Marina Tišma

Enhancement of phenolic compounds oxidation using laccase from Trametes versicolor in a microreactor

Laccases catalyse the oxidation of a wide range of substrates by a radical-catalyzed reaction mechanism, with a corresponding reduction of oxygen to water in a four-electron transfer process. Due to that, laccases are considered environmentally friendly enzymes, and lately there has been great interest in their use for the transformation and degradation of phenolic compounds. In this work, enzymatic oxidation of catechol and L-DOPA using commercial laccase from Trametes versicolor was performed, in continuously operated microreactors. The main focus of this investigation was to develop a new process for phenolic compounds oxidation, by application of microreactors. For a residence time of 72 s and an inlet oxygen concentration of 0.271 mmol/dm3, catechol conversion of 41.3% was achieved, while approximately the same conversion of L-DOPA (45.0%) was achieved for an inlet oxygen concentration of 0.544 mmol/dm3. The efficiency of microreactor usage for phenolic compounds oxidation was confirmed by calculating the oxidation rates; in the case of catechol oxidation, oxidation rates were in the range from 76.101 to 703.935 g/dm3/d (18–167 fold higher, compared to the case in a macroreactor). To better describe the proposed process, kinetic parameters of catechol oxidation were estimated, using data collected from experiments performed in a microreactor. The maximum reaction rate estimated in microreactor experiments was two times higher than one estimated using the initial reaction rate method from experiments performed in a cuvette. A mathematical model of the process was developed, and validated, using data from independent experiments.

Corn forage biological pretreatment by Trametes versicolor in a tray bioreactor

Trametes versicolor is a white-rot fungus known to be efficient in lignin removal due to its complex extracellular lignocellulolytic enzymatic system. Therefore, it can be used in the treatment of lignocellulose waste from agro, food, and wood industries. In a first experiment, corn forage treatment with T. versicolor was investigated in laboratory jars. In a second experiment, the process was scaled up to a tray bioreactor. In the tray bioreactor, the process of lignin degradation was improved, resulting in an increase in lignin conversion of up to 71% during seven days’ treatment.

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.

Decolorization of dyes by Aspergillus ochraceus cultivated under solid state fermentation on sugar beet waste

Solid state fermentation (SSF) is defined as fermentation process performed in the absence of free water on non-soluble materials which can act as physical support and source of nutrient to microorganisms. In this paper, Aspergillus ochraceus was cultivated in solid state fermentation using sugar industry waste. In order to decolorize dyes, two different methods were applied using sugar beet waste a) as a substrate for A. ochraceus cultivation and as dyes adsorbent ; and b) as a substrate for A. ochraceus cultivation with the aim of extracellular enzymes production that can be used for dyes decolorization in batch experiments. 100 % conversion of textile violet dye decolorization, 57 % of textile green dye decolorization, 41.1 % of congo red and 51.9 % conversion of metylene blue was reached in batch experiments using produced extracellular enzymes.

High-Pressure and Temperature Extraction of Phenolic Compounds from Corn Silage

Corn silage refers to stalks, leaves and cobs of maize plants that remain in fields after the corn harvest. Commonly it is used as a cattle feed, but recently it has been more often used together with cattle manure in biofuel production in anaerobic co-digestion. In this work high-pressure and temperature extraction of phenolic compounds from corn silage was performed. Process parameters (temperature, T = 90 – 180 °C; extraction time, t = 40 – 120 min; liquid – solid ratio, 10 – 20 mL/g; and solvent concentration (10 – 90 % aqueous ethanol, v/v) were studied. Box-Bhenken design was used in order to obtain the maximal extractability of phenolic compounds (namely total phenolic compoundsTPC and total extractible proanthocyanidins - TPA) and the maximal antiradical power (ARP) of obtained extracts. Experimental results of TPC, TPA, and ARP of corn silage extracts were in the range from 10.01 – 72.43 mgGallicAcid Equivalent/gdrybiomass, 0.27 – 3.21 mg/gdrybiomass and 1.25 – 16.76 mgDPPH/mLextract, respectively. Statistical results confirmed that temperature was the most significant factor affecting the observed responses (p < 0.05). Optimal extraction conditions for TPA and ARP were achieved at 180 °C, 120 min using 65 % ethanol and L/S ratio 10 while optimal conditions for TPC were achieved at 180 °C, 120 min using 10 % ethanol and L/S ratio 20. The results of this study evidenced that extracts from corn silage can be a good source of antioxidant compounds which can be used for production of food, cosmetic and pharmaceutical products.

Potential use of apple polyphenol oxidase for bioremediation of phenolic contaminants

Phenolic compounds, such as catechol, are released into the environment from a variety of industrial sources and they present serious ecosystem burden. This work examined possibility to use partially purified apple polyphenol oxidase (PPO) for bioremediation of phenolic contaminants. In order to optimize process conditions, optimal pH and temperature for PPO activity were determined, while PPO affinity toward various phenols, as well as effect of some salts and organic solvents which can be found in wastewaters, was used to confirm applicability of PPO in wastewater treatment. It was found that partially purified apple PPO shows maximal activity at pH 6.8 and 25 °C, but exhibit more than 85 % of its maximal activity in pH range from 5 to 8, and more than 90 % of activity in temperature range from 10 to 50 °C. PPO showed high affinity for various di-phenols, but lack of affinity toward mono-phenols. Sodium tetraborate decahydrate moderately inhibited PPO activity, while exposure of PPO to the presence of organic solvents ( = 5 %) caused 40 % loss of its activity. Catechol oxidation by PPO performed for just 5 min in a batch reactor at optimal process conditions resulted in 25 % conversion . Based on obtained data, it seems that partially purified apple PPO has reasonable potential in wastewater treatment.

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.

Scientific Report of the 9th International Congress “Flour-Bread ’17”

1 Josip Juraj Strossmayer University of Osijek, Faculty of Food Technology Osijek, Franje Kuhača 20, 31000 Osijek, Croatia 2 Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, via Emilia Parmense 84, 29122 Piacenza, Italy 3 Institute of Sciences of Food Production (ISPA), Research National Council (CNR), Via Amendola 122/O, 70126, Bari, Italy 4 Biomin Research Center, Technopark 1, 3430 Tulln, Austria 5 Croatian Institute of Public Health, Rockefeller street 7, 10000 Zagreb, Croatia 6 Institute of Field and Vegetable Crops, Maksima Gorkog 30, 21000 Novi Sad, Serbia

Soybean Straw, Corn Stover and Sunflower Stalk as Possible Substrates for Biogas Production in Croatia: A Review

Biomass availability is one of the key factors for biogas production in the future. Current status and possibility of utilization of harvest residues (soybean straw, corn stover and sunflower stalk) in Croatia for biogas production was given. In the last few decades, different pretreatment methods have been developed for degradation of different lignocellulosic biomass, but many of them are environmentally unfriendly and sometimes very expensive. More research and development is necessary to conduct in order to find both, economically and environmentally friendly pretreatment methods. This paper provides a review on mechanical, physical and biological methods used for different lignocellulose material pretreatment. Harvest residues are usually left in the field, but with the pretreatment process improvement, along with the soil protection they could be used for the production of huge amounts of energy in the future.