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Evaluation of the quality of pet foods using fast techniques and official methods. This paper was designed to evaluate the rancidity of 18 pet food samples using Alimentos grasos yahoo dating Diamed FATS kits and official AOCS methods for the quantification of free fatty acids, peroxide value and concentrations of malonaldehyde and alkenal in the lipid extracted.

Although expiration dates have passed, the samples presented good quality evidencing little oxidative rancidity. The results of this study suggest that the Brazilian pet food market is replete with products of excellent quality due to the competitiveness of this market sector.

Embora estivessem fora do prazo de validade, as amostras apresentaram boa qualidade, indicada pelos baixos valores de rancidez oxidativa. Alimentos grasos yahoo dating pet food market in Brazil has been growing rapidly. The highly competitive nature of the market means that the quality of the final product, especially the presence of rancidity resulting from lipid oxidation, can have a critical impact on sales and should be monitored.

The oil and fat components of the formula are responsible for the main sensory alterations that occur in pet foods during their shelf lives due to lipid oxidation, also known as rancidity.

Rancidity has a great economic impact on the food industry because it leads to undesirable flavors and odors. Since the acceptance of foods containing lipids in their constitution depends on the extent of their oxidation GRAY,monitoring lipid oxidation is crucial to determine the quality of pet foods.

Rancidity can be divided into hydrolytic rancidity and oxidative rancidity. Hydrolytic rancidity is the hydrolysis of an ester bond by lipase or moisture. It refers to Alimentos grasos yahoo dating and oil hydrolysis producing free fatty acids FFA by the action of enzymes present in the oilseed grains or of microbiological origin. Oxidative rancidity is Alimentos grasos yahoo dating complex and involves a considerable number of reactions.

The oxidation rate is affected by the fatty acid composition of the foods, degree of unsaturation of the fats, presence and activity of pro-oxidants and antioxidants, partial pressure of the oxygen and storage conditions of the foods, such as temperature, and exposure to light and humidity BELITZ; GROSCH, It is mediated by atmospheric oxygen and an unsaturated fat leading to the formation of initial products denominated hydroperoxides and final products such as aldehydes, polymers, glycerides, diglycerides, fatty acids, and etc.

Since many of the pet food manufacturers probably do not have a laboratory equipped for conventional routine analyses, it is very Alimentos grasos yahoo dating to use fast methods.

The peroxide contents present in the Alimentos grasos yahoo dating lipid from animal or vegetable sources are transitory components that decompose into a variety of carbonylic and other compounds, mainly 2,4 dienals and 2-alkenals, in the presence of p-anisidine in an acidic medium.

The anisidine value is defined as times the optical density of a solution containing 1. The TBA number is calculated as milligrams of "Alimentos grasos yahoo dating" per kilogram of sample. There is a vast literature on TBA test methods. According to the sensibility Table 1 and application Table 2they were divided into 3 ranges: Strong correlations were found between the kits and the AOCS official methods: Studies with complex matrices, in which lipid is not the only component of the food, are still lacking.

The samples showed different degrees of oxidation and none had past their expiration date. The packages were opened only on the first day of analysis. After that, the packages were sealed and the samples were kept frozen. On the first day of the analyses, the samples were evaluated by the official methods and on the following day by the respective kit.

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All tests were done in triplicate. The official methods adopted are described below.

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The titulant used was 0. Since using a more dilute titrant solution did not affect the correlation between the kit results and the results of the official method for refined vegetable oils, lard, and hydrogenated fats OSAWA et al.

The sample size was also reduced Alimentos grasos yahoo dating this case. In an attempt to eliminate the interference by water, the reagents isooctane, acetic acid, and p-anisidine were purified prior to analysis, as described by Osawaand their moisture contents were then determined. Purification of the reagents for the p-anisidine test. The isooctane was treated with sulfuric acid with occasional agitation for 24 hours. Afterwards, an aqueous solution of 0.

The solution was filtered and distilled, according to Swinehart and Fessenden and Fessenden Alimentos grasos yahoo dating, discarding the head and tail. This solution was kept in contact with anhydrous sodium sulfate until the day of the analyses, when it was filtered for use.

The glacial acetic acid used was treated with potassium permanganate in a ratio of 5 g per 1 L of acetic acid keeping it in contact for 24 hours. Similar to the procedure with isooctane, the solution was distilled and kept in contact with Alimentos grasos yahoo dating sodium sulfate until used.

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The p-anisidine crystals were dried in a vacuum desiccator for Absorbance readings were obtained from the same equipment used for the p-anisidine test. Moisture Alimentos grasos yahoo dating of the reagents. Alimentos grasos yahoo dating initial agitation was adjusted to 30 seconds and the titration end point to 30 mA, Alimentos grasos yahoo dating the equipment automatically stopped the transference of the titrant solution. For the water equivalence determination, 20 mg of water was injected into the titration vessel with a 1-mL syringe Microstat Tuberculin, United States.

Reagent A is a solvent. Reagent C is only used for the PeroxySafe kit and consists of an acidified iron solution. The material used for the kit determinations consisted of: The lipid contents of the samples were determined by acid hydrolysis, in duplicate, as described by Osawa Initially, some basic statistical parameters were evaluated such as: The linear regression was then studied to compare the FFA values obtained using the DiaMed kits with those obtained using the official method.

The software Minitab for Windows version Hydrolytic rancidity has occurred the samples studied, with increasing FFA formation during storage, as opposed to oxidative rancidity, indicated by the low peroxide values and concentrations of alkenals and malonaldehydes.

The pet food samples analyzed presented lipid contents from For the measurements determined using the kits, the following values were obtained on a lipid basis: For a kit to be considered reliable, the results obtained from it must be accurate and precise. In this study, the precision was evaluated from the CV values while the correlation or otherwise with the official methods determined if the kit was accurate or otherwise.

Both set of methods showed acceptable repeatability precision according to the low values for the CVs found for all the kits tested except for the p-anisidine test that was subjected to water interference even after purification of all reagents involved prior to the analyses.

Even though the samples had past the expiration date, in general, they had undergone little oxidation due to the antioxidant system used in the formulation of the pet foods. Six samples samples M, N, P, Q, R, and S presented alkenal concentrations below the detection limit of the kit adopting the minimum possible dilution Table 3. Nevertheless, the determinations made with these kits were more sensitive as they discriminated a larger number of samples in the Tukey test than the official methods Tables Alimentos grasos yahoo dating and 4.

Due to the small range of values for PV, p-anisidine, and TBA the correlation studies of these kits with the official methods were not done. A correlation coefficient r of 0. The r-value of "Alimentos grasos yahoo dating." However, when a titrator was used for the official method determination, the results with the kits needed to be corrected by a factor of 0.

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Possibly, the darker color of the lipid extracted interfered in the visualization of the titration end point resulting in the use of more titrant solution OSAWA et al. Thus, it contributed to the higher value of the correction factor if compared to that required for refined and olive oils or when a titrator was used instead of the analyst's perception. By trial and error, multiplying the results obtained with the kit by 1. For the peroxide value Alimentos grasos yahoo dating, the visualization of the end point of titration was difficult overestimating the PVs.

In addition, the results obtained with Alimentos grasos yahoo dating kit stressed the very small differences detected discriminating a higher number of significantly different samples from the AOCS official method Table 9.

This interfered in the test leading to lower results. The maximum value permitted for moisture in the samples is 0. After purification, the p-anisidine crystals had 1. In the "Alimentos grasos yahoo dating" test, the 1-butanol used had 0. Thus, the p-anisidine test suffered from an inherent interference by the Alimentos grasos yahoo dating and reagents present in the samples OSAWA et al.

The value for the control was much lower than the expected range of 14 to 15 nmol. This could be explained by the fact that the AlkalSafe TM STD kit was the only one in which the calibrators were ready to read solutions and did not depend on the reagents used in the control or in the sample tests. The TBA test generated less accurate results and mainly to a numerical order of 10 The AldeSafe STD TM kit, on the other hand, provided results to numerical orders of 10 0 to 10 2 making it easier to differentiate the samples from the malonaldehyde concentration values Table 4.

The TBA test is not an accurate measurement although it is widely used and well known. The authors adapted the method to achieve results to the magnitude of nmol. No other study was found correlating the results of this kit with those of the AOCS official method. The main advantages of applying kits to monitor the quality of pet foods are the significant reduction in the Alimentos grasos yahoo dating size, since lipid is not Alimentos grasos yahoo dating only compound present, and time and solvents saved for the extracting the lipids and performing the analysis.

The lipid extraction procedure adopted in this experiment for the "Alimentos grasos yahoo dating" with the official methods was time-consuming, presented low yields since no heating was allowed, had a lot of steps and used a lot of equipment and materials. Moreover, the large amounts of samples and reagents needed for the lipid extraction and subsequent conventional analyses make shelf-life studies unfeasible from the economic point of view, especially when the lipid content is very low.

The DiaMed FATS kits could be used with minimum residue generation, smaller amounts of sample, less time devoted to analysis, more precise results, and no need for a laboratory fully equipped with sophisticated equipment. The pet food samples evaluated presented good quality in terms of oxidative rancidity although they would be discarded for having passed the expiration date before being analyzed. This means that the sector is concerned about the quality of the products being commercialized.

The DiaMed FATS kits are precise and recommended for shelf-life studies of samples which require lipid extraction prior to analysis since they are fast, involve significantly less sample and reagents, are compact Alimentos grasos yahoo dating do not demand large areas or sophisticated equipment, and offer better work conditions and less risks to the analyst.

The results generated by this study suggested that they represent good alternatives in cases where the lipid content is low or the stage of oxidative rancidity is minimum considering the limitations in sensitivity of the official methods. Evelyne de Groove, and to Total Alimentos Brazil for the pet food samples provided. Official methods and recommended practices of the American Oil Chemists' Society.

American Oil Chemists' Society, Editora da Unicamp, Global 21sept. Analysis of lipid hydroperoxides. Journal of Lipid Science and Technologyv. Techniques and experiments for organic chemistry. También afecta el ¿qué? y ¿cómo? pueden afectar los alimentos a la persona68 y otros aceites vegetales, así como los pescados grasos como el salmón. obesidad; sexo; dieta; bajada de peso; [email protected] estado Alimentos grasos yahoo dating salud.

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