Carmen A. Campos

Sorbate–nitrite reactions in meat products

Abstract The effects of system composition and processing conditions on the formation of mutagenic reaction products (ethylnitrolic acid and 1,4-dinitro-2-methylpyrrole) from the reaction of potassium sorbate and sodium nitrite were investigated in model systems resembling meat products, using gas chromatography–mass spectrometry and high perfomance liquid chromatography. It was observed that 1,4-dinitro-2-methylpyrrole formation was precluded when ascorbic acid or cysteine were present. Ethylnitrolic acid was detected in all systems studied after heating at 35 or 60°C. Results highlight the need for minimizing the combined use of nitrites and sorbates in food products.

Sorbate destruction and non-enzymatic browning in model aqueous systems Destruccion de sorbatos y pardeamiento no enzimático en sistemas modelo acuosos

The effect of system composition on sorbate destruction and sensory damage due to non-enzy matic browning was studied in aqueous model systems with a water activity (a w) of 0.91 and a pH of 5.0-6.0. The rate constants of sorbate destruction could be described by first order kinetics and those from non-enzymatic browning by zero order kinetics. Both reactions were found to be related not only to temperature and pH but also to the humectants (NaCl, glycerol) used to depress a w. A higher preservative retention and a smaller amount of browning was produced by the use of a mixture of 35.0 g/kg of NaCl and 220.0 g/kg of glycerol as a humectant instead of one of them alone, citric acid instead of phosphoric acid as the acidifying agent, and glass flasks instead of polyethylene containers. The non-enzymatic browning reactions were greatly influenced by sorbic acid destruction. The inclusion of glycine was responsible for the enhanced sorbate destruc tion and browning development.

Determination of nitrites in meat systems: An improved procedure

Various analytical methods for nitrite determination in meat products, based on extraction of the preservative through digestion at 60-80 °C followed by colorimetric analysis gave relatively poor recoveries (44-65%) when applied to raw beef. An improved procedure was developed based on disintegration and dispersion of beef with sand prior to the extraction step and on the use of a higher concentration of N-(1-naphthyl) ethylenediamine dihydrochloride than normally used. The proposed technique resulted in almost 93% recovery of nitrites and showed a high precision revealed in a variation coefficient of 8̃%.

Effect of stabilizers, oil level and structure on the growth of Zygosaccharomyces bailii and on physical stability of model systems simulating acid sauces

The effect of xanthan gum, guar gum, oil and the structure promoted by these compounds on the growth of Zygosaccharomyces bailii and on physical stability of emulsified systems simulating acid sauces was studied. Furthermore, the effect of yeast growth on physical stability of emulsions was also evaluated. Yeast growth was evaluated by plate count and modeled by the modified Gompertz equation. Emulsions characteristics and their stability were determined by droplet size, zeta potential and rheological measurements. The latter was also used to evaluate structures effect on yeast growth. Physical characteristics of emulsions depended on system composition. Yeasts slightly affected droplet size. Z. bailii growth was satisfactorily modeled by the modified Gompertz equation. The specific growth rate (μm) and the asymptotic value (A) obtained depended on xanthan gum, guar gum and oil content. Furthermore, the structure promoted by these compounds exerted a significant effect on growth. In general, an increase in the solid character and yield stress through the addition of xanthan gum promoted a decrease in A parameter. On the contrary, a decrease in the solid character through the addition of guar gum promoted an increase in the A parameter. The results obtained stressed that stabilizers, oil and their structuring ability play an important role on Z. bailii growth.

Studies of the effect of ethylene diamine tetraacetic acid (EDTA) on sorbic acid degradation

Abstract The effect of ethylene diamine tetraacetic acid (EDTA) on sorbic acid degradation and the resultant browning was studied at 33, 45 and 57 °C in model aqueous systems with pH 5.0 and a water activity of 0.91. The EDTA enhanced sorbate degradation probably as a result of iron scavenging from the packaging material (glass or polypropylene) through EDTA complexation. We propose that EDTA-Fe 2+ complex catalyzes sorbic acid autoxidation, increasing the production of carbonyls which take part in nonenzymatic browning. Both effects might influence shelf-life of products containing sorbates and EDTA.

Interactions Between Additives: Its Effect on Sorbate Stability and Z. bailii Minimum Inhibitory Concentration in Model Aqueous Systems Resembling Salad Dressings

The effect on sorbate stability of several additives (EDTA, ascorbic and acetic acids) frequently present in the formulation of salad dressings, and the minimal inhibitory concentration (MIC) of sorbate concerning Z. bailii growth in the presence of that additives were studied in aqueous model systems of pH 3.5. The addition of EDTA, ascorbic acid and the use of acetic acid protected sorbic acid from destruction. In particular, the presence of 0.075 g/kg of EDTA was essential for minimizing sorbates destruction and keeping, after 90 days of storage at 33°C, its residual concentration above 0.400 g/kg. This value is the MIC for inhibiting the growth of Z. bailii when systems were packed in PET flasks and citric and acetic acids were used as acidulants. Packaging material, acidifying agent and EDTA level showed a strong influence on the effect of EDTA on sorbates stability. As an example, in the case of systems acidified only with citric acid and containing 0.075 g/kg or 0.500 g/kg of EDTA, it was necessary the use of glass flasks and the lowest concentration of EDTA to get a residual preservative concentration above the MIC after 90 days of storage at 33°C. Se estudió el efecto de varios aditivos (EDTA y ácidos ascórbico y acético) presentes frecuentemente en la formulación de aderezos para ensaladas en la estabilidad del ácido sórbico en sistemas modelo acuosos. También se determinó la mínima concentración inhibitoria de este conservante respecto al crecimiento de Z. bailii en presencia de dichos aditivos y a un pH de 3,5. La adición de EDTA, ácido ascórbico y el uso de ácido acético tuvieron un efecto protector en la destrucción del ácido sórbico. En particular, la presencia de 0.075 g/kg de EDTA resultó esencial para minimizar la destrucción del sorbato y mantener su concentración por encima de 0,400 g/kg, después de 90 días de almacenamiento a 33°C, ya que esa era la concentración mínima para inhibir el crecimiento de Z. bailii en sistemas envasados en frascos de PET y que contenían ácidos cítrico y acético como acidificantes. El material del envase y la concentración de EDTA ejercieron una fuerte influencia sobre la estabilidad de los sorbatos. Por ejemplo, en el caso de los sistemas acidificados sólo con ácido cítrico y con un 0,075 g/kg or 0,500 g/kg de EDTA, fue necesario el uso de frascos de vidrio y de la menor concentración del complejante para tener una concentración residual de ácido sórbico que fuese superior a la MIC después de 90 días a 33°C.

Sorbic acid stability in meat products of reduced water activity

This study investigated the behavior of sorbic acid in shelf-stable meats with 0.91 water activity during processing (70 °, 80 °, 90 °C) and accelerated storage (33 °, 45 °, 57 °C). In meat systems stored at 70 °, 80 ° and 90 °C, after approximately 0·5-3 days, the destruction rate of sorbic acid diminished. This change in behavior (break) was probably caused by the limited availability of oxygen and/or the inhibitory action of nonenzymatic browning products on sorbate destruction. Before the break, the rate constants were found to be related to temperature, pH, the acid used to adjust it and the humectants added to depress water activity (NaCl, glycerol, the mixture NaCl 3·5% and glycerol). After the break, none of the above mentioned effects were observed. In meat systems stored at 33 °, 45 ° and 57 °C the rate of destruction was constant with time. The rate constants of meat systems were higher than the ones obtained for aqueous systems of similar composition, revealing that meat components played an important role in the destruction of sorbates.

Inhibitory action of potassium sorbate degradation products against Staphylococcus aureus growth in laboratory media

The inhibitory action of potassium sorbate (KS) degradation products against Staphylococcus aureus growth was examined in model aqueous systems. KS degradation products formation was induced by the storage at 70 degrees C for 7 days or at 37 degrees C for 90 days of aqueous systems containing basically brain heart infusion, yeast extract and different amounts of KS at pH 5.5. After storage, residual amounts of KS were measured and each system was inoculated with a pool of three S. aureus strains at 10(4) colony forming units/ml. Degradation products from KS generally inhibited S. aureus growth by two to three log cycles. However, the population of S. aureus reached a higher level when the degradation products were formed at 37 degrees C suggesting that the nature of the degradation products seemed to depend on the temperature at which they were produced. The inhibitory activity produced by KS degradation products along with residual amounts of KS was smaller than the one produced by the initial amounts of the preservative.

Data on the physical characterization of oil in water emulsions

This article contains experimental data and images for the physical characterization of oil in water emulsions. Mentioned data are related to the research article “Effect of stabilizers, oil level and structure on the growth of Zygosaccharomyces bailii and on physical stability of model systems simulating acid sauces” (A.L. Zalazar, M.F. Gliemmo, C.A. Campos, 2016) [1]. Physical characterization of emulsions was performed through the evaluation of Span and Specific Surface Area (SSA) determined by light scattering using a Mastersizer. Furthermore, microscopy images were recorded by confocal scanning laser microscopy (CSLM). The latter are presented to collaborate in the analysis of emulsion microstructure.

Effect of gamma irradiation and storage time on microbial growth and physicochemical characteristics of pumpkin (Cucurbita Moschata Duchesne ex Poiret) puree

The effect of gamma irradiation (0–2 kGy) and storage time (0–28 days) on microbial growth and physicochemical characteristics of a packed pumpkin puree was studied. For that purpose, a factorial design was applied. The puree contained potassium sorbate, glucose and vanillin was stored at 25 ℃. Gamma irradiation diminished and storage time increased microbial growth. A synergistic effect between both variables on microbial growth was observed. Storage time decreased pH and color of purees. Sorbate content decreased with storage time and gamma irradiation. Mathematical models of microbial growth generated by the factorial design allowed estimating that a puree absorbing 1.63 kGy would have a shelf-life of 4 days. In order to improve this time, some changes in the applied hurdles were assayed. These included a thermal treatment before irradiation, a reduction of irradiation dose to 0.75 kGy and a decrease in storage temperature at 20 ℃. As a result, the shelf-life of purees increased to 28 days.