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Glavni proizvod anaerobne digestije je bioplin, koji je obnovljivo gorivo, a sporedni proizvod ovog procesa je digestat, koji se koristi kao gnojivo bogato hranjivim tvarima. Dodatni pozitivni učinci anaerobne digestije su razgradnja organskog otpada te smanjenje neugodnih mirisa i koncentracije patogenih mikroorganizama. Bioplin se uglavnom koristi za proizvodnju električne energije i topline, a u nekim slučajevima se pročišćava da bi se dobio biometan koji se koristi u mreži prirodnog plina, kao gorivo za motore s unutarnjim sagorijevanjem ili kao polazna kemikalija za kemijsku industriju. Zbog svega navedenog, razvoj proizvodnje bioplina ima pozitivne društveno-ekonomske i ekološke učinke. Bioplin proizveden u Hrvatskoj većinom se koristi za proizvodnju električne i toplinske energije u kogeneracijskim postrojenjima. Iako su u Hrvatskoj dostupne različite obnovljive sirovine koje bi se mogle iskoristiti za proizvodnju bioplina, njihov je potencijal do sada bio nedovoljno iskorišten. Kao sirovine za proizvodnju bioplina u nas se pretežno koriste gnojovka i nusproizvodi poljoprivrede, klaonica i prehrambene industrije. Racionalnijim korištenjem zemljišta i razvojem prehrambene industrije mogla bi se povećati količina poljoprivrednih ostataka i nusproizvoda koji nastaju preradom hrane. Usmjeravanjem i poticanjem korištenja ovih nusproizvoda za anaerobnu digestiju može se stimulirati brži razvoj proizvodnje bioplina u Hrvatskoj. Pored mogućeg povećanja vlastite proizvodnje električne energije i goriva, radi se o ekološki povoljnoj tehnologiji koja ima pozitivan društveno-ekonomski učinak.

Značajne količine raznovrsnih ostataka (odnosno lignocelulozne biomase) nastaju u poljoprivredi, prehrambenoj industriji i šumarstvu. Stoga je važno podići svijest o mogućnostima primjene takvih materijala koji se u današnje vrijeme ne bi trebali tretirati kao otpad, već se mogu koristiti kao obnovljive biotehnološke sirovine za proizvodnju kemikalija, drugih visokovrijednih proizvoda i biogoriva. Lignocelulozni materijal uglavnom sadrži celulozu, hemicelulozu i lignin. Predmet interesa ovog rada je lignocelulozni otpad iz poljoprivrede i prehrambene industrije kao mogući sirovinski temelj za napredak održive biotehnološke proizvodnje u Republici Hrvatskoj. Razmotrene su dostupne količine ovih lignoceluloznih sirovina, tipovi bioprocesa u kojima se one mogu koristiti, postupci predobrade koje je neophodno provesti prije provedbe samog bioprocesa te vrste biotehnoloških proizvoda koje je moguće dobiti.

Alternative to the use of fossil fuels are biofuels (e.g., bioethanol, biodiesel and biogas), which are more environmentally friendly and which can be produced from different renewable resources. In this investigation, bioethanol production from raw sugar beet cossettes (semi-solid substrate) by yeast Saccharomyces cerevisiae in a horizontal rotating tubular bioreactor (HRTB) was studied. Obtained results show that HRTB rotation mode (constant or interval) and rotation speed have considerable impact on the efficiency of bioethanol production in the HRTB. The main goal of this research was to develop a non-structural mathematical model of bioethanol production from raw sugar beet cossettes in the HRTB. The established mathematical model of bioethanol production in the HRTB describes substrate utilization and product formation (glycerol, ethanol and acetate) and presumes negative impact of high substrate concentration on the working microorganism (substrate inhibition) by using Andrews inhibition kinetics. All simulations of bioethanol production in the HRTB were performed by using Berkeley Madonna software, version 8.3.14 (Berkeley Madonna, Berkeley, CA, USA). The established non-structural bioprocess model describes relatively well the bioethanol production from raw sugar beet cossettes in the HRTB.

The underutilized biomass and different organic waste streams are nowadays in the focus of research for renewable energy production due to the effusive use of fossil fuels and greenhouse gas emission. In addition, one of the major environmental problems is also a constant increase of the number of organic waste streams. In a lot of countries, sustainable waste management, including waste prevention and reduction, has become a priority as a means to reduce pollution and greenhouse gas emission. Application of biogas technology is one of the promising methods to provide solutions for both actual energy-related and environmental problems. This review aims to present conventional and novel biogas production systems, as well as purification and upgrading technologies, nowadays applicable on a large scale, with a special focus on the CO2 and H2S removal. It also gives an overview of feedstock and the parameters important for biogas production, together with digestate utilization and application of molecular biology in order to improve the biogas production., Nedovoljno iskorištena biomasa i različiti tokovi organskog otpada su u današnje vrijeme u fokusu istraživanja proizvodnje obnovljive energije, zbog raširene upotrebe fosilnih goriva i emisije stakleničkih plinova. Osim toga, jedan od glavnih ekoloških problema je stalno povećanje broja tokova organskog otpada. U mnogim je zemljama održivo gospodarenje otpadom, uključujući prevenciju i smanjenje otpada, postalo prioritet radi smanjenja onečišćenja okoliša i emisije stakleničkih plinova. Primjena tehnologije proizvodnje bioplina jedna je od obećavajućih metoda traženja rješenja za aktualne energetske i ekološke probleme. Svrha je ovog preglednog rada bila prikazati konvencionalne i nove sustave za proizvodnju bioplina te tehnologije pročišćavanja i obogaćivanja bioplina, koje se danas primjenjuju u velikom mjerilu, s posebnim naglaskom na uklanjanje CO2 i H2S. Ovaj rad također daje pregled sirovina i parametara važnih za proizvodnju bioplina, kao i podataka o korištenju digestata i primjeni molekularne biologije za poboljšanje proizvodnje bioplina.

For biogas production, different renewable feedstocks, e.g., feces, manure, silage, industrial by-products, and municipal waste, can be used. Biogas production from various renewable feedstocks has positive socioeconomic and environmental impact. In Europe, biogas is mainly used for generating heat and electricity. It consists of methane (55–70% by volume), carbon dioxide (30–45% by volume), and small amounts of other compounds. In some cases, biogas is upgraded to pure biomethane and utilized as vehicle fuel, instead of fossil fuels, thus reducing the emissions of greenhouse gases. Biomethane can also serve as a platform chemical in chemical and biochemical synthesis to produce value-added products. The additional positive effects of anaerobic digestion of animal manure and slurries are organic waste degradation, reducing odors, and pathogens. Digestate, obtained as a by-product of anaerobic digestion, is rich in nutrients and therefore is applied as fertilizer in agriculture. Biogas production in Croatia is mainly based on manure and by-products from agriculture, food industry, and slaughterhouses. The obtained biogas is mostly used for electricity and heat generation. Potential for large-scale biogas production in Croatia is still insufficiently used, although various renewable feedstocks are available. More rational and focused management of lignocellulosic residues, animal excrements, food processing by-products, and biodegradable fraction of municipal waste could contribute to the development of Croatian biogas sector. Biogas production in Croatia can be affected by the changes of animal breeding capacity due to the struggle to cope with the European Union (EU) standards and prices. Concerning large unused agricultural areas, great potential lies in their rational exploitation for fast-growing biomass, e.g., for energy crops or perennial grasses. This review will discuss the potential of biogas in the industrial and farming sector, current state of biogas production, and various key drivers and barriers influencing biogas production in Croatia.

Brewers’ spent grains (BSG) are a by-product of the brewing industry that is mainly used as feedstock; otherwise, it has to be disposed according to regulations. Due to the high content of glucose and xylose, after pretreatment and hydrolysis, it can be used as a main carbohydrate source for cultivation of microorganisms for production of biofuels or biochemicals like 2,3-butanediol or lactate. 2,3-Butanediol has applications in the pharmaceutical or chemical industry as a precursor for varnishes and paints or in the food industry as an aroma compound. So far, Klebsiella pneumoniae, Serratia marcescens, Clostridium sp., and Enterobacter aerogenes are being used and investigated in different bioprocesses aimed at the production of 2,3-butanediol. The main drawback is bacterial pathogenicity which complicates all production steps in laboratory, pilot, and industrial scales. In our study, a gram-positive GRAS bacterium Paenibacillus polymyxa DSM 742 was used for the production of 2,3-butanediol. Since this strain is very poorly described in literature, bacterium cultivation was performed in media with different glucose and/or xylose concentration ranges. The highest 2,3-butanediol concentration of 18.61 g l–1 was achieved in medium with 70 g l–1 of glucose during 40 h of fermentation. In contrast, during bacterium cultivation in xylose containing medium there was no significant 2,3-butanediol production. In the next stage, BSG hydrolysates were used for bacterial cultivation. P. polymyxa DSM 742 cultivated in the liquid phase of pretreated BSG produced very low 2,3-butanediol and ethanol concentrations. Therefore, this BSG hydrolysate has to be detoxified in order to remove bacterial growth inhibitors. After detoxification, bacterium cultivation resulted in 30 g l–1 of lactate, while production of 2,3-butanediol was negligible. The solid phase of pretreated BSG was also used for bacterium cultivation after its hydrolysis by commercial enzymes. In these cultivations, P. polymyxa DSM 742 produced 9.8 g l–1 of 2,3-butanediol and 3.93 g l–1 of ethanol. On the basis of the obtained results, it can be concluded that different experimental setups give the possibility of directing the metabolism of P. polymyxa DSM 742 toward the production of either 2,3-butanediol and ethanol or lactate.

Brewers' spent grains (BSG) are a by-product of the brewing industry that is mainly used as feedstock; otherwise, it has to be disposed according to regulations. Due to the high content of glucose and xylose, after pretreatment and hydrolysis, it can be used as a main carbohydrate source for cultivation of microorganisms for production of biofuels or biochemicals like 2,3-butanediol or lactate. 2,3-Butanediol has applications in the pharmaceutical or chemical industry as a precursor for varnishes and paints or in the food industry as an aroma compound. So far

In Croatia, as part of the Mediterranean region where carob is grown, only carob liquor is produced, mostly as a domestic product. In contrast, pure spirit production by alcoholic fermentation and distillation of carob is very rare and the compounds responsible for the characteristic bouquet of carob spirit are unknown. Therefore, the aim of this study was to evaluate the potential of carob as a raw material (source of sugars, nutrients and yeast inhibitors) for the production of carob spirit using commercial yeast strains. Moreover, a preliminary characterization of the volatiles in the obtained distillates was considered. Fermentations were carried out in carob mash with or without added nutrients by five Saccharomyces cerevisiae strains at three different temperatures (20°C, 30°C and room temperature). The obtained wine was subjected to fractional distillation in a copper still to produce carob spirit with an alcohol content of 40 % vol. Analysis of sugars and fermentation products was performed by high performance liquid chromatography. Gas chromatography and gas chromatography coupled with MS detection was used to analyse the volatile components of the carob wine and brandy. Carob flour and S. cerevisiae strains can be efficiently used for the fermentation process to produce carob wine with ethanol content ranging from 46.4 to 50.5 gL-1 and corresponding yield coefficients ranging from 0.45 to 0.49 gg-1. More than ninety compounds detected in carob spirit, namely ethyl 2-methyl butanoate, ethyl 2-methyl propanoate, ethyl cinnamate, ethyl hexanoate, beta-ionone, ethyl butanoate and ethyl octanoate, contribute significantly to the fruity and floral bouquet of carob spirit. Thus, by using the tested yeast strains, a novel brandy rich in volatiles can be obtained. Carob brandy can be 82 an additional product in the carob processing chain and new potential, especially for small carob growers.

Agaricus bisporus, also known as the white button mushroom or champignon, is the most cultivated mushroom species worldwide. In addition to its favorable nutrient profile, it contains a number of compounds with antioxidant, antibacterial, anti-inflammatory, antitumor, and immunomodulatory activities. Waste biomass is a secondary product obtained from A. bisporus during the harvesting stage. It is underused, although it could be a cheap source of polysaccharides and antioxidants for use in food and feed production, or a source of nutraceuticals and cosmeceuticals. In this study, waste biomass was used as raw material for extraction of crude polysaccharides. The mean amount of crude polysaccharides extracted was 106 g/kg dry weight debris-free mushroom waste biomass. The crude polysaccharides recovered contained 11.57% α-glucan and 16.37% β-glucan. Total carbohydrates composed 44.18%. No significant differences were found in the Fourier transform infrared spectra, which confirmed the presence of protein, α-glucan, and β-glucan in all samples ; phenols were detected only in waste biomass and market-ready A. bisporus fruiting bodies. The total phenol content in methanol extracts of waste biomass and A. bisporus fruiting bodies was 6.16 and 11.25 mg gallic acid equivalents/g extract, respectively. Antioxidant capacities of methanol extracts from waste biomass, as determined by spectrophotometric techniques, were 22.67 μmol Trolox/g extract (ABTS radical scavenging), 51.77 μmol Fe2+/g extract (ferric- reducing antioxidant power), and 51.52% (DPPH radical scavenging). Although these values were lower than those for A. bisporus fruiting bodies, the waste biomass has great potential for use in food, feed, and other bioproducts of economic importance.

Velika količina lignoceluloznog otpada, kojeg čine uglavnom celuloza, hemiceluloza i lignin, nastaje u šumarstvu, poljoprivredi i prehrambenoj industriji. Obzirom na dostupne količine ovih jeftinih i obnovljivih sirovina u Republici Hrvatskoj, važno je razmotriti mogućnosti njihove primjene u proizvodnji bioetanola i raznih drugih biotehnoloških proizvoda. Lignocelulozni hidrolizati su složene smjese heksoza i pentoza te drugih spojeva od kojih neki mogu djelovati kao inhibitori fermentacije. U ovom radu dan je pregled kvasaca koji se koriste i/ili istražuju za proizvodnju etanola iz lignoceluloznih hidrolizata.

Functional foods are foods that provide positive health effects apart from the provision of essential nutrients. Along with nutraceuticals, they represent the top trends in the food industry. Fruit wines are considered functional foods. When assessing the fruit wine quality, a wide range of descriptors are taken into consideration, namely physicochemical and sensorial properties of fruit wine. Furthermore, within the context of the new food products development (e.g. functional products), functional properties of fruit wines are also taken into consideration. Functional properties are determined by the content of the biologically active components, such as polyphenols, vitamins and micro- and macrominerals. It is also important to consider the food-safety issues regarding the fruit wines consummation, that is, the presence of pesticides, mycotoxins and biogenic amines in different fruit wines. This chapter aims to give an overview of various factors used to evaluate the quality and the functional properties of fruit wines.

Fruit wines production has been growing steadily in recent years, and its market potential is strong, which correlates with the demand for and development of new functional products. Likewise, the production of fruit wines has become an integrated component of fruit processing industry, often compensating for post-harvest losses. Fruit wines represent a value-added fruit product. They contain nutritionally important components like minerals and antioxidants, as well as aromatic nuances typically from the fruits used. The paper gives a general overview of the production of fruit wines with a particular emphasis on the quality of fruit to be used for wine processing, as well as fermentation and post-fermentation processes.

Poljoprivreda, šumarstvo i prehrambena industrija izvori su velike količine lignocelulozne biomase, koja može poslužiti kao lako dostupna i jeftina obnovljiva sirovina za dobivanje različitih bioproizvoda. Jedan od takvih proizvoda je i bioetanol. Ovaj rad daje pregled bakterija koje se koriste i/ili istražuju za proizvodnju bioetanola iz lignoceluloznih sirovina. U navedenim istraživanjima proizvodnje bioetanola pomoću bakterija primijenjuju se različiti pristupi kako bi se povećala ekološka i ekonomska efikasnost procesa. Pored uobičajenih bioprocesa, koji se provode u više faza i uz pomoć monokulture, razvijaju se i visokointegrirani (konsolidirani) bioprocesi uz primjenu mikrobnih kokultura., Agriculture, forestry and food industry are sources of large quantities of lignocellulosic biomass, which can be used as an easily accessible and cheap renewable raw material for production of different bioproducts. One of these bioproducts is also bioethanol. This paper provides an overview of bacteria used and/or investigated for bioethanol production from lignocellulose-containing feedstocks. In the research of bioethanol production using bacteria, various approaches are applied in order to increase ecological and economic efficiency of bioprocess. In addition to conventional multi-stage bioprocesses that are carried out using monoculture, highly integrated (consolidated) bioprocesses and applications of microbial cocultures are also in developing stage.

β-D-Glucans (hereafter referred to as “β-glucans”) are glucose polymers which belong to a group of physiologically active compounds called “biological response modifiers” (BRMs). Their immunostimulatory activity makes them suitable for application in human and veterinary medicine, in pharmaceutical and chemical industries, as well as in production of food, feed and cosmetics. In the Western world, dietary supplements containing β-glucans up to now have been mostly produced from baker´s yeast, Saccharomyces cerevisiae. Among various compounds that can be isolated from yeast, β-glucans can be used in wound healing and treatment of various diseases, such as cancer, infectious diseases, hypercholesterolaemia and diabetes. Their antioxidative properties and synergistic effect with various drugs and treatments are also reported. In recent years there has been an increasing interest in isolation and use of β-glucan from brewer´s yeast, which is a byproduct of beer production. All samples of insoluble β-glucans, isolated in our experiments from brewer’s yeast using three different procedures and dried using three different methods, showed biological activity. β-Glucan preparations, obtained in modified drying conditions, showed noticeably higher ability of producing TNF-α. Use of spent brewer's yeast as a raw material for β-glucan production is technologically and economically justified.

Odstupanja od normalnog tijeka fermentacije predstavljaju veliki problem u proizvodnji vina. Važno je poznavati čimbenike koji utječu na tijek fermentacije kako bi se izbjeglo usporavanje i/ili zastoj fermentacije te spriječilo ekonomske gubitke. Brojna istraživanja pokazala su da odstupanja od normalnog tijeka fermentacije mogu imati više uzroka. U ovom radu su ukratko objašnjeni najvažniji čimbenici koji utječu na tijek fermentacije u proizvodnji vina, a mogu se grupirati u tri skupine - nedostatak nutrijenata, prisutnost spojeva koji inhibiraju alkoholnu fermentaciju te utjecaj enoloških postupaka. Pored zasebnih učinaka pojedinih čimbenika, moguće je i smanjenje brzine fermentacije zbog njihovog sinergističkog djelovanja, što fermentacijske probleme čini još složenijima.

Analizirano je pet vina Škrlet proizvedenih od istoimene autohtone sorte grožđa u Volodersko-Ivanićgradskom vinogorju (podregija Moslavina) i Petrinjskom vinogorju (podregija Pokuplje). Primjenom standardnih metoda analize određene su koncentracije reducirajućih šećera, ukupnih kiselina, hlapljivih kiselina, ekstrakta te slobodnog, vezanog i ukupnog SO2. Volumni udio etanola određen je primjenom dviju metoda - tekućinskom kromatografijom visoke djelotvornosti (HPLC) i plinskom kromatografijom (GC). Za određivanje udjela jabučne kiseline, mliječne kiseline i glicerola primijenjena je HPLC metoda. Većina uzoraka zadovoljila je Pravilnikom propisane kriterije za kvalitetna vina, dok je jedan odstupao s obzirom na koncentracije glicerola i ukupnih kiselina.

Solid state cultivation of Ganoderma lucidum biomass, strain BFWS Gal 4, originally isolated from the Slovenian forest, was studied in a horizontal stirred tank reactor. Periodic mixing of N = 80 rpm, 2 min/day was used. Production of fungal polysaccharides and fungal biomass on solid substrate based on beech sawdust, olive oil, and mineral salts was studied. Optimal moisture of the solid matrix was in the range of 80% to 74%. When the moisture content dropped below 57%, the growth of the mycelium and polysaccharide production stopped, but it revived when wet air was applied in further processing. Final concentration of biomass was 0.68 mg/g of solid substrate, while proportions of extracellular and intracellular polysaccharides were 4.5 mg/g and 1.05 mg/g, respectively.

Volatile aroma compounds production by two autochthonous Saccharomyces cerevisiae strains, isolated from Istria region, and three other yeast strains (Saccharomyces bayanus and two commercial Saccharomyces cerevisiae wine yeasts) was investigated on a small scale using synthetic VP4 medium and Graševina must at 12 and 20°C. The results obtained by gas chromatography analyses were compared with the aroma production properties of the native microflora, remaining after Graševina must sulphiting. In both media and at both temperatures, the wine yeasts investigated showed different metabolic profiles regarding the tested volatile aroma compounds, which should be taken in consideration for autochthonous wine production. Although the synthetic medium proved to be appropriate for the investigation of the fermentative properties, the determination of secondary aroma production by wine yeasts has to be conducted by must fermentation or possibly by fermentation of another synthetic medium whose composition would be more similar to must.

Two different procedures have been used for isolation of water-insoluble ß-glucans from brewer’s yeast: alkaline-acidic isolation (AA) and alkaline-acidic isolation with mannoprotein removal (AAM). The obtained ß-glucans were then dried by air-drying, lyophilization and combination of sonication and spray-drying. ß-Glucan preparations obtained by AA and AAM isolations had similar values of dry mass, total polysaccharides, proteins and organic elemental microanalysis. The mass fractions of ß-glucan in total polysaccharides were significantly affected by different isolation procedures. Fourier transform infrared (FTIR) spectra of all preparations had the appearance typical for (1→3)-ß-D-glucan. Lyophilization and especially air-drying caused a higher degree of agglomeration and changes in ß-glucan microstructure. Sonication followed by spray-drying resulted in minimal structural changes and negligible formation of agglomerates., Netopljivi β-glukani izolirani su iz pivskoga kvasca primjenom dvaju različitih postupaka: alkalno-kiselinskog (AK) i alkalno-kiselinskog s uklanjanjem manoproteina (AKM). Dobiveni pripravci β-glukana osušeni su na zraku, liofilizacijom i raspršivanjem uz prethodnu obradu ultrazvukom. Takvi su pripravci, dobiveni AK i AKM postupcima, imali približno iste vrijednosti suhe tvari, ukupnih polisaharida i proteina, te udjele ugljika, dušika i kisika određene organskom mikroanalizom. Na udio β-glukana u ukupnim polisaharidima bitno su utjecali različiti postupci izolacije. FT-IR spektri svih pripravaka imali su izgled tipičan za (1→3)-β-D-glukan. Sušenjem na zraku i liofilizacijom došlo je do značajnih promjena strukture čestica i aglomeracije ß-glukana. Sušenje raspršivanjem uz prethodnu obradu ultrazvukom nije dovelo do stvaranja nakupina čestica kao ni do znatnih promjena njihove strukture.

Biogenic amines (BA) are organic nitrogen compounds formed by decarboxylation of amino acids or by amination and transamination of aldehydes and ketones. The most important BA in wine are histamine, putrescine, cadaverine, tyramine, spermidine, spermine, tryptamine and β-phenylethylamine, and their content could vary due to different factors during wine production. They are mainly produced during malolactic fermentation by lactic acid bacteria, but could be also produced by yeasts during alcoholic fermentation. Concentration of BA in wine is important, because they act as moderators in many biological reactions in the human body. Concentrations of histamine, putrescine, cadaverine and tyramine were determined using high pressure liquid chromatography (HPLC) in eight different wines (four white and four red). The highest concentrations of cadaverine (8.228 mg/L) and tyramine (6.452 mg/L) were detected in white wine Vinko, while the highest level of putrescine (8.740 mg/L) was determined in white wine Chardonnay. In red wines putrescin concentration was significantly higher than levels of tyramine and cadaverine. Tyramine concentrations were lower in red than in white wines. Amounts of histamine were below detection limits in all samples, while concentrations of putrescine, cadaverine and tyramine were in agreement with Croatian wine legislation.

An ecogeographical survey of wild hop populations was conducted in the northwest of Croatia in two consecutive years. A total of 121 plants was documented on eight locations. Along with the passport data, the data on three phenotypic traits (no. of leaflets, cone shape, aroma) were gathered during collection, while the content of α -acids in hop cones was determined by lead conductance. Shanon’ s information index was calculated for each phenotypic trait and used as a measure of intra- and interpopulation diversity. For all analyzed traits, most of the total phenotypic diversity was attributable to differences among plants within populations. The differences in proportions of individuals having a particular trait state between all pairs of populations in the case of leaflet number and cone shapes were non-significant. Four out of 28 pairwise comparisons for aroma were proven significant, indicating the existence of differences in proportions of individuals across populations recorded to have 'typical hoppy', 'fine hop' or 'rough' aroma. No significant differences were observed for alpha-acids content among populations. Plant exhibiting elongated cone shape had significantly higher alpha-acids content than those having oval or round cone shapes. Similarly, plants categorized as 'rough' aroma hop cones had the highest content of alpha-acids compared with those categorized as 'typical hoppy' or 'fine hop aroma' hop cones.