoxications with C. botulinum toxin belong to the rare occuring food-poisonings; the mortality, however, is very high. C. botulinum produce seven different toxin types (type A to G), human intoxications are currently described to caused by toxin type A, B, E and F. C. botulinum is a strictly anaerobic growing bacterium, so the risk for the consumer’s health is mainly due to non-commercially produced food cans. A special form of botulism is the „infant botulism“. In contrast to the botulism of adults, where the disease is caused through toxin-containing food, spores of C. botulinum can sporulate and produce toxin in the intestines of an infant. The source of infant botulism can be honey, because it contains as a natural product C. botulinum spores. Because of the difficult and time-consuming cultural detection of C. botulinum, PCR methods to screen for the toxin genes A, B, E and F, which are relevant in the human medicine, have been used increasingly during the last years. In this presentation two real-time-PCR assays for C. botulinum, which can be applied in the routine laboratory, will be shown.     

Effect of food preservatives on the inhibitory activity of acidocin CH5 and bacteriocin D10

The effect of food preservatives on the activities of acidocin CH5 and bacteriocin D10 was evaluated. Lactobacillus delbrueckii subsp. lactis LTI30 was used as an indicator strain. Methyl paraben and propyl paraben at concentrations higher than 0.075 g/l enhanced the activity of acidocin CH5 up to 45% and 50% respectively. As regards bacteriocin D10, the synergistic effect was less pronounced. The inhibitory effect of EDTA applied alone at 0.1–0.2 mmol/l against the indicator atrain increased from 4% to 10%. EDTA (0.1–0.2 mmol/l) in combination with acidocin CH5 or bacteriocin D10 increased their inhibitory effects from 50% to 70% and from 10% to 50% respectively.     

Determination of Food Preservatives in Orange Juice by Reversed-Phase Liquid Chromatography

An isocratic high-performance liquid chromatographic (HPLC) method has been developed to determine benzoic acid, sorbic acid, and methyl and propyl esters of p-hydroxygenzoic acid (parabens) in orange juice. The HPLC system consists of a reversed-phase column (150 × 6.0 mm i.d.) packed with a rigid polystyrene-divinylbenzene gel, a solvent system of acetonitrile-0.05M KH₂P0₄ (40:60) with flow rate of 1.0 mL/min and 230 nm detection. Including sample preparation, a complete determination can be accomplished in 30 min. The method recovered 93% or more of all preservatives with the exception of high concentrations (500 ppm) of parabens.     

Antagonistic effect of fat on the antibotulinal activity of food preservatives and fatty acids

The effect of fat on the antibotulinal activity of 11 food preservatives, 12 free fatty acids, and nine lots of enzyme-modified cheese (EMC) was evaluated in a media system. Anhydrous milkfat or soybean oil was added to tubes of Trypticase–peptone–glucose–yeast extract medium (TPGY) supplemented with the additives (final pH adjusted to 5.9). Treatments were inoculated with 3-log₁₀ proteolytic Clostridium botulinum spores/ml (10-strain mixture of serotypes A and B) and incubated anaerobically at 30°C for up to 14 days. For the preservative and fatty acids studies, growth of C. botulinum was determined by measuring optical changes at OD_{640 nm}. Botulinal toxin production was determined in EMC-treatments using the mouse bioassay. Data revealed that the antibotulinal effects of nisin, and free fatty acids caprylic, capric, lauric, myristic, oleic, and linoleic acids were each significantly reduced in treatments supplemented with 20% fat (P<0.05). Similar trends were observed in TPGY supplemented with 20% fat and potassium sorbate, sorbic acid, monolaurin, polyphosphate emulsifier, or EDTA–lysozyme, but the differences were reduced. Fat was also antagonistic to the antibotulinal activity of five EMC-treatments. This study suggests that fat may reduce the efficacy of some antimicrobials added to or found naturally in foods.     

GC-MS法同时检测葡萄酒中10种防腐剂和抗氧化剂

利用离子阱气相色谱-质谱联用仪,优化了色谱、质谱仪器参数,利用质谱全扫描技术建立了同时检测葡萄酒中山梨酸、苯甲酸、脱氢乙酸、叔丁基对苯二酚（TBHQ）、叔丁基羟基茴香醚（BHA）、2,6-二叔丁基对甲酚（BHT）、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯等10种添加剂的方法。10种添加剂的检测限分别为0．11mg/L、0．072mg／L、0．046mg／L、0．035mg／L、0．032mg／L、0．020mg／L、0．035mg／L、0．042mg／L、0．035mg,／L、0．035mg／L,方法的精密度为2．9％～4．6％、回收率为82％～101％,应用于葡萄酒中食品添加剂的检测,效果良好,检测效率大大提高。     

对羟基苯甲酸酯类对杏果采后病害的控制

通过离体和体内实验研究对羟基苯甲酸酯类处理对杏果采后黑斑病和软腐病的控制。离体实验结果表明,对羟基苯甲酸酯类对互隔交链孢（Alternaria alternata）和匍枝根霉（Rhizopus stolonifer）菌丝生长具有一定的抑制作用,其中对羟基苯甲酸乙酯和对羟基苯甲酸丁酯抑制效果较好,并随着处理剂量的增加抑制效果显著增加,100 μL/L对羟基苯甲酸丁酯对A. alternata和R. stolonifer菌落生长的抑制效果佳,其对菌落直径的抑菌率分别达到了23.70%和62.48%,同时发现对羟基苯甲酸酯类对R. stolonifer的抑制作用较强。体内实验结果表明,对羟基苯甲酸酯类能有效地控制损伤接种的杏果黑斑病和软腐病的扩展,对软腐病的控制效果较好。其中240 μL/L的对羟基苯甲酸乙酯对杏果黑斑病和软腐病的抑制效果最佳。进一步通过正交试验确定了对羟基苯甲酸酯类与热水复合对杏果的最佳防腐处理条件为32 μL/L的对羟基苯甲酸丙酯,在50 ℃热水中浸泡7 min,该复合对采后杏果的病害控制效果最佳,验证实验表明,其对黑斑病和软腐病的抑菌率分别达到了32.22%和51.84%。     

Effects of Varying Levels of Chloride Salts on Clostridium Botulinum Toxin Production in Turkey Frankfurters

Inhibitory effects of sodium chloride (NaCl), potassium chloride (KCl), and magnesium chloride (MgCl₂) on C. botulinum inoculated turkey frankfurter emulsions were determined. Ionic strengths (I.S.) of 0.42, 0.55, and 0.68 were compared (equivalent to 2.5%, 3.25%, and 4.0% NaCl). Sodium nitrite levels were constant at 150 ppm. Inoculated emulsions (10³ spores/g) were incubated and maintained at 27°C. In-creasing NaCl from I.S. 0.42 to 0.68 delayed toxin production from 4 days to at least 40 days. KCl was almost as effective as NaCl at I.S. 0.42, but inferior at higher levels. MgCl₂ did not demonstrate any inhibitory effect. Fifty percent substitution of 2.5% NaCl with KCl or MgCl₂ generally reduced time for toxin production to occur.     

Nachweis von Clostridium botulinum Typ A, B, E und F mittels real-time-PCR

Clostridium botulinum is a Gram-positive, anaerobic, spore-performing bacterium with the ability to produce under certain conditions a protein with a characteristical neurotoxicity. Intoxications with C. botulinum toxin belong to the rare occuring food-poisonings; the mortality, however, is very high. C. botulinum produce seven different toxin types (type A to G), human intoxications are currently described to caused by toxin type A, B, E and F. C. botulinum is a strictly anaerobic growing bacterium, so the risk for the consumer’s health is mainly due to non-commercially produced food cans. A special form of botulism is the „infant botulism“. In contrast to the botulism of adults, where the disease is caused through toxin-containing food, spores of C. botulinum can sporulate and produce toxin in the intestines of an infant. The source of infant botulism can be honey, because it contains as a natural product C. botulinum spores. Because of the difficult and time-consuming cultural detection of C. botulinum, PCR methods to screen for the toxin genes A, B, E and F, which are relevant in the human medicine, have been used increasingly during the last years. In this presentation two real-time-PCR assays for C. botulinum, which can be applied in the routine laboratory, will be shown.

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Zusammenfassung: Clostridium botulinum z?hlt zu den anaeroben sporenbildenden Bakterien, die unter bestimmten Bedingungen in der Lage sind, sich in Lebensmitteln zu vermehren und ein Protein mit charakteristischer Neurotoxizit?t zu bilden. Intoxikationen mit Clostridium botulinum-Toxin geh?ren zu den seltenen lebensmittelassoziierten Intoxikationen; die Mortalit?t bei einer Erkrankung ist allerdings sehr hoch. C. botulinum produziert sieben unterschiedliche Toxintypen (Typ A-G), wobei für menschliche Erkrankungsf?lle bisher die Toxintypen A, B, E und F beschrieben sind. Da es sich bei den genannten Keimen um strikt anaerob wachsende Bakterien handelt, stellen vor allem nicht kommerziell hergestellte Konserven, wie z. B. Kesselkonserven, ein Risiko für den Verbraucher dar. Als besondere Form des Botulismus wird der so genannte „S?uglingsbotulismus“ beschrieben. Im Gegensatz zur der Erkrankung, die bei Erwachsenen auftritt und die durch die Aufnahme des bereits toxinhaltigen Lebensmittels verursacht wird, k?nnen Sporen von C. botulinum im Darm von S?uglingen auskeimen und dort Toxine bilden. Ursache für den S?uglingsbotulismus ist h?ufig Honig, der als Naturprodukt C. botulinum-Sporen enthalten kann. Da der kulturelle Nachweis von C. botulinum aufwendig und eine endgültige Differenzierung schwierig ist, wird im Bereich der Routinediagnostik seit einigen Jahren verst?rkt mit PCR-Nachweisverfahren gearbeitet, die ein schnelles Screening auf das Vorhandensein der vier in der Humanmedizin relevanten Toxingene A, B, E und F erm?glichen. In dieser Arbeit werden zwei real-time-PCR-Systeme vorgestellt, die im Bereich der Routinediagnostik einsetzbar sind.

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Eingegangen: 19. Januar 2007