Beef Samples Research Articles

Microbial Profiling of Biltong Processing Using Culture-Dependent and Culture-Independent Microbiome Analysis

Biltong is a South African air-dried beef product that does not have a heat lethality step, but rather relies on marinade chemistry (low pH from vinegar, ~2% salt, spices/pepper) in combination with drying at ambient temperature and low humidity to achieve microbial reduction during processing. Culture-dependent and culture-independent microbiome methodologies were used to determine the changes in the microbial community at each step during biltong processing through 8 days of drying. Culture-dependent analysis was conducted using agar-based methods to recover viable bacteria from each step in the biltong process that were identified with 16S rRNA PCR, sequencing, and BLAST searching of the NCBI nucleotide database. DNA was extracted from samples taken from the laboratory meat processing environment, biltong marinade, and beef samples at three stages of processing (post-marinade, day 4, and day 8). In all, 87 samples collected from two biltong trials with beef obtained from each of three separate meat processors (n = six trials) were amplified, sequenced with Illumina HiSeq, and evaluated with bioinformatic analysis for a culture-independent approach. Both culture-dependent and independent methodologies show a more diverse population of bacteria present on the vacuum-packaged chilled raw beef that reduces in diversity during biltong processing. The main genera present after processing were identified as Latilactobacillus sp., Lactococcus sp., and Carnobacterium sp. The high prevalence of these organisms is consistent with extended cold-storage of vacuum-packaged beef (from packers, to wholesalers, to end users), growth of psychrotrophs at refrigeration temperatures (Latilactobacillus sp., Carnobacterium sp.), and survival during biltong processing (Latilactobacillus sakei). The presence of these organisms on raw beef and their growth during conditions of beef storage appears to 'front-load' the raw beef with non-pathogenic organisms that are present at high levels leading into biltong processing. As shown in our prior study on the use of surrogate organisms, L. sakei is resistant to the biltong process (i.e., 2-log reduction), whereas Carnobacterium sp. demonstrated a 5-log reduction in the process; the recovery of either psychrotroph after biltong processing may be dependent on which was more prevalent on the raw beef. This phenomenon of psychrotrophic bloom during refrigerated storage of raw beef may result in a natural microbial suppression of mesophilic foodborne pathogens that are further reduced during biltong processing and contributes to the safety of this type of air-dried beef.

Influence of alternating magnetic field on the quality of beef and its protein during cold storage

SummaryMagnetic field is an appropriate physical field, it can be used as a process parameter for the preservation of meat products. In this study, fresh beef was subjected to an alternating magnetic field of 2 mT during cold storage at 4°C, then microbial indicators, physicochemical properties of beef samples and its protein indicators were investigated. The results showed that the alternating magnetic field could inhibit the microbial growth on beef sample, and TVB‐N content, drip loss and characteristic putrefactive amine were lower than the control. The total bacterial count and TVB‐N value of beef samples in the control exceeded the threshold value on the 8th day, respectively, while the samples in the alternating magnetic field exceeded the threshold value on the 13th day. Meanwhile, it demonstrated that the field could delay the transformation of free amino acids to biogenic amines and inhibit the accumulation of bitter amino acids, so maintaining its nutritional characteristics. With the extension of storage period, the sulfhydryl content of beef myofibrillar proteins subjected to alternating magnetic field was lower than that of the control. It demonstrated that the protein oxidation of samples was inhibited, which would also be the reason the Ca2+‐ ATPase activity of myofibrillar proteins was maintained at a low level during the period. Furthermore, the upward trend of carbonyl group content was delayed. It provides a reference for the application of alternating magnetic field on cold storage of meat.

Variations in the Metabolome of Unaged and Aged Beef from Black-and-White Cows and Heifers by 1H NMR Spectroscopy.

(1) Background: The selection of raw material and the postmortem processing of beef influence its quality, such as taste. In this study, the metabolome of beef from cows and heifers is examined for differences during aging. (2) Methods: Thirty strip loins from eight heifers and seven cows (breed code: 01-SBT) were cut into ten pieces and aged for 0, 7, 14, 21 and 28 days. Samples from the left strip loins were wet-aged in vacuum, while samples from right strip loins were dry-aged at 2 °C and 75% relative humidity. The beef samples were extracted with methanol-chloroform-water, and the polar fraction was used for 1H NMR analysis. (3) Results: The PCA and OPLS-DA showed that the metabolome of cows and heifers varied. Eight metabolites revealed significant differences (p < 0.05) in the samples from cows and heifers. The aging time and aging type of beef also affected the metabolome. Twenty-eight and 12 metabolites differed significantly (p < 0.05) with aging time and aging type, respectively. (4) Conclusions: The variations between cows and heifers and aging time affect the metabolome of beef. By comparison, the influence of aging type is present but less pronounced.

Characteristic flavor fingerprint disclosure of dzo beef in Tibet by applying SAFE-GC-O-MS and HS-GC-IMS technology

To understand the overall flavor of the dzo beef, fatty acids, volatile compounds and aroma profiles of dzo beef samples (raw beef (RB), broth (BT) and cooked beef (CB)) were investigated by head-space-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and gas chromatography-mass spectrometry (GC–MS). The fatty acid analysis showed a decrease in the ratio of polyunsaturated fatty acids, such as linoleic acid, which decreased from 2.60 % in RB to 0.51 % in CB. The principal component analysis (PCA) showed that HS-GC-IMS was able to distinguish different samples. A total of 19 characteristic compounds with odor activity value (OAV) > 1 were identified by gas chromatography–olfactometry (GC-O). Fruity, caramellic, fatty and fermented attributes were enhanced after stewing. Butyric acid and 4-methylphenol were responsible for the stronger off-odor in RB. 3-Hydroxy-2-butanone and 2,5-dimethyl-4-hydroxy-3(2H)-furanone with buttery and caramellic attributes were dominated in BT, while (E)-2-nonenal, (E,E)-2,4-decadienal and (E,E)-2,4-nonadienal prominently conferred fatty attribute on CB. Furthermore, anethole with anisic aroma was first identified in beef, which may be one of the typical chemical markers that distinguish dzo beef from other varieties.

Distributions of polychlorinated naphthalenes in beef from China and associated health risks

Polychlorinated naphthalenes (PCNs) are toxic and can accumulate through the food chain. PCNs have been detected in different categories of foods. Intake of animal-derived foods is an important pathway for human exposure to PCNs. However, information on PCNs in meat from farmed animals is scarce. In this study, PCNs were assessed in beef sourced from local markets in Beijing and six provinces in China. The mean PCN concentrations in beef samples from the seven regions varied from 41.2 to 88.7 pg/g wet weight (ww). The homologue profiles of PCNs in the specimens were similar, with tri- and di-CNs being dominant. The mean concentration of PCNs in the flank (74.7 pg/g ww) was higher than that in the round (58.2 pg/g ww) or shank (53.6 pg/g ww), likely because the former contained a higher proportion of lipids than the latter. Significantly different PCN distributions in beef and dairy cow milk were identified using machine learning. The toxic equivalencies (TEQs) of PCNs in all beef samples ranged from 0.0003 to 0.022 pg TEQ/g ww. PCNs contributed to approximately 4.6% of the total TEQ values of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, and PCNs in the beef. Health risks related to the intake of PCNs through beef consumption by the average person living in China were minimal.

Determination of oxprenolol, methandienone and testosterone in meat samples by UHPLC-Q-ToF

The presence of some drugs in meat samples can cause threat to human health, therefore, its analysis is highly desirable for food safety purposes. In this work, a solid-phase extraction procedure for the determination of oxprenolol, a non-selective beta-blocker, and such anabolic agents as methandienone and testosterone in beef meat samples has been developed. Extraction conditions were optimized to achieve high sensitivity and accuracy of the results. The procedure was validated using meat samples free from target analytes. As a result, high selectivity and sensitivity were observed with the detection limits between 0.25 and 1.25 ng/g, and the results were not affected by matrix components. The proposed procedure was applied to the analysis of real beef samples purchased in the market, and the results have revealed the presence of contaminated samples. The concentration of oxprenolol in the contaminated sample was 7 ng/g, methandienone content in the sample was 30 ng/g, while testosterone level was 4 ng/g.

Tenderization of Beef Semitendinosus Muscle by Pulsed Electric Field Treatment with a Direct Contact Chamber and Its Impact on Proteolysis and Physicochemical Properties.

In this study, the effects of pulse electric field (PEF) treatment on the tenderization of beef semitendinosus muscle were investigated. An adjustable PEF chamber was designed to make direct contact with the surface of the beef sample without water as the PEF-transmitting medium. PEF treatment was conducted with electric field strengths between 0.5 and 2.0 kV/cm. The pulse width and pulse number were fixed as 30 μs and 100 pulses, respectively. The impedance spectrum of PEF-treated beef indicated that PEF treatments induced structural changes in beef muscle, and the degree of the structural changes was dependent on the strength of the electric field. Cutting force, hardness, and chewiness were significantly decreased at 2.0 kV/cm (35, 37, and 34%, respectively) (p < 0.05). Troponin-T was more degraded by PEF treatment at 2.0 kV/cm intensity (being degraded by 90%). The fresh quality factors such as color and lipid oxidation were retained under a certain level of PEF intensity (1.0 kV/cm). These findings suggest that PEF treatment could tenderize beef texture while retaining its fresh quality.

Terrestrial animal livers as a source of PCDD/Fs, PCBs and PBDEs in the diet

The livers of terrestrial animals are an important source of vitamins and minerals, but with the liver being the major filtering and detoxifying organ, it retains xenobiotic material, especially persistent organic pollutants (POPs). The aim of the study was human health risk assessment related to the presence of certain POPs, namely polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in terrestrial animals' livers. HRGC-HRMS was used to determine analyte concentrations in 99 liver samples of chicken, pork, beef, and mutton livers obtained from Polish farms. The ovine livers were the most contaminated by ∑PCDD/F/dl-PCBs (0.06–2.21 pg WHO-TEQ g−1 wet weight), ∑ndl-PCBs (0.036–1.54 ng g−1 wet weight) and ∑PBDEs (0.21–2.27 ng g−1 wet weight). Samples were found of ovine and pork livers that exceeded the maximum concentration limits established for PCDD/Fs. The Kruskal–Wallis test showed that there were statistical differences between regions in the concentrations of the ∑PCDD/Fs and ∑PCDD/F-PCBs, but none in those of the ∑dl-PCBs, ∑ndl-PCBs or ∑PBDEs. According to Dunnett's test results, ovine liver samples from the Podlaskie province contained fewer ∑PCDD/F than those from the Dolnośląskie (p < 0.027) and Małopolskie (p < 0.0342) voivodeships. Taking into account PCDD/F contents and Tolerable Weekly Intake (2 pg WHO-TEQ/kg BW) (TWI2018), the lowest risk was associated with chicken liver consumption (TWI up to 11 % in the 95th percentile), pork (62 %) and bovine (92 %) livers should be eaten in limited amounts for risk avoidance, while mutton liver (400 %) should not be eaten at all. Additionally, there is no risk of ingestion of a harmful amount of PBDEs associated with consumption of the livers of terrestrial animals from Poland based on the margin of exposure values (>15).

Indentification of Beef in Beef and Chicken Experiments using Conducting Polymer Sensor Series and Kohonen Algorithm Method

Chicken, and beef each have a distinctive aroma. Identification of Chicken and beef based on the aroma of the meat using an electronic nose. This electronic nose uses a series of sensors consisting of 6 (six) pieces and uses a Conducting Polymer. This polymer has a high resistance so it is widely used as an insulator. However, this resistance has a certain limit where the polymer surface will turn into carbon and conduct electric current if exposed to excessive electric charge. This research was conducted by taking samples of chicken and beef as test samples where these meats were placed in a closed container at room temperature. Data is taken alternately every day to find out the odor of each meat where on the first day data is taken from the odor of chicken, and on the second day data is taken from the odor of beef. This condition is done to ensure the freshness of each meat. This study uses a Neural Network (NN) as pattern recognition and ATMega16 microcontroller as data acquisition. Neural Network is trained using Kohonen. The sensor used is a Conducting Polymer sensor because of the nature of the Conducting Polymer where the output is a voltage generated due to changes in the polymer resistance resistance. A two-layer neural network consisting of six input nodes and three output neurons is trained using the Kohonen algorithm with the training process completed in 31 iterations. The test was carried out 30 times for each exposure to steam from the odor of chicken and beef which was carried out alternately. The percentage of success of the system is 100%.&#x0D;

Improving the Shelf Life and Quality of Minced Beef by Cassia Glauca Leaf Extracts during Cold Storage

Minced beef is a popular meat product due to its low price and superior nutritional value. The contamination of minced beef is a significant risk for the worldwide meat market. Both natural and synthetic preservatives are used to expand the shelf life and improve the quality properties of meat. The harmful effects of synthetic preservatives make natural preservatives more appealing. Therefore, this research was performed to study the impact of different concentrations of Cassia glauca leaf extract (CGE) on increasing the shelf life of minced beef. Seventy-two minced beef samples were divided into control, 0.25, 0.5, and 1% w/w CGE treated groups. The control and treated samples were kept at 3 ± 1 °C in the refrigerator for 15 days. Minced beef samples’ sensory, chemical, and microbiological properties were assessed every three days. The gained results showed that the CGE addition effectively decreased the microbial count and maintained the minced beef’s sensory and chemical quality. Additionally, CGE extended the shelf life of minced meat up to 15 days under the proper refrigeration condition compared to the control group, which decomposed after the sixth day of refrigeration. Our study suggested that CGE could be used as a natural preservative for refrigerated minced meat.

Antibiotic-Resistant Bacteria, Antimicrobial Resistance Genes, and Antibiotic Residue in Food from Animal Sources: One Health Food Safety Concern.

Antibiotic-resistant bacteria causing foodborne serious illnesses can be found in contaminated food. Therefore, this study aimed to identify the pathogens, genes, and antimicrobial residues present in raw milk and meat. We collected 40 raw milk and 40 beef samples using the aseptic method from various parts of the Faisalabad metropolis, Pakistan. The samples were cultured on blood, MacConkey, and UTI chrome agar. The VITEK 2 compact system was used for microbial identification and determination of minimum inhibitory concentrations. Antimicrobial resistance genes for extended-spectrum β-lactamases, methicillin resistance in Staphylococcus aureus, and carbapenem resistance were identified using molecular techniques. ELISA was used to determine the tetracycline residue level in each sample. The beef samples showed polymicrobial contamination with 64 bacterial isolates, with Escherichia coli (29; 45.3%) and Klebsiella pneumoniae (11; 17.1%) predominating. The milk samples showed polymicrobial contamination with 73 bacterial isolates, with E. coli (22; 30%), K. pneumoniae (12; 16.4%), and S. aureus (10; 13.6%) forming the majority. Twenty-eight (43.7%) isolates from beef harbored tet genes, nineteen (29.6%) blaCTX-M, and fourteen (21.8%) blaNDM-1, and twenty-six (35.6%) isolates from milk harbored tet genes, nineteen (26%) blaTEM and blaCTX-M, and three (4%) blaNDM-1. Twenty-two (55%) each of the beef and milk samples exceeded the maximum residue limit for tetracycline. Polymicrobial contamination by bacteria possessing blaCTX-M, blaTEM, blaNDM-1, blaOXA, mecA, and tet genes was identified in food samples. The high tetracycline residue levels pose a serious health risk to consumers.

Joint-detection of Salmonella typhimurium and Escherichia coli O157:H7 by an immersible amplification dip-stick immunoassay

To explore the superiority of multifunctional nanocomposites and realize the joint-detection of foodborne pathogens, an immersible amplification dip-stick immunoassay (DSIA) was exploited for the sensitive detection of Salmonella typhimurium (S. typhi) and Escherichia coli O157:H7 (E. coli O157:H7). Saving for the basic colorimetric performance, the reporter molecule of CoFe2O4 (CFO) possesses multivalent elements (Co2+/3+, Fe2+/3+) as well as multifunction of superior catalase-like activity and magnetic properties. By dint of the catalytic activity of CFO, a directly immersible amplification can be simply achieved to endure the DSIA with an intensive signal and a dual-visible mode for the determination of S. typhi and E. coli O157:H7. In virtue of the magnetic separation and enrichment capability of the CFO, the DSIA can perform a matrix-interference-free detection and obtain a dynamic detection range of 102–108 CFU/mL and a low assay limit of 102 CFU/mL. Moreover, the DSIA has reasonable recovery rates for contamination monitoring of two target bacteria in milk and beef samples. Our research provides a persuasive supplement for the application of multifunctional nanocomposites in the ongoing dip-stick immunoassay and an alternative strategy for the efficient detection of foodborne pathogens.

Repressive epigenetic mechanisms, such as the H3K27me3 histone modification, were predicted to affect muscle gene expression and its mineral content in Nelore cattle

Epigenetic repression has been linked to the regulation of different cell states. In this study, we focus on the influence of this repression, mainly by H3K27me3, over gene expression in muscle cells, which may affect mineral content, a phenotype that is relevant to muscle function and beef quality. Based on the inverse relationship between H3K27me3 and gene expression (i.e., epigenetic repression) and on contrasting sample groups, we computationally predicted regulatory genes that affect muscle mineral content. To this end, we applied the TRIAGE predictive method followed by a rank product analysis. This methodology can predict regulatory genes that might be affected by repressive epigenetic regulation related to mineral concentration. Annotation of orthologous genes, between human and bovine, enabled our investigation of gene expression in the Longissimus thoracis muscle of Bos indicus cattle. The animals under study had a contrasting mineral content in their muscle cells. We identified candidate regulatory genes influenced by repressive epigenetic mechanisms, linking histone modification to mineral content in beef samples. The discovered candidate genes take part in multiple biological pathways, i.e., impulse transmission, cell signalling, immunological, and developmental pathways. Some of these genes were previously associated with mineral content or regulatory mechanisms. Our findings indicate that epigenetic repression can partially explain the gene expression profiles observed in muscle samples with contrasting mineral content through the candidate regulators here identified.

Multivariate analysis of heavy metals content of beef from Soroti, Uganda.

Information about food hygiene and quality in the sub-Saharan African countries remains scarce at a time when many of their citizenry are beginning to acquire the much coveted middle income status. Confounding this are challenges linked to monitoring on a continuous basis the safety of food produced by such lucrative industries as the beef industry. The objective of the current study was to initiate a process of encouraging changes in the status quo, by showing how a first step in that direction might look like. Using heavy metal contents of representative beef samples from butcheries in Soroti, Uganda, typical of a sub-Saharan country, we demonstrate how relationships and common sources of metals in food could be identified in a multivariate space. Beef samples from 40 sites were analyzed by atomic absorption spectrometry for iron (Fe), zinc (Zn), nickel (Ni), chromium (Cr), lead (Pb), copper (Cu), cobalt (Co) and cadmium (Cd). The study showed that all beef samples contained these metals, the extent of which were in the order: Fe>Zn>>Ni, Cr>Pb>Cu, Co>Cd. By correlation analysis, the pairs Ni and Cr, Cd and Co, Ni and Fe or Cr and Fe were found to be most likely coming from similar sources. At least three distinct characteristics of beef consumed in Soroti were also found, a distinction perhaps arising from three major categories of feedlots used to raise donor cattle. The incremental risk of children or adults developing cancer over a lifetime was estimated and found to fall into three categories, two of which are separately explained by the presence of Cr or Ni. The sources of these metals remain a matter of speculation on our part. More studies are needed to determine these sources and to understand the nature of cancer risk in the three categories of beef identified here.

Influence of biosafety protocols adopted for the prevention of SARS‐CoV‐2 in slaughterhouses and a positive effect on the reduction of Staphylococcus aureus presence in beef cuts

AbstractStaphylococcus aureus is a food quality indicator microorganism commonly found in human mucous membranes. With the emergence of the virus related to SARS‐CoV‐2, several prevention protocols were established. Therefore, this study assessed whether the adoption of SARS‐CoV‐2 protocols influenced the presence of S. aureus in beef samples. We analyzed the S. aureus results of 3654 beef samples between April and September 2019 and 2020. Mean percentages of the population of S. aureus were different between years (2.63%—2019; 1.13%—2020), revealing that after the adoption of the SARS‐CoV‐2 protocols there was a decrease in the presence of S. aureus. Concomitantly, a significant difference was also presented in the annual means of S. aureus load counts (2.30 log of CFU/g in 2019, and 1.60 log of CFU/g in 2020), of the sets of beef samples analyzed. Therefore, we suggest that the measures used to prevent SARS‐CoV‐2 can continue to be applied even after the pandemic, especially in the stages that involve beef handling in slaughterhouses.

Infrared Spectroscopy-Based Chemometric Analysis for Lard Differentiation in Meat Samples

One of the most pressing concerns for the consumer market is the detection of adulteration in meat products due to their preciousness. The rapid and accurate identification mechanism for lard adulteration in meat products is highly necessary, for developing a mechanism trusted by consumers and that can be used to make a definitive diagnosis. Fourier Transform Infrared Spectroscopy (FTIR) is used in this work to identify lard adulteration in cow, lamb, and chicken samples. A simplified extraction method was implied to obtain the lipids from pure and adulterated meat. Adulterated samples were obtained by mixing lard with chicken, lamb, and beef with different concentrations (10%–50% v/v). Principal component analysis (PCA) and partial least square (PLS) were used to develop a calibration model at 800–3500 cm⁻¹. Three-dimension PCA was successfully used by dividing the spectrum in three regions to classify lard meat adulteration in chicken, lamb, and beef samples. The corresponding FTIR peaks for the lard have been observed at 1159.6, 1743.4, 2853.1, and 2922.5 cm⁻¹, which differentiate chicken, lamb, and beef samples. The wavenumbers offer the highest determination coefficient R² value of 0.846 and lowest root mean square error of calibration (RMSEC) and root mean square error prediction (RMSEP) with an accuracy of 84.6%. Even the tiniest fat adulteration up to 10% can be reliably discovered using this methodology.

Occurrence of Klebsiella pneumoniae and Salmonella spp. in beef and cow milk from central Kerala

Klebsiella pneumoniae is a clinically important opportunistic pathogen and Salmonella spp. is a major food-borne pathogen causing gastroenteritis worldwide. The present study was conducted to determine the occurrence of K. pneumoniae and Salmonella spp. in beef and cow milk collected from central Kerala. The study was conducted in a span of 10 months from, January 2022 to October 2022. A total of 400 samples, comprising of 200 raw cow milk samples and 200 beef samples, were collected from different milk societies and retail shops of Thrissur and Palakkad districts. The K. pneumoniae and Salmonella spp. were isolated by conventional culture techniques on MacConkey agar and Xylose lysine deoxycholate agar, respectively. When conventional culture technique was used, 57.50 per cent and 10.25 per cent samples were positive for K. pneumoniae and Salmonella spp., respectively. The molecular confirmation of K. pneumoniae was carried out by PCR targeting genus specific gyrA followed by species specific rpoB gene. Salmonella spp. was confirmed on PCR by amplifying species specific invA gene and spvC gene was targeted to evaluate the virulent nature of the isolates. Out of the 400 milk and beef samples analysed 50.75 per cent were positive for K. pneumoniae and 10.25 per cent were positive for Salmonella spp. Implementation of standard hygiene practices during production, distribution chain are required to avoid the contamination of milk and beef samples indented for human consumption.

Antioxidant activity of venison subjected to in vitro cooking and gastrointestinal digestion and isolation of its 2,2-diphenyl-1-picrylhydrazyl radical scavenging peptides.

Venison, a type of game meat, has several health benefits because it contains not only high protein and low fat but also bioactive peptides with several physiological properties, including antioxidative and angiotensin-converting enzyme inhibitory properties. The aim of the present study was to investigate the antioxidant activity of venison treated by in vitro cooking and gastrointestinal digestion. We subjected venison along with pork and beef to in vitro cooking and digestion and assessed their antioxidant activity via 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH-RS) and hydrophilic oxygen radical absorbance capacity (H-ORAC) assays. The peptide contents of all types of cooked and digested meat samples were higher than those of the untreated and cooked samples. The DPPH-RS activities and H-ORAC of digested venison, pork, and beef were increased compared with those of untreated samples. DPPH-RS activity was significantly higher in the digested venison samples than in the digested pork and beef samples. In this study, several fractions of digested venison from the chromatography exhibited DPPH-RS activity. Peptide analysis, using liquid-chromatography with tandem mass spectrometry, unveiled two peptides DIDDLELTLAK and TQTVCNFTDGALVQHQEWDGK with high DPPH-RS activities. Thus, venison is a rich source of antioxidant peptides and potentially demonstrate an antioxidation ability by digestive enzymes in vivo.

Comparing the use of chloroform to petroleum ether for Soxhlet extraction of fat in meat

Context Soxhlet extraction is commonly used for determining fat content of meat, because it is the basis of the AOAC Final Action method for this analysis. Petroleum ether is used as an extraction solvent but other solvents, such as chloroform, can be used. Chloroform has been stated to be a safer solvent than petroleum ether and is used extensively for Soxhlet extraction for meat research in Australia; yet, there has been no report that validates its use for this purpose. Aim To compare the use of chloroform with that of petroleum ether as an extraction solvent for Soxhlet fat extraction in beef. Methods The fat content of six beef samples, reported as chemical lean (CL, 100 – %fat), was determined using Soxhlet fat extraction with chloroform (by two independent research providers) and petroleum ether (b.p. 40–60°C, using three commercial providers). Passing–Bablok regression and Bland–Altman plot analysis were used to identify any differences and bias between the methods respectively. Key results Passing–Bablok regression showed that there was no difference between the use of chloroform and the use of petroleum ether as a solvent for Soxhlet fat extraction in beef. Bland–Altman plot analysis indicated that there was no bias evident between the uses of each solvent. Thus, this would indicate that chloroform can be used as a solvent for Soxhlet fat extraction, providing equivalency to petroleum ether. While some minor differences were apparent, this is most likely attributable to sample heterogeneity. Conclusions Chloroform was found to provide equivalency to petroleum ether for fat extraction from meat. While some minor differences were apparent in the fat content of meat, this has been attributed to likely sample heterogeneity. Implications Chloroform can be used as an extraction solvent for Soxhlet fat extraction of beef.

Effects of different storage temperatures on microbial spoilage and bacterial community structure of fresh beef by high-throughput sequencing technology

Comparsion of the effects of the chilling (4 ºC), superchilling (-2 ºC) and frozen (-18 ºC) storage on microbial spoilage and bacterial community structure of fresh beef was evaluated by high-throughput sequencing technology in this study. The results indicated that storage temperature can significantly affect the degree of microbial spoilage and bacterial community structure of fresh beef during storage. At the species level, the primary dominant bacterial species in beef samples was Pseudomonas fragi with relative abundance of 37.78% followed by Myroides phaeus and Brochothrix thermosphacta with 10.95% and 4.64%, respectively, at the beginning of storage. Both superchilling and frozen storage can effectively inhibit the growth of P. fragi, while the chilling storage failed to demonstrate strong inhibition for growth of P. fragi. Similar result was found for Myroides phaeus. The chilling, superchilling and frozen storage can not effectively inhibit the growth of Brochothrix thermosphacta and Acinetobacter johnsonii. The difference of microbial spoilage in beef stored in three kinds of storage may be related to the difference of the bacterial community structure and the formation of dominant spoilage bacteria. These results revealed that superchilling and frozen storage can effectively inhibit the formation of dominant spoilage bacteria, resulting in a good freshness preservation.