Optimization of parameters for obtaining surimi-like material from mechanically separated chicken meat using response surface methodology

Surimi is a semi-processed washed fish mince protein concentrate mixed with cryoprotectants for frozen storage, which is the primary constituent of processed foods. Mechanically separated chicken meat (MSCM) is a common ingredient of comminuted sausages mainly due to its low price. The present work aimed to define the adequate parameters to obtain surimi-like material from MSCM using response surface methodology, and to characterize the chemical and textural properties of this product. The MSCM was utilized in the elaboration of surimi-like material using the bleaching method with sodium bicarbonate and sodium chloride solutions. For this purpose, the effect of process parameters viz: temperature (T=2, 7, and 12 °C), time (t=5, 10, and 15 min/cycles) and washing solution: MSCM ratio (R=2:1, 4:1, and 6:1w/w) were evaluated using response surface methodology. The highest composite design averages obtained were 10.7 % for protein content, 1,003.4 g for breaking force, 645.8 g.cm for gel strength, 9.0 N for cutting strength, and 24.1 N.s for work of shearing at the optimum combination of processing conditions of 7 °C, 10 min and 4:1 washing solution:MSCM ratio, corresponding to the central points of the proposed experimental design. The obtained models had high determination coefficients, explaining 95.85, 98.23, 98.41, and 96.08%of total variability in protein content, cutting strength, breaking force, and work of shearing variabilities, respectively. According to the folding test the surimi-like material presented the same characteristics of a high quality surimi (FT=5)

Enhanced Incentive Motivation for Sucrose-Paired Cues in Adolescent Rats: Possible Roles for Dopamine and Opioid Systems

Vulnerability to the effects of drugs of abuse during adolescence may be related to altered incentive motivation, a process believed to be important in addiction. Incentive motivation can be seen when a neutral stimulus acquires motivational properties through repeated association with a primary reinforcer. We compared adolescent (postnatal day (PND) 24–50) and adult (>PND 70) rats on a measure of incentive motivation: responding for a conditioned reinforcer (CR). Rats learned to associate the delivery of 0.1 ml of 10% sucrose with a conditioned stimulus (CS; light and tone); 30 pairings per day were given over 14 days. Then, we measured responding on a lever delivering the CS (now a CR) after injections of amphetamine (0, 0.25 or 0.5 mg/kg). We also examined responding for CR when the CS and sucrose were paired or unpaired during conditioning, and responding for the primary reinforcer (10% sucrose) in control experiments. Finally, we examined the effects of D1 and D2 dopamine receptor antagonists (SCH 39166 and eticlopride, respectively) and an opioid receptor antagonist (naltrexone) on responding for a CR in adolescent rats. Adolescents but not adults acquired responding for a CR, but adolescents responded less than adults for the primary reinforcer. Responding for a CR depended upon the pairing of the CS and sucrose during conditioning. Both dopamine and opioid receptor antagonists reduced responding for the CR. Therefore, incentive motivation may be enhanced in adolescents compared with adults, and incentive motivation may be mediated in part by both dopamine and opioid systems