Effect of beef ultimate pH and large structural protein changes with aging on meat tenderness

This study investigated the effect of ultimate pH (pH_u) in beef on the degradation of large structural proteins during refrigerated storage using SDS-PAGE. M. longissimus dorsi from bull carcasses were selected and classified into three groups: low pH_u (≤ 5.79), intermediate pH_u (5.80–6.19) and high pH_u (≥ 6.2) muscles. Samples were then stored at − 1.5 °C for 1, 2, 7, 14, 21 and 28 days. Meat tenderness was measured at each aging time. Depending on meat pH_u, different protein patterns and degradation rates of structural proteins were found. Rapid changes of large structural proteins took place within 48 h post mortem. Besides titin and nebulin, degradation of filamin was clearly revealed. Two more large protein bands corresponding to myosin family members also exhibited fast decline with storage time. It suggested that the fast degradation of these proteins is a key factor in the improvement of meat tenderness.     

Ultra-fast freezing and low storage temperatures are not necessary to maintain the functional properties of manufacturing beef

The effects of freezing rates and subsequent storage temperatures on the functional properties of meat were assessed. In the first trial, 24 Semitendinosus muscles were allocated to four freezing treatments to determine the effect of freezing rate alone (no frozen storage) on the functional properties of thawed muscle proteins. In the second trial, the effect of freezing rate, storage temperature and time were determined: 24 semimembranosus muscles were assigned to 30 treatment combinations using an incomplete factorial design with two freezing rates × three storage temperatures × five storage times. All samples individually sealed in water impermeable bags were thawed in water at 10?°C and then analysed. The rate of freezing alone in both trials and for both muscles had no effect on protein solubility; sulphydryl content; surface hydrophobicity; emulsion activity index or meat colour. Slowly frozen semimembranosus had more drip than fast frozen muscles. Semimembranosus muscle sarcoplasmic protein solubility increased and myofibrillar protein solubility decreased with storage temperature below -18?°C. Storage temperature did not affect the other attributes measured. Functional properties were mainly affected by storage time and the interaction between storage time and freezing rate. It is concluded that the current practice of blast freezing and storage at -18 to 20?°C is sufficient to maintain the quality of manufacturing beef.     

Cooked sausage batter cohesiveness as affected by sarcoplasmic proteins

In the first trial, m. semitendinosus and m. biceps femoris were held at 0, 10 and 35?°C until they entered rigor, and in the second trial, minced m. semitendinosus was washed in water for 15, 30, 45 or 60 min. The samples from both the trials were then used to make a finely comminuted sausage batter. Soluble sarcoplasmic protein (SSP) levels decreased with increasing rigor temperature (P < 0.05) or washing (P < 0.01). Cooked batter shear stress was not affected by SSP level, but batter shear strain decreased with the decreasing SSP level associated with an increasing rigor temperature (P < 0.05) or washing (P < 0.01). Reducing the SSP content lowered the cook yield (P < 0.05) and emulsion stability (P < 0.01) of the batter from the washed samples compared to that of controls. The results suggest that sarcoplasmic proteins are important in determining the strain values (cohesiveness) of cooked sausage batter.     

Magnetic susceptibility of amorphous and heat-treated vanadate glasses

X-ray diffraction and magnetic susceptibility measurements were used to study the effect of addition of iron on the crystallization process and magnetic properties of the vanadium borophosphate system before and after heat treatment. The glass composition was 78 mol% V₂O₅-15 mol% P₂O₅-7 mol% B₂O₃, the Fe₂O₃ was added with concentration ranging from 0.05 up to 1 mol%. The X-ray diffraction showed that the V₂O₅ was the only phase separated during the heat treatment process. The intensity of the characteristic V₂O₅ peaks increased with increasing Fe₂O₃ content. The magnetic susceptibility was found to decrease for the sample containing 0.05 mol% Fe₂O₃. This could be explained by the presence of most of the iron ions in the ferrous state and the presence of a covalent bond between the ferrous ions and the oxygen ions. An increase in the magnetic susceptibility was found in samples containing an iron content of more than 0.05. This increase could be explained according to the change of Fe²⁺ ions to Fe³⁺ which has higher paramagnetic behaviour.     

Reactions of 4-Benzylidene-3-methyl-5-oxopyrazoline,pyrazole blue,and rubazoic acid with GRIGNARD reagents

While 4-benzylidene-3-methyl-5-oxopyrazoline 1 and pyrazole blue 2 with GRIGNARD reagents gave 1,4-addition, rubazoic acid 3 gave 1, 2-addition on both sides with ethylmagnesium bromide.     

Investigation of the candesartan cilexetil antihypertensive drug microencapsulation by PLA-PVP K30 biodegradable polymers: Experimental optimization and release kinetics modelling

Candesartan is an angiotensin receptor blocker (ARB) used to treat hypertension. However, its poor aqueous solubility and oral bioavailability have limited its therapeutic applications. In order to increase bioavailability and control the release of candesartan condensation, microspheres containing biodegradable polymers (polyvinylpyrrolidone [PVP K30] and polylactic acid [PLA]) in different ratios were prepared by the o/o solvent evaporation method using Span 80 as a surfactant. In addition, the impact of encapsulation parameters (i.e., PVP K30 and PLA concentrations) on the encapsulation ratio and release percentage was investigated by the mixed factorial design method. The release kinetics of the microspheres was simulated by combining two methods, the Dragonfly algorithm and a support vector machine (DA-SVM). The experimental data were in good agreement with the predicted data, with a coefficient of determination close to unity and a mean square error close to zero. Fourier-transfer infrared spectrometry (FTIR) analysis revealed the presence of condensation in all formulations without reporting distortion in the spectra. Scanning electron microscopy (SEM) confirmed the successful synthesis of microspheres, whose sizes were between 12 and 26 μm. Formulations with a PLA-drug ratio of 6:1 (N15, N17, and N18) showed the highest encapsulation efficiency (68%, 71%, and 70%, respectively), while formulations that do contain PVP K30, such as N5, N4, and N3, showed a higher release (83%, 84%, and 89%, respectively), indicating that the agent (PVP K30) enhanced the bioavailability and release of candesartan. Overall, N3 showed a higher drug release rate at 12 h and important encapsulation efficiency, making it the optimal formulation obtained in this study.