The antioxidant and antimicrobial effects of equivalent concentrations of fresh garlic (FG), garlic powder (GP) and garlic oil (GO) were investigated against lipid oxidation and microbial growth in raw chicken sausage during storage at 3 degrees C. The antioxidant activities were compared to that of a standard synthetic antioxidant; butylated hydroxyanisole (BHA). The initial mean levels of thiobarbituric acid (TBA) value and peroxide value (POV) were 0.140 and 6.32, respectively. However after 21 days of storage, TBA and POV ranged from 0.151 to 4.92, respectively, in FG (50 g/kg) formulated samples to 0.214 and 8.64, respectively, in GO (0.06 g/ kg) formulation. Addition of either garlic or BHA (0.1 g/kg) significantly delayed lipid oxidation when compared with control. The antioxidant activities of the various materials added followed the order FG>GP>BHA>GO. On the other hand, the initial aerobic plate count (APC) in the samples was 4.41 log(10) CFU/g. Addition of FG (30 g/kg) or GP (9 g/kg) significantly reduced the APC and, subsequently, the shelf-life of the product was extended to 21 days. However, addition of GO or BHA resulted in no significant difference in APC when compared with control. Sensory analysis indicated that FG had a significant stronger flavor than the other sausage formulations. The results suggest that fresh garlic and garlic powder, through their combined antioxidant and antimicrobial effects, are potentially useful in preserving meat products.

Myosin molecules are cleaved by chymotrypsin digestion into two fragments: subfragment 1, which originates from the globular heads of myosin, and the myosin rod, which originates from the helical tail of the myosin molecule. The heat-induced gelation of these subfragments was compared to that of intact myosin by measuring rigidity, turbidity, and other physico-chemical characteristics of each system. Two features of the heat-induced gelation of myosin, aggregation and three-dimensional network formation were found to be imparted by the subfragment 1 and the rod, respectively. The former involves disulfide exchange and the latter relates to conformational changes arising from a partially irreversible helix-coil transition during heating. Possible relationships are suggested between these physicochemical changes of the myosin head and tail regions upon heating and the heat-induced gelation of myosin.

MAKOTO ISHIOROSHI, KUNIHIKO SAMEJIMA and TSUTOMU YAW/ -ABSTRACT The heat-induced gelation of myosin was optimally developed at temperatures between 60" and 70°C and at pH 6.0 as studied quantitatively by measuring shear modulus of myosin in 0.6M KCl. No difference was observed in the gelation profile, when KC1 was replaced by NaCl. The shear modulus of the gel formed at 65°C and pH 6.0 increased proportionally to the 1.8 power of myosin concentration. Although the heat gelling ability of myosin as measured by the shear modulus did not increase with increasing salt concentration from 0.4-LOM, irrespective of storage time at 0°C of the stock myosin solution (0.6M KCl) or suspension (0.1M KCl), it varied drastically with time of storage at salt concentrations between 0.1 and 0.3. This variation in shear modulus at O.l-0.3M KC1 was apparent due to the storage conditions. These changes in the salt concentration dependence of the heat gelation of myosin corresponded well with the changes in solubility of myosin during storage. Studies on selected physico-chemical properties of the original stock myosin during sl:orage indicated gradual increase in viscosity with little inactivation of ATPase as well as very slight decrease in sulfhydryl content, suggesting the spontaneous transformation (aggregation) of myosin molecules to a less soluble state.

The rabbit muscle contractile proteins, myosin, actin and reconstituted actomyosin were mixed in 0.1–1.0 M KCl, 20 mM buffers, pH 5.0–8.0, and were tested quantitatively for thermally induced gelation properties by measuring the rigidity (shear modulus) of the system at 20–70°. Scanning electronmicroscopy (SEM) was also used to study the structure of the gels formed by gelation of myosin in the presence of F‐actin. Under the standard condition, i.e. at 0.6 M KCl, pH 6.0 and 65°, decrease of the myosin/actin mole ratio to about 1.5–2.0 in the reconstituted acto‐myosin system resulted in substantial augmentation of the rigidity of the gel formed. Further decreases in the myosin ratio relative to F‐actin reduced the rigidity value of the gel to close to the level of myosin alone. Gel‐formability of the reconstituted actomyosin was maximal at pH 5.5–6.0 and between 0.5 and 0.8 M KCl and decreased considerably at other pH values and KCl concentrations. The SEM studies revealed progressive changes in three dimensional ordering as actin concentration in the actomyosin varied. These were in concordance with the results of gel strength.

Gelation of myosin in 0.6M KC1 at pH 7.0 and 6.0 during heating at various temperatures between 25-70°C was quantitatively measured by a simple shear modulus tester devised in our laboratory. Shear modulus data indicated that gelation occurs with a stepwise elevation of temperature from 30-60°C. Heat-treatment of the protein solution remarkably influenced the structure and water mobility in the system. Myosin gel formed by heating had a micro-network structure, which was not-present in the original myosin solution. The myosin gel had a slower value of spin-spin relaxation time compared to that of the original untreated sample, suggesting that the water mobility in the gel system was somehow restricted. The heat-induced gelation of myosin may be the result of the development of a three dimensional network structure which holds water in a less mobilized state.