Chemical Characterization of Meat Related to Animal Diet

There is currently much interest in the comparative health benefits of various meat products, including pasture-fed beef. However, little is known about the specific pasture-finishing diets (mixed forages, alfalfa, or sainfoin, compared to grain) on meat quality, consumer preferences, and human health. Thus, additional information is needed to better understand and develop new animal feeding regimes for optimum animal growth, meat flavor, and meat nutritional quality. The objective of the current study was to examine how animal diets, including secondary metabolites in the diet, affect meat chemical characteristics, meat quality, and nutritional value. In study 1 (Chapter 3), grain- vs. pasture-fed beef rib steaks were evaluated. Ribs from pasture-fed animals had a much lower fat content (P \u3c 0.01), which was its main positive nutritional attribute. Pasture-fed beef had more (P \u3c 0.05) omega-3 polyunsaturated fatty acids (PUFAs) and conjugated linoleic acid (CLA) than grain-fed beef, but was only a moderately good source of PUFA, compared to salmon. Pasture-fed beef had higher antioxidant capacity and lower measures of oxidation (P \u3c 0.05). Pasture and grain diets influenced the volatile profile of cooked meat. Flavor descriptors barny, gamey, and grassy were associated with pasture feeding, and were uniquely shown in this study to be positively correlated with specific aroma volatiles benzaldehyde, toluene, dimethyl sulfone, 3- heptanone, 2-ethyl-1-hexanol, and hexadecanoic acid methyl ester (P \u3c 0.05). In study 2 (Chapter 4), the effects of legume pasture-finishing of beef cattle on meat quality were evaluated, comparing alfalfa pasture (containing saponins) versus sainfoin pasture (containing tannins). No strong differences (P \u3e 0.05) were found between the two legume diets in all meat characteristics, indicating that sainfoin was similar to alfalfa as a cattle forage. Similar (P \u3e 0.05) low TBA values after 12 d of storage at 2 °C were obtained from both diets, comparable to pasture-fed beef from study 1. This verified the prolonged retail shelf life benefit of forage-fed beef, compared to grain-fed beef. In study 3 (Chapter 5), lambs fed four different diets, plain/control (P), tanninsrich diet (T), saponins-rich diet (S), or choice of them (C), were evaluated on metabolomics profiles using GC/MS technique. Forty metabolites were detected (30 named and 10 unknown). A principal component analysis (PCA) plot showed a clear separation of P, T, and S diet treatments while the C diet was overlapped with S and P diets, indicating that S or P diets were preferred while the T diet was avoided. In summary, the effects of ruminant diets on meat characteristics depended on the type and concentration of plant secondary compounds (PSC), especially the PSC levels contained in the pastures

Microbial Growth Inhibition and Decomposition of Milk Mineral and Sodium Tripolyphosphate Added to Media or Fresh Ground Beef

Milk mineral (MM) is a type II antioxidant (metal chelator) that can bind iron and prevent iron catalysis of lipid oxidation. Thus, MM might have microbial growth inhibition effects on iron-dependent bacteria. Objective 1 was to evaluate effects of MM on growth of non-pathogenic iron-dependent bacterial strains (Listeria innocua, Eschericia coli, Pseudomonas fluorescens). MM (1.5 % w/v) did not significantly inhibit growth of Listeria and E. coli. However, growth of Pseudomonas fluorescens was consistently and significantly reduced by ~1 log colony forming units per ml (CFU/ml) with all levels of MM (0.5, 0.75, 1.5 % w/v). All levels of MM also had no growth inhibition effects against the mixed microflora of fresh ground beef during storage for up to 10 days at 2°C. In conclusion, MM had little or no effect to inhibit microbial growth. The strong affinity of MM to ionic iron inhibits lipid oxidation, but does not inhibit bacterial growth supported by other forms of iron (heme or amino acid + iron complexes). Several studies report that MM has greater antioxidant effect than sodium tripolyphosphate (STP) in ground meats, especially at longer storage time. Objective 2 was to compare stability of MM and STP in ground beef patties by monitoring the decomposition to soluble orthophosphates (Pi). Patties (control) and patties with 0.75 % MM or 0.5 % STP were stored at 2 or 22°C for 0, 1, or 2 days. CFU/g and Pi were measured. As expected, CFU/g at 22°C was much higher than treatment at 2°C. Pi levels at 2°C were lower (P \u3c 0.05) than at 22°C. At day 0, for both temperatures, patties formulated with MM had the highest Pi levels. However, after 2 days storage, samples with added STP had the highest level of Pi, followed by MM and control. Thus, decomposition as measured by release of Pi was significantly higher for STP than for MM added to beef patties. There was a significant positive correlation (0.77) between CFU/g and Pi during storage of beef patties for 2 days at 22°C. In conclusion, increased Pi during storage of beef patties was at least partially due to bacterial phosphatases. A third experiment was conducted to examine the stability of 0.75 % MM or 0.5 % STP added to growing cultures of Pseudomonas fluorescens at 2°C or 22°C for 0, 1, and 2 days. Neither MM nor STP was stable in autoclaved media (Pi increased significantly). The factors responsible for decomposition of MM or STP in autoclaved media remain to be determined

Ginseng extract G115 improves locomotor function in rotenone-induced parkinsonism rats via an antioxidant effect

Exposure to certain pesticides including rotenone, a mitochondrial complex I inhibitors, may cause the oxidative damage to the dopaminergic neurons and contribute to Parkinson’s disease. Herein we demonstrate that ginseng extract G115 could attenuate locomotor activity impairment in rotenone-induced parkinsonism rats. Rotenone was shown to significantly impair the movement of rat related to its ability to reduce free radical scavenging capability and superoxide dismutase (SOD) activity in the rat brain. Ginseng extract G115 (400 mg/kg) given 14 days before and concurrently with rotenone significantly protected against rotenone-induced locomotor impairment at day 17, but not day 20. In addition, the treatment with ginseng extract G115 (400 and 800 mg/kg) significantly prevented the loss of free radical scavenging and SOD activities in rotenone-treated rats while inhibiting the lipid peroxidation. Together, the present study provides mechanistic insight into rotenone-mediated PD as well as the information of ginseng extract that is promising for the prevention

Untargeted metabolomics reveal pathways associated with neuroprotective effect of oxyresveratrol in SH-SY5Y cells

Abstract Oxyresveratrol has been documented benefits for neurodegenerative disease. However, the specific molecular mechanisms and pathways involved is currently limited. This study aimed to investigate the potential neuroprotective mechanisms of oxyresveratrol using rotenone-induced human neuroblastoma SH-SY5Y cytotoxicity. Cells were divided into the following groups: control, rotenone, and oxyresveratrol pre-treated before being exposed to rotenone. Cellular assays were performed to investigate neuroprotective effects of oxyresveratrol. The results showed that 20 μM oxyresveratrol was effective in preventing rotenone-induced cell death and decreasing ROS levels in the cells. The alteration of metabolites and pathways involved in the neuroprotective activities of oxyresveratrol were further investigated using LC-QTOF-MS/MS untargeted metabolomics approach. We hypothesized that oxyresveratrol's neuroprotective effects would be associated with neurodegenerative pathways. A total of 294 metabolites were identified. 7,8-dihydrobiopterin exhibited the highest VIP scores (VIP > 3.0; p < 0.05), thus considered a biomarker in this study. Our results demonstrated that pretreatment with oxyresveratrol upregulated the level of 7,8-dihydrobiopterin compared to the positive control. Pathway analysis verified that 7,8-dihydrobiopterin was primarily associated with phenylalanine, tyrosine, and tryptophan metabolism (impact = 1, p < 0.001), serving as essential cofactors for enzymatic function in the dopamine biosynthesis pathway. In conclusion, oxyresveratrol may be benefit for the prevention of neurodegenerative diseases by increasing 7,8-dihydrobiopterin concentration

How do prolonged anchorage-free lifetimes strengthen non-small-cell lung cancer cells to evade anoikis? – A link with altered cellular metabolomics

Abstract Background Malignant cells adopt anoikis resistance to survive anchorage-free stresses and initiate cancer metastasis. It is still unknown how varying periods of anchorage loss contribute to anoikis resistance, cell migration, and metabolic reprogramming of cancerous cells. Results Our study demonstrated that prolonging the anchorage-free lifetime of non-small-cell lung cancer NCI-H460 cells for 7 days strengthened anoikis resistance, as shown by higher half-life and capability to survive and grow without anchorage, compared to wild-type cells or those losing anchorage for 3 days. While the prolonged anchorage-free lifetime was responsible for the increased aggressive feature of survival cells to perform rapid 3-dimensional migration during the first 3 h of a transwell assay, no significant influence was observed with 2-dimensional surface migration detected at 12 and 24 h by a wound-healing method. Metabolomics analysis revealed significant alteration in the intracellular levels of six (oxalic acid, cholesterol, 1-ethylpyrrolidine, 1-(3-methylbutyl)-2,3,4,6-tetramethylbenzene, β-alanine, and putrescine) among all 37 identified metabolites during 7 days without anchorage. Based on significance values, enrichment ratios, and impact scores of all metabolites and their associated pathways, three principal metabolic activities (non-standard amino acid metabolism, cell membrane biosynthesis, and oxidative stress response) offered potential links with anoikis resistance. Conclusions These findings further our insights into the evolution of anoikis resistance in lung cancer cells and identify promising biomarkers for early lung cancer diagnosis