!" " #" $#" !"#!$ %& ’ ()!$ * +,!$ Mechanical Engineering Graduate Program, Universidade do Vale do Rio dos Sinos (Unisinos), Av. Unisinos, 950, CEP 93022%000 -" & ."!$ / +0#!"# Department of Food Engineering, Universidade do Vale do Rio dos Sinos (Unisinos), Av. Unisinos, 950, CEP 93022%000 ! " # $ # % % & # ’( ) ) * " & & + $ , - - 1! 2/ According to Lin et al. (2010), fossil fuels accounted for 88% of global energy demand in 2009, with a share of 35% for oils. Also the IEO2009 – International Energy Outlook (2009), projects a use of 17 million m 3 of liquids per day in 2030. Biofuels, like ethanol or biodiesel are expected to supply almost 1 million m 3 per day in 2030. The major obstacle for widespread use of fats and oils as fuels and chemicals is the high cost of the finished products relative to petroleum (Graboski and McCormick, 1998). Another important issue concerns “first%generation” biodiesel feedstocks. According to Lin et al. (2010), 75% is obtained from food%grade oils, threatening the economic viability of biodiesel industry, since the end cost depends on the price of the feedstock. One potential solution to this problem is employment of alternative feedstocks of varying type, quality, and cost. These feedstocks may include soapstocks, acid oils, tall oils, used cooking oils, and waste restaurant greases, various animal fats, non%food vegetable oils, and oils obtained from trees and microorganisms such as algae (Lin et al., 2010). Among animal fats, stand out the ones originated from silage processing of fishing industry waste. Besides, of the total fishery production, about 50% by weight represent miscellaneous waste (viscera, fins, spine, head,...), for which the amount of oil varies from 40 to 65% (Arruda et al., 2007). Fish silage is defined as a liquid product produced from the whole fish or parts of it, to which acids, enzymes or lactic%acid%producing bacteria are added, with the liquefaction of the mass provoked by the action of enzymes from the fish (Arruda et al. 2009). In order to replace diesel as fuel, the substitute must have similar properties, considering it will be used in the same equipments. The most important properties, according to Graboski and McCormick (1998), are related to combustion, like cetane number, flash point and heat of combustion. In a recent work, Cherng%Yuan Lin and Rong%Ji Li (2009) verified that biodiesel produced from crude fish oil shows higher cetane number, higher heating value and lower flash point than biodiesel made from waste cooking oil. Nevertheless, flow properties, as pour and cloud point, viscosity and surface tension play an important role in the viability of employing a particular fuel. These properties are also important for combustion quality due to its influence in spray formation. Considering flow properties, some studies in straight vegetable oils (SVO), animal fat, residues and its esthers have been performed to evaluate regular diesel replacement with biofuels. Gopakumar et al. (2010) studied the properties of bio%oil produced from fast pyrolysis of pine wood and obtained a Newtonian behavior of the viscosity after a shear rate greater than 20 s %1 with a value higher than that of diesel fuel, but