Biomarkers of meat tenderness: Present knowledge and perspectives in regards to our current understanding of the mechanisms involved

Biomarkers of the meat quality are of prime importance for meat industry, which has to satisfy consumers' expectations and, for them, meat tenderness is and will remain the primary and most important quality attribute. The tenderization of meat starts immediately after animal death with the onset of apoptosis followed by a cooperative action of endogenous proteolytic systems. Before consideration of the biomarkers identified so far, we present here some new features on the apoptotic process. Among them, the most important is the recent discovery of a complex family of serpins capable to inhibit, in a pseudo-irreversible manner, caspases, the major enzymes responsible of cell dismantling during apoptosis. The biomarkers so far identified have been then sorted and grouped according to their common biological functions. All of them refer to a series of biological pathways including glycolytic and oxidative energy production, cell detoxification, protease inhibition and production of Heat Shock Proteins. Some unusual biomarkers are also presented: annexins, galectins and peroxiredoxins. On this basis, a detailed analysis of these metabolic pathways allowed us to identify some domains of interest for future investigations. It was thus emphasized that mitochondria, an important organelle in the production of energy from carbohydrates, lipids and proteins are a central element in the initiation and development of apoptosis. It was therefore stressed forward that, in fact, very little is known about the postmortem fate of these organelles and their multiple associated activities. Other topics discussed here would provide avenues for the future in the context of identifying reliable predictors of the ultimate meat tenderness.     

Non-destructive assessment of instrumental and sensory tenderness of lamb meat using NIR hyperspectral imaging

The purpose of this study was to develop and test a hyperspectral imaging system (900–1700 nm) to predict instrumental and sensory tenderness of lamb meat. Warner–Bratzler shear force (WBSF) values and sensory scores by trained panellists were collected as the indicator of instrumental and sensory tenderness, respectively. Partial least squares regression models were developed for predicting instrumental and sensory tenderness with reasonable accuracy (R_cv = 0.84 for WBSF and 0.69 for sensory tenderness). Overall, the results confirmed that the spectral data could become an interesting screening tool to quickly categorise lamb steaks in good (i.e. tender) and bad (i.e. tough) based on WBSF values and sensory scores with overall accuracy of about 94.51% and 91%, respectively. Successive projections algorithm (SPA) was used to select the most important wavelengths for WBSF prediction. Additionally, textural features from Gray Level Co-occurrence Matrix (GLCM) were extracted to determine the correlation between textural features and WBSF values.     

Assessment of in vitro antioxidant, antibacterial and immune activation potentials of aqueous and ethanol extracts of Phyllanthus niruri

BACKGROUND: Recently much attention has been paid to biologically active plants because of their low production cost and fewer adverse effects compared with chemical drugs. In the present investigation the bioactivity of Phyllanthus niruri ethanol and aqueous extracts was evaluated in vitro. RESULTS: The ethanol extract of P. niruri showed a high level of flavonoid content (123.9 ± 0.002 mg g^?1), while the aqueous extract showed the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH; IC₅₀6.85 ± 1.80 µmol L^?1) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS; 46.44 ± 0.53 µmol L^?1) free radical scavenging activities with high phenol content (376 ± 0.02 mg g^?1) and elevated levels of ferric reducing antioxidant power (FRAP; 23 883 ± 0.019 mmol g^?1) with excellent antibacterial activity against Staphylococcus aureus (20 mm inhibition zone) and Streptococcus agalactiae (12 mm inhibition zone), respectively, in addition to the best immune activation potential of human peripheral blood mononuclear cells (450.5%). CONCLUSIONS: It is clear from our results that both extracts of P. niruri has excellent bioactivity roles via elevated levels of antibacterial, antioxidant and percentage of peripheral blood mononuclear cell proliferation, which could lead to the development of medications for clinical use. Copyright © 2012 Society of Chemical Industry     

Wheat batter physical properties as influenced by starch/flour types and egg contents

Batter liquid–solid phase interactions can play a critical role in determining the functionality, including adherence, appearance and texture of end use coated product. Batter chemical composition is a key factor affecting batter characteristics. The effect of substituting wheat flour with fractions of rice flour, native corn starch, modified waxy corn starch, tapioca starch and lupine flour ranging from 26 to 56% of the solid phase and egg levels ranging from 6 to 35% of the liquid phase on the rheological properties of batter systems was studied. Results indicated that lupine flour had the greatest water holding capacity (WHC) ranging from 93.9 to 119.3% of various lupine flour percent to egg levels used. Flow behaviour index of batter flour treatments ranged from 0.91 to 1.87; values that were significantly (P?<?0.05) greater than a 100% control wheat flour. Consistency coefficient of treatments ranged from 0.01 to 0.37 mPa sⁿ; values that were significantly lower than wheat flour (i.e., 5 mPa sⁿ). Egg level used in this study had minimal effect on treatment rheological properties. The changes in WHC and viscoelastic properties of treatments were attributed to changes in protein and fibre contents and structure as a result of replacing wheat flour with starch/flour. Protein–starch–lipid matrix formation and variation in water absorption kinetics of treatments most probably wrought batter functionality. The increase in pasting properties with the increase in starch/flour contribution suggested an increased contribution of starch in forming a net effect of batter treatments pasting viscosities. Results of this study provide vital information for the potential use of starch types to enhance the rheological properties of coating applications including adhesion and water holding capacity of substituted batter treatment.     

Antioxidant and anticholinesterase activity of essential oils and ethanol extracts of <Emphasis Type="Italic">Thymus algeriensis</Emphasis> and <Emphasis Type="Italic">Teucrium polium</Emphasis> from Algeria

This study aimed to investigate the cholinesterase (ChE) inhibitory and antioxidant activities of essential oil (EO) and ethanolic extract (EE) of two Lamiaceae medicinal plants from Algeria: Thymus algeriensis Boiss. & Reut. and Teucrieum polium subsp capitatum. The chemical composition of EOs analyzed by GC and GC–MS revealed the presence of carvacrol (43.2%), p-cymene (18.7%) and γ-terpinene (14.8%) as major compounds in T. algeriensis, while germacrene D (25.0%), bicyclogermacrene (10.4%), β-pinene (11.3%) and spathulenol (5.8%) were the most important components in T. polium oil. The best inhibitory activity on acetylcholinesterase (AChE) was exhibited by the EO of T. algeriensis. On the other hand, T. polium oil was more efficient against butyrylcholinesterase (BChE) than against AChE, whereas EEs showed weak or no inhibitory effect, particularly against AChE. Antioxidant activity was evaluated by β-carotene bleaching, ferric and cupric reducing powers and inhibition of ABTS^?+, DPPH^? and superoxide radicals. EOs showed different antioxidant trends depending on the assay used while ethanol extracts had high activity with all tests.     

Effects of sodium and potassium fertilisers on the composition of herbage and its acceptability to dairy cows

Fertilisation of herbage with Na can increase acceptability to cows, but the influence of fertiliser rate and fertilisation by K is unknown. In experiment 1, ten cows were grazed on pasture plots that had just been fertilised with 0–132 kg-Na ha⁻¹ (current Na) and had received 0–64 kg-Na ha⁻¹ in the previous grazing season (residual Na). Herbage Na concentration increased in proportion to current Na from 2·7 to 4·9 g-Na kg⁻¹ dry matter (DM) and also increased with increasing residual Na from 2·2 to 4·5 g-Na kg⁻¹ DM. Herbage K concentrations were low (10 g kg⁻¹ DM at 0 kg-Na ha⁻¹) and were only slightly reduced by Na fertiliser. Herbage Mg and Ca concentrations and DM digestibility were maximum at 66–99 kg-current-Na ha⁻¹. Cows grazed current-Na-fertilised plots to a lower height and spent more time grazing them. In experiment 2, pasture plots received no fertiliser, low and high isomolar and independent applications of Na and K or a combination of the two. The herbage was more mature than in experiment 1 and Na concentration of the herbage without Na fertilizer was high (5 g kg⁻¹ DM). Na fertiliser, therefore, only slightly increased Na concentration, more in clover than in grass, and had little effect on K concentration. K fertiliser increased K concentration from 16 to 20 g kg⁻¹ DM and reduced Na concentration to 3·5 g kg⁻¹ DM. Sodium fertiliser, therefore, only increased the acceptability of herbage to cattle when herbage Na concentrations were initially low (less than 5 g kg⁻¹ DM) and were increased substantially by the application of the fertiliser. © 1998 SCI.     

Analysis of cooling curve to determine the end point of freezing

The cooling curve method used for the measurement of freezing point of food is further analyzed to explore whether it can be used to identify the end point of freezing or glass transition. In this method, slope of the cooling curve is determined and plotted as a function of time to identify the end point of freezing (T′_m). Initially, the slope is decreased and then reached a minimum value, which is identified as the nucleation of ice. Then the slope is increased until the end point of freezing. The end point of freezing is identified when the slope starts to decrease from its highest value or plateau. Sucrose solutions and starch gels were used to measure its T′_m in identifying validity of the proposed method. The measured values of T′_m by the proposed method is very close to the literature values.