Discriminatory power of MALDI-TOF MS protein profiling analysis of pork meat and meat products.

Forty different sample preparation methods were tested to obtain the most informative MALDI-TOF MS protein profiles of pork meat. Extraction by 25% formic acid with the assistance of zirconia-silica beads followed by defatting by methanol:chloroform mixture (1:1, v/v) and deposition by using the layer-by-layer method was determined as the optimum sample preparation protocol. The discriminatory power of the method was then examined on samples of pork meat and meat products. The method was able to discriminate between selected salami based on the production method and brand and was able to monitor the ripening process in salami. However, it was not able to differentiate between different brands of pork ham or closely located parts of pork meat. In the latter case, a more comprehensive analysis using LC-MS/MS was used to assess the differences in protein abundance and their relation to the outputs of MALDI - TOF MS profiling.

The Effect of High-Pressure Processing on the Survival of Non-O157 Shiga Toxin-Producing Escherichia coli in Steak Tartare: The Good- or Best-Case Scenario?

Samples of steak tartare were artificially contaminated with a cocktail of Shiga toxin-producing Escherichia coli (STEC) O91, O146, O153, and O156 to the level of 3 log and 6 log CFU/g. Immediately after vacuum packing, high-pressure processing (HPP) was performed at 400 or 600 MPa/5 min. Some of the samples not treated with HPP were cooked under conditions of 55 °C for 1, 3, or 6 h. HPP of 400 MPa/5 min resulted in a 1-2 log reduction in the STEC count. In contrast, HPP of 600 MPa/5 min led to the elimination of STEC even when inoculated to 6 log CFU/g. Nevertheless, sub-lethally damaged cells were resuscitated after enrichment, and STEC was observed in all samples regardless of the pressure used. STEC was not detected in the samples cooked in a 55 °C water bath for 6 h, even after enrichment. Unfortunately, the temperature of 55 °C negatively affected the texture of the steak tartare. Further experiments are necessary to find an optimal treatment for steak tartare to assure its food safety while preserving the character and quality of this attractive product.

Cooking loss in retail beef cuts: The effect of muscle type, sex, ageing, pH, salt and cooking method.

The aim of the study was to compare cooking losses in beef (striploin and cube roll) during various cooking methods (grilling, roasting, broiling) in two different cooking devices (convection oven and clamshell grill). A total of 400 samples of meat were cooked (an internal temperature of more than 70 °C) and analysed. Cooking losses of slices of striploin ranged between 24.5% and 34.8%, with losses of 25.9-35.8% when whole cuts of meat were roasted. Losses fell within similar ranges (24.7-33.7%) for cube roll. Beef after 21 days of dry ageing showed generally lower cooking losses. Principal component analysis confirmed a strong negative correlation between cooking losses and salt content, saltiness and juiciness, which were positively correlated with one another. The majority of the sensory properties were positively correlated with pH, while their relationship with Warner-Bratzler (WB) test was negative. Roasting in a convection oven would seem to be the most suitable method of cooking striploin, followed by broiling in a convection oven, with grilling in last place. The highest score for the majority of sensory properties and the lowest WB values were recorded in meat roasted in a convection oven, particularly in the meat of bulls aged for 21 days.

Effect of preservatives on the shelf-life and sensory characteristics of pasteurized liquid whole egg stored at 4°C.

The study focused on the effects of traditional (benzoate-sorbate and triphosphates) and alternative (nisin, Laktocid, Defence JB, and Galimax Flavor) food preservatives on the microbiological quality and sensory properties of pasteurized liquid whole eggs (LWE). The LWE samples with the addition of a test preservative and a control were stored at 4°C for 45 D. The selected microbiological parameters, sensory attributes, and color space parameters were determined. The results were statistically analyzed by means of factorial ANOVA, followed by the Tukey post hoc test. The multivariate method of principal component analysis based on the correlation matrix was employed to assess the relationships between pH and sensory characteristics of LWE. Total plate counts at the end of storage differed significantly, being the lowest in samples with benzoate-sorbate (1.69 ± 0.12 log cfu.g-1) and Laktocid (2.12 ± 0.12 log cfu.g-1). The final counts of lactic acid bacteria on day 45 were lower in the samples with benzoate-sorbate, triphosphates, nisin, and Laktocid (maximum 1.01 ± 1.44 log cfu.g-1). The amounts of yeasts at the end of storage did not differ among samples with different preservatives; none were detected in any samples with the exception of Defence JB (1.28 ± 1.90 log cfu.g-1). The lowest final mold count was observed in LWE with Laktocid (0.92 ± 1.29 log cfu.g-1). In conclusion, Laktocid showed great potential as a preservative; it had however a negative impact on pH value and the sensory properties of LWE.