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PubMed1996

Heat resistance of Escherichia coli O157:H7 in apple juice.

The objective was to determine the effect of cider composition on the heat resistance of Escherichia coli O157:H7. The average D52 value in a model Empire apple juice was 18 min with a z value of 4.8 degrees C. Increasing the Brix from 11.8 to 16.5 degrees had no effect on thermal resistance, while increasing L-malic acid from 0.2 to 0.8%, or reducing the pH from 4.4 to 3.6 sensitized the cells to heat. The greatest effect on heat resistance was afforded by the preservatives benzoic and sorbic acids: D50 values in ciders containing 1,000 mg/l were 5.2 min in the presence of sorbic acid and only 0.64 min in the presence of benzoic acid. Commercial apple juice concentrates yielded lower numbers of survivors than single-strength juices even though their higher sugar concentrations of about 46 degrees Brix increased heat resistance.

Benzoic Acid↗
PubMed2006

Determination of neurotoxin gene expression in Clostridium botulinum type A by quantitative RT-PCR.

Real time reverse transcription (RT)-PCR was used to quantify the expression of the botulinum neurotoxin type A (BoNT/A) gene (cntA) by normalization with the expression of 16S rRNA. The method were confirmed by monitoring the mRNA levels of cntA during growth in five type A strains. In all but one of the strains the expression of cntA mRNA was maximal in the late exponential phase, and approximately 35-fold greater than in the early exponential phase. The concentration of the extracellular BoNT/A complex detected by ELISA was highest in stationary phase. Sodium nitrite and sorbic acid completely inhibited growth at 20 ppm and 4 mg ml-1, respectively. CntA expression became lower in proportion to the concentration of sorbic acid, and this reduction was confirmed by mouse bioassay. Our results show that real time RT-PCR can be used to quantify levels of C. botulinum type A neurotoxin transcripts and to assess the effects of food additives on botulinal risk.

Animals↗
PubMed2005

Naturally occurring antifungal agents against Zygosaccharomyces bailii and their synergism.

Polygodial was found to exhibit a fungicidal activity against a food spoilage yeast, Zygosaccharomyces bailii, with the minimum fungicidal concentration (MFC) of 50 microg/mL (0.17 mM). The time-kill curve study showed that polygodial was fungicidal at any growth stage. The primary action of polygodial comes from its ability to disrupt the native membrane-associated function of integral proteins as nonionic surface active agents (surfactants) followed by a decrease in plasma membrane fluidity. The fungicidal activity of polygodial was increased 128-fold in combination with a sublethal amount (equivalent of 1/2 MFC) of anethole and vice versa relative to the fungicidal activity of anethole. The fungicidal activity of sorbic acid was enhanced 512-fold in combination with 1/2 MFC of polygodial. Conversely, the fungicidal activity of polygodial was enhanced 128-fold in combination with 1/2 MFC of sorbic acid.

Allylbenzene Derivatives↗
PubMed1992

Genotoxicity and cell transformation studies with sorbates in Syrian hamster embryo fibroblasts.

Sorbic acid, sodium sorbate and potassium sorbate were tested for their genotoxic potential in the Syrian hamster embryo (SHE) fibroblast micronucleus assay and the SHE cell transformation test in vitro. Sorbic acid and potassium sorbate showed no activity in either test system. When freshly prepared sodium sorbate solutions were used, no genotoxic or cell-transforming activity was detected. However, sodium sorbate as stored solution, which previously had been heated and sonicated to facilitate solubilization, yielded a positive response in both test systems. It is concluded that oxidation products of sodium sorbate that possess genotoxic and cell-transforming properties are formed under conditions of heating, sonication and storage.

Animals↗
PubMed1988

Toxic effects of ophthalmic preservatives on cultured rabbit corneal epithelium.

We investigated the effects of the ophthalmic preservatives thimerosal and sorbic acid on the proliferation and survival of rabbit corneal epithelial cells in tissue culture. Normally, explants of corneal epithelium grow vigorously during the first 7 days in culture. With 0.004% thimerosal present in the culture medium, the normal proliferation of corneal cells is suppressed completely. When 0.1% sorbic acid is present, proliferation is delayed and the lifespan of the corneal cells is reduced. After a 1-h exposure to concentrations of thimerosal of 0.0005% or greater, virtually all corneal cells present in established cultures are killed. These results suggest that use of ophthalmic preparations containing these chemicals may affect the metabolic and proliferative capacity of the corneal epithelium adversely.

Animals↗
PubMed2004

Screening the yeast deletant mutant collection for hypersensitivity and hyper-resistance to sorbate, a weak organic acid food preservative.

Certain yeasts cause large-scale spoilage of preserved food materials, partly as a result of their ability to grow in the presence of the preservatives allowed in food and beverage preservation. This study used robotic methods to screen the collection of Saccharomyces cerevisiae gene deletion mutants for both increased sensitivity and increased resistance to sorbic acid, one of the most widely-used weak organic acid preservatives. In this way it sought to identify the non-essential, non-redundant activities that influence this resistance, activities that might be the potential targets of new preservation strategies. 237 mutants were identified as incapable of growth at pH 4.5 in presence of 2 mM sorbic acid, while 34 mutants exhibit even higher sorbate resistance than the wild-type parental strain. A number of oxidative stress-sensitive mutants, also mitochondrial mutants, are sorbate-sensitive. This appears to reflect the importance of sustaining a reducing intracellular environment (high reduced glutathione levels and NADH/NAD and NADPH/NADP ratios). Sorbate resistance is also very severely compromised in mutants lacking an acidified vacuole, in vacuolar protein sorting (vps) mutants, in mutants defective in ergosterol biosynthesis (erg mutants) and with several defects in actin and microtubule organization. Sorbate resistance is, however, elevated with the loss of the Yap5 transcription factor; with single losses of two B-type cyclins (Clb3p, Clb5p); and with loss of a plasma membrane calcium channel activated by endoplasmic reticulum stress (Cch1p/Mid1p).

Drug Resistance, Fungal↗
PubMed1985

Species specificity of nonimmunologic contact urticaria: guinea pig, rat, and mouse.

In order to find the most suitable animal species for studies on nonimmunologic contact urticaria (NICU), human NICU agents: 20% benzoic acid (BA), 10% sorbic acid (SA), 15% cinnamic acid (CA), 20% cinnamic aldehyde (CAL), 1.0% diethyl fumarate (DEF), 0.2% methyl nicotinate (MN), all in absolute ethyl alcohol, and 100% dimethyl sulfoxide (DMSO) were each applied to the earlobes of guinea pigs, rats, and mice. Guinea pig ear reacted with swelling to all agents tested. The mean maximal increase in thickness of the guinea pig ear, measured with a micrometer, was 114 +/- 46%. No response to BA, SA, CA, DEF, or MN was noted in the rat or mouse ear. However, DMSO and CAL caused significant ear swelling both in the mouse and the rat. Thus, the guinea pig ear is more sensitive to a variety of human NICU agents than is rat or mouse ear. The striking differences in species reactivity to NICU agents suggest the possibility that there are several mechanisms (mediators) involved in reactions to different substances. The guinea pig ear swelling test remains the best quantitative animal method available for screening human NICU agents.

Animals↗
PubMed1982

Food additives and food components in total diets in the Netherlands.

1. During a period of 2 years, every 2 months 126 different food items forming a 'market basket' were purchased, prepared and divided into twelve food commodity groups. The 'market basket' was based on a study of the dietary pattern of 16- to 18-year-old male adolescents. In the (homogenized) food groups various additives and components of nutritional importance were determined. From the concentrations of the additives and components in the food groups and the daily consumption of each food group, a mean daily intake of all components analysed was calculated. 2. The mean daily amounts of benzoic acid (34 mg), sorbic acid (6 mg), glutamic acid (660 mg) and sulphite (3 mg) were all far below the acceptable daily intake (ADI) value. Butylated hydroxytoluene and gallates were not detectable, while butylated hydroxyanisole (BHA) was found in only a few instances; the maximum amount of BHA was also very low (4 mg). 3. The mean daily intakes of fluorine (0.8 mg), iodine (0.21 mg), phosphorus (1860 mg) and alpha-tocopherol (9.4 mg) seem safe and adequate. Cholesterol intakes of 25% above the maximum of 300 mg/d, as advised by the Dutch Bureau for Nutrition Education, were found. The mean fat intake appeared to be 40% of total daily energy, protein content 13% of total energy and total (available) carbohydrate 46% of total energy. The daily dietary fibre content (18 g) and the daily amount of linoleic + linolenic acid (6% of total energy) were considered too low. The daily level of sodium (4.2 g) was not considered too high. 4. It is recommended that the study should be repeated regularly, e.g. every few years, in order to monitor trends in the concentrations of significant food components in total diets.

Adolescent↗
PubMed1988

Inhibitory effects of selected Turkish spices and oregano components on some foodborne fungi.

The inhibitory effects of 10 selected Turkish spices, oregano essential oil, thymol and carvacrol towards growth of 9 foodborne fungi were investigated in culture media with pH 3.5 and 5.5. The antifungal effects of sodium chloride, sorbic acid and sodium benzoate and the combined use of oregano with sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only sodium chloride were also tested under the same conditions for comparison. Of the spices tested, only oregano at 1.0, 1.5, 2.0% (w/v) levels showed effect on all fungi. 8% (w/v) sodium chloride was less effective than oregano. Oregano essential oil, thymol or carvacrol at concentrations of 0.025% and 0.05% completely inhibited the growth of all fungi, showing greater inhibition than sorbic acid at the same concentrations. The combined use of oregano and sodium chloride exhibited a synergistic antifungal effect.

Antifungal Agents↗
PubMed1988

The relationship of insects to the deterioration of stored grain by fungi.

The data presented tests the hypothesis that knowledge of basic biological relationships between insects and fungi in the stored grain ecosystem can open new paths for management of the system. Evidence indicates: (1) some storage insect species are disseminators of storage fungi and some are exterminators; (2) some storage fungi attract storage insects and promote their population increases and other repel and secrete toxins harmful to insects; (3) certain morphophysiologic, biochemical similarities of fungi and the early developmental stages of insects suggest that new protective chemicals, 'insecticidal fungicides', could be designed or specifically sought. A specific example of a naturally occurring compound with dual action, sorbic acid (2,4-hexadienoic acid), is given and its effect on both insects and fungi is discussed. Sorbic acid is the only compound in the U.S. presently labelled by the FDA (Food and Drug Administration) as GRAS (Generally Regarded as Safe) and registered by the EPA (Environmental Protection Agency) for use on grain (maize) in storage.

Animals↗
PubMedDate not supplied

Nutritional aspects of food preservatives.

Despite the benefits attributed to food preservatives, some concern still remains regarding their safety and possible influence on nutrients. Surprisingly, there is quite a lack of scientific knowledge in this field. In order to describe a few examples, the effects of the extensively used sulphite on thiamine, folates, pyridoxal and other nutrients have been reported. Among its antibrowning effects, inhibition of ascorbic acid browning is also considered. As far as sorbic acid is concerned, notwithstanding its easy reaction with protein, probably the acid environment of the stomach determines the breakdown of the sorbic-protein adducts. Detoxication of nitrite by tocopherol and ascorbic acid leads, in the last case, to dehydroascorbic acid and its oxidative products with loss of vitamin activity. Any oxidizing substance destroys ascorbic acid, vitamin E and free vitamin A. Phosphates are largely used with different aims, including preservation, in food processing. Their antimicrobial activity is due to both a direct effect and an interaction with other antimicrobials. Sequestering capacity of phosphates and its nutritional implications are discussed. Also mechanisms of action of organic acids are reported, focusing on sorbic acid effects on single amino acids and proteins. Finally, the little information available about the potential impact of food preservatives on nutritional functions is presented.

Animals↗
PubMed1998

The pdr12 ABC transporter is required for the development of weak organic acid resistance in yeast.

Exposure of Saccharomyces cerevisiae to sorbic acid strongly induces two plasma membrane proteins, one of which is identified in this study as the ATP-binding cassette (ABC) transporter Pdr12. In the absence of weak acid stress, yeast cells grown at pH 7.0 express extremely low Pdr12 levels. However, sorbate treatment causes a dramatic induction of Pdr12 in the plasma membrane. Pdr12 is essential for the adaptation of yeast to growth under weak acid stress, since Deltapdr12 mutants are hypersensitive at low pH to the food preservatives sorbic, benzoic and propionic acids, as well as high acetate levels. Moreover, active benzoate efflux is severely impaired in Deltapdr12 cells. Hence, Pdr12 confers weak acid resistance by mediating energy-dependent extrusion of water-soluble carboxylate anions. The normal physiological function of Pdr12 is perhaps to protect against the potential toxicity of weak organic acids secreted by competitor organisms, acids that will accumulate to inhibitory levels in cells at low pH. This is the first demonstration that regulated expression of a eukaryotic ABC transporter mediates weak organic acid resistance development, the cause of widespread food spoilage by yeasts. The data also have important biotechnological implications, as they suggest that the inhibition of this transporter could be a strategy for preventing food spoilage.

ATP-Binding Cassette Transporters↗
PubMed1992

Effect of preservatives on patulin production by Penicillium expansum.

Penicillium expansum has been grown on Capek-Dox medium using glucose and fructose as carbon source. Preservatives used in fruit processing and introduced in the medium were sorbic acid, formic acid, benzoic acid, SO2 and saccharose. Sulphur dioxide had a most inhibitory effect on mycelium growth and patulin production, formic acid concentration of 0.025% increased the amount of patulin by about 30% as compared to the culture with no preservatives. However its higher concentrations inhibited synthesis of this mycotoxin. Sorbic acid concentration of 0.1% stimulated the fungus strains examined in patulin synthesis but its highest amounts were detected using 0.0125% benzoic acid increased patulin secretion from 8 to 50% as compared to the control, depending on the strain examined. Saccharose concentration up to 50% clearly decreased patulin content in the medium until its total disappearance.

Benzoates↗
PubMed2002

Simultaneous determination of preservatives in beverages, vinegar, aqueous sauces, and quasi-drug drinks by stir-bar sorptive extraction (SBSE) and thermal desorption GC-MS.

A method for the simultaneous determination of seven preservatives - sorbic acid, benzoic acid, and p-hydroxybenzoic acid ethyl, isopropyl, propyl, isobutyl, and butyl esters - in beverages, vinegar, aqueous sauces, and quasi-drug drinks has been developed using the stir-bar sorptive extraction technique then thermal desorption GC-MS analysis. The extraction conditions - pH, sample volume, extraction temperature, salt addition, and extraction time - were examined. d5-Benzoic acid and p-hydroxybenzoic acid sec-butyl ester were added as surrogate internal standards to compensate for the effect of sample matrix and coexisting analytes on the sorptive extraction. The linearity of the method was good over the concentration range from 1 to 1000 microg mL(-1) for sorbic acid, 10-1000 microg mL(-1) for benzoic acid, and 0.1-100 microg mL(-1) for p-hydroxybenzoic acid ethyl, isopropyl, propyl, isobutyl, and butyl esters, and the correlation coefficients were higher than 0.9984. The limit of detection ranged from 0.015 to 3.3 microg mL(-1). The recoveries (95-105%) and precision (RSD: 0.86-6.0%) of the method were examined by analyzing a sparkling soft drink, white wine, red wine, balsamic vinegar, soy sauce, and quasi-drug drink samples fortified at the 5 to 50 microg mL(-1) level.

Acetic Acid↗
PubMedDate not supplied

[Adverse reactions to food preservatives].

We relate our experiences about the number of exacerbations that certain food preservatives such as sorbic acid, benzoic acid, sodium benzoate, metabisulfite and sodium nitrate can provoke in 62 patients affected with ASA-triad in steroid dependent intrinsic asthma with nasal polyps and acute bronchospasm caused by aspirin ingestion, and in 80 patients with chronic urticaria (C.U.) as well as the first assays of the possible usefulness of the HRT (Histamine release test automatized using whole blood) for the etiologic diagnosis process. In the cases of ASA-triad, and after the ingestion of aspirin (alternating with lactose in identical capsule), we consider the result as positive when the reduction of FEV1 is superior to 20% from its baseline value. Regarding the cases of C.U., the symptoms always exacerbate twice as much with the same substance within 24 hours of its administration. We have performed the HRT on 59 patients (14 with ASA-triad, 11 with steroid dependent intrinsic asthma; 20 with C.U. were negative to oral intake of analgesics/additives and 14 with C.U. showed positive results). Successive dilutions were incubated for 30 minutes using: pyrazolones, acetylsalicylate of lysine, sodium salicylate, sodium benzoate and 4-hydroxybenzoic acid which did not produce liberation of histamine in 100 controlled individuals. All the determinations were done in duplicate, considering positive those superior to 20% of the difference between total and basal histamine. We have not observed any significant descent of the FEV1 with benzoate and salicylate in our group of 62 patients with ASA-triad, nor any manifestations presented with sodium metabisulfite, sodium nitrate and sorbic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1969

Growth of Staphylococcus aureus MF31 on the top and cut surfaces of Southern custard pies.

A Staphylococcus strain was inoculated on the top and cut surfaces of freshly baked Southern custard pies which were then packaged in a pasteboard carton and held at 30 C. Daily plate counts of surface sections 0.3 inch (0.76 cm) in thickness were made. The top surface inoculum showed a 24-hr lag time. This was due to the protective action of a top cakelike layer as shown by homogenization of the mix and coating of the surface. Substitution of all sweeteners with dextrose completely inhibited growth on the top surface. Further addition of dextrose to lower water activity (Aw) to 0.9 prevented growth on the cut surface as well, but such pies were organoleptically unacceptable. Growth on the top surface could also be prevented by 80 mug of undissociated sorbic acid per g in combination with 100 mug of undissociated propionic acid per g in the baked pie. Growth on the cakelike top surface was always retarded longer than on the cut surface provided the packaging allowed evaporation of surface moisture. Reducing the Aw of a different type of cream pie to 0.907 prevented top surface growth. It was concluded that baked cream pies with a cakelike top layer could be marketed with a "refrigerate after opening" label, provided the package maintains the moisture gradient caused by the surface skin and either a combination of 80 mug of undissociated sorbic acid per g and 100 mug undissociated propionic acid per g is present in the baked pie or the Aw of the baked pie is 0.920 or lower.

Food Microbiology↗
PubMed1999

Zygosaccharomyces lentus: a significant new osmophilic, preservative-resistant spoilage yeast, capable of growth at low temperature.

Zygosaccharomyces lentus is a yeast species recently identified from its physiology and 18S ribosomal sequencing (Steels et al. 1999).The physiological characteristics of five strains of this new yeast so far isolated were investigated, particularly those of technical significance for a spoilage yeast, namely temperature range, pH range, osmotolerance, sugar fermentation, resistance to food preservatives such as sorbic acid, benzoic acid and dimethyldicarbonate (DMDC; Velcorin). Adaptation to benzoic acid, and growth in shaking and static culture were also investigated. Zygosaccharomyces lentus strains grew over a wide range of temperature (4-25 degrees C) and pH 2.2-7.0. Growth at 4 degrees C was significant. Zygosaccharomyces lentus strains grew at 25-26 degrees C in static culture but were unable to grow in aerobic culture close to their temperature maximum. All Z. lentus strains grew in 60% w/v sugar and consequently, are osmotolerant. Zygosaccharomyces lentus strains could utilize sucrose, glucose or fructose as a source of fermentable sugar, but not galactose. Zygosaccharomyces lentus strains were resistant to food preservatives, growing in sorbic acid up to 400 mg l-1 and benzoic acid to 900 mg l-1 at pH 4.0. Adaptation to higher preservative concentrations was demonstrated with benzoic acid. Resistance to DMDC was shown to be greater than that of Z. bailii and Saccharomyces cerevisiae. This study confirms that Z. lentus is an important food spoilage organism potentially capable of growth in a wide range of food products, particularly low pH, high sugar foods and drinks. It is likely to be more significant than Z. bailii in the spoilage of chilled products.

Antifungal Agents↗
PubMed1976

Rapid screening procedure for the determination of preservatives in ground beef: sulfites, benzoates, sorbates, and ascorbates.

A procedure is described for the examination of large numbers of ground beef samples for the 4 most commonly used preservatives. A single sample solution is prepared and aliquots are taken for the various tests. Sulfite is determined colorimetrically with acid-bleached prosaniline. Ascorbic acid is titrated with 2,6-dichloroindophenol. Benzoic and sorbic acids are measured by ultraviolet absorption. Negative samples are rapidly sorted out in this procedure and positive samples are completed for quantitative determination of the preservative. Recoveries are 95% for sodium sulfite, 103% for sodium benzoate, 90% for potassium sorbate, and 81% expected recovery for sodium ascorbate. The limit of detection is 0.005% for potassium sorbate, and 0.001% for the 3 other perservatives.

Ascorbic Acid↗