Optimization of extruder cooking conditions for the manufacture of fish feeds using response surface methodology

Abstract A composite blend consisting of sunflower cake, maize germ, wheat bran, fresh water shrimps and cassava flour was extruded using a single‐screw extruder to produce expanded fish feed pellets. The effects of temperature (80–120 °C), die diameter (2–4 mm), and feed pre‐conditioning time (50–150 s; steam 400 kPa) on properties of the pellets (expansion ratio, bulk density, floatability, durability, water absorption, water solubility, water stability, and in‐vitro protein digestibility) were investigated using response surface methodology. Regression equations describing the effect of each variable on the product responses were obtained. The pellets extruded using a factor combination of 120 °C extruder barrel temperature, 2 mm die diameter, and 100 s of feed pre‐conditioning time gave most desirable pellet floatability (100%), durability index (99%), expansion ratio (2.64), water absorption index (4.12), water solubility index (9.31), water stability (87%), bulk density (479 g/L), and in vitro protein digestibility (69.97%) with a composite desirability of 0.88. Practical applications Extrusion is a modern feed processing method whose use is fast gaining popularity among small feed processors in developing countries. However, extrusion is a process that involves many parameters that need to be optimized for desirable end properties. These findings guide fish feed manufacturers on the optimum conditions for single screw extruders for production of feeds with desirable properties especially for the fish types that are top feeders. In addition, the results offer important insights on how temperature, die diameter, and feed pre‐conditioning, may be manipulated to influence properties of extruded aquafeed when using simple low‐cost small‐scale extruders

Evaluation and comparison of the pathogenic agents and risk factors of bacterial vaginosis

Introduction: Vaginal infections and discharge are among the most common complaints that bring the patient to the gynecologic clinics.The purpose of the present study is to evaluate pathogenic agents and risk factors of bacterial vaginosis . Methods: A case- control study was performed on 200 patients. The case group (n=100) complained of vaginal discharge and bacterial vaginosis was the diagnosis , and the control group n=100), did not have any vaginal discharge and had referred to the clinic just for seeking a contraceptive method. The vaginal samples were examined for vaginal PH and direct microscopic) examination was done for gram stains, candidiasis, inflammatory cells, and presence of clue cells, red blood cells and white blood cells so whiff test and culture in different medias were performed . Results: Anaerobic bacteria including peptostreptococcus, peptococcus, bacterioids, and obligate anaerobic lactobacillus were found in 8 of control group and 63 of study group. Difference in two groups was statistically significant. Lactobacillus was found in 81 of control group and 23 of study group with significant differences. Gardenella vaginalis was found in 88 of study group and 34 of control group. Bacterioid species were found in 15 of study group and 5 of control group. Seventy seven percent of participants were married for 6-20 years.41 of study group and 16 of control group had parity of 3-4 (P<0.05). IUD was used in 27 of study group and 17 of control group, respectively while condom and interrupted coitus were more common in the .control group Conclusion: Anaerobic bacteria and gardenella vaginalis were more common in patients with non- specific vaginal discharge. Candom and coitus interruptus have protective effect on vaginal .discharge, and IUD can increase its incidene