Recovery of Cold Impacted Escherichia Coli O157:H7 Bacteria in Ground Beef

Escherichia coli in fresh minced meat was injured by cooling at 4 °C. A bacterial population has three different physiology which are uninjured or normal cells, sublethally injured cells (or injured cells ), and lethally injured cells (or dead cells). Cell injury is defined as any damage to the components of cells themselves by any stresses which weaken the ability of cells to survive or multiply. This will increase the sensitivity of cells to any harmful factors. The cells can repair their injury which can be extended 48hour depending on the nature of stress and degree of injury. The purpose of this study was to: supplemented some cultural media and preparation new cultural media to isolated E.coli with compounds that supplemented the bacterial growth such as yeast extract, sodium pyruvate, n-propyl gallate, catalase, and Tween. Various concentrations of the compound were tested minced beef meat with mixed it and compared with traditional media. The rest of the compound had variable effects on the recovery of cold stressed cells but they weren’t as efficient as needed. It is, therefore recommended that 0.5% of both catalase and tween 80 be used to supplement tryptic soy agar (TSA) in the repair detection procedure.

Comparative assessment of quality and safety of minced meat

As a result of the examination of minced meat, it was found that the samples of industrial production (minced pork and minced beef), the packaging and completeness of the labeling corresponded to the requirements of Technical Regulations of the Customs Union 005/2011 and Technical Regulations of the Customs Union 022/2011, while the samples of mince of non-industrial production (minced pork and beef and minced beef) were packed at the point of retail sale in plastic bags without labeling indicating the type of minced meat. In terms of organoleptic indicators, minced meat samples No. 1, No. 2 and No. 4 met the requirements of GOST R 55365-2012 and were classified as “fresh” bouillon. During the determination of biochemical and bacterioscopic indicators for freshness, it was found that in the samples of industrial minced meat No. 2 and non-industrial production No. 3 there was an increased content of amino-ammonia nitrogen and pH. At the same time, in the sample in No. 3 a non-standard color was noted during the reaction with Nessler’s reagent: dirty green color. No. 2 had a weakly positive reaction to peroxidase during the reaction with the same reagent. Bacterioscopic examination of smears - minced meat imprints in samples No. 2 and No. 3 revealed no more than 30 gram-negative rods, which can be the food poisoning reasons. These results are typical for suspected meat. In terms of the content of heavy metals, the insignificant excess of the norm of cobalt in sample No. 1 and manganese in sample No. 2 was revealed. The content of toxic elements: lead and cadmium in all samples did not exceed the permissible level.

RESEARCH INTO THE THERMOPHYSICAL CHARACTERISTICS OF MUSCLE AND ADIPOSE TISSUES IN THE FREEZING–THAWING PROCESS

The paper presents a study of the thermophysical characteristics of meat systems based on minced beef and pork with different morphological composition in the freezing–thawing process, and those of model systems based on minced beef with addition of adipose tissue (raw fat). The method used to detect and compare the thermodynamic changes consisted in determining the effective specific heat capacity by freeze-thaw thermograms and was based on a set of informational parameters related to it (cryoscopic temperature, cryoscopic interval of temperatures, specific heat of phase transition in the cryoscopic temperature interval, change of enthalpy in the interval of temperatures of the sample tested, proportion of moisture that changes its physical state in the cryoscopic temperature interval). It has been shown that the morphological structure of meat (the ratio of muscle, connective, and adipose tissues) significantly affects the thermophysical parameters of meat systems during freezing and defrosting. It has been found that under the conditions of a freeze–thaw cycle, an increase in the content of connective tissue leads to a higher proportion of moisture that changes its physical state in the cryoscopic temperature interval, while an increase in the adipose tissue content in a meat system reduces the moisture that changes its physical state in the cryoscopic temperature interval. When adipose tissue was introduced into meat systems, the freezing process resulted in a higher rate of formation of ice crystals and a lower rate of moisture migration from cells to the intercellular space, and crystal formation became a controlled process. When manufacturing semi-finished frozen meat products, regulating the ratio of muscle and adipose tissues makes it possible to influence the stability of the properties of meat systems in the technological cycle “freezing – storage – thawing” and to create products with the required functional, technological, and thermophysical parameters. This research can be a basis for developing the recipe compositions and technological parameters of manufacturing semi-finished frozen meat products and finished products based on them

Artificial neural network prediction of microbiological quality of beef minced meat processed for fast-food meals

In this study, the microbiological quality of 72 minced beef meat samples collected during six months from a local butcher was defined after laboratory analysis and developing advanced mathematical models. This new simultaneous approach provided adequate precision for the prediction of the microbiological profile of minced beef meat as one of the easily spoiled products with a short shelf life. For the first time, an artificial network model was developed to predict the microbiological profile of beef minced meat in a fast-food restaurant according to meat and storage temperatures, butcher identification, and work shift. A concurrent statistical study of practical analysis and the developing mathematical models provided adequate precision for the prediction of the microbiological profile of minced beef meat. The developed ANN provided a good prediction of the microbiological profile of beef minced meat with an overall R2 of 0.867 during the training cycle.

Effect of the improved protein-mineral additive on structural-mechanical characteristics of minced meat

The results of research on the effect of protein-mineral improved additive (PMIA) on the rheological parameters of minced meat, which can be used for manufacturing culinary products, including chopped semi-finished products of a high degree of readiness, are presented. It has been proven, that the additive can be used both as an ingredient, enriching calcium-digestible compounds and to improve a number of technological properties of minced meat, in particular after freezing, storage and thawing. The aim of the study was to determine the dependences of changes in the structural and mechanical characteristics of minced meat after the addition of PMIA and subsequent freezing to a temperature of –16…–18 °C and storage for 20 days. It has been found, that the addition of up to 7 % of PMIA leads to a marked increase in the conditionally instantaneous modulus of elasticity and highly elastic modulus in 4.4 times for minced beef and 2.7 and 4.4 times for chicken, respectively. It has been established, that the best stabilization of these indicators after freezing occurs at the content of PMIA at the level of 2…5 %. Studies of plastic viscosity and adhesion have shown that the use of up to 7 % of PMIA leads to an increase of 11…20 % and 26…64 %, respectively. After freezing, the plastic viscosity and adhesion of minced beef in the control decreased by 22.0 and 52 %, respectively, minced chicken – by 23.4 and 40.9 %. In the samples with a content of 7 % of PMIA, the decrease in plastic viscosity and adhesion is 7.2 and 4.4 % in minced beef and in chicken – 5.9 and 3.1 % respectively. It has been proven, that the use of PMIA in the amount of up to 7 % in the technology of minced meat production minimizes the negative destructive effect of low temperatures on the structural and mechanical characteristics of the finished product. Thus, it is expedient to use up to 7.0 % of the improved protein-mineral additive in the composition of minced meat to enrich the finished product with digestible calcium compounds and improve their structural and mechanical characteristics, in particular after freezing and storage

Pistachio Hull Extract as a Practical Strategy to Extend the Shelf Life of Raw Minced Beef: Chemometrics in Quality Evaluation

The agricultural processing industry produces a notable quantity of by-products rich in bioactive compounds, which can be exploited for agri-food applications. From pistachio industrial processing, pistachio’s hull is one of the major by-products. This work aimed to evaluate the potential of pistachio hull, as a potential source of natural antioxidant, to preserve the meat quality. Here, we investigated the impact of aqueous pistachio hull extract (PHE) at 0.156% (PHE1), 0.312% (PHE2), and 0.625% (PHE3) on the quality of raw minced beef meat stored for 14 days at 4°C. At the end of storage, mesophilic total viable plate, psychotropic and Enterobacteriaceae counts, showed significantly lower ( P < 0.05 ) microbial count in PHE samples. PHE3 revealed a powerful inhibitory effect on lipid/protein oxidation, and sensory characteristics were positively ( P < 0.05 ) affected. Principal component analysis and heat map indicated complex and close synchronized relations among lipid/protein oxidation processes, microbial loads, and sensory attributes. Obtained results using univariate and multivariate statistical analysis underlined the importance of using different mathematical approaches, which are complementary to each other and could provide considerable information about the minced beef meat treated by PHE. Therefore, compared to synthetic antioxidants, PHE could be a clean-label alternative that can protect and enhance the quality of meat products.