Changes In Pork Research Articles

Heat/Cold Stress and Methods to Mitigate Its Detrimental Impact on Pork and Poultry Meat: A Review.

This paper aims to provide an updated review and current understanding of the impact of extreme temperatures-focusing on heat stress (HS)-on the quality of pork and poultry meat, particularly amidst an unprecedented global rise in environmental temperatures. Acute or chronic HS can lead to the development of pale, soft, and exudative (PSE) meat during short transportation or of dark, firm, and dry (DFD) meat associated with long transportation and seasonal changes in pork and poultry meat. While HS is more likely to result in PSE meat, cold stress (CS) is more commonly linked to the development of DFD meat. Methods aimed at mitigating the effects of HS include showering (water sprinkling/misting) during transport, as well as control and adequate ventilation rates in the truck, which not only improve animal welfare but also reduce mortality and the incidence of PSE meat. To mitigate CS, bedding on trailers and closing the tracks' curtains (insulation) are viable strategies. Ongoing efforts to minimize meat quality deterioration due to HS or CS must prioritize the welfare of the livestock and focus on the scaleup of laboratory testing to commercial applications.

Unveiling microwave and Roasting-Steam heating mechanisms in regulating fat changes in pork using cell membrane simulation

Fat reduction due to heating or cooking is an important issue in a healthy diet. In the current study, pork subcutaneous back fat was treated via microwave heating (MH) within 10—90 s and roasting - steam heating (RSH) within 2—30 min and their dynamic changes of individual adipocytes were explored by using vesicles as a bio-membrane model. The result showed that MH and RSH significantly increased fat loss (P < 0.05), with the maximum losses being 74.1 % and 65.6 %, respectively. The mechanical strength of connective tissue decreased and then increased slightly. The microstructure demonstrated that MH and RSH treatments facilitated a large outflow of fat, showing that the particle size of the vesicle and individual adipocytes increased and then decreased. It is thus feasible to study the dynamic changes of individual adipocytes in regulating fat reduction using cell membrane simulation.

Battery-Free Pork Freshness Estimation Based on Colorimetric Sensors and Machine Learning

In this study, a compact smart-sensor tag is developed for estimating pork freshness. The smart sensor tag can be placed in areas where packaged meat is stored or displayed. Antennas and simulated models were developed to maximize the efficiency of radio frequency (RF) energy harvesting. The proposed smart sensor tag includes a red, green, and blue sensor that detects changes in the freshness of meat. To detect the color changes in pork stored at a perishable hot temperature in an outdoor environment, this study applies Hue, Saturation, and Value conversion using machine learning, through which the freshness can be determined with a high degree of accuracy. Validation experiments of the sensor tag performance demonstrate that meat freshness can be detected at distances up to 50 cm from the RF using only the RF energy harvesting without changing the battery source. The 1D convolutional neural network model outperforms the traditional MLP and ConvLSTM models in terms of accuracy and loss.

Dynamic relationships among changes in prices of beef, pork, and chicken in Japan: A Bayesian approach

In this paper, we investigate the interdependence among changes in the prices of beef, pork, and chicken in Japan using a time-varying coefficient vector autoregressive model. Our empirical analysis using monthly data from January 1990 to March 2014 shows that changes in beef prices have long-term influences on changes in pork and chicken prices. Moreover, current changes in the prices of beef, pork, and chicken are closely related to changes in their prices in the preceding two months. Additionally, we do not find that the bovine spongiform encephalopathy outbreak announced by the Japanese government in September 2001 had a long-term influence on the dynamic relationships among changes in the prices of beef, pork, and chicken in Japan.

The butterfly effect in the price of agricultural products: A multidimensional spatial-temporal association mining

With the advent of the era of big data, data mining methods show their powerful information mining ability in various fields, seeking the association information hidden in the data, which is convenient for people to make scientific decisions. This paper analyses the butterfly effect in the agricultural product industry chain from the perspective of producer and consumer by using multidimensional time and space theory and proposes a new price forecasting method. We consider that the price change of agricultural products is not only affected by the balance of market supply and demand but also by the factors of time and space. Taking the pig industry chain of Sichuan Province as an example, this paper explores and excavates the data from 2010 to 2020 in the time dimension. Interestingly, we found that the price changes in pork in the market are generally highly correlated with the prices of slaughtered pigs, piglets a few weeks ago and the prices of multiple feed a few months ago. Based on the precise time-space factors, we improved the price forecasting model, greatly improved the accuracy of price prediction, and proved the effectiveness of multidimensional spatiotemporal association mining. The research in this paper is helpful to establish a brand-new agricultural product price prediction theory, which is of great significance to the development of the agricultural economy and global poverty alleviation.

Morphological structure properties of the musculus longissimus dorsi in pigs in the process of autolysis

A multitude of physical and bio-chemical processes take place during autolysis, including ATP break-up (dephosphorylation) that leads to glycogen phosphorylation, intensive accumulation of myofibrillar proteins, concentration of lactic (and phosphorous) acids that affect the state of muscle proteins. This, in turn, affects the technological properties of meat. Histological examination of the longest back muscle of pigs showed a distinct cross-striation of muscle fibers. Histological examination of the longest back muscle of pigs showed a distinct cross-striation of muscle fibers. During autolysis, micro-cracks appeared with minor breaks in sarcolemma, and only some muscle fibers areas had contraction nodes. During autolysis, micro-cracks appeared with minor breaks in sarcolemma, and only some muscle fibers areas had contraction nodes. Raw meat, which was classified as DFD (dark, sticky) according to the quality criteria, had a different structure. Cross-section of its fibers were rounder, fibers were tightly placed to each other, cell structures only slightly damaged. Analysis of the histological and ultrastructural changes in pork of different quality groups shows that the processes of deterioration of muscles in PSE and DFD groups cause significant changes in optical and geometrical properties of the surface and near-surface layers and affect the development of autolytic processes and intensity of destructive changes.

Changes in pork and shark (Rhizopriondon terraenovae) protein emulsions due to exogenous and endogenous proteolytic activity

Protein unfolding is the main emulsifying mechanism in meat products. However, myofibrillar protein depletion resulting from endogenous or exogenous protease activity affects the emulsifying properties. The objective of this work was to study the effect of endogenous and exogenous proteases on protein depletion, emulsifying and viscosity properties in a model meat emulsion. Pork and shark meat were treated with a Pseudomonas fluorescens protease extract; endogenous proteolytic activity was studied in non-treated meat; samples were stored at 4 and 15 °C up to 15 days and emulsions formulated with extracted myofibrillar proteins. Endogenous proteolytic activity of shark meat extracts was significantly higher as compared to pork, promoting more extended protein degradation. This resulted in lower viscosity of protein extracts and emulsions. However, viscosity increased in both species throughout the study time, probably due to protein unfolding and molecular interaction. Emulsion capacity and stability increased in pork but decreased in shark, due to exogenous protease addition.

Post-mortem changes in pork using parallel needles for both light scattering and low-frequency electrical properties

Parallel 16-gauge hypodermic needles 3 mm apart were used to measure the optical and electrical properties of 60 samples of sternocephalicus muscle from 15 pigs in the first few hours after slaughter (mean sampling time 150 ± 84 min post mortem). Altogether, 1992 sets of measurements were made automatically under computer control at 27.3 ± 4.4 °C. Samples were illuminated at 633 nm by light from a helium-neon laser passing through an optical fiber in one hypodermic needle. Scattered light was collected by an optical fiber in the other needle and measured with a photomultiplier. The myofibers themselves appeared to act as optical fibers, channelling light more readily along, rather than across their length. This effect was confirmed ( p ≤ 0.01) from 450 to 700 nm with white light from a xenon arc. Laser scattering decreased post mortem ( r = −0.18, p ≤ 0.001). The electrical properties of meat between the needles were measured at a low frequency (20 Hz), concurrently with optical measurements. Capacitance across the longitudinal axes of myofibers was lower than when measured with needles coaxial with the myofibers (4.23 ± 1.20 μF versus 4.44 ± 1.38 μF, respectively, p ≤ 0.01). The lowest ( p ≤ 0.001) capacitance was along the longitudinal axes of myofibers (4.04 ± 1.21 μF). Resistance across fibers did not differ significantly from coaxial resistance (1823 ± 253 Ω versus 1834 ± 302 Ω, respectively). The highest ( p ≤ 0.001) resistance was along the fibers (1962 ± 278 Ω). Capacitance increased ( r = 0.35, p ≤ 0.001) post mortem, while resistance first increased ( r = 0.19, p ≤ 0.005) before decreasing overall ( r = −0.30, p ≤ 0.001). This transient change in resistance was unlikely to have been caused by the effect of temperature on electrolyte conductance. In measurements made with needle electrodes coaxial with the longitudinal axes of myofibers, scattering was correlated with capacitance and resistance ( r = 0.31 and r = −0.14, respectively, p ≤ 0.001) with little effect from time of measurement. In this orientation, simultaneous measurement of light scattering and low-frequency electrical capacitance might enhance the early post-mortem prediction of pork quality.

Measurement of Postmortem Changes in Pork by High-Speed Compression Hysteresis

Measurement of Postmortem Changes in Pork by High-Speed Compression Hysteresis

Post-mortem spectrophotometry of pork and beef using quartz optical fibres

A high intensity xenon illuminator, a diffraction grating monochromator and a photomultiplier were linked to pork or beef samples with a bifurcated light guide composed of quartz optical fibers in a random pattern. When muscle fibres and optical fibres were parallel and coaxial, absorbance was greater than when they were perpendicular. As judged by the coefficient of variation at different wavelengths, the effect of fat in the measuring field was not uniform at all wavelengths. For the study of optical changes in pork, from slaughter to 24 h, the fibre-optic probe was maintained in a stationary position. The changes detected were: (1) a slight transient increase in absorbance at all wavelengths in the first few hours post mortem, (2) an eventual decline in absorbance at all wavelengths to reach minimum values at 24 h and (3) a spectrally limited decrease in absorbance, peaking somewhere in the 390 to 450 nm range, which started immediately post mortem.

Bacteriology of prepacked pork with reference to the gas composition within the pack.

SUMMARYBacteriological changes in pork stored at 16 and 2° under gas permeable and gas impermeable films and ‘aerobic’conditions have been studied. The concentrations of CO2, O2 and N2 in the atmosphere within the packs were also determined. The groups of bacteria isolated from prepacked pork were Pseudomonas‐Achromobacter spp., Kurthia spp., Microbacterium thermosphactum, Enterobacter‐Hafnia spp. and lactobacilli. Their importance is discussed in relation to storage temperature and gas composition within the packs.

Post‐Mortem Changes in Muscle II. Chemical and Physical Changes in Pork

SUMMARYThe chemical changes occurring from 0 to 24 and/or 48 hr post‐mortem were followed in longissimus dorsi muscle from 18 pork carcasses. In an attempt to induce soft, watery pork, one side from each of 13 carcasses was placed at 37°C immediately after slaughter, and the other side of each carcass was subjected to ‐29°C. Values for pH, glycogen, total reducing sugars, and lactic acid differed markedly at 0 time. Carcasses from Poland China pigs showed a stoichiometric relationship between the post‐mortem decrease in glycogen and the corresponding accumulation of lactic acid and total reducing sugars. This relationship was less apparent in Hampshire pigs. The 37°C treatment did not consistently result in soft, watery and pale muscle, as was expected from other reports. This suggests that exposure of muscle to a low pH at a high temperature per se does not necessarily cause the soft, watery, and pale appearance. A loss in fibrillar water‐binding capacity as a result of low pH values and high muscle temperatures confirmed earlier investigations. However, the decrease in fibrillar water‐binding capacity as a result of the low pH at high muscle temperatures did not usually make the muscle appear soft and watery. Results indicate that even though a loss in fibrillar water‐binding capacity occurs as a consequence of a low pH and high temperature, and is a characteristic frequently encountered in soft, watery muscle, low fibrillar water‐binding capacity by itself is not the primary causal factor in making pork muscle appear soft and watery. Post‐mortem levels of ATP, creatine phosphate, lactic acid, total reducing sugars and glycogen are reported and compared with literature values.