Effects of temperature and slice thickness on the kinetics of mushroom drying (Agaricus bisporus) in an infra-red dryer

Cilj ovog rada bio je ispitati utjecaj različitih temperatura i debljine sloja na brzinu sušenja šampinjona i utvrditi koji matematički model najbolje opisuje kinetiku sušenja. Šampinjoni debljine 1, 2 i 3 mm su sušeni u laboratorijskom infracrvenom sušilu “Mettler Lj 16” pri temperaturama 65, 70, 75 i 80 °C. Šampinjoni su prethodno bili blanširani u vodi pri 80 °C tijekom 3 min. Također, ispitan je utjecaj rehidratacije na osušene uzorke debljine 3 mm pri četiri gore navedene temperature te udio vode, proteina i pepela u svježim, blanširanim i osušenim šampinjonima debljine 3 mm. Rezultati ovog rada pokazuju da kod iste temperature vrijeme sušenja šampinjona raste s debljinom sloja uzorka, odnosno da kod iste debljine sloja uzorka pri višim temperaturama sušenje iziskuje manje vremena nego sušenje pri nižim temperaturama. Uz to, pokazalo se da je najbolja moć rehidratacije kod šampinjona sušenih pri 75 °C dok su ostali uzorci upili podjednaku količinu vode. Određivanje kemijskog sastava pokazalo je da su šampinjoni bogati vrijednim nutritivnim sastojcima koji ostaju sačuvani i nakon sušenja. Statističkom obradom podataka pomoću kompjuterskih programa Sigmaplot 9.0 (nelinearna regresija) i Microsoft Excel dobiven je matematički model za sve četiri temperature koji se dobro slaže sa eksperimentalnim vrijednostima (R > 0,99).The aim of this paper was to examine the influence of drying at different temperatures and of the thickness of the mushroom slice (cylindrically cut) on the velocity of mushroom drying, and to find a mathematical model that best describes the kinetics of mushroom drying. The influence of rehydration on dried samples 3 mm thick was also examined. The mushroom samples 1, 2, and 3 mm thick were dried in the laboratory infrared drier the “Mettler Lj 16” at temperatures of 65, 70, 75, and 80 °C. The mushrooms were previously blanched in water at 80 °C for 3 min. Also, the effect of rehydration of dried samples 3 mm thick at four temperature values mentioned previously were examined. Finally, the content of water, ash, and proteins in fresh, blanched, and dried mushrooms 3 mm thick was determined. The results of this experiment show that at the same temperature the drying of mushrooms takes a longer time with thicker samples, and conversely, that sample slices of the same thickness dry faster at higher temperatures, and they dry more slowly at lower temperatures. In addition, it was illustrated that the best ability of rehydration is for mushrooms dried at 75 °C while other samples absorbed mostly the same water content. The chemical analysis showed that mushrooms are rich in precious nutritive components which remained preserved after drying. Through a statistical analysis of data using the Sigmaplot 9.0 (nonlinear regression) and Microsoft Excel computer programs, a mathematical model was acquired for all four temperatures and is consistent with the experimental values (R>0,99)