THE EFFECT OF PROCESSING METHOD AND STORAGE TIME ON CONSTITUENTS OF TURKISH SAUSAGES (SUCUK)

Turkish sausages ( sucuk ) were produced by two methods (heat processing and traditional). Their moisture, pH and water activity and lipid stability were studied during refrigerated storage (4  ±  2C/90 days). Heat-processed (Therm) sausages had higher moisture content, water activity and pH values, and low thiobarbituric acid (TBA) values, free fatty acids (FFA) and peroxide values. FFA content of Therm sausages increased from 2.5 to 5.5% during storage and was significantly ( P <  0.05) affected by storage time. In the case of traditionally produced (Trad) sausages, there was no significant impact of storage time, but their TBA value increased from 0.38 to 0.48 mg MA/kg, while only a slight increase was observed in Therm sausages, from 0.41 to 0.43 mg MA/kg. Storage time significantly ( P <  0.05) increased the TBA value of Trad sausages.

PRACTICAL APPLICATIONS

In the current study, the effect of processing methods (heat processing and traditional) and storage time on some constituents of Turkish sausages was studied. Processing method significantly affected proximate composition of the sausages. On the other hand, lipolytic and oxidative changes were observed in both heat-processed and traditional sausages during storage. This could be attributed to hydrolytic enzymes and residual oxygen in vacuum packs. In practical applications, low oxygen permeability packing materials or modified gas atmosphere packing are recommended for both processing methods.     

PROTEOLYTIC CHANGES DURING PROCESSING IN TURKISH DRY‐CURED MEAT PRODUCT (PASTIRMA) WITH DIFFERENT SALT LEVELS

ABSTRACT

The effects of different salt (NaCl) contents on proteolytic changes during processing in the dry‐cured meat product past?rma were investigated. Past?rma samples were produced with three different NaCl levels (3, 6 and 9%) and proteolytic changes were monitored. A progressive increase in nonprotein nitrogen (NPN) and free amino acids (FAAs) was detected during processing. High‐salt past?rma samples had the highest FAAs. Drying and pressing stages before pasting with çemen resulted in a decrease in water‐soluble nitrogen (WSN) and a slight increase in NPN and FAA. High salt level and processing time resulted in the accumulation of FAAs. The increase in WSN, NPN and FAA contents after çemen treatment indicated that the çemen used in the pasting process had an impact on accumulation of these components in past?rma. However, no significant effect of salt level was observed on WSN and NPN. Sarcoplasmic proteins decreased considerably after salting due to drainage. Myofibrillar proteins degraded during processing, particularly in samples with 6 and 9% NaCl.

PRACTICAL APPLICATIONS

Proteolysis is one of the most important biochemical changes occurring during the processing of dry‐cured meat products such as ham or past?rma. The effect of additional salt concentrations and processing stages on proteolysis in Turkish dry‐cured meat product, past?rma, was studied during processing. Processing stages (salting, drying, pressing and pasting with çemen mixture) resulted in increases in NPN and FAA contents. High salt level (9% NaCl) and processing stages, particularly pasting with çemen mixture, facilitated the accumulation of FAA. Salting resulted in denaturation or insolubilization of proteins. Insolubilization of sarcoplasmic proteins was clearly seen in samples with 6 and 9% NaCl, depending on increased salt concentration during processing. In contrast, myofibrillar proteins in samples with 6 and 9% NaCl degraded during processing. From these results, processing conditions (salt concentration of past?rma and pasting with çemen) can determine the compounds released from protein breakdown during processing.

     

Water-Binding Capacity of Ground Lamb-Soy Mixtures with Different Levels of Water and Salt and Internal End-Point Temperatures

Ground lamb and textured soy protein mixtures were prepared with and without sodium chloride (NaCl) and with different levels of water, and were cooked to different internal end-point temperatures. Mixtures with NaCl were more firm and contained more “bound-type” and less “free-type” water. Increasing the amount of water added to the mixture increased cooking loss, expressible fluid, “free-type” and “bound-type” water, freezable water, and moisture content; however, mixtures with 20% added water had the same amount of “free-type” water and expressible fluid as those with 30%. Increasing end-point temperature resulted in increases in cooking loss and decreases in “bound-type” and “free-type” water, but had no effect on firmness.     

PIEZOELECTRIC RESPONSE OF PZT NANOSTRUCTURES OBTAINED BY FOCUSED ION BEAM

ABSTRACT

Pb(Zr_x,Ti_{1 - x})O₃ (PZT) microscale island (1μ m～ 100 nm) was fabricated by Focused Ion Beam (FIB) before and after its crystallization. In the first case the FIB etching is realized on amorphous films and a post annealing treatment, at the crystallization temperature of the PZT films, is necessary to cristallize the film in the perovskite phase. In the second case the etching are made on crystallized films. Local electrical properties were evaluated by piezoresponse force microscopy (PFM) technique and the degradations induce in the films are studies by Raman spectroscopy. Compared to the PZT island fabricated after crystallization, the result shows that there is noticeable enhancement in nanoscale electrical properties of PZT island fabricated before crystallization, especially when the island size decreases.     

TRACKING PERFORMANCE OF CONTROL METHODS

In this work, the optimal temperature control of a styrene solution polymerization reactor with two different control algorithms is considered. DMC and PFD control mefhods are used to accomplish the optimal temperature control of the polystyrene reactor. Reactor optimal temperature profiles at different initiator initiation concentrations were obtained by applying maximum principle to the mathematical model of the free radical batch polymerization reactor lo produce polystyrene with desired conversion and molecular weight in a minimum lime. The results obtained from the experimental implementation of DMC and PID controller for the control of optimal temperature path of the polymerization reactor were compared.     

APPLICATION OF ADAPTIVE PID CONTROL WITH GENETIC ALGORITHM TO A POLYMERIZATION REACTOR

This article describes the application of adaptive PID control with genetic algorithm (GA) to a jacketed batch polymerization reactor. This method was used to keep the polymerization reactor temperature at the desired optimal path, which was determined by the Hamiltonian maximum principle method. The reactor was simulated and the model equations of this jacketed polymerization reactor were solved by means of Runge-Kutta-Felthberg methods. A genetic algorithm can be a good solution for finding the optimum PID parameters because unlike other techniques it does not impose many limitations and it is simple. In this research, suitability of these parameters was checked by the integral absolute error (IAE) criterion. The control parameters in the PID algorithm were changed with time during the control of a polymerization reactor. It was seen that the genetic algorithm was able to tune the PID controller used in this system in terms of higher robustness and reliability by changing the parameters continuously.     

Optimisation of bacteriocin production of Lactococcus lactis subsp. lactis MA23, a strain isolated from Boza

Lactococcus lactis subsp. lactis MA23 produces a bacteriocin (6400 AU/mL) that inhibits the growth of many Gram‐positive bacteria but is not active against Gram‐negative bacteria. This bacteriocin inhibits growth of lactococcal strains that are producing nisin, lacticin or lactococcin suggesting it to be different from these bacteriocins. The nutritional requirements and optimal growth conditions for MA23 bacteriocin production were studied with fed‐batch fermentations. The optimal pH, carbon source and nitrogen source for bacteriocin production were pH 6.5, sucrose (0.5%) and yeast extract (1%), respectively.     

Pole assignment problem: a structural investigation

Based on the structure of a closed-loop system under a specified feedback pattern, a qualitative analysis of the problem of pole assignability is considered. The problem is first formulated algebraically, in terms of the relation p = g(f) between the vector p of the closed-loop characteristic polynomial coefficients and the vector f of the non-zero elements of the feedback matrix. Then, translation to the structural framework is achieved by means of two theorems which give graph-theoretical sufficient conditions for solvability. These structural conditions also guarantee genericity of pole assignability.