Delaying the spoilage of fresh and processed meats

Abstract

Various anti-microbial treatments were studied with respect to their use for the sheif-h'fe extension of meat and meat products. The treatments studied were bacteriocins (pediocin AcH and nisin), organic acids, immobilization, ion chelators, high pressure and irradiation. These were then compared using statistical analysis so as to identify treatment effects on the dynamics of growth of the spoilage bacteria. The experiments focused especially on exploiting the potendal of pediocin AcH for this purpose. Statistical analysis of preliminary data indicated that pediocin AcH had an inhibitory effect on meat microflora although the level of the activity was not adequate for a significant extension in shelf life. Also the effect of pediocin when used in conjunction with immobilization and organic acids was not very clear. Of the organic acids, acetic acid proved more effective in reducing and controlling the numbers of spoilage microflora. In order to study the use of pediocin AcH, large amounts of the bacteriocin were needed. The first step of the study was therefore geared towards the production of large amounts of the bacteriocin and the analysis of the prepared solution for its level of purity. A scale-up method was developed for the purification of pediocin from 50 liters of culture. Next, the action of the bacteriocin on Listeria monocytogenes, cells in both broth and meat systems was studied. This was done primarily to address the issue of bacteriocin activity in foods systems. Pediocin AcH at 200,000 arbitrary units (ALT) effected greater reduction of microbial numbers when acting in combination with 1.5% lactic acid than when used alone. This anti-listerial activity and additive effect were adversely affected by increasing salt concentrations. In the next step, Pediocin AcH was applied to various samples of ground beef and the surviving microflora isolated and characterized. With low levels of bacteriocin (10,000 AU/g) the survivors consisted most of Staphylococcus aureus. Micrococcus luteus, Pseudomonas spp., Acinetobacter spp., some lactic acid bacteria (LAB) and Bacillus spp., most of which dominate spoilage microflora of meat. Increasing the level of Pediocin to 100,0(X) AU/g caused a decrease in the numbers ofS. aureus, M. luteus, LAB and Bacillus spp. but did not affect Pseudomonas spp. and Acinetobacter spp. The persistence of Pediocin AcH in raw and cooked meat was studied at different storage temperatures. The bacteriocin persisted in sterile raw ground meat for up to 4 d at 25°C, for 15 d at 7°C and for more than 6 months in frozen samples. In cooked meat, bacteriocin was detectable for up to 6 d when stored at 25°C and for more than 3 months at 4°C. The bacteriocin also remained unaffected by irradiation up to doses of 7.0 kGy and high hydrostatic pressure of up to 100 kpsi. The next experiment focused on determining if the use of ion chelators (like EDTA and Maltol), Triton X-IOO, and Tween 80 in conjunction with pediocin extended the target range of the bacteriocin to gram-negative bacteria. The e...

Real-Time and Rapid Food Quality Monitoring Using Smart Sensory Films with Image Analysis and Machine Learning

“…Spline regression models can be used to add extra predictive data while raising the power or precision of the known predictors. In our case, the cubic Spline model is used to avoid overfitting and add precision to the model regarding various colors of RGB based upon pH values of pork loin meat from both experimental and collected data sets. ,− Also, Spline was used to estimate the gaps in our experimental data, while validating the estimations and/or predictions for high accuracy was derived for each color component, RGB, at an adjusted R-square of 0.888, 0.8948, and 0.6807, respectively (Tables S6–S8). To remove the gaps in data sets and meanwhile make reliable, valid estimations and predictions, the experimental and collected data at known fixed points, such as at pH 6.0 and 5.8 with associated RGB values, were estimated using the Spline technique, which allowed the flexibility between estimations but avoided the overfitting of data causing added randomness instead of precision in our food quality model.…”

“…The criteria for literature data selection include food type (pork lion,) and pH range (2.6–10), which matches the same condition as in our experimental cases. The literature data (Table S11) − has been used to further strengthen our model. To obtain an accurate food spoilage classification using the sensory film colormaps and machine learning method, we identified three relevant spoilage parameters (pH, acetic acid (AA) content, and storage time (ST) representing categories pH, AA, ST).…”

Use of pediocin with other barriers for control of Listeria monocytogenes on ready-to-eat (RTE) processed meats

“…Macronutrients, such as protein, carbonates and fat, are also not affected by doses up to 10 kGy. Sundaram (1999) employed different treatment combinations using pediocin combined with irradiation (3 kGy) and high hydrostatic pressure (HHP) (75,00 psi for 5 min) as well as other treatments to extend the shelf-life of raw and cooked lean beefsteaks. This study indicated that pediocin is tolerant to stresses of irradiation and HHP at certain levels.…”

“…Free radicals cause extensive damage to cellular components by reacting with them. The damage to cells includes deoxyribonucleic acid (DNA) strand breaks, base damage, denaturation of proteins (Sundaram, 1999) and cytoplasmic membranes (Mendonca, 2002). Breaking bonds in DNA results in the loss of a cell's ability to replicate.…”

“…A study by Sundaram (1999) suggested synergistic effects between pediocin and irradiation treatments.…”