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.     

Study of the miscibility of poly(ethyl methacrylate-co-4-vinylpyridine)/poly(styrene-co-cinnamic acid) blends

Summary The miscibility of a series of poly(ethyl methacrylate-co-4-vinylpyridine) with poly(styrene-co-cinnamic acid), is investigated by differential scanning calorimetry. The results show that each blend is miscible as ascertained by a single composition dependent glass transition temperature. The Tg's of the blends exhibit positive deviations from the weight average Tg's of the blend components. The thermograms data exploited according to the Kwei and Schneider approaches suggest the occurrence of strong specific intermolecular attractive interactions within the binary systems. The strength of these interactions, as estimated from the Kwei q-values, increases with the proton donor and proton acceptor contents in the copolymers. Received: 23 January 1999/Revised version: 29 April 1999/Accepted: 1 June 1999     

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.