Moisture sorption properties of smoked chicken sausages from spenthenmeat R.R.B. Singh a, *,K.H.Rao a , A.S.R. Anjaneyulu b ,G.R.Patil c a Division of Dairy Technology, National Dairy Research Institute, Karnal-132 001, India b Livestock Products Technology Division, Indian Veterinary Research Institute, Izatnagar-243 122, India c Department of Animal Husbandry & Dairying, Marathwada Agricultural University, Parbhani-431402, India Received 23 September 1999; accepted 6 July 2000 Abstract Moisture sorption characteristics of smoked chicken sausages from spent hen meat were investigated at 5, 25 and 50  Covera wateractivity(a w )rangeof0.11±0.87.Sigmoidal(type-II)desorptionisothermswereobservedforthesesamples.Thesorptiondata were analysed using mathematical equations of Caurie, Halsey, GAB and Oswin. The Halsey equation gave the best ®t over the entiretemperaturerange.GABmodelalsodescribedtheisothermsfairlywell.TheGABandBETmonolayermoisturevalueswere not signi®cantly dierent (P>0.01) and decreased with increasing temperature. The number of adsorbed monolayers, density and amountofboundwaterandsurfaceareaofadsorptionalsodecreasedasthesorptiontemperatureincreased.Thepores,ingeneral, enlarged with rising temperature. # 2001ElsevierScienceLtd.Allrightsreserved. Keywords: Smokedsausages;Spenthenmeat;Sorptionisotherm;Boundwater;Poresize 1. Introduction Thepoultryindustryisfacedwithaverylargenumber of spent hens Ð on a global basis there are about 2.6 billion each year Ð and there is a need for this major resource to be used more eciently and pro®tably. Spent hens are byproducts of the egg industry and the meat obtained from these birds has poor functional properties.Furthermore,whilethequalityofbroilersas raw material for manufacture of processed meat pro- ducts has been improved through breeding,feedingand management,spenthenmeatposesseriousproblemswith regard to both processing and utilization. Smoked chickensausageisoneofthepopularemulsiontypepro- ductssuitableforeectiveutilizationoftoughmeatfrom spenthens(Kondaiah&Panda,1992;Panda,1996). In order to optimise quality attributes in new food formulations, data on physical properties including equilibrium moisture content are needed which may be expressedinmoisturesorptionisotherms(Lim,Tang,& He, 1995). Numerous models and equations have been used for describing water sorption isotherms of food materials.SuchequationshavebeenreviewedbyChirife and Iglesias (1978) and Chirife (1983). However, experience has shown that no single equation gives accurate ®t for sorption isotherm data over the entire rangeof a w fordierenttypesoffoods.Karel(1973)has attributed it to the fact that the sorption isotherm of each food product is in¯uenced by integrated hygro- scopic properties of its numerous constituents and that the depression of a w isduetoacombinationoffactors, eachofwhichcouldbepredominantinagivenrangeof a w in a food system. In addition, knowledge of the rate at which a food stu approaches equilibrium provides aninsightintothein¯uenceoftheinternalstructureon the observed behaviour (Roman, Rotstein, Urbiasin, & 1979). Related information on these aspects of poultry meatandmeatproductsarelimited. Protein/water interactions are important to most functionsperformedbyproteinsinfoodproducts.Thus water sorption, a w , swelling, voluminosity, water hold- ingcapacity,coagulationetc.aresomeoftheimportant propertiesdependentonprotein/waterinteractions.The rate and extent of interactions of functional ingredients with water at low, intermediate and high water con- centrations and the concomitant changes in chemical 0963-9969/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII:S0963-9969(00)00145-9 Food Research International 34 (2001) 143±148 www.elsevier.com/locate/foodres * Correspondingauthor.Tel.:+91-184-252800;fax:+91-184-250042. E-mail address: rrb@ndri.hry.nic.in (R.R.B. Singh).