Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumDuring extrusion changes of carbohydrate complex of corn grits and of bread particlesoccur; starch content is diminished, owing to its degradation into dextrins. Such changescause changes of the in vitro, as well as in vivo digestibility of starch, while thegelatinization of starch assures better accessibility of enzymes for degradation ofstarches and also cause the inactivation of amylase inhibitors [2].The goal of these investigations is to find out the effects of extrusion on quality ofmixtures of corn grits and bread crumbs.MATERIALS AND METHODSBasic chemical composition (moisture, crude proteins, crude fiber, crude fats andmineral substances contents) of the mixtures of corn grits and bread crumbs, weredetermined according to the AOAC methods (1980). Starch content, as well as the totaland reducing sugars contents were determined according to the Rule Book on themethods of physical and chemical controlling of cereals, milling- and bakery products,pastry and rapid frozen dough (1988), ad the volume weight was determined accordingto the Rule Book on sampling methods and methods of conducting physical, chemicaland microbiological analyses of animal feeds (1987).The total counts of microorganisms, yeasts and molds, isolation and identification ofSalmonella and of sulphite-reducing clostridia were determined according to the Rulebook on the methods ob conducting of microbiological analyses and super-analyses offoodstuffs (1980).For detection of the presence of coagulase-positive staphylococci, proteus sp. andEscherichia coli internal modified method was applied in the part of preparing ofsamples. 50 g of the examined samples was weighted in the Erlenmeyer flask and to it450 mL of the prepared sterile nutritive medium was added. So obtained sample wasgently homogenized and incubated 24 hours at 37ºC. Isolations and identifications wereperformed according to the Rule book on the methods of analyses and super analyses ofthe foodstuffs (1980).EXTRUDING OF CORN GRITS AND OF BREAD CRUMBSIn the process of extruding of corn grits and bread crumbs, corn grits with 12% ofmoisture and bread crumbs were mixed in the ratios of 60:40 and 50:50 in the counterflow mixer, and after that, the obtained mixtures were moisturized to 18% of watercontent. For extruding of corn the extruder with the capacity of 900 kg/h was used. Theinstalled extruder electromotor power was 100 kW. And that of the screw dosing unit –1.1 kW. Extrusion temperatures were 90 and 95ºC, and nozzle diameter was 7.5 mm.RESULTS AND DISCUSSIONTable 1 shows chemical and granulometric contents of the corn grits. These resultsindicate that the energetic proteinaceous feed contained 1544 kJ/100 g of energy and75.23% of starch, 6.88% of proteins and 1.14% of fats. The granulometric analysisshowed that the size of only 9.8% of particles was over 550 μm and 81% over 250 μm,170