Sorbic acid, 1-p-tolylhydrazide

Development of a LC-MS/MS method for the simultaneous determination of sorbic acid, natamycin and tylosin in Dulce de leche.[Pubmed:27283692]

Food Chem. 2016 Nov 15;211:748-56.

A simple extraction, rapid routine method for the simultaneous determination of sorbic acid, natamycin and tylosin in Dulce de leche, a traditional South American product, by liquid chromatography-tandem mass spectrometry has been developed and fully validated. The limits of detection were set to 24.41mgkg(-1) (sorbic acid), 0.10mgkg(-1) (natamycin) and 2mugkg(-1) (tylosin). Recoveries ranged from 95% to 110%. Proportionally, internal standardization was more efficient than external standard, resulting in a smaller measurement of uncertainty. In total, 35 commercial samples from Brazil, Argentina and Uruguay have been assessed. The proposed method was tested on other dairy desserts, demonstrating to be versatile. Although tylosin was not detected in any sample, a high rate of non-compliance was found, with 67.39% of samples above the maximum allowed for sorbic acid and a maximum concentration of 2105.36+/-178.60mgkg(-1). In two samples, natamycin was irregularly found.

In-capillary derivatization with o-phthalaldehyde in the presence of 3-mercaptopropionic acid for the simultaneous determination of monosodium glutamate, benzoic acid, and sorbic acid in food samples via capillary electrophoresis with ultraviolet detection.[Pubmed:27156753]

J Chromatogr A. 2016 Jun 3;1449:156-65.

For the rapid simultaneous determination of monosodium glutamate (MSG), benzoic acid (BA), and sorbic acid (SA) in canned food and other processed food samples, we developed a method that combines in-capillary derivatization with separation by capillary electrophoresis. This method employs the rapid derivatization of MSG with o-phthalaldehyde (OPA) in the presence of 3-mercaptopropionic acid (3-MPA) and enables the detection of the resulting OPA-MSG derivative and of non-derivatized BA and SA at 230nm. The composition of the background electrolyte and the parameters of derivatization and separation are as follows: 25mM borax containing 5mM OPA and 6mM 3-MPA, separation voltage 25mV, injection at 30mbar for 20s, and column temperature 25 degrees C. Because of the high reaction rate and suitably adapted effective electrophoretic mobilities, band broadening due to the derivatization reaction at the start of the separation process is kept to a minimum. The optimized method is validated with respect to LOD, LOQ, linearity, recovery, and precision. This method can be applied to real samples such as soy, fish, oyster and sweet and sour chili sauces after application of appropriate clean-up steps. Mechanisms of zone broadening and zone focusing are discussed showing the validity of the employed theoretical approach regarding the dependence of the peak shape for OPA-MSG on the concentration of MSG in the sample.

Quantifying the effect of sorbic acid, heat and combination of both on germination and outgrowth of Bacillus subtilis spores at single cell resolution.[Pubmed:26338121]

Food Microbiol. 2015 Dec;52:88-96.

Bacillus subtilis spores are a problem for the food industry as they are able to survive preservation processes. The spores often reside in food products, where their inherent protection against various stress treatments causes food spoilage. Sorbic acid is widely used as a weak acid preservative in the food industry. Its effect on spore germination and outgrowth in a combined, 'hurdle', preservation setting has gained limited attention. Therefore, the effects of mild sorbic acid (3 mM), heat-treatment (85 degrees C for 10 min) and a combination of both mild stresses on germination and outgrowth of B. subtilis 1A700 spores were analysed at single spore level. The heat-treatment of the spore population resulted in a germination efficiency of 46.8% and an outgrowth efficiency of 32.9%. In the presence of sorbic acid (3 mM), the germination and outgrowth efficiency was 93.3% and 80.4% respectively whereas the combined heat and sorbic acid stress led to germination and outgrowth efficiencies of 52.7% and 27.0% respectively. The heat treatment clearly primarily affected the germination process, while sorbic acid affected the outgrowth and generation time. In addition a new 'burst' time-point was defined as the time-point at which the spore coat visibly breaks and/or is shed. The combined stresses had a synergistic effect on the time of the end of germination to the burst time-point, increasing both the mean and its variation more than either of the single stresses did.

Survival of the functional yeast Kluyveromyces marxianus B0399 in fermented milk with added sorbic acid.[Pubmed:26547644]

J Dairy Sci. 2016 Jan;99(1):120-9.

In this study, the survival of the functional yeast Kluyveromyces marxianus B0399 in an industrially produced fermented milk was evaluated. In particular, the yeast viability was assessed throughout the entire shelf-life of the product (30 d) to ensure the presence of the effective yeast dose (20 million viable cells for each serving of 125 g) while avoiding, by sorbic acid addition, yeast growth, which could affect product quality and stability. To find the best combination of yeast and sorbic acid concentration, 13 different combinations were tested, and then 2 of them were chosen for industrial production. In production at lower concentrations (30 million viable cells, 150 mg/kg of sorbic acid) the effective dose was maintained only at 4 and 6 degrees C, whereas at higher dosages (70 million viable cells, 250 mg/kg of sorbic acid) the effect of temperature was less evident. In all the trials, the concentration of sorbic acid was not affected by microbial metabolism and remained stable throughout the entire shelf-life.