Sandra Budžaki

Enzyme-catalysed Biodiesel Production from Edible and Waste Cooking Oils

Biodiesel synthesis was performed as transesterification of edible and waste cooking sunflower oil catalysed by free lipase from Thermomyces lanuginosus (Lipolase 100L). Experiments were performed at three different temperatures (T = 40, 50 and 60 °C) as one-step and four-step reactions with methanol. The highest fatty acids methyl esters (FAME) content (C = 95 %) was achieved in the one-step transesterification reaction of edible sunflower oil performed at 40 °C.

Specific Heat and Thermal Conductivity of the Croatian Unleavened Dough

A line heat source probe method was used to determine thermal conductivity of the Croatian unleavened dough in a temperature range of 27–125°C. For estimation of the specific heat of the Croatian unleavened dough, a mixing method was used. The maximum value of 4.0 ± 0.8 kJ/(kg °C) was determined at 57.1°C for the potato dough, and the minimum value of 1.4 ± 0.6 kJ/(kg °C) was determined at 35.3°C for the Kroštula dough. Thermal conductivity first increased with temperature and then decreased after reaching its maximum value. Minimum value of 0.29 ± 0.04 W/(m °C) was determined at 123.8°C for the Kroštula dough. Further on, a set of empirical equations was established using regression analysis to correlate the results and to predict the specific heat and thermal conductivity of the Croatian unleavened dough within the studied temperature range and moisture levels.

Influence of cookies composition on temperature profiles and qualitative parameters during baking.

Summary During baking of bakery products temperature of baking, temperature profiles, moisture content, volume and colour changes are strongly coupled. The objective of this paper was to study the influence of the cookies composition on temperature profiles and quality parameters (width and thickness, colour formation and textural properties: hardness, fracturability and work of breaking force) during baking process. Composition of cookies differs due to flour type and initial moisture content. Cookies were baked at 205 °C and temperature was measured in the centre of samples which were 7 mm thick with a 60 mm diameter. The results of temperature profiles of the cookies during baking have shown the same trend for all of the 18 samples. Samples with the higher initial water content have lower values of total colour difference and also significantly affect textural properties.

Proximate analysis of cold-press oil cakes after biological treatment with Trametes versicolor and Humicola grisea

In order to increase the current knowledge on cold‐press oil cakes composition, the present study aims to determine the chemical composition of oil cakes from hull‐less pumpkin (Cucurbita pepo L.), flax (Linum usitatissimum L.), and hemp (Canabis sativa L.) before and after the biological treatment with Trametes versicolor and Humicola grisea using fungal‐based solid‐state technology. After 10 days of treatment, the content of ash, total nitrogen, total proteins, and total organic carbon increased in all the three oil cakes, while the content of ether extracts decreased. After treatment, the concentration of soluble carbohydrates decreased in pumpkin and hemp seed oil cakes, whereas it increased in flaxseed oil cake. During treatment with T. versicolor, the content of fructose significantly increased in hull‐less pumpkin seed oil cake. Fiber content decreased in pumpkin and flaxseed oil cakes after treatment with both of the fungi, whereas it increased in flaxseed oil cake.

Rationalization of cooling water consumption in extraction system B-811 LSV.

Summary Water (drinkable) is vital natural resource, and during the last few decades it is imperative to reduce its needless consumption. Extraction devices are known for their significant cooling water consumption and laboratory scale devices mainly use drinkable water. Aim of this paper was rationalization of cooling water consumption during extractions in universal extraction system B-811 LSV by recirculating cooling water trough cooling tower. In order to obtain the data for cooling tower design, measurements of cooling water flow, inlet and outlet cooling water temperatures, air humidity and temperature were conducted. Design of cooling tower based on obtained values resulted in cylindrical cooling tower, 81.45 cm height and with base radius of 13.96 cm. Cooling water consumption was reduced 56.87%.