Mateja Grubor

Volatile Composition and Sensory Profile of Oyster Mushroom as Affected by Drying Method

ABSTRACT The smell of food is one of the most important factors in assessing its quality. In this study, the influence of drying method on aroma/volatile compounds of oyster mushrooms (Pleurotus ostreatus Jacq.) was evaluated. The drying methods tested were convective drying (CD), freeze-drying (FD), vacuum microwave drying (VMD), and a combination of convective predrying and VM finish drying (CPD–VMFD). The volatile compounds were extracted by solid-phase microextraction and identified by gas chromatography–mass spectrometry. The best fitting model to describe the drying kinetics of the oyster mushroom was Henderson and Pabis model. Thirty-four volatiles in fresh oyster mushrooms were identified, with 3-octanone (2,890 µg/100 g dry basis) and 3-octanol (991 µg/100 g) being the major components. The total concentration of volatiles of fresh mushroom (4,506 µg/100 g) was drastically reduced by all drying treatments, although the highest contents were found after: (i) CPD (50°C)–VMFD (480 W) (245 µg/100 g) and (ii) VMD at 480 W (143 µg/100 g). According to the sensory data, the products dried using the treatment CPD (50°C)–VMFD (480 W) were those closer to the fresh mushrooms.

Biomass valorisation of Arundo donax L., Miscanthus × giganteus and Sida hermaphrodita for biofuel production

Abstract In the context of the growing demand for biomass, which is being encouraged by the EU directives on the promotion of the use of renewable energy, recent investigations have been increasingly focused on fast-growing energy crops. The aim of this study was to investigate the energy properties of three types of agricultural energy crops: Arundo donax L., Miscanthus × giganteus and Sida hermaphrodita. This investigation looked into the content of non-combustible and combustible matter, higher and lower heating values, lignocellulose content, and biomass macro-elements. The results indicate that the energy values of these crops are comparable, while their lignocellulose content shows significant variations. Thus, Arundo donax L. can best be utilised as solid biofuel due to its highest lignin content, while Miscanthus × giganteus and Sida hermaphrodita L. can be used for both liquid and solid biofuels production. As far as Arundo donax L. is concerned, a higher ash level should be taken into consideration.

Energy valorization of Miscanthus x giganteus biomass: A case study in Croatia

The aim of this study is to determine the calorific values, chemical composition (proximate and ultimate analysis, micro and macro elements) and cell structure (composition of lignocellulose) of Miscanthus x giganteus biomass cultivated in Croatian. Research results represents the average values of biomass (n = 108) cultivated at two locations in Croatia (Bistra, Medvednica), during the three-year research period, three harvest periods (autumn, winter, spring) per year and two fertilizer treatments (N0 i N50). Determined average values of some important parameters are: low calorific value - 17.25 MJ/kg, ash content - 1.49 %, carbon content - 48.75 %, nitrogen content - 0.47 %, sulfur content - 0.07 %, cellulose content - 49.22 % and lignin content - 29.25 %. The obtained results have shown that Miscanthus x giganteus has potential to be a significant source of good quality raw material in the production of solids biofuels.

Effects of different air drying temperature on sunflower seeds oil and ash content

The aim of this paper was to determine the impact of different air temperature (60 °C, 80 °C and 100 °C) at air drying velocity of 1.0 ms-1 during convection drying thermal process on the sunflower seeds oil and ash content. The research was conducted at 4 different sunflower seeds hybrid Apollo, NK Brio, PR 63 and PR 90 A 63 D 82, which by their characteristics are early and medium early hybrids.. Based on the results, the curve of water speed release from the sunflower seeds, the activation energy, as well as changes in oil content and ash content before and after the convective drying was obtained. It was established that the NK Brio hybrid fastest release water compared to other hybrids during drying which is confirmed by minimum value of activation energy and that the increasing of air drying temperature increases oil content, while reduces ash content.